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Iron oxyhydroxide mineralization on microbial extracellular polysaccharides
Chan, Clara S.; Fakra, Sirine C.; Edwards, David C.; Emerson, David; Banfield, Jillian F.
Iron biominerals can form in neutral pH microaerophilic environments where microbes both catalyze iron oxidation and create polymers that localize mineral precipitation. In order to classify the microbial polymers that influence FeOOH mineralogy, we studied the organic and mineral components of biominerals using scanning transmission X-ray microscopy (STXM), micro X-ray fluorescence ({mu}XRF) microscopy, and high-resolution transmission electron microscopy (HRTEM). We focused on iron microbial mat samples from a creek and abandoned mine; these samples are dominated by iron oxyhydroxide-coated structures with sheath, stalk, and filament morphologies. In addition, we characterized the mineralized products of an iron-oxidizing, stalk-forming bacterial culture isolated from the mine. In both natural and cultured samples, microbial polymers were found to be acidic polysaccharides with carboxyl functional groups, strongly spatially correlated with iron oxyhydroxide distribution patterns. Organic fibrils collect FeOOH and control its recrystallization, in some cases resulting in oriented crystals with high aspect ratios. The impact of polymers is particularly pronounced as the materials age. Synthesis experiments designed to mimic the biomineralization processes show that the polysaccharide carboxyl groups bind dissolved iron strongly but release it as mineralization proceeds. Our results suggest that carboxyl groups of acidic polysaccharides are produced by different microorganisms to create a wide range of iron oxyhydroxide biomineral structures. The intimate and potentially long-term association controls the crystal growth, phase, and reactivity of iron oxyhydroxide nanoparticles in natural systems.
Iron oxyhydroxide mineralization on microbial extracellular polysaccharides
Iron oxyhydroxide mineralization on microbial extracellular polysaccharides Clara S. Chan a Iron biominerals can form in neutral pH microaerophilic environments where microbes both catalyze iron, and high-resolution transmission electron microscopy (HRTEM). We focused on iron microbial mat samples from
CO? sequestration through mineral carbonation of iron oxyhydroxides.
Lammers, Kristin; Murphy, Riley; Riendeau, Amber; Smirnov, Alexander; Schoonen, Martin A A; Strongin, Daniel R
Carbon dioxide sequestration via the use of sulfide reductants and mineral carbonation of the iron oxyhydroxide polymorphs lepidocrocite, goethite, and akaganeite with supercritical CO(2) (scCO(2)) was investigated using in situ attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The exposure of the different iron oxyhydroxides to aqueous sulfide in contact with scCO(2) at ?70-100 ░C resulted in the partial transformation of the minerals to siderite (FeCO(3)) and sulfide phases such as pyrite (FeS(2)). The relative yield of siderite to iron sulfide bearing mineral product was a strong function of the initial sulfide concentration. The order of mineral reactivity with regard to the amount of siderite formation in the scCO(2)/sulfide environment for a specific reaction time was goethite < lepidocrocite ? akaganeite. Given the presence of goethite in sedimentary formations, this conversion reaction may have relevance to the subsurface sequestration and geologic storage of carbon dioxide. PMID:22066460
The role of iron oxyhydroxides in phosphorus chemistry of some East Texas forest soilsĀ
Hass, Amir
in the forest floor were determined. Total P (PT) in the forest floor, and total and Mehlich-1 P and citratedithionite (CD) and acid ammonium-oxalate (AAO) extractable P, Al, Fe, and Mn within the mineral soil upper 100 cm were determined. Colorimetric...
The role of iron oxyhydroxides in phosphorus chemistry of some East Texas forest soils
Hass, Amir
in the forest floor were determined. Total P (PT) in the forest floor, and total and Mehlich-1 P and citratedithionite (CD) and acid ammonium-oxalate (AAO) extractable P, Al, Fe, and Mn within the mineral soil upper 100 cm were determined. Colorimetric...
Assessing the utility of trace and rare earth elements as biosignatures in microbial iron oxyhydroxides
NASA Astrophysics Data System (ADS)
Heim, Christine; Simon, Klaus; Ionescu, Danny; Reimer, Andreas; De Beer, Dirk; Quķric, Nadia-Valķrie; Reitner, Joachim; Thiel, Volker
Microbial iron oxyhydroxides are common deposits in natural waters, recent sediments and mine drainage systems and often contain significant accumulations of trace and rare earth elements (TREE). TREE patterns are widely used to characterize minerals and rocks, and to elucidate their evolution and origin. Whether and which characteristic TREE signatures distinguish between a biological and an abiological origin of iron minerals is still not well understood. Long-term flow reactor studies were performed in the ─sp÷ Hard Rock Laboratory to investigate the development of microbial mats dominated by iron-oxidizing bacteria, namely Mariprofundus sp. and Gallionella sp. The experiments investigated the accumulation and fractionation of TREE under controlled conditions and enabled us to assess potential biosignatures evolving within the microbial iron oxyhydroxides. Concentrations of Be, Y, Zn, Zr, Hf, W, Th, Pb, and U in the microbial mats were 1e3- to 1e5-fold higher than in the feeder fluids whereas the rare earth elements and Y (REE+Y) contents were 1e4 and 1e6 fold enriched. Except for a hydrothermally induced Eu anomaly, the normalized REE+Y patterns of the microbial iron oxyhydroxides were very similar to published REE+Y distributions of Archaean Banded Iron Formations. The microbial iron oxyhydroxides from the flow reactors were compared to iron oxyhydroxides that were artificially precipitated from the same feeder fluid. These abiotic and inorganic iron oxyhydroxides show the same REE+Y distribution patterns. Our results indicate that the REE+Y mirror quite exactly the water chemistry, but they do not allow to distinguish microbially mediated from inorganic iron precipitates. All TREE studied showed an overall similar fractionation behavior in biogenic, abiotic and inorganic iron oxyhydroxides. Exceptions are Ni and Tl, which were only accumulated in the microbial iron oxyhydroxides and may point to a potential usage of these elements as microbial biosignatures.
Microbial reduction of ferric iron oxyhydroxides as a way for remediation of grey forest soils heavily polluted with toxic metals by infiltration of acid mine drainage
NASA Astrophysics Data System (ADS)
Georgiev, Plamen; Groudev, Stoyan; Spasova, Irena; Nicolova, Marina
The abandoned uranium mine Curilo is a permanent source of acid mine drainage (AMD) which steadily contaminated grey forest soils in the area. As a result, the soil pH was highly acidic and the concentration of copper, lead, arsenic, and uranium in the topsoil was higher than the relevant Maximum Admissible Concentration (MAC) for soils. The leaching test revealed that approximately half of each pollutant was presented as a reducible fraction as well as the ferric iron in horizon A was presented mainly as minerals with amorphous structure. So, the approach for remediation of the AMD-affected soils was based on the process of redoxolysis carried out by iron-reducing bacteria. Ferric iron hydroxides reduction and the heavy metals released into soil solutions was studied in the dependence on the source of organic (fresh or silage hay) which was used for growth and activity of soil microflora, initial soil pH (3.65; 4.2; and 5.1), and the ion content of irrigation solutions. The combination of limestone (2.0 g/ kg soil), silage addition (at rate of 45 g dry weight/ kg soil) in the beginning and reiterated at 6 month since the start of soil remediation, and periodical soil irrigation with slightly acidic solutions containing CaCl2 was sufficient the content of lead and arsenic in horizon A to be decreased to concentrations similar to the relevant MAC. The reducible, exchangeable, and carbonate mobile fractions were phases from which the pollutants was leached during the applied soil remediation. It determined the higher reduction of the pollutants bioavailability also as well as the process of ferric iron reduction was combined with neutralization of the soil acidity to pH (H2O) 6.2.
XAS evidence of As(V) association with iron oxyhydroxides in a contaminated soil at a former arsenical pesticide processing plant.
CancĶs, B; Juillot, F; Morin, G; Laperche, V; Alvarez, L; Proux, O; Hazemann, J L; Brown, G E; Calas, G
The molecular-level speciation of arsenic has been determined in a soil profile in the Massif Central near Auzon, France that was impacted by As-based pesticides by combining conventional techniques (XRD, selective chemical extractions) with X-ray absorption spectroscopy (XAS). The arsenic concentration is very high at the top (>7000 mg kg(-1)) and decreases rapidly downward to a few hundreds of milligrams per kilogram. A thin layer of schultenite (PbHAsO4), a lead arsenate commonly used as an insecticide until the middle of the 20th century, was found at 10 cm depth. Despite the occurrence of this As-bearing mineral, oxalate extraction indicated that more than 65% of the arsenic was released upon dissolution of amorphous iron oxides, suggesting a major association of arsenic with these phases within the soil profile. Since oxalate extraction cannot unambiguously distinguish among the various chemical forms of arsenic, these results were confirmed by a direct in situ determination of arsenic speciation using XAS analysis. XANES data indicate that arsenic occurs mainly as As(V) along the soil profile except for the topsoil sample where a minor amount (7%) of As(III) was detected. EXAFS spectra of soil samples were fit by linear combinations of model compounds spectra and by a shell-by-shell method. These procedures clearly confirmed that As(V) is mainly (at least 80 wt %) associated with amorphous Fe(III) oxides as coprecipitates within the soil profile. If any, the proportion of schultenite, which was evidenced by XRD in a separate thin white layer, does not account for more than 10 wt % of arsenic in soil samples. This study emphasizes the importance of iron oxides in restricting arsenic dispersal within soils following dissolution of primary As-bearing solids manufactured for use as pesticides and released into the soils. PMID:16475314
Simulated atmospheric processing of iron oxyhydroxide minerals at low pH: Roles of particle size and acid anion in iron dissolution
Rubasinghege, Gayan; Lentz, Robert W.; Scherer, Michelle M.; Grassian, Vicki H.
A number of recent studies have shown that iron dissolution in Fe-containing dust aerosol can be linked to source material (mineral or anthropogenic), mineralogy, and iron speciation. All of these factors need to be incorporated into atmospheric chemistry models if these models are to accurately predict the impact of Fe-containing dusts into open ocean waters. In this report, we combine dissolution measurements along with spectroscopy and microscopy to focus on nanoscale size effects in the dissolution of Fe-containing minerals in low-pH environments and the importance of acid type, including HNO3, H2SO4, and HCl, on dissolution. All of these acids are present in the atmosphere, and dust particles have been shown to be associated with nitrate, sulfate, and/or chloride. These measurements are done under light and dark conditions so as to simulate and distinguish between daytime and nighttime atmospheric chemical processing. Both size (nano- versus micron-sized particles) and anion (nitrate, sulfate, and chloride) are found to play significant roles in the dissolution of ?-FeOOH under both light and dark conditions. The current study highlights these important, yet unconsidered, factors in the atmospheric processing of iron-containing mineral dust aerosol. PMID:20360560
Adsorption of selenium by amorphous iron oxyhydroxide and manganese dioxide
Balistrieri, L.S.; Chao, T.T.
This work compares and models the adsorption of selenium and other anions on a neutral to alkaline surface (amorphous iron oxyhydroxide) and an acidic surface (manganese dioxide). Selenium adsorption on these oxides is examined as a function of pH, particle concentration, oxidation state, and competing anion concentration in order to assess how these factors might influence the mobility of selenium in the environment. The data indicate that 1. 1) amorphous iron oxyhydroxide has a greater affinity for selenium than manganese dioxide, 2. 2) selenite [Se(IV)] adsorption increases with decreasing pH and increasing particle concentration and is stronger than selenate [Se(VI)] adsorption on both oxides, and 3. 3) selenate does not adsorb on manganese dioxide. The relative affinity of selenate and selenite for the oxides and the lack of adsorption of selenate on a strongly acidic surface suggests that selenate forms outer-sphere complexes while selenite forms inner-sphere complexes with the surfaces. The data also indicate that the competition sequence of other anions with respect to selenite adsorption at pH 7.0 is phosphate > silicate > molybdate > fluoride > sulfate on amorphous iron oxyhydroxide and molybdate ??? phosphate > silicate > fluoride > sulfate on manganese dioxide. The adsorption of phosphate, molybdate, and silicate on these oxides as a function of pH indicates that the competition sequences reflect the relative affinities of these anions for the surfaces. The Triple Layer surface complexation model is used to provide a quantitative description of these observations and to assess the importance of surface site heterogeneity on anion adsorption. The modeling results suggest that selenite forms binuclear, innersphere complexes with amorphous iron oxyhydroxide and monodentate, inner-sphere complexes with manganese dioxide and that selenate forms outer-sphere, monodentate complexes with amorphous iron oxyhydroxide. The heterogeneity of the oxide surface sites is reflected in decreasing equilibrium constants for selenite with increasing adsorption density and both experimental observations and modeling results suggest that manganese dioxide has fewer sites of higher energy for selenite adsorption than amorphous iron oxyhydroxide. Modeling and interpreting the adsorption of phosphate, molybdate, and silicate on the oxides are made difficult by the lack of constraint in choosing surface species and the fact that equally good fits can be obtained with different surface species. Finally, predictions of anion competition using the model results from single adsorbate systems are not very successful because the model does not account for surface site heterogeneity. Selenite adsorption data from a multi-adsorbate system could be fit if the equilibrium constant for selenite is decreased with increasing anion adsorption density. ?? 1990.
Pressure-Induced Hydrogen Bond Symmetrization in Iron Oxyhydroxide
NASA Astrophysics Data System (ADS)
Xu, Weiming; Greenberg, Eran; Rozenberg, Gregory Kh.; Pasternak, Moshe P.; Bykova, Elena; Boffa-Ballaran, Tiziana; Dubrovinsky, Leonid; Prakapenka, Vitali; Hanfland, Michael; Vekilova, Olga Yu.; Simak, Sergei I.; Abrikosov, Igor A.
Under high pressures the hydrogen bonds were predicted to transform from a highly asymmetric soft O-H⋯O to a symmetric rigid configuration in which the proton lies midway between the two oxygen atoms. Despite four decades of research on hydroxyl containing compounds, pressure induced hydrogen bond symmetrization remains elusive. Following single crystal x-ray diffraction, M÷ssbauer and Raman spectroscopy measurements supported by ab initio calculations, we report the H-bonds symmetrization in iron oxyhydroxide, FeOOH, resulting from the Fe3+ high-to-low spin crossover at above 45 GPa.
Oxygen and hydrogen isotope compositions of pedogenic phyllosilicates and iron oxyhydroxides: Development of modern surface domain arrays and implications for paleotemperature reconstructions
NASA Astrophysics Data System (ADS)
Tabor, N. J.; Montanez, I. P.
Mineralogic, chemical, and oxygen and hydrogen isotope compositions of 68 different modern soil and paleosol phyllosilicate and iron oxyhydroxide samples are presented. The chemical and mineralogic data are used in conjunction with published thermodynamic data to calculate hydrogen and oxygen isotope fractionation factors for each sample. These temperature-dependent fractionation values are then combined with modern global oxygen and hydrogen isotope compositions of meteoric water and temperature data from the IAEA database to construct modern surface domains (MSD) for each phyllosilicate and iron oxyhydroxide sample with the coordinates dD and d18O. The hydrogen isotopic compositions of the phyllosilicates range from -108S to -24S, whereas the oxygen isotopic compositions range from +10.2S to +22.7S. The hydrogen isotopic compositions of the iron oxyhydroxides range from -113S to -154S, whereas the oxygen isotopic compositions range from +3.1S to -3.2S. All of the phyllosilicate samples from modern soils plot within the MSD and yield equilibrium temperatures of formation similar to measured temperatures at each respective site. These results suggest that published thermodynamic data provide good estimates of natural systems. Paleo-equatorial Permo-Pennsylvanian phyllosilicates and iron oxyhydroxides plot within the MSD, or at slightly higher temperatures than MSD values (25 to 35░ C). Eocene kaolinites plot within the MSD with equilibrium temperatures above modern temperatures (22░). Late Triassic iron oxyhydroxides from Argentina plot within the modern surface domain at temperatures of 12░ C. However, the phyllosilicate data points plot well outside their respective MSDs, suggesting the phyllosilicate ? D values of these Triassic samples have likely been altered by proton-diffusion.
Spectroscopic Investigations of Metal Speciation on Nanoscale Iron Oxyhydroxide Aggregates
NASA Astrophysics Data System (ADS)
Kim, C. S.; Lentini, C. J.; Reinsch, B. C.; Dale, J.; Stegemeier, J.
Iron oxyhydroxide nanomaterials play an important role in the mobility of aqueous metal species through both sorption and desorption processes. The natural aggregation of such nanophases in aqueous environmental systems can lead to changes in their structure, available surface area, and reactivity and may additionally modify the mechanisms by which metal ions are adsorbed and retained. In this study, spectroscopic techniques were used to investigate the speciation of metals onto and within nanoscale iron oxyhydroxides exposed to various geochemical conditions which induce nanoparticle aggregation and growth. Suspensions of ~5 nm diameter iron oxyhydroxide nanoparticles were synthesized and aggregated through variations in pH (7-10), ionic strength (0.001-1 M), and temperature (25,50,75░C)/time (up to 96 hours) in the presence of 0.5 mM Cu(II) or Zn(II). A second set of experiments introduced the metals after aggregation had been induced (pH and ionic strength-based aggregation only). One aliquot of each suspension was then analyzed with atomic absorption spectroscopy to determine the initial uptake, while a second aliquot was subjected to a desorption step in which the pH was lowered to values below the macroscopic absorption edges of the relevant metals prior to AA analysis. X-ray absorption spectroscopy (XAS) analysis of selected samples was then conducted to assess the speciation of the metals associated with the solid phase following both the adsorption and desorption steps and determine the conditions that yielded the most strongly bound, incorporated metal species. Results indicate that the desorption step removes weakly-bound metal species but retains metals that appear to be more structurally incorporated into/onto the nanoparticle aggregates. Samples exposed to metals before aggregation were also found to incorporate metals more thoroughly than those that were aggregated before being exposed to metals. These findings have implications for the long-term removal of hazardous metals from the aqueous phase and the development of possible remediation strategies targeting contaminated environments.
Sequestration of non-pure carbon dioxide streams in iron oxyhydroxide-containing saline repositories
Garcia, S.; Rosenbauer, Robert J.; Palandri, James L.; Maroto-Valer, M. Mercedes
Iron oxyhydroxide, goethite (?-FeOOH), was evaluated as a potential formation mineral reactant for trapping CO2 in a mineral phase such as siderite (FeCO3), when a mixture of CO2-SO 2 flue gas is injected into a saline aquifer. Two thermodynamic simulations were conducted, equilibrating a CO2-SO2 fluid mixture with a NaCl-brine and Fe-rich rocks at 150 ░C and 300 bar. The modeling studies evaluated mineral and fluid composition at equilibrium and the influence of pH buffering in the system. Results show siderite precipitates both in the buffered and unbuffered system; however, the presence of an alkaline pH buffer enhances the stability of the carbonate. Based on the model, an experiment was designed to compare with thermodynamic predictions. A CO2-SO2 gas mixture was reacted in 150 ml of NaCl-NaOH brine containing 10 g of goethite at 150 ░C and 300 bar for 24 days. Mineralogical and brine chemistry confirmed siderite as the predominant reaction product in the system. Seventy-six mg of CO2 are sequestered in siderite per 10 g of goethite.
The nanosphere iron mineral(s) in Mars soil
NASA Technical Reports Server (NTRS)
Banin, A.; Ben-Shlomo, T.; Margulies, L.; Blake, D. F.; Mancinelli, R. L.; Gehring, A. U.
A series of surface-modified clays containing nanophase (np) iron/oxyhydroxides of extremely small particle sizes, with total iron contents as high as found in Mars soil, were prepared by iron deposition on the clay surface from ferrous chloride solution. Comprehensive studies of the iron mineralogy in these 'Mars-soil analogs' were conducted using chemical extractions, solubility analyses, pH and redox, x ray and electron diffractometry, electron microscopic imaging specific surface area and particle size determinations, differential thermal analyses, magnetic properties characterization, spectral reflectance, and Viking biology simulation experiments. The clay matrix and the procedure used for synthesis produced nanophase iron oxides containing a certain proportion of divalent iron, which slowly converts to more stable, fully oxidized iron minerals. The noncrystalline nature of the iron compounds precipitated on the surface of the clay was verified by their complete extractability in oxalate. Lepidocrocite (gamma-FeOOH) was detected by selected area electron diffraction. It is formed from a double iron Fe(II)/Fe(III) hydroxyl mineral such as 'green rust', or ferrosic hydroxide. Magnetic measurements suggested that lepidocrocite converted to the more stable meaghemite (gamma-Fe203) by mild heat treatment and then to nanophase hematite (aplha-Fe203) by extensive heat treatment. Their chemical reactivity offers a plausible mechanism for the somewhat puzzling observations of the Viking biology experiments. Their unique chemical reactivities are attributed to the combined catalytic effects of the iron oxide/oxyhydroxide and silicate phase surfaces. The mode of formation of these (nanophase) iron oxides on Mars is still unknown.
Associations between iron oxyhydroxide nanoparticle growth and metal adsorption/structural incorporation
Kim, C.S.; Lentini, C.J.; Waychunas, G.A.
The interaction of metal ions and oxyanions with nanoscale mineral phases has not yet been extensively studied despite the increased recognition of their prevalence in natural systems as a significant component of geomedia. A combination of macroscopic uptake studies to investigate the adsorption behavior of As(V), Cu(II), Hg(II), and Zn(II) onto nanoparticulate goethite ({alpha}-FeOOH) as a function of aging time at elevated temperature (75 C) and synchrotron-based X-ray studies to track changes in both the sorption mode and the rate of nanoparticle growth reveal the effects that uptake has on particle growth. Metal(loid) species which sorb quickly to the iron oxyhydroxide particles (As(V), Cu(II)) appear to passivate the particle surface, impeding the growth of the nanoparticles with progressive aging; in contrast, species that sorb more slowly (Hg(II), Zn(II)) have considerably less impact on particle growth. Progressive changes in the speciation of these particular metals with time suggest shifts in the mode of metal uptake with time, possibly indicating structural incorporation of the metal(loid) into the nanoparticle; this is supported by the continued increase in uptake concomitant with particle growth, implying that metal species may transform from surface-sorbed species to more structurally incorporated forms. This type of incorporation would have implications for the long-term fate and mobility of metals in contaminated regions, and affect the strategy for potential remediation/modeling efforts.
Biogenic iron oxyhydroxide formation at mid-ocean ridge hydrothermal vents: Juan de Fuca Ridge
Toner, Brandy M.; Santelli, Cara M.; Marcus, Matthew A.; Wirth, Richard; Chan, Clara S.; McCollom, Thomas; Bach, Wolfgang; Edwards, Katrina J.
Here we examine Fe speciation within Fe-encrusted biofilms formed during 2-month seafloor incubations of sulfide mineral assemblages at the Main Endeavor Segment of the Juan de Fuca Ridge. The biofilms were distributed heterogeneously across the surface of the incubated sulfide and composed primarily of particles with a twisted stalk morphology resembling those produced by some aerobic Fe-oxidizing microorganisms. Our objectives were to determine the form of biofilm-associated Fe, and identify the sulfide minerals associated with microbial growth. We used micro-focused synchrotron-radiation X-ray fluorescence mapping (mu XRF), X-ray absorption spectroscopy (mu EXAFS), and X-ray diffraction (mu XRD) in conjunction with focused ion beam (FIB) sectioning, and highresolution transmission electron microscopy (HRTEM). The chemical and mineralogical composition of an Fe-encrusted biofilm was queried at different spatial scales, and the spatial relationship between primary sulfide and secondary oxyhydroxide minerals was resolved. The Fe-encrusted biofilms formed preferentially at pyrrhotite-rich (Fe1-xS, 0<_ x<_ 0.2) regions of the incubated chimney sulfide. At the nanometer spatial scale, particles within the biofilm exhibiting lattice fringing and diffraction patterns consistent with 2-line ferrihydrite were identified infrequently. At the micron spatial scale, Fe mu EXAFS spectroscopy and mu XRD measurements indicate that the dominant form of biofilm Fe is a short-range ordered Fe oxyhydroxide characterized by pervasive edge-sharing Fe-O6 octahedral linkages. Double corner-sharing Fe-O6 linkages, which are common to Fe oxyhydroxide mineral structures of 2-line ferrihydrite, 6-line ferrihydrite, and goethite, were not detected in the biogenic iron oxyhydroxide (BIO). The suspended development of the BIO mineral structure is consistent with Fe(III) hydrolysis and polymerization in the presence of high concentrations of Fe-complexing ligands. We hypothesize that microbiologically produced Fe-complexing ligands may play critical roles in both the delivery of Fe(II) to oxidases, and the limited Fe(III) oxyhydroxide crystallinity observed within the biofilm. Our research provides insight into the structure and formation of naturally occurring, microbiologically produced Fe oxyhydroxide minerals in the deep-sea. We describe the initiation of microbial seafloor weathering, and the morphological and mineralogical signals that result from that process. Our observations provide a starting point from which progressively older and more extensively weathered seafloor sulfide minerals may be examined, with the ultimate goal of improved interpretation of ancient microbial processes and associated biological signatures.
Adsorption\\/coprecipitation of trace elements from water with iron oxyhydroxide
J. O. Leckie; M. M. Benjamin; K. Hayes; G. Kaufman; S. Altmann
This study has examined the adsorptive\\/coprecipitation behavior of several inorganic cations and anions in systems containing freshly precipitated x-ray amorphous iron oxyhydroxide. The project examined experimentally several simple, well-characterized model systems to establish type behavior in sufficient detail to allow interpretation of subsequent experimental work on less well-characterized waste materials. A prominent feature of this project was evaluation of the
Adsorption/coprecipitation of trace elements from water with iron oxyhydroxide
Leckie, J.O.; Benjamin, M.M.; Hayes, K.; Kaufman, G.; Altmann, S.
This study has examined the adsorptive/coprecipitation behavior of several inorganic cations and anions in systems containing freshly precipitated x-ray amorphous iron oxyhydroxide. The project examined experimentally several simple, well-characterized model systems to establish type behavior in sufficient detail to allow interpretation of subsequent experimental work on less well-characterized waste materials. A prominent feature of this project was evaluation of the feasibility of utilizing iron-bearing waste liquids as source materials for the precipitation of amorphous iron oxyhydroxide in trace element removal processes. The roles of complexing ligands and competing metals and ligands, and their significance in controlling the distribution of trace elements at the solution/oxide interface have been characterized. From this research a new semi-quantitative model of oxide surfaces has been proposed, as well as a model to describe adsorption of various metal-ligand complexes. Experimental results indicate the adsorption/coprecipitation process with amorphous iron oxyhydroxide is feasible for removing trace elements from a variety of power plant waste streams. In addition, the feasibility of using an acid-metal cleaning waste containing high concentrations of dissolved iron as the iron source for coprecipitation of trace elements has been confirmed. The adsorptive removal of trace elements from real waste streams in complex systems (real wastes) using either reagent iron sources or acid-metal cleaning waste can be interpreted in terms of the generalized behavior of model systems. Trace elements considered included Zn, Cd, and Cu, selenites, chromates, and arsenates.
Sedimentary Iron Oxyhydroxides Fluxes in Lago Cardiel (Argentina): Estimating Late Holocene Wind Intensity in Southernmost Patagonia
NASA Astrophysics Data System (ADS)
Ariztegui, D.; Waldmann, N.; Gilli, A.; Anselmetti, F. S.
In analogy to their marine counterparts, iron oxyhydroxides in lacustrine sediments are potential archives of environmental change. Eolian particles, commonly coated with Fe oxides, are the most frequent source of detritic iron oxyhydroxides in lake basins. They provide a climate-sediment connection that is applied here to an ultra high-resolution study of a laminated core from Southern Patagonia. These results show fluctuations in the amount of iron oxyhydroxides covering the last ca. 1800 years that are attributed to past changes in wind intensity. Located at 49░ S on the Patagonian plateau of Argentina, Lago Cardiel closed-basin occupies a tectonic depression of ca. 20 km diameter and a maximum water depth of 76 m. Today, this very arid but sensitive rain-shadow area west of the Andes is seasonally influenced by the southern westerlies. Thus, the lake provides an ideal location to trace changes in their strength and influence on the local sedimentological regime through time. A ca. 10 m long sedimentary core with a high sedimentation rate of approximately 56 cm/100 yr allows the detailed study of laminated sediments with variable degree of development and thickness. Magnetic susceptibility microprofiles at one mm scale reveals comparatively higher values in the black laminae than the light olive grey silty clay. Analogously, these changes are mirrored by fluctuations in trace element content that may indicate a seasonal change in the influx of iron oxyhydroxides to the basin. Image analyses in the laminated sections of the core show a conspicuous frequency of changes that can be attributed to the forcing mechanisms behind their formation. Thus, these new data with a higher temporal resolution refine previous results from the same core and relate these changes to local wind activity, which seems to be directly induced by the intensification or weakening of the westerly storm tracks. Furthermore, it provides an independent proxy for wind intensity confirming previous studies that were based on indicators at a lower time resolution such as seismic stratigraphy and pollen analysis.
Electron transport in pure and substituted iron oxyhydroxides by small-polaron migration
Alexandrov, Vitali Y.; Rosso, Kevin M.
Iron oxyhydroxides (FeOOH) are common crystalline forms of iron that play a critical role in technology and the natural environment via a variety of important reduction-oxidation reactions, including electrical semiconduction as an aspect. However, a basic understanding of the electron transport properties of these systems is still lacking. We examine the electron mobility in goethite (?-FeOOH), akaganķite (?-FeOOH), and lepidocrocite (? -FeOOH) polymorphs by means of density functional theory based (DFT+U) calculations.We show that room temperature charge transport should be dominated by the small-polaron hopping type, and that the attendant mobility should be highest for pure goethite and akaganķite. Hopping pathways through the various lattices are discussed in terms of individual electron exchange steps and rates for each. Given the usual occurrence of compositional impurities in natural iron oxyhydroxides, we also investigate the effect of common stoichiometric defects on the electron hopping activation energies such as Al and Cr substitutional cations in goethite, and Cl anions in the channels of akaganķite.
Zn(II) and Cu(II) adsorption and retention onto iron oxyhydroxide nanoparticles: effects of particle aggregation and salinity
Background Iron oxyhydroxides are commonly found in natural aqueous systems as nanoscale particles, where they can act as effective sorbents for dissolved metals due to their natural surface reactivity, small size and high surface area. These properties make nanoscale iron oxyhydroxides a relevant option for the remediation of water supplies contaminated with dissolved metals. However, natural geochemical processes, such as changes in ionic strength, pH, and temperature, can cause these particles to aggregate, thus affecting their sorption capabilities and remediation potential. Other environmental parameters such as increasing salinity may also impact metal retention, e.g. when particles are transported from freshwater to seawater. Results After using synthetic iron oxyhydroxide nanoparticles and nanoparticle aggregates in batch Zn(II) adsorption experiments, the addition of increasing concentrations of chloride (from 0.1 M to 0.6 M) appears to initially reduce Zn(II) retention, likely due to the desorption of outer-sphere zinc surface complexes and subsequent formation of aqueous Zn-Cl complexes, before then promoting Zn(II) retention, possibly through the formation of ternary surface complexes (supported by EXAFS spectroscopy) which stabilize zinc on the surface of the nanoparticles/aggregates. In batch Cu(II) adsorption experiments, Cu(II) retention reaches a maximum at 0.4 M chloride. Copper-chloride surface complexes are not indicated by EXAFS spectroscopy, but there is an increase in the formation of stable aqueous copper-chloride complexes as chloride concentration rises (with CuCl+ becoming dominant in solution at ~0.5 M chloride) that would potentially inhibit further sorption or encourage desorption. Instead, the presence of bidentate edge-sharing and monodentate corner-sharing complexes is supported by EXAFS spectroscopy. Increasing chloride concentration has more of an impact on zinc retention than the mechanism of nanoparticle aggregation, whereas aggregation condition is a stronger determinant of copper retention. Conclusions Based on these model uptake/retention studies, iron oxyhydroxide nanoparticles show potential as a strategy to remediate zinc-contaminated waters that migrate towards the ocean. Copper retention, in contrast, appears to be optimized at an intermediate salinity consistent with brackish water, and therefore may release considerable fractions of retained copper at higher (e.g. seawater) salinity levels. PMID:24843322
NASA Astrophysics Data System (ADS)
Banin, A.
A mineralogical model for the Mars fine soil that includes as major components smectite clays absorbed and coated with amorphous iron oxyhydroxides and perhaps mixed with small amounts of better-crystalized iron oxides as separate phases is proposed. Also present as accessory minerals are sulfate minerals such as kieserite (MgSO4.H2O) and/or anhydrite (CaSO4), rutile (TiO2), and maghemite (Fe2O3) or magnetite (Fe3O4), the last two as magnetic components. Carbonates may be present at low concentrations only (less than 1 to 2 pct). However, a prime question to be addressed by a Mars Sample Return Mission shall be related to the mineralogical composition of the soil, and its spatial variability.
Remote Sensing of Soils, Minerals, and Geomorphology
Remote Sensing of Soils, Minerals, and Geomorphology Remote Sensing of Soils,Remote Sensing, solid Earth comprised of bedrock and the weathered bedrock called soil. Ę Remote sensing can play, and geomorphology (landforms). Remote Sensing of Soils, Minerals, and Geomorphology Remote Sensing of Soils
Adsorption of antimony onto iron oxyhydroxides: adsorption behavior and surface structure.
Guo, Xuejun; Wu, Zhijun; He, Mengchang; Meng, Xiaoguang; Jin, Xin; Qiu, Nan; Zhang, Jing
Antimony is detected in soil and water with elevated concentration due to a variety of industrial applications and mining activities. Though antimony is classified as a pollutant of priority interest by the United States Environmental Protection Agency (USEPA) and Europe Union (EU), very little is known about its environmental behavior and adsorption mechanism. In this study, the adsorption behaviors and surface structure of antimony (III/V) on iron oxides were investigated using batch adsorption techniques, surface complexation modeling (SCM), X-ray photon spectroscopy (XPS) and extended X-ray absorption fine structure spectroscopy (EXAFS). The adsorption isotherms and edges indicated that the affinity of Sb(V) and Sb(III) toward the iron oxides depended on the Sb species, solution pH, and the characteristics of iron oxides. Sb(V) adsorption was favored at acidic pH and decreased dramatically with increasing pH, while Sb(III) adsorption was constant over a broad pH range. When pH is higher than 7, Sb(III) adsorption by goethite and hydrous ferric oxide (HFO) was greater than Sb(V). EXAFS analysis indicated that the majority of Sb(III), either adsorbed onto HFO or co-precipitated by FeCl3, was oxidized into Sb(V) probably due to the involvement of O2 in the long duration of sample preservation. Only one Sb-Fe subshell was filtered in the EXAFS spectra of antimony adsorption onto HFO, with the coordination number of 1.0-1.9 attributed to bidentate mononuclear edge-sharing ((2)E) between Sb and HFO. PMID:24910911
Neptunium and Plutonium Sorption to Snake River Plain, Idaho Soil
Mincher, Bruce Jay; Fox, Robert Vincent; Cooper, David Craig; Groenewold, Gary Steven
The behavior of Np and Pu on soil collected from the subsurface disposal area at the Idaho National Engineering and Environmental Laboratory was investigated by performing short-duration, sorption experiments to measure sorption isotherms. Neptunium sorption can be described with a Freundlich isotherm; however, Pu sorption can only be described in this fashion as a conservative estimate of minimum sorption. Geochemical modeling predictions suggest that initial sorption of Np is controlled predominantly by surface complexation on clay minerals, while Pu is controlled by a competition between complexation with iron oxyhydroxides and the precipitation of hydrolysis products. Longer-term sorption is governed by the transformation of these species to oxide minerals. Solution ionic strength and carbonate alkalinity did not significantly affect Np or Pu soil sorption.
Mineralization of cellulose in frozen boreal soils
NASA Astrophysics Data System (ADS)
Oquist, Mats G.; Segura, Javier; Sparrman, Tobias; Nilsson, Mats; Schleucher, Jurgen
Soils of high-latitude ecosystems store a large fraction of the global soil carbon. In boreal forests, the microbial mineralization of soil organic matter (SOM) during winter can affect the ecosystems net carbon balance. Recent research has shown that microorganisms in the organic surface layer of boreal forest soil can mineralize and grow on simple, soluble monomeric substrates under frozen conditions. However, any substantial impacts of microbial activity in frozen soils on long-term soil carbon balances ultimately depends on whether soil microorganisms can utilize and grow the more complex, polymeric constituents of SOM. In order to evaluate the potential for soil microorganisms to metabolize carbon polymers at low temperatures, we incubated boreal forest soil samples amended with [13C]-cellulose and studied the microbial catabolic and anabolic utilization of the substrate under frozen and unfrozen conditions (-4 and +4░C). Freezing of the soil markedly reduced microbial utilization of the cellulose. The [13C]-CO2 production rate in the samples at +4░C were 0.52 mg CO2 SOM -1 day-1 while rates in the frozen samples (-4░C) were 0.01 mg CO2 SOM -1 day-1. However, newly synthetized [13C]-enriched cell membrane lipids, PLFAs, were detected in soil samples incubated both above and below freezing, confirming that cellulose can sustain also anabolic activity of the microbial populations under frozen conditions. The reduced metabolic rates induced by freezing indicate constraints on exoenzymatic activity, as well as substrate diffusion rates that we can attribute to reduced liquid water content of the frozen soil. We conclude that the microbial population in boreal forest soil has the capacity to metabolize, and grow, on polymeric substrates at temperatures below zero, which involves maintaining exoenzymatic activity in frozen soils. This capacity manifests the importance of SOM mineralization during the winter season and its importance for the net carbon balance of soils of high-latitude ecosystems.
Soil Microbial Mineralization of Cellulose in Frozen Soils
NASA Astrophysics Data System (ADS)
Segura, J.; Haei, M.; Sparrman, T.; Nilsson, M. B.; Schleucher, J.; Oquist, M. G.
Soils of high-latitude ecosystems store a large fraction of the global soil carbon pool. In boreal forests, the mineralization of soil organic matter (SOM) during winter by soil heterotrophic activity can affect the ecosystems net carbon balance. Recent research has shown that microorganisms in the organic surface layer of boreal forest soil can mineralize and grow on simple, monomeric substrates under frozen conditions. However, any substantial impacts of microbial activity in frozen soils on long-term soil carbon balances depend on whether soil microorganisms can utilize the more complex, polymeric substrates in SOM. In order to evaluate the potential for soil microorganisms to metabolize carbon polymers at low temperatures, we incubated boreal forest soil samples amended with [13C]-cellulose and studied the microbial catabolic and anabolic utilization of the substrate under frozen and unfrozen conditions (-4 and +4░C). The [13C]-CO2 production rate in the samples at +4░C were 0.524 mg CO2 SOM -1 day-1 while rates in the frozen samples (-4░C) were 0.008 mg CO2 SOM -1 day-1. Thus, freezing of the soil markedly reduced microbial utilization of the cellulose. However, newly synthetized [13C]-enriched cell membrane lipids, PLFAs, were detected in soil samples incubated both above and below freezing, confirming microbial growth also in the frozen soil matrix. The reduced metabolic rates induced by freezing indicate constraints on exoenzymatic activity, as well as substrate diffusion rates that we can attribute to reduced liquid water content of the frozen soil. We conclude that the microbial population in boreal forest soil has the capacity to metabolize, and grow, on polymeric substrates at temperatures below zero. This also involves maintaining exoenzymatic activity in frozen soils. This capacity manifests the importance of SOM mineralization during the winter season and its importance for the net carbon balance of soils of high-latitude ecosystems.
Mineralization of metsulfuron-methyl in Chinese paddy soils
Technology Transfer Automated Retrieval System (TEKTRAN)
A laboratory study was conducted to investigate the mineralization of metsulfuron-methyl (MSM) in paddy soils in response to soil moisture, temperature and soil properties. The results indicated that MSM mineralization was relatively limited in the paddy soils when soil temperature was low. Only 2.2...
Recycling Ni from Contaminated and Mineralized Soils.
Technology Transfer Automated Retrieval System (TEKTRAN)
Rare plant species accumulate potentially valuable concentrations of some metals. Alyssum murale readily accumulates over 2% Ni in aboveground dry matter when grown on Ni-mineralized serpentine soils in Oregon, allowing production of ōhayö biomass with at least 400 kg Ni ha-1 with low levels of fer...
Stability of hydroxylated minerals on Mars: A study on the effects of exposure to ultraviolet radiation
Albert S. Yen; Bruce Murray; George R. Rossman; Frank J. Grunthaner
The density and composition of the Martian atmosphere allow solar ultraviolet photons with wavelengths as short as 190 nm to reach the surface. We investigate the hypothesis that this UV radiation is capable of inducing the release of water from iron oxyhydroxide minerals resulting in the formation of oxide phases. These experiments, which utilize a quadrupole mass spectrometer to monitor
Application of solution-mineral equilibrium chemistry to solution mining of uranium ores
A. C. Riese; C. J. Propp
Modern methods of uranium solution mining are typically accompanied by gains and losses of mass through reagent consumption by rock-forming minerals, with subsequent formation of clay minerals, gypsum, carbonates, and iron oxyhydroxides. A systematic approach to alleviate such problems involves the application of leach solutions that are in equilibrium with the host-rock minerals but in disequilibrium with the ore-forming minerals.
Poliovirus Adsorption by 34 Minerals and Soils
Moore, Rebecca S.; Taylor, Dene H.; Sturman, Lawrence S.; Reddy, Michael M.; Fuhs, G. Wolfgang
The adsorption of radiolabeled infectious poliovirus type 2 by 34 well-defined soils and mineral substrates was analyzed in a synthetic freshwater medium containing 1 mM CaCl2 and 1.25 mM NaHCO3 at pH 7. In a model system, adsorption of poliovirus by Ottawa sand was rapid and reached equilibrium within 1 h at 4░C. Near saturation, the adsorption could be described by the Langmuir equation; the apparent surface saturation was 2.5 ū 106 plaque-forming units of poliovirus per mg of Ottawa sand. At low surface coverage, adsorption was described by the Freundlich equation. The soils and minerals used ranged from acidic to basic and from high in organic content to organic free. The available negative surface charge on each substrate was measured by the adsorption of a cationic polyelectrolyte, polydiallyldimethylammonium chloride. Most of the substrates adsorbed more than 95% of the virus. In general, soils, in comparison with minerals, were weak adsorbents. Among the soils, muck and Genesee silt loam were the poorest adsorbents; among the minerals, montmorillonite, glauconite, and bituminous shale were the least effective. The most effective adsorbents were magnetite sand and hematite, which are predominantly oxides of iron. Correlation coefficients for substrate properties and virus adsorption revealed that the elemental composition of the adsorbents had little effect on poliovirus uptake. Substrate surface area and pH, by themselves, were not significantly correlated with poliovirus uptake. A strong negative correlation was found between poliovirus adsorption and both the contents of organic matter and the available negative surface charge on the substrates as determined by their capacities for adsorbing the cationic polyelectrolyte, polydiallyldimethylammonium chloride. PMID:6274259
The nanophase iron mineral(s) in Mars soil
NASA Technical Reports Server (NTRS)
Banin, A.; Ben-Shlomo, T.; Margulies, L.; Blake, D. F.; Mancinelli, R. L.; Gehring, A. U.
A series of surface-modified clays containing nanophase (np) iron oxide/oxyhydroxides of extremely small particle sizes, with total iron contents as high as found in Mars soil, were prepared by iron deposition on the clay surface from ferrous chloride solution. Comprehensive studies of the iron mineralogy in these "Mars-soil analogs" were conducted using chemical extractions, solubility analyses, pH and redox, x ray and electron diffractometry, electron microscopic imaging, specific surface area and particle size determinations, differential thermal analyses, magnetic properties characterization, spectral reflectance, and Viking biology simulation experiments. The clay matrix and the procedure used for synthesis produced nanophase iron oxides containing a certain proportion of divalent iron, which slowly converts to more stable, fully oxidized iron minerals. The clay acted as an effective matrix, both chemically and sterically, preventing the major part of the synthesized iron oxides from ripening, i.e., growing and developing larger crystals. The precipitated iron oxides appear as isodiametric or slightly elongated particles in the size range 1-10 nm, having large specific surface area. The noncrystalline nature of the iron compounds precipitated on the surface of the clay was verified by their complete extractability in oxalate. Lepidocrocite (gamma-FeOOH) was detected by selected area electron diffraction. It is formed from a double iron Fe(II)/Fe(III) hydroxy mineral such as "green rust," or ferrosic hydroxide. Magnetic measurements suggested that lepidocrocite converted to the more stable maghemite (gamma-Fe2O3) by mild heat treatment and then to nanophase hematite (alpha-Fe2O3) by extensive heat treatment. After mild heating, the iron-enriched clay became slightly magnetic, to the extent that it adheres to a hand-held magnet, as was observed with Mars soil. The chemical reactivity of the iron-enriched clays strongly resembles, and offers a plausible mechanism for, the somewhat puzzling observations of the Viking biology experiments. Their unique chemical reactivities are attributed to the combined catalytic effects of the iron oxide/oxyhydroxides and silicate phase surfaces. The reflectance spectrum of the clay-iron preparations in the visible range is generally similar to the reflectance curves of bright regions on Mars. This strengthens the evidence for the predominance of nanophase iron oxides/oxyhydroxides in Mars soil. The mode of formation of these nanophase iron oxides on Mars is still unknown. It is puzzling that despite the long period of time since aqueous weathering took place on Mars, they have not developed from their transitory stage to well-crystallized end-members. The possibility is suggested that these phases represent a continuously on-going, extremely slow weathering process.
Hydrogeomorphology influences soil nitrogen and phosphorus mineralization in floodplain wetlands
Noe, Gregory B.; Hupp, Cliff R.; Rybicki, Nancy B.
Conceptual models of river¢floodplain systems and biogeochemical theory predict that floodplain soil nitrogen (N) and phosphorus (P) mineralization should increase with hydrologic connectivity to the river and thus increase with distance downstream (longitudinal dimension) and in lower geomorphic units within the floodplain (lateral dimension). We measured rates of in situ soil net ammonification, nitrification, N, and P mineralization using monthly incubations of modified resin cores for a year in the forested floodplain wetlands of Difficult Run, a fifth order urban Piedmont river in Virginia, USA. Mineralization rates were then related to potentially controlling ecosystem attributes associated with hydrologic connectivity, soil characteristics, and vegetative inputs. Ammonification and P mineralization were greatest in the wet backswamps, nitrification was greatest in the dry levees, and net N mineralization was greatest in the intermediately wet toe-slopes. Nitrification also was greater in the headwater sites than downstream sites, whereas ammonification was greater in downstream sites. Annual net N mineralization increased with spatial gradients of greater ammonium loading to the soil surface associated with flooding, soil organic and nutrient content, and herbaceous nutrient inputs. Annual net P mineralization was associated negatively with soil pH and coarser soil texture, and positively with ammonium and phosphate loading to the soil surface associated with flooding. Within an intensively sampled low elevation flowpath at one site, sediment deposition during individual incubations stimulated mineralization of N and P. However, the amount of N and P mineralized in soil was substantially less than the amount deposited with sedimentation. In summary, greater inputs of nutrients and water and storage of soil nutrients along gradients of river¢floodplain hydrologic connectivity increased floodplain soil nutrient mineralization rates.
Fractionation of Fe isotopes by soil microbes and organic acids
Brantley, Susan L.; Liermann, Laura; Bullen, Thomas D.
Small natural variations in Fe isotopes have been attributed to biological cycling. However, without understanding the mechanism of fractionation, it is impossible to interpret such variations. Here we show that the ?56Fe of Fe dissolved from a silicate soil mineral by siderophore-producing bacteria is as much as 0.8% lighter than bulk Fe in the mineral. A smaller isotopic shift is observed for Fe released abiotically by two chelates, and the magnitude of the shift increases with affinity of the ligand for Fe, consistent with a kinetic isotope effect during hydrolysis of Fe at the mineral surface. Fe dissolved abiotically without chelates shows no isotopic shift. The ?56Fe of the exchange fraction on soil grains is also lighter by ~0.6%-1% than Fe from both hornblende and iron oxyhydroxides. The kinetic isotope effect is therefore preserved in open systems such as soils. when recorded in the rock record, Fe isotopic fractionation could document Fe transport by organic molecules or by microbes where such entities were present in the geologic past.
Response of Microbial Soil Carbon Mineralization Rates to Oxygen Limitations
NASA Astrophysics Data System (ADS)
Keiluweit, M.; Denney, A.; Nico, P. S.; Fendorf, S. E.
The rate of soil organic matter (SOM) mineralization is known to be controlled by climatic factors as well as molecular structure, mineral-organic associations, and physical protection. What remains elusive is to what extent oxygen (O2) limitations impact overall rates of microbial SOM mineralization (oxidation) in soils. Even within upland soils that are aerobic in bulk, factors limiting O2 diffusion such as texture and soil moisture can result in an abundance of anaerobic microsites in the interior of soil aggregates. Variation in ensuing anaerobic respiration pathways can further impact SOM mineralization rates. Using a combination of (first) aggregate model systems and (second) manipulations of intact field samples, we show how limitations on diffusion and carbon bioavailability interact to impose anaerobic conditions and associated respiration constraints on SOM mineralization rates. In model aggregates, we examined how particle size (soil texture) and amount of dissolved organic carbon (bioavailable carbon) affect O2 availability and distribution. Monitoring electron acceptor profiles (O2, NO3-, Mn and Fe) and SOM transformations (dissolved, particulate, mineral-associated pools) across the resulting redox gradients, we then determined the distribution of operative microbial metabolisms and their cumulative impact on SOM mineralization rates. Our results show that anaerobic conditions decrease SOM mineralization rates overall, but those are partially offset by the concurrent increases in SOM bioavailability due to transformations of protective mineral phases. In intact soil aggregates collected from soils varying in texture and SOM content, we mapped the spatial distribution of anaerobic microsites. Optode imaging, microsensor profiling and 3D tomography revealed that soil texture regulates overall O2 availability in aggregate interiors, while particulate SOM in biopores appears to control the fine-scale distribution of anaerobic microsites. Collectively, our results suggest that texture and particulate organic matter content are useful predictors for the impact of O2 limitations on SOM mineralization rates.
Radon sources emanation in granitic soil and saprolite
Wollenberg, H.; Flexser, S. [Lawrence Berkeley Lab., CA (United States); Brimhall, G.; Lewis, C. [California Univ., Berkeley, CA (United States). Dept. of Geology and Geophysics
Petrological and geochemical examinations of soil, saprolite, and quartz diorite protolith have been made at the Small Structures field site, Ben Lomond Mountain, California. Variations in Ra in soil and saprolite are mainly controlled by heterogeneities inherited from the parent quartz diorite. Fission-track radiography shows that U is concentrated in the primary accessory minerals, zircon and sphene. However, most importantly for Rn emanation, U is also concentrated in secondary sites: weathered sphene, biotite and plagioclase, grain coatings, and Fe-rich fracture linings which also contain a rare-earth phosphate mineral. This occurrence of U along permeable fracture zones suggests that soil-gas Rn from depth (> 2 m) is a significant contributor to Rn availability near the surface. Zones highest in emanation occur where fine pedogenic phases: gibbsite, amorphous silica, and iron oxyhydroxide are most abundant. Mass balance analyses of this soil-saprolite profile are in progress and preliminary indicate that a high-emanation zone corresponds to the upper portion of a zone of accumulation of U and Ba.
Ectomycorrhizal fungi in mineral soil * AND N. ROSENSTOCK
Bruns, Tom
units of fungal interaction with soil. Mycelia growth is regulated in response to substrate-sample analysis of ectomycorrhizal community and soil chemical variables. Species-specific substrate preferencesEctomycorrhizal fungi in mineral soil A. ROSLING 1, * AND N. ROSENSTOCK 2 1 Department of Forest
nt adsorptionby soil minerals,in Elenletils in Soil-Plant -Aninal
Short, Daniel
-matterreactions involving [. Giordano, and W. L. Lindsay Soil ScienceSociety of America t of Fertilizers, Commonweahh0cesse.s nt adsorptionby soil minerals,in Elenletils in Soil-Plant - Aninal rrk. USA. .. ( l96l). Molybdenumreactions ium and titanium, Soil Sci. Soc. i on the exhaustion of sewage e chemistry of lead in soil: solid
Review of XRD-based quantitative analyses of clay minerals in soils: the suitability of mineral intensity factors
Maren Kahle; Markus Kleber; Reinhold Jahn
The determination of the types and relative amounts of the minerals present in soil forms an essential component of most soil characterization efforts. This paper reviews protocols for XRD-based quantitative clay mineral analysis in soils, with emphasis on methods using mineral intensity factors in combination with the so-called 100% approach. We summarize methodological differences and characteristic features and give information
Surface interactions of black carbon and soil minerals
J. Lehmann; K. Heymann; B. Nguyen
An important mechanism for stabilization of organic matter in soils is its interaction with mineral surfaces. Studies that investigate the nature and strength of such interactions have focused on non-pyrogenic materials, and examination of interactions between minerals and black carbon are scarce. In a chronosequence of black carbon ages, we can show that aluminum and silicon rapidly accumulates on black
Uranium Sequestration by Aluminum Phosphate Minerals in Unsaturated Soils
Jerden, James L. Jr. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL, 60439 (United States)
A mineralogical and geochemical study of soils developed from the unmined Coles Hill uranium deposit (Virginia) was undertaken to determine how phosphorous influences the speciation of uranium in an oxidizing soil/saprolite system typical of the eastern United States. This paper presents mineralogical and geochemical results that identify and quantify the processes by which uranium has been sequestered in these soils. It was found that uranium is not leached from the saturated soil zone (saprolites) overlying the deposit due to the formation of a sparingly soluble uranyl phosphate mineral of the meta-autunite group. The concentration of uranium in the saprolites is approximately 1000 mg uranium per kg of saprolite. It was also found that a significant amount of uranium was retained in the unsaturated soil zone overlying uranium-rich saprolites. The uranium concentration in the unsaturated soils is approximately 200 mg uranium per kg of soil (20 times higher than uranium concentrations in similar soils adjacent to the deposit). Mineralogical evidence indicates that uranium in this zone is sequestered by a barium-strontium-calcium aluminum phosphate mineral of the crandallite group (gorceixite). This mineral is intimately inter-grown with iron and manganese oxides that also contain uranium. The amount of uranium associated with both the aluminum phosphates (as much as 1.4 weight percent) has been measured by electron microprobe micro-analyses and the geochemical conditions under which these minerals formed has been studied using thermodynamic reaction path modeling. The geochemical data and modeling results suggest the meta-autunite group minerals present in the saprolites overlying the deposit are unstable in the unsaturated zone soils overlying the deposit due to a decrease in soil pH (down to a pH of 4.5) at depths less than 5 meters below the surface. Mineralogical observations suggest that, once exposed to the unsaturated environment, the meta-autunite group minerals react to form U(VI)- bearing aluminum phosphates. (author)
Mineralization of biochars in soils of contrasting mineral composition from Australia
NASA Astrophysics Data System (ADS)
Fang, Y. Y.; Singh, B.; Singh, B. P.; Krull, E.
Biochar application to soils is considered an attractive management strategy because of its agronomic benefits and mitigation of greenhouse gas emissions in some soils. However, the stability of biochars in soils with varying mineral composition has not been comprehensively evaluated. In this study, we measured the stability of two wood biochars (450 and 550░C; Eucalyptus saligna; ?13C ~-36ē) at three incubation temperatures (20, 40 and 60░C). The biochars (2% w/w) were incubated in the laboratory at 70% WHC with four soils (Inceptisol, Vertisol, Oxisol, Entisol) of contrasting soil properties including mineralogical composition. The results show that between 0.3 and 7% of added biochar C was mineralised during 12-month period. The lowest mineralization was observed in the Vertisol amended with the 550░C biochar incubated at 20░C, while the highest value occurred in the same soil amended with the 450░C biochar incubated at 60░C. The mineralization rate of biochar-C increased with increasing incubation temperature, and the mineralisation rate of 450░C biochar was consistently higher than the 550░C biochar in all soils. Biochar C stability was also influenced by soil types particularly at higher temperatures (40 and 60░C). The biochar application in the Inceptisol caused a positive priming of soil-C at all incubation temperatures; whereas in the other soils with higher clay content, biochar suppressed the mineralisation of soil-C over time.
Mineralization of nitrogen by protozoan activity in soil
P. J. Kuikman
In general, more than 95% of the nitrogen in soils is present in organic forms. This nitrogen is not directly available to plants unless microbial decomposition takes place with the release of mineral nitrogen. In modern agriculture, nitrogen is often applied to arable soils as a fertilizer to support high levels of crop production. Nitrogen is one of the essential
Effect of tebuthiuron on soil N mineralization and nitrification
L. L. Goodroad
Herbicides have potential for economical and efficient site preparation following timber harvest. The effects of tebuthiu?ron, one of the herbicides approved for this use, on soil nitrogen (N) mineralization and nitrification were determined in laboratory incubations. Tebuthiuron was added at rates from 0 to 1000 ?g g to three soils. There was no effect of tebuthiuron additions of less than
Mineral protection of soil carbon counteracted by root exudates
NASA Astrophysics Data System (ADS)
Keiluweit, Marco; Bougoure, Jeremy J.; Nico, Peter S.; Pett-Ridge, Jennifer; Weber, Peter K.; Kleber, Markus
Multiple lines of existing evidence suggest that climate change enhances root exudation of organic compounds into soils. Recent experimental studies show that increased exudate inputs may cause a net loss of soil carbon. This stimulation of microbial carbon mineralization (`primingÆ) is commonly rationalized by the assumption that exudates provide a readily bioavailable supply of energy for the decomposition of native soil carbon (co-metabolism). Here we show that an alternate mechanism can cause carbon loss of equal or greater magnitude. We find that a common root exudate, oxalic acid, promotes carbon loss by liberating organic compounds from protective associations with minerals. By enhancing microbial access to previously mineral-protected compounds, this indirect mechanism accelerated carbon loss more than simply increasing the supply of energetically more favourable substrates. Our results provide insights into the coupled biotic-abiotic mechanisms underlying the `primingÆ phenomenon and challenge the assumption that mineral-associated carbon is protected from microbial cycling over millennial timescales.
Soil mineral surfaces of paddy soils are accessible for organic carbon accumulation after decalcification
NASA Astrophysics Data System (ADS)
Wissing, Livia
We studied organic carbon (OC) accumulation due to organo-mineral associations during soil development on calcareous parent material. Two chronosequences in Zhejiang Province, PR China, were investigated; one under paddy cultivation with a maximum soil age of 2000 years, and the other under upland crops where the oldest soil was 700 years old. Bulk soils and soil fractions of the uppermost A horizons were analyzed for OC concentrations and radio carbon contents. Total pedogenic iron (Fed) concentration was determined by dithionite extraction and the proportion of oxalate extractable iron (Feox) was extracted by using the method of Schwertmann (1964). The specific surface area (SSA) of soil minerals was measured by the BET-N2 method (Brunauer et al., 1938) under four conditions: untreated, after organic matter removal, after iron removal and after removal of both. Within 700/2000 years of pedogenesis, we observed no change in clay mineral composition and no additional formation of the SSA of soil minerals. But the soils differed in the degree of decalcification, OC accumulation and in the formation of iron. Paddy soil management led to an enhanced decalcification and larger OC accumulation. Management-induced redox cycles caused larger proportions of Feox in paddy soils. Their large SSA, added to the surface area of clay minerals, provided additional options for OC covering. Unexpectedly, there was no evidence of formation of secondary minerals during soil development, which could provide new surfaces for OC accumulation. However, the study revealed higher OC coverings of mineral surfaces after decalcification in paddy soils. As carbonate and Ca2+ ions seemed to interconnect clay minerals, making their surface accessible to OC, the faster dissolution of carbonate and leaching of Ca2+ ions in paddy soils made additional clay mineral surfaces available to OC. In contrast, the surface area of minerals in non-paddy soils, in which decalcification was much lower, seemed to be partly inaccessible for OC covering due to strong microaggregation by cementation with carbonate and Ca2+-bridging. The smaller accumulation of mineral-associated SOM in non-paddy soils was additionally confirmed by the retarded replacement of the inherited carbon. The accelerated decalcification of paddy soils led to enhanced accessibility of mineral surfaces for OC covering, which intensified OC accumulation from the early stages of soil formation onward. References Brunauer, S., Emmett, P.H., Teller, E., (1938). Adsorption of gases in multimolecular layers. J. Am. Chem. Soc. 60 (2), 309-319. Schwertmann, U., 1964. Differenzierung der Eisenoxide des Bodens durch Extraktion mit Ammoniumoxalat-L÷sung. Zeitschrift f³r Pflanzenernõhrung, D³ngung, Bodenkunde 105 (3), 194-202.
Effects of acidity on mineralization: pH-dependence of organic matter mineralization in weakly acidic soils
Denis Curtin; C. A. Campbell; Abdul Jalil
The literature is ambiguous regarding the influence of acidity on mineralization of soil organic matter. Although mineralization is often regarded as being relatively insensitive to acidity, reports of agronomically-significant increases in N mineralization after liming of acid soils are common. We analyzed 61 soils (pH 5.1¢7.9), representing all agro-ecological zones of Saskatchewan, Canada, to determine the pH-dependence of N mineralization.
Soil texture and nitrogen mineralization potential across a riparian toposequence in a semi-arid savanna
J. Scott Bechtold; Robert J. Naiman
Soil texture is an important influence on nutrient cycling in upland soils, with documented relationships between mineral particle size distribution and organic matter retention, nitrogen (N) mineralization, microbial biomass and other soil properties. However, little is known of the role of mineral particle size in riparian soils, where fluvial sorting creates strong spatial contrasts in the size distribution of sediments
Long-Term Mineral Soil Carbon Response to Forest Harvesting in New England
R. A. Neurath; L. M. Zummo; A. J. Friedland
Soils are the largest global terrestrial carbon reservoir. In temperate systems, mineral soil horizons contain the largest fraction of the soil carbon pool. Disturbance of mineral soil due to land-use change results in the mineralization and release of carbon as carbon dioxide to the atmosphere. The dynamics of this response are poorly understood. We examined a chronosequence of forested plots
Adsorption coefficients for TNT on soil and clay minerals
NASA Astrophysics Data System (ADS)
Rivera, Rosßngela; Pab¾n, Julissa; Pķrez, Omarie; Mu±oz, Miguel A.; Mina, Nairmen
To understand the fate and transport mechanisms of TNT from buried landmines is it essential to determine the adsorption process of TNT on soil and clay minerals. In this research, soil samples from horizons Ap and A from Jobos Series at Isabela, Puerto Rico were studied. The clay fractions were separated from the other soil components by centrifugation. Using the hydrometer method the particle size distribution for the soil horizons was obtained. Physical and chemical characterization studies such as cation exchange capacity (CEC), surface area, percent of organic matter and pH were performed for the soil and clay samples. A complete mineralogical characterization of clay fractions using X-ray diffraction analysis reveals the presence of kaolinite, goethite, hematite, gibbsite and quartz. In order to obtain adsorption coefficients (K d values) for the TNT-soil and TNT-clay interactions high performance liquid chromatography (HPLC) was used. The adsorption process for TNT-soil was described by the Langmuir model. A higher adsorption was observed in the Ap horizon. The Freundlich model described the adsorption process for TNT-clay interactions. The affinity and relative adsorption capacity of the clay for TNT were higher in the A horizon. These results suggest that adsorption by soil organic matter predominates over adsorption on clay minerals when significant soil organic matter content is present. It was found that, properties like cation exchange capacity and surface area are important factors in the adsorption of clayey soils.
Surface interactions of black carbon and soil minerals
NASA Astrophysics Data System (ADS)
Lehmann, J.; Heymann, K.; Nguyen, B.
An important mechanism for stabilization of organic matter in soils is its interaction with mineral surfaces. Studies that investigate the nature and strength of such interactions have focused on non-pyrogenic materials, and examination of interactions between minerals and black carbon are scarce. In a chronosequence of black carbon ages, we can show that aluminum and silicon rapidly accumulates on black carbon surfaces after deposition to soil and reaches equilibrium after about 20 years in an Oxisol in Western Kenya. In an attempt to investigate the nature of the interaction between black carbon and mineral surfaces, we utilized near-edge x-ray fine structure (NEXAFS) spectroscopy of black carbon particles in soil aggregates and artificial mixtures of minerals and black carbon. Cluster analyses of the stack images using scanning transmission x-ray microscopy (STXM) revealed greater amounts of carboxyl contents, but also accumulation of aliphatic compounds. The latter may not stem from oxidized surfaces of black carbon particles themselves but adsorbed non-black carbon material. Mixing black carbon and minerals clearly showed changes in peak intensities of the C(1s) NEXAFS spectra indicating a chemical interaction between black carbon and mineral surfaces.
Characterizing regional soil mineral composition using spectroscopyand geostatistics
Mulder, V.L.; de Bruin, S.; Weyermann, J.; Kokaly, Raymond F.; Schaepman, M.E.
This work aims at improving the mapping of major mineral variability at regional scale using scale-dependent spatial variability observed in remote sensing data. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and statistical methods were combined with laboratory-based mineral characterization of field samples to create maps of the distributions of clay, mica and carbonate minerals and their abundances. The Material Identification and Characterization Algorithm (MICA) was used to identify the spectrally-dominant minerals in field samples; these results were combined with ASTER data using multinomial logistic regression to map mineral distributions. X-ray diffraction (XRD)was used to quantify mineral composition in field samples. XRD results were combined with ASTER data using multiple linear regression to map mineral abundances. We testedwhether smoothing of the ASTER data to match the scale of variability of the target sample would improve model correlations. Smoothing was donewith Fixed Rank Kriging (FRK) to represent the mediumand long-range spatial variability in the ASTER data. Stronger correlations resulted using the smoothed data compared to results obtained with the original data. Highest model accuracies came from using both medium and long-range scaled ASTER data as input to the statistical models. High correlation coefficients were obtained for the abundances of calcite and mica (R2 = 0.71 and 0.70, respectively). Moderately-high correlation coefficients were found for smectite and kaolinite (R2 = 0.57 and 0.45, respectively). Maps of mineral distributions, obtained by relating ASTER data to MICA analysis of field samples, were found to characterize major soil mineral variability (overall accuracies for mica, smectite and kaolinite were 76%, 89% and 86% respectively). The results of this study suggest that the distributions of minerals and their abundances derived using FRK-smoothed ASTER data more closely match the spatial variability of soil and environmental properties at regional scale.
What shapes edaphic communities in mineral and ornithogenic soils of Cierva Point, Antarctic Peninsula?
G. Mataloni; G. Gonzßlez Garraza; M. B÷lter; P. Convey; P. Fermani
Three mineral soil and four ornithogenic soil sites were sampled during summer 2006 at Cierva Point (Antarctic Peninsula) to study their bacterial, microalgal and faunal communities in relation to abiotic and biotic features.Soil moisture, pH, conductivity, organic matter and nutrient contents were consistently lower and more homogeneous in mineral soils. Ornithogenic soils supported larger and more variable bacterial abundances than
A disconnect between O horizon and mineral soil carbon - Implications for soil C sequestration
Garten Jr, Charles T [ORNL
Changing inputs of carbon to soil is one means of potentially increasing carbon sequestration in soils for the purpose of mitigating projected increases in atmospheric CO{sub 2} concentrations. The effect of manipulations of aboveground carbon input on soil carbon storage was tested in a temperate, deciduous forest in east Tennessee, USA. A 4.5-year experiment included exclusion of aboveground litterfall and supplemental litter additions (three times ambient) in an upland and a valley that differed in soil nitrogen availability. The estimated decomposition rate of the carbon stock in the O horizon was greater in the valley than in the upland due to higher litter quality (i.e., lower C/N ratios). Short-term litter exclusion or addition had no effect on carbon stock in the mineral soil, measured to a depth of 30 cm, or the partitioning of carbon in the mineral soil between particulate- and mineral-associated organic matter. A two-compartment model was used to interpret results from the field experiments. Field data and a sensitivity analysis of the model were consistent with little carbon transfer between the O horizon and the mineral soil. Increasing aboveground carbon input does not appear to be an effective means of promoting carbon sequestration in forest soil at the location of the present study because a disconnect exists in carbon dynamics between O horizon and mineral soil. Factors that directly increase inputs to belowground soil carbon, via roots, or reduce decomposition rates of organic matter are more likely to benefit efforts to increase carbon sequestration in forests where carbon dynamics in the O horizon are uncoupled from the mineral soil.
Rapid mineral differentiation among horizons of a meadow soil
NASA Astrophysics Data System (ADS)
Szalai, Zoltßn; Ringer, Marianna; Kiss, Klaudia; Horvßth Szab¾, Kata; Nķmeth, Tibor; Sipos, Pķter; Madarßsz, Balßzs; Jakab, Gergely
Soil development under hydromorphic conditions may results intense mineral transformation and rapid vertical differentiation in the profile. Original papers refer more than hundreds of years for this kinds of mineral transformations. We suppose that this process could be more rapid. Present paper focuses on the profile development of a sandy meadow soil (calcic, gleyic Phaeozem ferric, arenic) from the soil mineralogical viewpoint. The main aim was to explore the degree of mineral phase alteration via soil formation during a half-century under hydromorphic conditions. The studied soil is located in a swampy area (near to Ceglķdbercel, Hungary). The parent material deposited during an extremely heavy flood event in 1963. The reference (parent) material can be found near to the study site. We combined routine field tests (carbonate content, dipididil test) with laboratory measurements (selective extractions for the determination of amorphous and crystalline Fe, and Mn content; X-ray phase analysis; X-ray fluorescence spectroscopy; particle sizing by laser diffraction; NDIR and FT-IR and DRS spectrometry), whereas Eh and pH measured by field monitoring station. The most intense mineralogical transformations developed in the zone of the heaviest redox oscillation. Results show that well developed horizons have emerged during fifty years in the studied soil. This time was enough for bivalent and trivalent iron mineral crystallisation and smectite formation in this zone. The high proportion of amorphous and colloidal phases refers to very intensive recent processes. Soil formation under hydromorphic conditions proceeds at higher speeds contrariwise to the century time scale reported in sources (discussing non-waterlogged cases). Support of the Hungarian Research Fund OTKA under contracts K100180 (for Z. Szalai) and K100181 (for T Nķmeth) are gratefully acknowledged.
Potassium Fixation and Supply by Soils with Mixed Clay Minerals.
Hipp, Billy W.
B-1090 December 1969 1 potassium Fixation and Supply By Soils With Misd Clay Minerals I KUS A&M UNIVERSITY Tcrv Agricultural Experiment Station r i 0. Kunkel, Acting Director, College Station, Texas Summary to the plants while Cameron clay... supplied onl!. Studies were made on three agriculturally important me/me of exchangeable K. The capacity of all a soils of South Texas and Northern Mexico to determine soils to fix K increased with increasing remo\\dl i their potassium (K)-supplying power...
Bromide Adsorption by Reference Minerals and Soils
Technology Transfer Automated Retrieval System (TEKTRAN)
Bromide, Br-, adsorption behavior was investigated on amorphous Al and Fe oxide, montmorillonite, kaolinite, and temperate and tropical soils. Bromide adsorption decreased with increasing solution pH with minimal adsorption occurring above pH 7. Bromide adsorption was higher for amorphous oxides t...
Anaerobic N mineralization in paddy soils in relation to inundation management, physicochemical soil fractions, mineralogy and soil properties
NASA Astrophysics Data System (ADS)
Sleutel, Steven; Kader, Mohammed Abdul; Ara Begum, Shamim; De Neve, Stefaan
Anaerobic N mineralization measured from (saturated) repacked soil cores from 25 paddy fields in Bangladesh and was previously found to negatively related to soil N content on a relative basis. This suggests that other factors like soil organic matter (SOM) quality or abiotic factors instead control the anaerobic N mineralization process. We therefore assessed different physical and chemical fractions of SOM, management factors and various soil properties as predictors for the net anaerobic N mineralization. 1░ First, we assessed routinely analyzed soil parameters (soil N and soil organic carbon, texture, pH, oxalate- and pyrophosphate-extractable Fe, Al, and Mn, fixed-NH4 content). We found no significant influences of neither soil mineralogy nor the annual length of inundation on soil N mineralization. The anaerobic N mineralization correlated positively with Na-pyrophosphate-extractable Fe and negatively with pH (both at P<0.01). At this stage it is, however, not known if these relations between net evolution of NH4 and pH and Fe content are causal or indirect. 2░ Second, the 25 samples collected from farmers' fields were physically fractionated into particulate OM and silt and clay associated OM. The silt and clay sized OM was further chemically fractionated by oxidation with 6%NaOCl to isolate an oxidation-resistant OM fraction, followed by extraction of mineral bound OM with 10%HF thereby isolating the HF-resistant OM. None of the physicochemical SOM fractions were found useful predictors anaerobic N mineralization. The linkage between these chemical soil N fractions and N supplying processes actually occurring in the soil thus appears to be weak. Regardless, we hypothesize that variation in strength of N-mineral and N-OM linkages is likely to explain variation in bio-availability of organic N and proneness to mineralization. Yet, in order to separate kinetically different soil N fractions we then postulated that an alternative approach would be required, which instead isolates soil N fractions on the basis of bonding strength. In this respect bonding strength should be seen as opposite of proneness to dissolution of released N into water, the habitat of soil microorganisms mediating soil N mineralization. We hypothesize that soil N extracted by water at increasing temperatures would reflect such N fractions with increasing bonding strength, in turn equivalent to decreasing bio-availability. Although water has frequently been used to extract labile SOM, its use has mostly been limited to 100░C. 3░ Third we developed sub critical water extraction (SCWE) at 100░C, 150░C and 200░C to isolate SOM fractions from the set of 25 paddy soil samples. In all cases, SCWE organic carbon (SCWE-OC) and N (SCWE-N) increased exponentially with the increase of temperature. SCWE preferentially extracted N over OC with increasing temperature. The efficiency of SCWE and the selectivity towards N were both lower in soils with increasingly reactive clay mineralogy. No correlations were found between the SCWE fractions and anaerobic N mineralization rate. In conclusion, SOM quantity and SOM quality, here represented by C and N distribution over physicochemical fractions, don't seem to dominantly determine anaerobic N mineralization in primarily young floodplain paddy soils. Other factors with exceeding control (pH and pyrophosphate extractable Fe) appear to exist. Possibly, the specific young genesis stage of most of the soils included (termed 'floodplain' soils) results in a limited availability of readily reducible Fe. Being an important alternative electron acceptor under submerged conditions, the availability of Fe, which is also controlled by pH, may be a bottleneck in the anaerobic N mineralization process. This needs to be further investigated by controlled incubation experiments with detailed follow-up of pH, redox potential, Fe in solution and mineral N.
Layer of organic pine forest soil on top of chlorophenol-contaminated mineral soil enhances contaminant degradation.
Sinkkonen, Aki; Kauppi, Sari; Simpanen, Suvi; Rantalainen, Anna-Lea; Str÷mmer, Rauni; Romantschuk, Martin
Chlorophenols, like many other synthetic compounds, are persistent problem in industrial areas. These compounds are easily degraded in certain natural environments where the top soil is organic. Some studies suggest that mineral soil contaminated with organic compounds is rapidly remediated if it is mixed with organic soil. We hypothesized that organic soil with a high degradation capacity even on top of the contaminated mineral soil enhances degradation of recalcitrant chlorophenols in the mineral soil below. We first compared chlorophenol degradation in different soils by spiking pristine and pentachlorophenol-contaminated soils with 2,4,6-trichlorophenol in 10-L buckets. In other experiments, we covered contaminated mineral soil with organic pine forest soil. We also monitored in situ degradation on an old sawmill site where mineral soil was either left intact or covered with organic pine forest soil. 2,4,6-Trichlorophenol was rapidly degraded in organic pine forest soil, but the degradation was slower in other soils. If a thin layer of the pine forest humus was added on top of mineral sawmill soil, the original chlorophenol concentrations (high, ca. 70 ?g g(-1), or moderate, ca. 20 ?g g(-1)) in sawmill soil decreased by >40 % in 24 days. No degradation was noticed if the mineral soil was kept bare or if the covering humus soil layer was sterilized beforehand. Our results suggest that covering mineral soil with an organic soil layer is an efficient way to remediate recalcitrant chlorophenol contamination in mineral soils. The results of the field experiment are promising. PMID:22752813
Mineralization of N in Soils Amended with Dairy Manure as Affected by Wetting/Drying Cycles
Technology Transfer Automated Retrieval System (TEKTRAN)
Interest in manure management and its effects on nitrogen (N) mineralization has increased in recent years. The focus of this research was to investigate the N mineralization rates of different soil types in Coastal Plain soils and compare them to a soil from Illinois. Soils with and without dairy ...
Stability of Soil Carbon Fractions - Aggregation Versus Mineral Association
NASA Astrophysics Data System (ADS)
Mueller, C. W.; Koegel-Knabner, I.
Models that seek to describe the dynamics of soil organic C typically distinguish between two or more C fractions according to differences of biochemical and microbial degradation. The rates are a consequence of recalcitrance, accessibility and interactions. Soil aggregation is an important mechanism controlling the accessibility of substrates by microbes and enzymes and thus the dynamics of minerals bound C are interacting with soil aggregate dynamics. In this study we focused on C fractions isolated by particle size fractionation. The main objective of our study was to differentiate between C stabilization of soil fractions due to accessibility/aggregation or to association with minerals. For a detailed understanding of these processes and the sources of respired soil CO2 we combined the measurement of heterotrophic respiration, CO2-13C analyses and radiocarbon dating of the respired CO2 in a long-term laboratory mineralization experiment. For the experiment we took soil material from the A horizon of an Albic Luvisol under Norway spruce forest (Picea abies) in southern Germany. The air dried bulk soil (< 2000 Ąm) was subjected to ultrasonication (1st step 60 J ml-1; 2nd step 440 J ml-1) and separated according to particle size in three fractions: > 63 Ąm to 2000 Ąm - sand, > 6.3 Ąm to 63 Ąm - silt and silt/clay fraction < 6.3 Ąm - clay. Solid-state 13C-CPMAS NMR spectroscopy was used to analyze the composition of bulk soil and fractions. The incubation of the three fractions and the bulk soil was done for 250 days in triplicate at 20 degree Celsius and 70% of maximal water holding capacity. A relative enrichment of alkyl C and an increase of the alkyl / O/N-alkyl C ratios in the order of sand < silt < clay were observed by 13C-NMR. On a long term the sand fraction and the bulk soil showed a sustained C bioavailability. For the silt and clay fraction similar respiration rates and a low C bioavailability were detected. The recombined fractions (by calculation) showed 35% higher amounts of respired CO2-C than the bulk soil. This difference accounts for the absence of restricted accessibility due to soil aggregation. Because of the high amounts of mineral bound C the main source of CO2-C (70%) in the recombined fraction is the clay fraction. Nevertheless the recalcitrance of mineral bound C is restricting the positive effects of aggregate disruption on the C turnover. The small fast decomposing C pool of the sand fraction is of minor importance to the total soil respiration balance. CO2-13C signatures showed higher values of the silt and clay fractions in contrast to the sand fraction, indicating a lower bioavailability of 13C-depleted carbon sources in the small fractions. The analyses of CO2-14C showed a shift to the utilization of older C sources with time.
Effects of aluminosilicate minerals in clay soil fractions on pore water hydroxide ion concentrations in soil/cement matricesĀ
Cook, Evan Russell
between clay minerals and calcium hydroxide. Pozzolanic reactions between aluminosilicate minerals in soils and portiandite or calcium silicate hydrate, generated by cement hydration, may significantly reduce the hydroxide ion concentration in soi...
Mineral Dissolution and Precipitation due to Carbon Dioxide-Water-Rock Interactions: The Significance of Accessory Minerals in Carbonate Reservoirs (Invited)
NASA Astrophysics Data System (ADS)
Kaszuba, J. P.; Marcon, V.; Chopping, C.
Accessory minerals in carbonate reservoirs, and in the caprocks that seal these reservoirs, can provide insight into multiphase fluid (CO2 + H2O)-rock interactions and the behavior of CO2 that resides in these water-rock systems. Our program integrates field data, hydrothermal experiments, and geochemical modeling to evaluate CO2-water-rock reactions and processes in a variety of carbonate reservoirs in the Rocky Mountain region of the US. These studies provide insights into a wide range of geologic environments, including natural CO2 reservoirs, geologic carbon sequestration, engineered geothermal systems, enhanced oil and gas recovery, and unconventional hydrocarbon resources. One suite of experiments evaluates the Madison Limestone on the Moxa Arch, Southwest Wyoming, a sulfur-rich natural CO2 reservoir. Mineral textures and geochemical features developed in the experiments suggest that carbonate minerals which constitute the natural reservoir will initially dissolve in response to emplacement of CO2. Euhedral, bladed anhydrite concomitantly precipitates in response to injected CO2. Analogous anhydrite is observed in drill core, suggesting that secondary anhydrite in the natural reservoir may be related to emplacement of CO2 into the Madison Limestone. Carbonate minerals ultimately re-precipitate, and anhydrite dissolves, as the rock buffers the acidity and reasserts geochemical control. Another suite of experiments emulates injection of CO2 for enhanced oil recovery in the Desert Creek Limestone (Paradox Formation), Paradox Basin, Southeast Utah. Euhedral iron oxyhydroxides (hematite) precipitate at pH 4.5 to 5 and low Eh (approximately -0.1 V) as a consequence of water-rock reaction. Injection of CO2 decreases pH to approximately 3.5 and increases Eh by approximately 0.1 V, yielding secondary mineralization of euhedral pyrite instead of iron oxyhydroxides. Carbonate minerals also dissolve and ultimately re-precipitate, as determined by experiments in the Madison Limestone, but pyrite will persist and iron oxyhydroxides will not recrystallize.
Sorption of tebuconazole onto selected soil minerals and humic acids.
Cadkovß, Eva; Komßrek, Michael; Kaliszovß, Regina; Koudelkovß, V?ra; Dvo?ßk, Ji?Ē; Van?k, AleÜ
The aim of the present study was to investigate tebuconazole sorption on common soil minerals (birnessite, ferrihydrite, goethite, calcite and illite) and humic acids (representing soil organic matter). Tebuconazole was used (i) in the commercial form Horizon 250 EW and (ii) as an analytical grade pure chemical. In the experiment with the commercially available tebuconazole, a significant pH-dependent sorption onto the oxides was observed (decreasing sorption with increasing pH). The highest sorption was found for ferrihydrite due to its high specific surface area, followed by humic acids, birnessite, goethite and illite. No detectable sorption was found for calcite. The sorption of analytical grade tebuconazole on all selected minerals was significantly lower compared to the commercial product. The sorption was the highest for humic acids, followed by ferrihydrite and illite and almost negligible for goethite and birnessite without any pH dependence. Again, no sorption was observed for calcite. The differences in sorption of the commercially available and analytical grade tebuconazole can be attributed to the additives (e.g., solvents) present in the commercial product. This work proved the importance of soil mineralogy and composition of the commercially available pesticides on the behavior of tebuconazole in soils. PMID:22428895
Fibrous-clay mineral formation and soil evolution in Aridisols of northeastern Patagonia, Argentina
Ahmad, Sajjad
Fibrous-clay mineral formation and soil evolution in Aridisols of northeastern Patagonia, Argentina Patagonia identified fibrous-clay minerals in calcic and petrocalcic horizons developed on old fluvio the occurrence of fibrous-clay minerals in the arid soil environment, and ii) to establish the relationship
Distinct temperature sensitivity of soil carbon decomposition in forest organic layer and mineral soil.
Xu, Wenhua; Li, Wei; Jiang, Ping; Wang, Hui; Bai, Edith
The roles of substrate availability and quality in determining temperature sensitivity (Q10) of soil carbon (C) decomposition are still unclear, which limits our ability to predict how soil C storage and cycling would respond to climate change. Here we determined Q10 in surface organic layer and subsurface mineral soil along an elevation gradient in a temperate forest ecosystem. Q10 was calculated by comparing the times required to respire a given amount of soil C at 15 and 25░C in a 350-day incubation. Results indicated that Q10 of the organic layer was 0.22-0.71 (absolute difference) higher than Q10 of the mineral soil. Q10 in both the organic layer (2.5-3.4) and the mineral soil (2.1-2.8) increased with decreasing substrate quality during the incubation. This enhancement of Q10 over incubation time in both layers suggested that Q10 of more labile C was lower than that of more recalcitrant C, consistent with the Arrhenius kinetics. No clear trend of Q10 was found along the elevation gradient. Because the soil organic C pool of the organic layer in temperate forests is large, its higher temperature sensitivity highlights its importance in C cycling under global warming. PMID:25270905
Distinct temperature sensitivity of soil carbon decomposition in forest organic layer and mineral soil
Xu, Wenhua; Li, Wei; Jiang, Ping; Wang, Hui; Bai, Edith
The roles of substrate availability and quality in determining temperature sensitivity (Q10) of soil carbon (C) decomposition are still unclear, which limits our ability to predict how soil C storage and cycling would respond to climate change. Here we determined Q10 in surface organic layer and subsurface mineral soil along an elevation gradient in a temperate forest ecosystem. Q10 was calculated by comparing the times required to respire a given amount of soil C at 15 and 25░C in a 350-day incubation. Results indicated that Q10 of the organic layer was 0.22¢0.71 (absolute difference) higher than Q10 of the mineral soil. Q10 in both the organic layer (2.5¢3.4) and the mineral soil (2.1¢2.8) increased with decreasing substrate quality during the incubation. This enhancement of Q10 over incubation time in both layers suggested that Q10 of more labile C was lower than that of more recalcitrant C, consistent with the Arrhenius kinetics. No clear trend of Q10 was found along the elevation gradient. Because the soil organic C pool of the organic layer in temperate forests is large, its higher temperature sensitivity highlights its importance in C cycling under global warming. PMID:25270905
Evaluation of an In Situ Net Soil Nitrogen Mineralization Method in Dryland Agroecosystems
Technology Transfer Automated Retrieval System (TEKTRAN)
Direct quantitative measurement of soil net N mineralization in agricultural soils under field conditions has not been widely used. A potential method of in situ net N mineralization was investigated in the fallow phase of 3-yr no-till crop rotation at two sites. Undisturbed soil cores (5 by 15 cm) ...
[Soil nitrogen net mineralization and nitrification in typical Calamagrostis angustifolia wetlands in Sanjiang Plain].
Sun, Zhi-Gao; Liu, Jing-Shuang
From June 2004 to July 2005, the dynamics of soil inorganic N pool and N net mineralization/nitrification rates in typical meadow Calamagrostis angustifolia wetland (TMCW) and marsh meadow C. angustifolia wetland (MMCW) in Sanjiang Plain were studied by top-closed PVC tube in situ incubation method, with the affecting factors and annual N net mineralization/nitrification investigated. The results showed that the soil inorganic N in the two wetlands had evident dynamic characteristics. The NH4(+) -N and NO3(-) -N contents were much higher in TMCW soil than in MMCW soil, and the soil N net mineralization/nitrification rates in the two wetlands presented significant fluctuations. Biological immobilization, denitrification, and abundant precipitation in rainy season were the main reasons inducing the N net mineralization/nitrification rates to be negative, and temperature, precipitation, soil organic matter content, soil C/N ratio and soil pH were the main factors resulting in the significant differences of soil inorganic N pool and N net mineralization/ nitrification rates between the two wetlands. The annual N net mineralization and nitrification and the percentage of nitrified N in mineralized N were much higher in TMCW soil than in MMCW soil, suggesting that TMCW soil was superior to MMCW soil in N availability and available N-maintaining capacity. PMID:17974243
Mineral exploration and soil analysis using in situ neutron activation
Senftle, F.E.; Hoyte, A.F.
A feasibility study has been made to operate by remote control an unshielded portable positive-ion accelerator type neutron source to induce activities in the ground or rock by "in situ" neutron irradiation. Selective activation techniques make it possible to detect some thirty or more elements by irradiating the ground for periods of a few minutes with either 3-MeV or 14-MeV neutrons. The depth of penetration of neutrons, the effect of water content of the soil on neutron moderation, gamma ray attenuation in the soil and other problems are considered. The analysis shows that, when exploring for most elements of economic interest, the reaction 2H(d,n)3He yielding ??? 3-MeV neutrons is most practical to produce a relatively uniform flux of neutrons of less than 1 keV to a depth of 19???-20???. Irradiation with high energy neutrons (??? 14 MeV) can also be used and may be better suited for certain problems. However, due to higher background and lower sensitivity for the heavy minerals, it is not a recommended neutron source for general exploration use. Preliminary experiments have been made which indicate that neutron activation in situ is feasible for a mineral exploration or qualititative soil analysis. ?? 1976.
GEMAS: Mineral magnetic properties of European agricultural soils
NASA Astrophysics Data System (ADS)
Kuzina, Dilyara; Kosareva, Lina; Fattakhova, Leysan; Fabian, Karl; Nourgaliev, Danis; Reimann, Clemens
The GEMAS survey of European agricultural soil provides a unique opportunity to create the first comprehensive overview of mineral magnetic properties in agricultural soil on a continental scale. Samples from the upper 20 cm were taken in large agricultural fields (Ap-sample) at a density of 1 site/2500 km2. After air drying and sieving to < 2 mm, low (460 Hz), and high frequency (4600 Hz) magnetic susceptibility k was measured on 2500 samples using a Bartington MS2B sensor to obtain frequency dependence of magnetic susceptibility kfd. Hysteresis properties are determined using a J coercivity spectrometer, built in the paleomagnetic laboratory of Kazan University, providing for each sample a modified hysteresis loop, backfield curve, acquisition curve of isothermal remanent magnetization, and a viscous IRM decay spectrum. Each measurement set is obtained in a single run from zero field up to 1.5 T and back to -1.5 T, taking approximately 15 minutes. This allows to measure a wide range of magnetic parameters for large sample collections. Because the GEMAS geochemical atlas provides a comprehensive set of geochemical measurements characterizing the individual soil samples, the new data allow to study magnetic parameters in relation to chemical and geological parameters. The results show a clear large scale spatial distribution with e.g. broad distinct lows of k over sandy sediments of the last glaciation in central northern Europe and other sedimentary basins. More localized positive k anomalies occur near young volcanism, or old basalts exposed on the surface. On the other hand, frequency dependence of k displays a much more scattered behavior, indicating either high noise level, or large local variability. Clearly distinguishable, small-scale patterns in the randomized data set indicate that the latter is more likely. This indicates that local influences on soil magnetic properties, including anthropogenic effects, may be easier detected by frequency dependence than by k itself, which is largely controlled by geological and climatic background variability. Mapping the isothermal mineral magnetic properties shows again a clear relation to large scale European geology. Thereby, the GEMAS data set of magnetic parameters provides a continent wide reference of the natural background in Ap soil. For the first time the geological background variability of magnetic minerals for national and local soil studies is defined at the European scale.
Microbial mineralization of atrazine and 2,4-dichlorophenoxyacetic acid in riparian pasture and forest soils
J. A. Entry; W. H. Emmingham; P. K. Donelly
Microbial biomass and mineralization of atrazine [2-chloro-4(ethylamino)-6(isopropylamino)s-triazine] and 2,4-D (2,4-dichlorphenoxyacetic acid) were examined in the top 10 cm of riparian pasture soils and in the litter layer and top 10 cm of mineral soils of riparian forest ecosystems. The riparian forest litter had higher levels of active and total fungal biomass than forest or pasture mineral soils in winter, spring,
Interaction of root exudates with the mineral soil constituents and their effect on mineral weathering
NASA Astrophysics Data System (ADS)
Mimmo, T.; Terzano, R.; Medici, L.; Lettino, A.; Fiore, S.; Tomasi, N.; Pinton, R.; Cesco, S.
Plants release significant amounts of high and low molecular weight organic compounds into the rhizosphere. Among these exudates organic acids (e.g. citric acid, malic acid, oxalic acid), phenolic compounds (e.g. flavonoids), amino acids and siderophores of microbial and/or plant origin strongly influence and modify the biogeochemical cycles of several elements, thus causing changes in their availability for plant nutrition. One class of these elements is composed by the trace elements; some of them are essential for plants even if in small concentrations and are considered micronutrients, such as Fe, Zn, Mn. Their solubility and bioavailability can be influenced, among other factors, by the presence in soil solution of low molecular weight root exudates acting as organic complexing agents that can contribute to the mineral weathering and therefore, to their mobilization in the soil solution. The mobilized elements, in function of the element and of its concentration, can be either important nutrients or toxic elements for plants. The objective of this study was to assess the influence of several root exudates (citric acid, malic acid, oxalic acid, genistein, quercetin and siderophores) on the mineralogy of two different soils (an agricultural calcareous soil and an acidic polluted soil) and to evaluate possible synergic or competitive behaviors. X-ray diffraction (XRD) coupled with Electron Probe Micro Analysis (EPMA) was used to identify the crystalline and amorphous phases which were subjected to mineral alteration when exposed to the action of root exudates. Solubilization of trace metals such as Cu, Zn, Ni, Cr, Pb, Cd as well as of major elements such as Si, Al, Fe and Mn was assessed by means of Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Soil microorganisms have proven to decrease mineral weathering by reducing the concentration of active root exudates in solution. Results obtained are an important cornerstone to better understand the biogeochemical processes acting in the rhizosphere which can play an important role in the availability of trace elements (either nutrient or toxic) for plant uptake. Research is supported by MIUR - FIRB "Futuro in ricerca", internal grant of Unibz (TN5031 & TN5046) and the Autonomous Province of Bolzano (Rhizotyr TN5218).
The structure of iron-oxyhydroxide mounds affected by iron-oxidizing bacteria at shallow submarine hydrothermal vent in Satsuma Iwo-Jima
NASA Astrophysics Data System (ADS)
Kuratomi, T.; Kiyokawa, S.; Ikehara, M.; Goto, S.; Hoshino, T.; Ikegami, F.; Minowa, Y.
Satsuma Iwo-Jima, located 38km south of Kyusyu island, Japan, is preserved and identified on occurring iron precipitation at shallow ocean where can be recorded modern analogy of iron precipitation and sedimentation. This is a volcanic island in the northwestern rim of Kikai caldera. Iron- and silica-rich mounds (0.5-3m wide and 0.2-7m high) are developing with hydrothermal activity (pH=5.5, 50-60 degree Celsius), and there is high deposition rate of iron-oxides (33 cm/year). In this study, we analyzed samples (20-30 cm long) recovered from iron oxidized mounds at seafloor by the observation with CT scan, FE-SEM and thin-sectioned samples, and the chemical analysis with EDS, XRF, XRD and DNA, and found that the structure of mounds has unique information. Each mounds are formed two layers: blackish hard layer and brownish soft layer. The inside of samples is constructed from the aggregation of convex structure (3-4 cm) covered by hard layers as a rim. Petrographic observations indicate that both layers have filament-like forms, and the form in soft layer is perpendicular to that in the hard layer. The number of iron oxides particles observed on filament-like forms in soft layer increases toward hard layer. Hard layer consists of aggregation of bacillus-like form as the chain of particle (about 2 um). At soft layer, on the other hand, bacteria-like form with smaller particles (<0.5 um) is observed. Bacteria-like form could be classified into 3 types (helix, ribbon-like, twisted). Furthermore, hard layers consist of ferrihydrite and opal-A (Si: 26.8%, Fe: 56.0%) and soft one is composed by ferrihydrite, opal-A and silica mineral (Si: 36.5%, Fe: 43.5%). Mariprofundus ferrooxydansknown as iron-oxidizing bacteria belonging to Zeta-proteobacteria identified in this matter. Bacteria-like form is considered to be the stalk made by iron-oxidizing bacteria. Such neutrophilic iron-oxidizing bacteria prefers an environment of redox interface between hydrothermal water and seawater, and their activity made hard rim at outer soft layer. This high deposition rate of iron hydroxides probably derives from the chemical reaction of oxidizing ferrous to ferric around stalks of iron-oxidizing bacteria.
Soil Nitrogen Mineralization Potential for Improved Fertilizer Recommendations and Decreased Nitrate Contamination of Groundwater
Franzluebbers, Alan; Haney, Richard; Hons, Frank
In order to prevent overfertilization, which could lead to groundwater contamination, rapid and accurate soil testing procedures are needed to evaluate agricultural surface soils for their potential to mineralize C and N. Our objectives were...
Soil Nitrogen Mineralization Potential for Improved Fertilizer Recommendations and Decreased Nitrate Contamination of GroundwaterĀ
Franzluebbers, Alan; Haney, Richard; Hons, Frank
In order to prevent overfertilization, which could lead to groundwater contamination, rapid and accurate soil testing procedures are needed to evaluate agricultural surface soils for their potential to mineralize C and N. ...
Identifying soils with potential of expanding sulfate mineral formation using electromagnetic inductionĀ
Fox, Miranda Lynn
Sulfate-bearing soils are a problem in highway construction as they combine with materials used for lime stabilization to form minerals, particularly ettringite, that expand and induce heave in the stabilized soil. This research involves...
Net and gross nitrogen mineralization in drained and reflooded fen soils.
M³nchmeyer, U; Russow, R; Augustin, J
One purpose of new land use concepts for degraded fens (organic soils with high N content) is the reduction of the mineralization process due to very high groundwater levels. However, knowledge of nitrogen mineralization process (net and gross) in degraded fen soils affected by reflooding is very small. Therefore, the objectives of our study were (a) to evaluate the suitability of 15N pool dilution method for measurements of gross mineralization rates in degraded fen soils and (b) to investigate how the reflooding of a degraded fen affects the net and gross nitrogen mineralization in a short-term incubation experiment. The usability of the 15N pool dilution method was diminished by the low recovery of the applied 15NH4+ at time zero. The recovery of the added 15NH4+ in the extractable soil NH4+ pool was only 13.5% for the drained soil and 59.6% for the reflooded soil. However, the gross mineralization rates were similar for both soils and exceeded always the net rates substantially. The cumulative net mineralization rate was higher for the reflooded soil (1.58 micrograms N*cm-3*d-1) than for the drained soil (-0.67 microgram N*cm-3*d-1). Differences between the two soils were also found in the nitrification intensity and the loss of 15N. This was probably one reason for the higher net mineralization rate in the reflooded soil. PMID:11022327
In situ mineralization of nitorgen and phosphorus of arctic soils after perturbations simulating climate change
Sven Jonasson; Mats Havstr÷m; Michael Jensen; Terry V. Callaghan
Seasonal net nitrogen (N) and phosphorus (P) mineralization was investigated at Abisko, Swedish Lapland in soils of a subarctic heath and in soils of a colder (by about 4░ C), high altitude fellfield by (a) using in situ soil incubation in soils which had been shaded or subjected to two levels of increased temperature, combined with (b) reciprocal transplantation of
Positive and negative carbon mineralization priming effects among a variety of biochar-amended soils
Andrew R. Zimmerman; Bin Gao; Mi-Youn Ahn
Pyrogenic carbon (biochar) amendment is increasingly discussed as a method to increase soil fertility while sequestering atmospheric carbon (C). However, both increased and decreased C mineralization has been observed following biochar additions to soils. In an effort to better understand the interaction of pyrogenic C and soil organic matter (OM), a range of Florida soils were incubated with a range
Kinetics of di-(2-ethylhexyl)phthalate mineralization in sludge-amended soil
Madsen, P.L.; Thyme, J.B.; Henriksen, K.; Moeldrup, P.; Roslev, P. (Aalborg Univ. (Denmark). Environmental Engineering Lab.)
Sewage sludge is frequently used as a soil fertilizer although it may contain elevated concentrations of priority pollutants including di-(2-ethylhexyl)phthalate (DEHP). In the present study, the kinetics of microbial [[sup 14]C]DEHP mineralization was studied in laboratory microcosms with sewage sludge and agricultural soil. A biphasic model with two independent kinetic expressions was used to fit the mineralization data. The initial mineralization activity was described well by first-order kinetics, whereas mineralization in long-term incubations was described better by fractional power kinetics. The mineralization activity was much lower in the late phase presumably due to a decline in the bioavailability of DEHP caused by diffusion-limited desorption. The initial DEHP mineralization rate in sludge-amended soil varied between 3.7 and 20.3 ng of DEHP (g dw)[sup [minus]1]d[sup [minus]1] depending on incubation conditions. Aerobic DEHP mineralization was 4--5 times faster than anaerobic mineralization, DEHP mineralization in sludge-amended soil was much more temperature sensitive than was DEHP mineralization in soil without sludge. Indigenous microorganisms in the sewage sludge appeared to dominate DEHP degradation in sludge-amended soil. It was estimated that > 41% of the DEHP in sludge-amended soil will have escaped mineralization after 1 year. In the absence of oxygen, > 68% of the DEHP will not be mineralized within 1 year. Collectively, the data suggest that a significant fraction of the DEHP in sludge-amended soils may escape mineralization under in situ conditions.
R E V I E W Mineral soil carbon fluxes in forests and implications for
Vermont, University of
R E V I E W Mineral soil carbon fluxes in forests and implications for carbon balance assessments, VT 05819, USA Abstract Forest carbon cycles play an important role in efforts to understand and mitigate climate change. Large amounts of carbon (C) are stored in deep mineral forest soils, but are often
In situ investigation of dissolution of heavy metal containing mineral particles in an acidic forest soil
Andreas Birkefeld; Rainer Schulin; Bernd Nowack
We report the application of an in situ method to obtain field dissolution rates of fine mineral particles in soils. Samples with different metal-containing mineral and slag particles (lead oxide, copper concentrate and copper slag) from the mining and smelting industry were buried in the topsoil of an acidic forest soil for up to 18 months. In addition we studied
Technology Transfer Automated Retrieval System (TEKTRAN)
To preserve soil fertility, organic and mineral fertilizers are often applied to agricultural fields. Mineral fertilizers such as phosphates and super phosphates contain a certain amount of long-lived alpha activity due to 238-U, 230-Th, amongst others. The fate of U in soil systems is quite complex...
Spectroscopic Interpretation of PAH-Spectra in Minerals and Its Possible Application to Soil Monitoring
Ko, Eun-Joung; Kim, Kyoung-Woong; Park, Kihong; Kim, Ju-Yong; Kim, Jiwon; Hamm, Se-Yeong; Lee, Jung-Hwan; Wachsmuth, Uwe
In order to properly assess the feasibility of using Laser-Induced Fluorescence (LIF) spectroscopy for soil monitoring, the variation of fluorescence intensity due to the heterogeneity and complexity of soil media was investigated. Different soil minerals showed fluorescence spectral structures distinguishable from the contaminants, implying dissimilar interactions or the binding of contaminants on mineral surfaces. More interestingly, solvent and water addition showed different responses in the fluorescence spectral structure showing their effect on the interactions between contaminants and minerals. These results support the claim that the spectral structure contains information on contaminant-mineral interactions; therefore contaminants can be used as a fluorescence probe for these interactions. PMID:22319331
Effects of Some Plant Residues on Nitrogen Mineralization and Biological Activity in Soils
Emine Erman KARA
The objective of this experiment was to determine the rate of decomposition and nitrogen mineralization of plant residues in soil under laboratory conditions. The experiment consisted of six treatments: control, industrial tobacco residues, rice straw, rice straw + mineral nitrogen, rice husks and rice husks+mineral nitrogen. The plant materials were added at a rate of 2000 mg\\/kgC and the amount
Soil mineral nitrogen and nitrate leaching losses in soil tillage systems combined with a catch crop
Maria Stenberg; Helena Aronsson; B÷rje Lindķn; Tomas Rydberg; Arne Gustafson
Annual nitrogen leaching losses from arable land in south Sweden usually amount to 15¢45kgha?1. The objective of this three-year study was to investigate the timing effect of mouldboard ploughing (early autumn, late autumn or spring) on soil mineral nitrogen content and nitrate leaching in a cropping system with spring-sown small grain crops (barley, oats and wheat). Late autumn ploughing was
Effects of Willows (Salix brachycarpa) on Populations of Salicylate-Mineralizing Microorganisms in Alpine Soils
S. K. Schmidt; D. A. Lipson; T. K. Raab
We used the substrate-induced growth-response (SIGR) method to quantify salicylate-mineralizing microbes and total microbial biomass in soils from under willows (Salix brachycarpa) and in surrounding meadows dominated by the sedge Kobresia myosuroides. Willows had a strong effect on the biomass of salicylate-mineralizing microbes in both years of this study. There were always higher biomass levels of salicylate mineralizers in soils
Statistical analysis of mineral soils in the Odra valley
NASA Astrophysics Data System (ADS)
Hudak, Magda; Rojna, Arkadiusz
The aim of this article is to present the results of statistical analyses of laboratory experiment results obtained from an ITB ZW-K2 apparatus, Kamie?ski tubes and grain-size distribution curves. Beside basic statistical parameters (mean, sum, minimum and maximum), correlation analysis and multivariate analysis of variance at significance levels ? < 0.01 and ? < 0.05 were taken into account, as well as calculations of LSD confidence half-intervals. The research material was collected from the valley of the Odra river near the town of S?ubice in Lubuskie province. The research involved mineral, non-rock fine-grained, non-cohesive soils lying at the depth of 0.3-1.5 m.
Effects of mycorrhizal fungus isolates on mineral acquisition by Panicum virgatum in acidic soil
R. B. Clark; R. W. Zobel; S. K. Zeto
Plant ability to withstand acidic soil mineral deficiencies and toxicities can be enhanced by root-arbuscular mycorrhizal\\u000a fungus (AMF) symbioses. The AMF benefits to plants may be attributed to enhanced plant acquisition of mineral nutrients essential\\u000a to plant growth and restricted acquisition of toxic elements. Switchgrass (Panicum virgatum L.) was grown in pHCa (soil:10?mM CaCl2, 1?:?1) 4 and 5 soil (Typic
Influence of leaf litter quality on N mineralization in soils of subtropical humid forest regrowths
K. Maithani; A. Arunachalam; R. S. Tripathi; H. N. Pandey
Laboratory net N mineralization as influenced by leaf litter quality of several subtropical tree species was studied in soils\\u000a of forest regrowths of three different age groups. Concentrations of NH4\\u000a + and NO3\\u000a ¢ in the soil generally increased with age of forest regrowth. However, during incubation concentrations fluctuated markedly.\\u000a In the ōsoil onlyö treatment, the cumulative N mineralization, ammonification
Adsorption and structural fractionation of dissolved organic matter (DOM) by soil mineral surfaces
NASA Astrophysics Data System (ADS)
Avneri, Shani; Polubesova, Tamara; Chefetz, Benny
Dissolved organic matter (DOM) represents a small but highly reactive fraction of the soil organic matter (SOM). One of the important processes affecting the fate of DOM in soils is its interactions with mineral phases. Adsorptive fractionation of DOM by soils and minerals has been observed previously, however detailed changes in composition of DOM due to its interactions with mineral soils were not yet elucidated. In this research the adsorption and physico-chemical fractionation of DOM by soil poor with organic matter and rich with iron oxides and clay fraction was investigated. The changes in DOM structural composition were studied using separation with polymeric resins. The following fractions were obtained: hydrophobic acid (HoA), hydrophobic neutral (HoN), hydrophilic acid (HiA), hydrophilic base (HiB), and hydrophilic neutral (HiN). Two types of DOM were studied: DOM extracted from composted biosolids (compost DOM) and DOM from Suwanee River (SRNOM). Sorption affinity of DOM to soil mineral surfaces was source and chemistry dependent. SRNOM, which was characterized by higher content of aromatic and carboxylic groups demonstrated higher affinity to the studied soil than compost DOM. For both DOM samples preferential adsorption of HoA by soil (50-85% from adsorbed carbon) was observed. Desorption of both DOM types demonstrated significant hysteresis (up to 90-100% of dissolved organic carbon was retained by the soil after 3 cycles of desorption stages). This suggests that DOM desorption behavior was affected by HoA dominant adsorption to the soil mineral fraction, and not by DOM source. Results of this study indicate that interactions of different types of DOM with mineral soil may result in similar changes in composition and properties of DOM both in the supernatant as well as in the adsorbed phase. The change in DOM composition due to its interaction with soil minerals may influence the interactions of pollutants with DOM and soil particle surfaces.
Mechanistic roles of soil humus and minerals in the sorption of nonionic organic compounds from aqueous and organic solutions
Chiou, C.T.; Shoup, T.D.; Porter, P.E.
Mechanistic roles of soil humus and soil minerals and their contributions to soil sorption of nonionic organic compounds from aqueous and organic solutions are illustrated. Parathion and lindane are used as model solutes on two soils that differ greatly in their humic and mineral contents. In aqueous systems, observed sorptive characteristics suggest that solute partitioning into the soil-humic phase is the primary mechanism of soil uptake. By contrast, data obtained from organic solutions on dehydrated soil partitioning into humic phase and adsorption by soil minerals is influenced by the soil-moisture content and by the solvent medium from which the solute is sorbed. ?? 1985.
Exploitation of potassium by various crop species from primary minerals in soils rich in micas
K. Mengel; Rahmatullah
We investigated the question of whether exchangeable K+ is a reliable factor for K+ availability to plants on representative arable soils (Aridisols) rich in K+-bearing minerals. Five soils with different textures were collected from different locations in Pakistan and used for pot experiments. The soils were separated into sand, silt, and clay fractions and quartz sand was added to each
Nitrogen Mineralization in a Semiarid Silt Loam Soil in the Pacific Northwest
Technology Transfer Automated Retrieval System (TEKTRAN)
The mineralization of nitrogen from soil organic matter or plant residues can provide a substantial amount of nitrogen for crop growth. Microbial activity in a soil may be adversely affected by either very high or low soil water content. A field study was conducted to determine the affect of three...
ORIGINAL PAPER Labile organic C and N mineralization of soil aggregate size
Yu, Qiang
intensity is suggested. Keywords Soil organic carbon . Microbial biomass carbon . Dissolved organic carbon. Han State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese AcademyORIGINAL PAPER Labile organic C and N mineralization of soil aggregate size classes in semiarid
Tillage and amendment effects on soil carbon and nitrogen mineralization and phosphorus release
W. L. Kingery; C. W. Wood; J. C. Williams
The influence of tillage and nutrient amendment management on nutrient cycling processes in soil have substantial implications for environmentally sound practices regarding their use. The effects of 2 years of tillage and soil amendment regimes on the concentrations of soil organic matter variables (carbon (C), nitrogen (N) and phosphorus (P)) and C and N mineralization and P release were determined
Carbon and nitrogen mineralization in vineyard acid soils amended with a bentonitic winery waste
NASA Astrophysics Data System (ADS)
Fernßndez-Calvi±o, David; RodrĒguez-Salgado, Isabel; Pķrez-RodrĒguez, Paula; DĒaz-Ravi±a, Montserrat; N¾voa-Mu±oz, Juan Carlos; Arias-Estķvez, Manuel
Carbon mineralization and nitrogen ammonification processes were determined in different vineyard soils. The measurements were performed in samples non-amended and amended with different bentonitic winery waste concentrations. Carbon mineralization was measured as CO2 released by the soil under laboratory conditions, whereas NH4+ was determined after its extraction with KCl 2M. The time evolution of both, carbon mineralization and nitrogen ammonification, was followed during 42 days. The released CO2 was low in the analyzed vineyard soils, and hence the metabolic activity in these soils was low. The addition of the bentonitic winery waste to the studied soils increased highly the carbon mineralization (2-5 fold), showing that the organic matter added together the bentonitic waste to the soil have low stability. In both cases, amended and non-amended samples, the maximum carbon mineralization was measured during the first days (2-4 days), decreasing as the incubation time increased. The NH4+ results showed an important effect of bentonitic winery waste on the ammonification behavior in the studied soils. In the non-amended samples the ammonification was no detected in none of the soils, whereas in the amended soils important NH4+ concentrations were detected. In these cases, the ammonification was fast, reaching the maximum values of NH4 between 7 and 14 days after the bentonitic waste additions. Also, the percentages of ammonification respect to the total nitrogen in the soil were high, showing that the nitrogen provided by the bentonitic waste to the soil is non-stable. The fast carbon mineralization found in the soils amended with bentonitic winery wastes shows low possibilities of the use of this waste for the increasing the organic carbon pools in the soil.On the other hand, the use of this waste as N-fertilizer can be possible. However, due its fast ammonification, the waste should be added to the soils during active plant growth periods.
Association of individual soil mineral constituents and heavy metals as studied by sorption experiments and analytical electron microscopy analyses
Pķter Sipos; Tibor Nķmeth; Vikt¾ria Kovßcs Kis; Ilona Mohai
Sorption characteristics of bulk soil samples and discrete soil mineral constituents were studied by Cu, Zn and Pb batch sorption experiments and analytical electron microscopy analyses. Copper and zinc sorbed mostly on soil mineral constituents, while lead was associated mainly to soil organic matter. Additionally, the competitive situation resulted in increase of the role of iron oxides in Pb sorption.
Minerals are important for your body to stay healthy. Your body uses minerals for many different jobs, including building bones, making ... regulating your heartbeat. There are two kinds of minerals: macrominerals and trace minerals. Macrominerals are minerals your ...
Isolation and identification of phytate-degrading bacteria and their contribution to phytate mineralization in soil.
Horii, Sachie; Matsuno, Toshihide; Tagomori, Junta; Mukai, Masaki; Adhikari, Dinesh; Kubo, Motoki
To better understand the phosphorus (P) cycling in an agricultural soil environment, amounts of total, organic and inorganic P in 10 agricultural soil samples were analyzed. Since a large proportion (57.8%) of the total P in the soils was in organic form, a method was developed to evaluate the mineralization rate of organic P in the soil by adding phytate to the soil and analyzing the change in water-soluble P (WSP) content after incubating it for 3 days. Moreover, the relationship between the phytate mineralization activity and bacterial biomass in 60 agricultural soils was also investigated, where the phytate mineralization activity ranged from 0 to 61.7% (average: 18.8%), and the R▓ value between phytate mineralization activity and indigenous bacterial biomass was 0.11 only. Phytate-degrading bacteria were isolated from the soil environment, and identified as Pseudomonas rhodesiae JT29, JT32, JT33, JT34, JT35, Pseudomonas sp. JT30, and Flavobacterium johnsoniae JT31. When P. rhodesiae JT29 and F. johnsoniae JT31 were inoculated into the agricultural soils, the phytate mineralization activities were increased up to 16 and 27 times, respectively. It was concluded that promotion of effective phytate-degrading bacterial strains could improve the sustainable P management in the agricultural soils. PMID:24201147
Temperature Sensitivity of Soil Organic Carbon Mineralization along an Elevation Gradient in the Wuyi Mountains, China
Xu, Xia; Ruan, Honghua; Wang, Jiashe
Soil organic carbon (SOC) actively participates in the global carbon (C) cycle. Despite much research, however, our understanding of the temperature sensitivity of soil organic carbon (SOC) mineralization is still very limited. To investigate the responses of SOC mineralization to temperature, we sampled surface soils (0¢10 cm) from evergreen broad-leaf forest (EBF), coniferous forest (CF), sub-alpine dwarf forest (SDF), and alpine meadow (AM) along an elevational gradient in the Wuyi Mountains, China. The soil samples were incubated at 5, 15, 25, and 35░C with constant soil moisture for 360 days. The temperature sensitivity of SOC mineralization (Q10) was calculated by comparing the time needed to mineralize the same amount of C at any two adjacent incubation temperatures. Results showed that the rates of SOC mineralization and the cumulative SOC mineralized during the entire incubation significantly increased with increasing incubation temperatures across the four sites. With the increasing extent of SOC being mineralized (increasing incubation time), the Q10 values increased. Moreover, we found that both the elevational gradient and incubation temperature intervals significantly impacted Q10 values. Q10 values of the labile and recalcitrant organic C linearly increased with elevation. For the 5¢15, 15¢25, and 25¢35░C intervals, surprisingly, the overall Q10 values for the labile C did not decrease as the recalcitrant C did. Generally, our results suggest that subtropical forest soils may release more carbon than expected in a warmer climate. PMID:23342038
Spatial Arrangment of Organic Compounds on a Model Mineral Surface: Implications for Soil Organic Matter Stabilization
Petridis, Loukas [ORNL; Ambaye, Haile Arena [ORNL; Jagadamma, Sindhu [ORNL; Kilbey, S. Michael [University of Tennessee, Knoxville (UTK); Lokitz, Bradley S [ORNL; Lauter, Valeria [ORNL; Mayes, Melanie [ORNL
The complexity of the mineral organic carbon interface may influence the extent of stabilization of organic carbon compounds in soils, which is important for global climate futures. The nanoscale structure of a model interface was examined here by depositing films of organic carbon compounds of contrasting chemical character, hydrophilic glucose and amphiphilic stearic acid, onto a soil mineral analogue (Al2O3). Neutron reflectometry, a technique which provides depth-sensitive insight into the organization of the thin films, indicates that glucose molecules reside in a layer between Al2O3 and stearic acid, a result that was verified by water contact angle measurements. Molecular dynamics simulations reveal the thermodynamic driving force behind glucose partitioning on the mineral interface: The entropic penalty of confining the less mobile glucose on the mineral surface is lower than for stearic acid. The fundamental information obtained here helps rationalize how complex arrangements of organic carbon on soil mineral surfaces may arise
Degradation and mineralization of atrazine by a soil bacterial isolate.
Radosevich, M; Traina, S J; Hao, Y L; Tuovinen, O H
An atrazine-degrading bacterial culture was isolated from an agricultural soil previously impacted by herbicide spills. The organism was capable of using atrazine under aerobic conditions as the sole source of C and N. Cyanuric acid could replace atrazine as the sole source of N, indicating that the organism was capable of ring cleavage. Ring cleavage was confirmed in 14CO2 evolution experiments with [U-14C-ring]atrazine. Between 40 and 50% of ring-14C was mineralized to 14CO2. [14C]biuret and [14C]urea were detected in spent culture media. Cellular assimilation of 14C was negligible, in keeping with the fully oxidized valence of the ring carbon. Chloride release was stoichiometric. The formation of ammonium during atrazine degradation was below the stoichiometric amount, suggesting a deficit due to cellular assimilation and metabolite-N accumulation. With excess glucose and with atrazine as the sole N source, free ammonium was not detected, suggesting assimilation into biomass. The organism degraded atrazine anaerobically in media which contained (i) atrazine only, (ii) atrazine and glucose, and (iii) atrazine, glucose, and nitrate. To date, this is the first report of a pure bacterial isolate with the ability to cleave the s-triazine ring structure of atrazine. It was also concluded that this bacterium was capable of dealkylation, dechlorination, and deamination in addition to ring cleavage. PMID:7887609
Significant progress has been made in elucidating sorption reactions that control the partitioning of metals from solution to mineral surfaces in contaminated soil/sediment systems. Surface complexation models have been developed to quantify the forward reaction with reasonable ...
Significant progress has been made in elucidating sorption reactions that control the partitioning of metals from solution to mineral surfaces in contaminated soil/sediment systems. Surface complexation models have been developed to quantify the forward reaction, however, these ...
Formation of carbon dioxide hydrate in soil and soil mineral suspensions with electrolytes.
Lamorena, Rheo B; Lee, Woojin
We have identified the effects of solid surface (soil, bentonite, kaolinite, nontronite, and pyrite) and electrolyte (NaCl, KCl, CaCl2, and MgCl2) types on the formation and dissociation of CO2 hydrate in this study. The hydrate formation experiments were conducted by injecting CO2 gas into the soil suspensions with and without electrolytes in a 50 mL pressurized vessel. The formation of CO2 hydrate in deionized water was faster than that in aqueous electrolyte solutions. The addition of soil suspensions accelerated the formation of CO2 hydrate in the electrolyte solutions. The hydrate formation times in the solid suspensions without electrolytes were very similar to that in the deionized water. We did not observe any significant differences between the hydrate dissociation in the solid suspension and that in the deionized water. The pHs of clay mineral suspensions decreased significantly after CO2 hydrate formation and dissociation experiments, while the pH of the soil suspension slightly decreased by less than pH 1 and that of pyrite slightly increased due to the dissolution of CO2 forming carbonic acid. The results obtained from this research could be indirectly applied to the fate of CO2 sequestered into geological formations as well as its storage as a form of CO2 hydrate. PMID:18497119
Isolation and characterization of an isoproturon mineralizing Sphingomonas sp. strain SH from a French agricultural soil
Sabir Hussain; Marion Devers-Lamrani; Najoi El Azhari; Fabrice Martin-Laurent
The phenylurea herbicide isoproturon, 3-(4-isopropylphenyl)-1,1-dimethylurea (IPU), was found to be rapidly mineralized in\\u000a an agricultural soil in France that had been periodically exposed to IPU. Enrichment cultures from samples of this soil isolated\\u000a a bacterial strain able to mineralize IPU. 16S rRNA sequence analysis showed that this strain belonged to the phylogeny of\\u000a the genus Sphingomonas (96% similarity with Sphingomonas
Kinetics of di-(2-ethylhexyl)phthalate mineralization in sludge-amended soil
Peter Lindequist Madsen; Jesper Bandsholm Thyme; Kaj Henriksen; P. Moeldrup; Peter Roslev
Sewage sludge is frequently used as a soil fertilizer although it may contain elevated concentrations of priority pollutants including di-(2-ethylhexyl)phthalate (DEHP). In the present study, the kinetics of microbial [[sup 14]C]DEHP mineralization was studied in laboratory microcosms with sewage sludge and agricultural soil. A biphasic model with two independent kinetic expressions was used to fit the mineralization data. The initial
Mineralization of Three Organic Manures Used as Nitrogen Source in a Soil Incubated under Laboratory Conditions
M. Kaleem Abbasi; Munazza Hina; Abdul Khalique; Sumyya Razaq Khan
The rate and timing of manure application when used as nitrogen (N) fertilizer depend on N?releasing capacity (mineralization) of manures. A soil incubation study was undertaken to establish relative potential rates of mineralization of three organic manures to estimate the value of manure as N fertilizer. Surface soil samples of 0¢15Ācm were collected and amended with cattle manure (CM), sheep
Nutrient Mineralization from Deoiled Neem Seed in a Savanna Soil from Nigeria
John O. Agbenin; Stephen O. Ibitoye; Abel S. Agbaji
The mineralization of nutrients from deoiled neem seed (neem seed cake), the residue left after oil extraction, was examined in a typical savanna soil with a view to determining its potential for fertility improvement. The neem seed cake (NSC) application rates were 0, 2.5, and 5.0ĀgĀkg soil (0, 5, and 10ĀtonsĀha). The concentrations of ammonium?nitrogen (NH4?N) and nitrate (NO3)?N mineralized
Effects of mulch and mineral fertilizer on crop, weevil and soil quality parameters in highland banana
H. Ssali; B. D. McIntyre; C. S. Gold; I. N. Kashaija; F. Kizito
The decline of cooking banana production in parts of East Africa hasbeen associated with a loss of soil fertility and increased pest pressure.Previous work indicated that the use of mineral fertilizers at recommendedratesis not financially viable on plantations where pest pressure is high. Theobjectives of this study were to determine the effects of half the recommendedrates of mineral fertilizers and
Long-term crop rotation effects on soil attributes, soybean mineral nutrition, yield, and seed composition
Technology Transfer Automated Retrieval System (TEKTRAN)
Study objectives were to measure how soil chemical and physical attributes as well as soybean [Glycine max (L.) Merr.] stover dry weight and mineral concentrations, seed yield, and seed composition (protein, oil, and minerals) responded to soybean-maize (Zea mays L.) 2-yr rotation (S-C); soybean-spr...
Soil Mineral¢Organic Matter--Microorganism Interactions: Fundamentals and Impacts
P. M. Huang
Minerals, organic matter, and microorganisms are integral parts of the pedosphere and related environments. These three components are not separate entities but rather a united system constantly in association and interactions with each other in the terrestrial environment. Interactions of these components mediated by soil solution and atmosphere govern mechanisms of mineral weathering reactions, formation of short-range ordered (SRO) metal
Nitrogen mineralization in paddy soils of the Chinese Taihu Region under aerobic conditions
Marco Roelcke; Yong Han; Zucong Cai; J÷rg Richter
In order to make more efficient use of mineral nitrogen fertilizers, the mineralization of organic N has to be fully understood and taken into account when meeting the nitrogen demand of crops. Aerobic long-term incubation experiments (147 days) based on the method by Stanford and Smith (1972, Soil Sci Soc Am Proc 36: 465), modified by Nordmeyer and Richter (1985,
A simple method to determine mineralization of (14) C-labeled compounds in soil.
Myung, Kyung; Madary, Michael W; Satchivi, Norbert M
Degradation of organic compounds in soil is often determined by measuring the decrease of the parent compound and analyzing the occurrence of its metabolites. However, determining carbon species as end products of parent compound dissipation requires using labeled materials that allow more accurate determination of the environmental fate of the compound of interest. The current conventional closed system widely used to monitor degradation of (14) C-labeled compounds in soil is complex and expensive and requires a specialized apparatus and facility. In the present study, the authors describe a simple system that facilitates measurement of mineralization of (14) C-labeled compounds applied to soil samples. In the system, soda lime pellets to trap mineralized (14) C-carbon species, including carbon dioxide, were placed in a cup, which was then inserted above the treated soil sample in a tube. Mineralization of [(14) C]2,4-D applied to soil samples in the simple system was compared with that in the conventional system. The simple system provided an equivalent detection of (14) C-carbon species mineralized from the parent compound. The results demonstrate that this cost- and space-effective simple system is suitable for examining degradation and mineralization of (14) C-labeled compounds in soil and could potentially be used to investigate their mineralization in other biological matrices. PMID:24677225
Resources for a lunar base: Rocks, minerals, and soil of the Moon
NASA Technical Reports Server (NTRS)
Taylor, Lawrence A.
The rocks and minerals of the Moon will be included among the raw materials used to construct a lunar base. The lunar regolith, the fragmental material present on the surface of the Moon, is composed mostly of disaggregated rocks and minerals, but also includes glassy fragments fused together by meteorite impacts. The finer fraction of the regolith (i.e., less than 1 cm) is informally referred to as soil. The soil is probably the most important portion of the regolith for use at a lunar base. For example, soil can be used as insulation against cosmic rays, for lunar ceramics and abodes, or for growing plants. The soil contains abundant solar-wind-implanted elements as well as various minerals, particularly oxide phases, that are of potential economic importance. For example, these components of the soil are sources of oxygen and hydrogen for rocket fuel, helium for nuclear energy, and metals such as Fe, Al, Si, and Ti.
Resources for a lunar base: Rocks, minerals, and soil of the Moon
NASA Astrophysics Data System (ADS)
Taylor, Lawrence A.
The rocks and minerals of the Moon will be included among the raw materials used to construct a lunar base. The lunar regolith, the fragmental material present on the surface of the Moon, is composed mostly of disaggregated rocks and minerals, but also includes glassy fragments fused together by meteorite impacts. The finer fraction of the regolith (i.e., less than 1 cm) is informally referred to as soil. The soil is probably the most important portion of the regolith for use at a lunar base. For example, soil can be used as insulation against cosmic rays, for lunar ceramics and abodes, or for growing plants. The soil contains abundant solar-wind-implanted elements as well as various minerals, particularly oxide phases, that are of potential economic importance. For example, these components of the soil are sources of oxygen and hydrogen for rocket fuel, helium for nuclear energy, and metals such as Fe, Al, Si, and Ti.
Effects of redox conditions on the adsorption of dissolved organic matter to soil minerals and differently aged paddy soils
NASA Astrophysics Data System (ADS)
Sauerwein, Meike; Hanke, Alexander; Kaiser, Klaus; Kalbitz, Karsten
Effects of redox conditions on the adsorption of dissolved organic matter to soil minerals and differently aged paddy soils Meike Sauerwein1, Alexander Hanke2, Klaus Kaiser3, Karsten Kalbitz2 1) Dept. of Soil Ecology, Bayreuth Centre of Ecology and Environmental Research (BayCEER), University of Bayreuth, 95440 Bayreuth, Germany, firstname.lastname@example.com 2) Institute of ecosystem dynamics and biodiversity, University of Amsterdam, 1018 WV, Netherlands, firstname.lastname@example.com, firstname.lastname@example.com 3) Soil Sciences, Martin Luther University Halle, 06099 Halle, Germany, firstname.lastname@example.com Current knowledge on dissolved organic matter (DOM) in soils is based mainly on observations and experiments in aerobic environments. Adsorption to soil minerals is an important mechanism of DOM retention and stabilization against microbial decay under oxic conditions. Under anoxic conditions where hydrous iron oxides, the potential main adsorbents of DOM, possibly dissolve, the importance of adsorption seems questionable. Therefore, we studied the adsorption of DOM to selected soil minerals and to mineral soils under oxic and anoxic conditions. In detail, we tested the following hypotheses: 1. Minerals and soils adsorb less DOM under anoxic conditions than under oxic ones. 2. The reduced adsorption under anoxic conditions is result of the smaller adsorption to hydrous Fe oxides whereas adsorption to clay minerals and Al hydroxides is not sensitive to changes in redox conditions 3. DOM adsorption will increase with the number of redox cycles, thus time of soil formation, due to increasing contents of poorly crystalline Fe oxides. This will, however, cause a stronger sensitivity to redox changes as poor crystalline Fe oxides are more reactive. 4. Aromatic compounds, being preferentially adsorbed under oxic conditions, will be less strongly adsorbed under anoxic conditions. We chose paddy soils as models because their periodically and regular exposure to changing redox cycles, with anoxic conditions during the rice growing period and oxic conditions during harvest and growth of other crops. Soils of a unique chronosequence of paddy soils (50, 300, 700 and 2000 years) in China were studied in direct comparison to non-paddy soils of the same age. In additions, selected soil minerals (goethite, ferrihydrite, amorphous Al hydroxide, hydrobiotite, nontronite and ripodolite), differing in their response to changes in redox conditions, were studied in order to indentify those mineral constituents responsible for redox-induced changes in DOM adsorption to the test soils. The DOM for the adsorption was extracted from composted rice straw as a surrogate for DOM percolating in paddy soils. Batch adsorption experiments were carried out with DOM pre-incubated to give oxic and anoxic conditions and maintaining these redox conditions during the whole procedure. The redox potential resulting from anoxic pre-incubation was about 100 mV, thus in the range of Fe reduction. Besides of dissolved organic carbon (DOC), we determined changes in the composition of DOM by the specific UV absorbance. We also analyzed main cations, anions and redox-sensitive elements to give a comprehensive picture of the effects of changing redox conditions on the dynamics of organic C, N, P, S, Fe and Al. First results indicated indeed less adsorption of DOM to Fe oxides under anoxic than under oxic conditions, with a more pronounced effect for ferrihydrite than for goethite. Maximum adsorption of DOM was more than 50% larger under oxic than under anoxic conditions. The effect was less pronounced but still detectable for clay minerals such as hydrobiotite, nontronite, and ripodolite. The specific UV absorbance of DOM contact with minerals was 20-50% stronger under anoxic than under oxic conditions. These changes in DOM composition indicated that preferential adsorption of aromatic compounds might be limited to aerated soils. We conclude that adsorption, although less strong than under oxic conditions, is an important mechanism of DOM retention also under anoxic conditions. Decreasi
Soil attributes, soybean mineral nutrition and yield in diverse crop rotations under no-till conditions
Technology Transfer Automated Retrieval System (TEKTRAN)
Development of sustainable agricultural systems depends on understanding complex relationships between soil attributes, crop rotations, and crop yield. Objectives were to measure how soil chemical and physical attributes as well as soybean (Glycine max Merr.) stover dry weight and mineral concentra...
Technology Transfer Automated Retrieval System (TEKTRAN)
The impact of transgenic plants containing Bacillus thuringiensis (Bt) toxin on soil processes has received recent attention. In these studies we examined the influence of the lepidopterean Bt Cry1Ac toxin on mineralization and bioavailability of the herbicide glyphosate in two different soils. The ...
A rapid and cost effective method for soil carbon mineralization under static incubations
Technology Transfer Automated Retrieval System (TEKTRAN)
Soil incubations with subsequent measurement of carbon dioxide (CO2) evolved are common soil assays to estimate C mineralization rates and active organic C. Two common methods used to detect CO2 in laboratory incubations are gas chromatography (GC) and alkali absorption followed by titration (NaOH)...
Sulfur dynamics of two Spodosols were ascertained using soil columns constructed from homogenized mineral soil from northern hardwood ecosystems at the Huntington Forest (HF) in the Adirondack Mountains of New York and Bear Brook Watershed in Maine (BBWM). olumns were leached for...
Nitrogen Mineralization Response to Tillage Practices on Low and High Nitrogen Soils
Technology Transfer Automated Retrieval System (TEKTRAN)
In strip tillage, crop residue is left on soil surface, decreasing the contact between soil and the residue, and therefore reducing decomposition rates compared to conventional tillage methods. Decomposition rates directly affect carbon and nitrogen ratios, which can affect nitrogen mineralization r...
Factors Affecting Mineral Nitrogen Transformations by Soil Heating: A Laboratory Simulated Fire Study.
Technology Transfer Automated Retrieval System (TEKTRAN)
Two forest soils from the Sierra Nevada Mountains of California were brought into the laboratory and subjected to simulated burning in a muffle furnace at several durations, oven temperatures, and water contents. Soils were analyzed for NO3-, NH4+, mineral N, total N, total C, and C:N responses to t...
DIVISION S-10--WETLAND SOILS Carbon Accumulation and Storage in Mineral Subsoil beneath Peat
Moore, Tim
DIVISION S-10--WETLAND SOILS Carbon Accumulation and Storage in Mineral Subsoil beneath Peat Tim R subsoil (Turunen and Moore, 2003). TheyWe showed that sandy subsoils beneath peat near Ramsey Lake conditions beneath the peat. soils beneath the forest, those beneath the peat contained similar In this paper
Technology Transfer Automated Retrieval System (TEKTRAN)
A field study was conducted during 2004-2005 to determine nitrogen (N) mineralization of broiler litter (BL) in two Coastal Plain soils of differing texture, sandy or clayey. The soils were a Tifton loamy sand (fine-loamy, siliceous, thermic, Plinthic Kandiudults) and a Greenville sandy clay loam (...
Influence of organic and mineral fertilisers on soil biological and physical properties
S Marinari; G Masciandaro; B Ceccanti; S Grego
The aim of this research was to study in a field experiment the influence of different fertiliser applications on soil biological and physical properties. Vermicompost (VC) from biological sludge, stabilised dairy manure or mineral nitrogen fertiliser (NH4NO3) were applied to a corn crop (Zea mays L.) at 200 kg N ha?1. Soil enzyme activity (acid phosphatase, dehydrogenase and protease BAA)
A Simulation of the Interaction of Acid Rain with Soil Minerals
ERIC Educational Resources Information Center
Schilling, Amber L.; Hess, Kenneth R.; Leber, Phyllis A.; Yoder, Claude H.
The atmospheric issue of acid rains is subjected to a five-part laboratory experiment by concentrating on the chemistry of the infiltration process of acid rainwater through soils. This procedure of quantitative scrutiny helps students realize the efficacy of soil minerals in the consumption of surplus acidity in rainwater.
Mineralization of soil organic matter in two elevated CO2 by warming experiments in grassland
Technology Transfer Automated Retrieval System (TEKTRAN)
Experimentally elevated atmospheric CO2 has enhanced carbon (C) allocation belowground, while ecosystem warming has led to losses of soil C due to enhanced mineralization of soil organic matter (SOM). Few investigations of possible interactions between elevated CO2 and temperature have been reported...
Performance of exogenous sugarcane germplasm on mineral soils of Florida, USA
Technology Transfer Automated Retrieval System (TEKTRAN)
The Canal Point (CP) breeding program has been very successful in producing commercial sugarcane cultivars for growers on organic soils in Florida. However 20% of sugarcane is cultivated on mineral soils in Florida, and growers have expressed interest in germplasm released from programs exclusively...
Kuldip Kumar; Carl J. Rosen; Satish C. Gupta
Application of sugar beet processing by-products to agricultural land has become a common practice to reduce disposal costs. This study was conducted to estimate N mineralization in soils amended with sugar beet processing by-products. Field moist Bearden and Angus soils adjusted to 80% field capacity water content and amended with beet pulp, beet tailings, spoiled and fresh sugar beet roots
Soil mineral genesis and distribution in a saline lake landscape of the Pantanal Wetland, Brazil
Ahmad, Sajjad
Soil mineral genesis and distribution in a saline lake landscape of the Pantanal Wetland, Brazil S Geografia, Universidade de SŃo Paulo, SŃo Paulo, Brazil b Soil & Water Sciences Program, Department SŃo Paulo, Piracicaba, Brazil a b s t r a c ta r t i c l e i n f o Article history: Received 20 August
Differential Adsorption of Occluded and Nonoccluded Insect-Pathogenic Viruses to Soil-Forming Minerals
Christian, Peter D.; Richards, Andrew R.; Williams, Trevor
Soil represents the principal environmental reservoir of many insect-pathogenic viruses. We compared the adsorption and infectivity of one occluded and two nonoccluded viruses, Helicoverpa armigera single nucleopolyhedrovirus (HaSNPV) (Baculoviridae), Cricket paralysis virus (CrPV) (Dicistroviridae), and Invertebrate iridescent virus 6 (IIV-6) (Iridoviridae), respectively, in mixtures with a selection of soil-forming minerals. The relative infective titers of HaSNPV and CrPV were unchanged or slightly reduced in the presence of different minerals compared to their titers in the absence of the mineral. In contrast, the infective titer of IIV-6 varied according to the mineral being tested. In adsorption studies, over 98% of HaSNPV occlusion bodies were adsorbed by all the minerals, and a particularly high affinity was observed with ferric oxide, attapulgite, and kaolinite. In contrast, the adsorption of CrPV and IIV-6 differed markedly with mineral type, with low affinity to bentonites and high affinity to ferric oxide and kaolinite. We conclude that interactions between soil-forming minerals and insect viruses appear to be most important in nucleopolyhedroviruses, followed by invertebrate iridescent viruses, and least important in CrPV, which may reflect the ecology of these pathogens. Moreover, soils with a high content of iron oxides or kaolinite would likely represent highly effective reservoirs for insect-pathogenic viruses. PMID:16820456
Shedding light on carbon-mineral complexation in the soil environment: impacts on C sequestration and cycling
Sparks, Donald L.
42 Shedding light on carbon-mineral complexation in the soil environment: impacts on C sequestration and cycling Sparks, D.L. & C. Chen Department of Plant and Soil Sciences and firstname.lastname@example.com) Abstract Organic matter (OM)-mineral complexation plays a critical role in soil carbon (C) stabilization
Microbial nitrogen dynamics in organic and mineral soil horizons along a latitudinal transect in western Siberia
NASA Astrophysics Data System (ADS)
Wild, Birgit; Schnecker, J÷rg; Knoltsch, Anna; Takriti, Mounir; Mooshammer, Maria; Gentsch, Norman; Mikutta, Robert; Alves, Ricardo J. Eloy; Gittel, Antje; Lashchinskiy, Nikolay; Richter, Andreas
Soil N availability is constrained by the breakdown of N-containing polymers such as proteins to oligopeptides and amino acids that can be taken up by plants and microorganisms. Excess N is released from microbial cells as ammonium (N mineralization), which in turn can serve as substrate for nitrification. According to stoichiometric theory, N mineralization and nitrification are expected to increase in relation to protein depolymerization with decreasing N limitation, and thus from higher to lower latitudes and from topsoils to subsoils. To test these hypotheses, we compared gross rates of protein depolymerization, N mineralization and nitrification (determined using 15N pool dilution assays) in organic topsoil, mineral topsoil, and mineral subsoil of seven ecosystems along a latitudinal transect in western Siberia, from tundra (67░N) to steppe (54░N). The investigated ecosystems differed strongly in N transformation rates, with highest protein depolymerization and N mineralization rates in middle and southern taiga. All N transformation rates decreased with soil depth following the decrease in organic matter content. Related to protein depolymerization, N mineralization and nitrification were significantly higher in mineral than in organic horizons, supporting a decrease in microbial N limitation with depth. In contrast, we did not find indications for a decrease in microbial N limitation from arctic to temperate ecosystems along the transect. Our findings thus challenge the perception of ubiquitous N limitation at high latitudes, but suggest a transition from N to C limitation of microorganisms with soil depth, even in high-latitude systems such as tundra and boreal forest.
Mineral Contamination from Cemetery Soils: Case Study of Zandfontein Cemetery, South Africa
Jonker, Cornelia; Olivier, Jana
The burial of coffins may pose an environmental and health hazard since the metals that are used in coffin-making may corrode or degrade into harmful toxins. These may leach into the surrounding soils and groundwater. Very little research has been conducted world-wide on the mineral contamination potential of cemeteries, and virtually none in South Africa. The aim of the study is to determine whether burial practices affect the mineral content of soils in cemeteries. This was done by comparing the mineral concentrations of soils within the Zandfontein Cemetery in Tshwane (Gauteng, South Africa) to those off-site as well as those in zones with high burial loads with those zones with fewer burials. Twenty three soil samples were collected from various sites on- and off-site and analyzed for 31 minerals using ICP-AES. It was found that mineral concentrations of soils within the Zandfontein Cemetery were considerably higher than those off-site. Soil samples in multiple burials blocks also have elevated metal concentrations. These excess metals are probably of anthropogenic origin associated with burial practices and could pose an environmental and human health hazard. Strict monitoring of water quality in boreholes in the vicinity of the cemetery is recommended. PMID:22470306
Adsorption of Pesticides and Their Biodegraded Products on Clay Minerals and Soils
Yuichi Fushiwaki; Kohei Uranob
Adsorption isotherms of 10 pesticides and their biodegradation intermediates on clay minerals and soils were investigated to predict the fate of pesticides in the environment. The adsorption isotherms were expressed by the Freundlich isotherm equation. Penta- chloronitrobenzene, 2,4,6-trichlorophenyl-4'-nitro- phenylether, and various intermediates were highly adsorbed on soils, although isoprothiolane was only slightly adsorbed. The adsorbabilities of pesticides on ando soil,
Lunar mineral feedstocks from rocks and soils: X-ray digital imaging in resource evaluation
NASA Technical Reports Server (NTRS)
Chambers, John G.; Patchen, Allan; Taylor, Lawrence A.; Higgins, Stefan J.; Mckay, David S.
The rocks and soils of the Moon provide raw materials essential to the successful establishment of a lunar base. Efficient exploitation of these resources requires accurate characterization of mineral abundances, sizes/shapes, and association of 'ore' and 'gangue' phases, as well as the technology to generate high-yield/high-grade feedstocks. Only recently have x-ray mapping and digital imaging techniques been applied to lunar resource evaluation. The topics covered include inherent differences between lunar basalts and soils and quantitative comparison of rock-derived and soil-derived ilmenite concentrates. It is concluded that x-ray digital-imaging characterization of lunar raw materials provides a quantitative comparison that is unattainable by traditional petrographic techniques. These data are necessary for accurately determining mineral distributions of soil and crushed rock material. Application of these techniques will provide an important link to choosing the best raw material for mineral beneficiation.
Carbon mineralization and soil fertility at high altitude grasslands in the Bolivian Andean
NASA Astrophysics Data System (ADS)
Zornoza, R.; Mu±oz, M. A.; Faz, A.
The high grasslands of Apolobamba provide a natural habitat for a high number of wild and domestic camelids such as vicuna (Vicugna vicugna) and alpaca (Lama pacos) in Bolivia. Because of the importance of the camelid raising for the Apolobambßs inhabitant economy, it is fundamental to determine the natural resources condition and their availability for the camelid support. The soil organic matter plays a crucial role in the maintenance of the soil fertility at high grasslands. On the other hand, soil respiration is the primary pathway for CO2 fixed by plants returning to the atmosphere and its study is essential to evaluate the soil organic matter mineralization and the global C cycle. Based on this, the objectives of this research were to: (i) evaluate the soil fertility and (ii) determine soil organic matter mineralization on the basis of CO2 releases in Apolobamba. Regarding the lastly vicuna censuses carried out in the studied area, eight representative zones with dissimilar vicuna densities were selected. Other characteristics were also considered to select the study zones: (1) alpaca densities, (2) vegetation communities (3) plant cover and (4) landscape and geo-morphological description. Soil samples from different samplings were collected. Soil respiration was determined at two temperatures: 15 ░C (based on the highest atmosphere temperature that was registered in the area) and 25 ░C, in order to monitor the increase in soil respiration (Q10). The physico-chemical soil results pointed out the good soil fertility. However, erosive processes could be taken place likely caused by the alpaca grazing. High total organic carbon contents were observed corresponding to the highest soil respiration at 15 ░C. This observation was supported by the relationship found between the total organic carbon and the soil respiration. A noticeable increase of the soil respiration when the temperature increased 10 ░C was reported (from 1083 ▒ 47 g C m-2 yr-1 at 15 ░C to 2786 ▒ 343 g C m-2 yr-1 at 25 ░C ) which indicated the organic matter mineralization increase and likely the high C reservoirs decrease. Additionally, high Q10 values were observed (13.8 ▒ 1.5 in subsurface). This indicates that basically climate conditions are actually controlling organic matter mineralization and it is more evident in zones with high total organic carbon contents. Although no vicuna affection on the soil fertility was observed, the camelid grazing generally causes a reduction in the soil respiration rate in Apolobamba. Therefore, it should be undertaken some protection actions to prevent the biodiversity affection bringing camelid overexploitation under control in Bolivian Andean. Keywords: biodiversity, high grasslands, camelid grazing, carbon mineralization, soil respiration
Soil moisture influence on the interannual variation in temperature sensitivity of soil organic carbon mineralization in the Loess Plateau
NASA Astrophysics Data System (ADS)
Zhang, Y. J.; Guo, S. L.; Zhao, M.; Du, L. L.; Li, R. J.; Jiang, J. S.; Wang, R.; Li, N. N.
Temperature sensitivity of soil organic carbon (SOC) mineralization (i.e., Q10) determines how strong the feedback from global warming may be on the atmospheric CO2 concentration; thus, understanding the factors influencing the interannual variation in Q10 is important for accurately estimating local soil carbon cycle. In situ SOC mineralization rate was measured using an automated CO2 flux system (Li-8100) in long-term bare fallow soil in the Loess Plateau (35░12' N, 107░40' E) in Changwu, Shaanxi, China from 2008 to 2013. The results showed that the annual cumulative SOC mineralization ranged from 226 to 298 g C m-2 yr-1, with a mean of 253 g C m-2 yr-1 and a coefficient of variation (CV) of 13%, annual Q10 ranged from 1.48 to 1.94, with a mean of 1.70 and a CV of 10%, and annual soil moisture content ranged from 38.6 to 50.7% soil water-filled pore space (WFPS), with a mean of 43.8% WFPS and a CV of 11%, which were mainly affected by the frequency and distribution of precipitation. Annual Q10 showed a quadratic correlation with annual mean soil moisture content. In conclusion, understanding of the relationships between interannual variation in Q10, soil moisture, and precipitation are important to accurately estimate the local carbon cycle, especially under the changing climate.
Food Safety Issues: Mineral fertilizers and soil amendments
Technology Transfer Automated Retrieval System (TEKTRAN)
Fertilizers and other soil amendments are required to maintain soil fertility, but some may be naturally rich in trace elements, or contaminated. Thus, as part of the overall consideration of using fertilizers and soil amendments, one should consider the levels of trace elements present in relation...
Microbial Contribution to Organic Carbon Sequestration in Mineral Soil
Technology Transfer Automated Retrieval System (TEKTRAN)
Soil productivity and sustainability are dependent on soil organic matter (SOM). Our understanding on how organic inputs to soil from microbial processes become converted to SOM is still limited. This study aims to understand how microbes affect carbon (C) sequestration and the formation of recalcit...
Uranium Sequestration by Aluminum Phosphate Minerals in Unsaturated Soils
Jerden; James L. Jr
A mineralogical and geochemical study of soils developed from the unmined Coles Hill uranium deposit (Virginia) was undertaken to determine how phosphorous influences the speciation of uranium in an oxidizing soil\\/saprolite system typical of the eastern United States. This paper presents mineralogical and geochemical results that identify and quantify the processes by which uranium has been sequestered in these soils.
Effects of flooding and warming on soil organic matter mineralization in Avicennia germinans mangrove forests and Juncus roemerianus salt marshes
NASA Astrophysics Data System (ADS)
Lewis, David Bruce; Brown, Jewel A.; Jimenez, Kristine L.
Under a changing climate, coastal wetlands experience sea level rise, warming, and vegetation change, all of which may influence organic matter mineralization. In coastal wetlands of subtropical west-central Florida (USA), we investigated how soil carbon (C) and nitrogen (N) mineralization respond to soil water, temperature, and ecosystem type (Avicennia germinans mangrove forest vs. Juncus roemerianus salt marsh). We evaluated how soil respiration and mineral N concentration varied along a soil moisture gradient, and whether these relationships differed between ecosystem types. Then, we manipulated soils in a 28-d laboratory incubation to evaluate how potentially mineralizable C and N respond to temperature (23 vs. 27Ā░C), soil hydroperiod (inundated 4 vs. 20Āh/d), and soil source. Soil saturation and inundation suppressed short-term (minutes to weeks) C mineralization from near-surface soils. Soil CO2 efflux declined by 65% as soil moisture increased from 75% to 85%, and potentially mineralizable C was 18% lower with a 20-h hydroperiod than with a 4-h hydroperiod. Organic C quality appears to be greater in A.Āgerminans than in J.Āroemerianus soils, as A.Āgerminans soils had higher field CO2 efflux rates and greater mineralizable C:N (despite lower total C:N). Increasing incubation temperature from 23 to 27Ā░C elevated potentially mineralizable C by 40%, indicating that two symptoms of climate change (increased inundation from sea level rise, and warming) may have opposing effects on soil C mineralization. Temperature sensitivity of C mineralization was high for long-hydroperiod soils, however, suggesting that protection of soil organic matter (SOM) due to prolonged inundation will be undermined by warming. Potentially mineralizable N was greater in J.Āroemerianus soils, although in situ mineral N was not different between ecosystems, instead correlating positively with SOM. These results indicate that models forecasting soil elevation responses to climate change might include inundation effects on mineralization rates.
Bacteria-mineral interactions in soil and their effect on particle surface properties
NASA Astrophysics Data System (ADS)
Miltner, Anja; Achtenhagen, Jan; Goebel, Marc-Oliver; Bachmann, J÷rg; Kõstner, Matthias
Interactions between bacteria or their residues and mineral surfaces play an important role for soil processes and properties. It is well known that bacteria tend to grow attached to surfaces and that they get more hydrophobic when grown under stress conditions. In addition, bacterial and fungal biomass residues have recently been shown to contribute to soil organic matter formation. The attachment of bacteria or their residues to soil minerals can be expected to modify the surface properties of these particles, in particular the wettability. We hypothesize that the extent of the effect depends on the surface properties of the bacteria, which change depending on environmental conditions. As the wettability of soil particles is crucial for the distribution and the availability of water, we investigated the effect of both living cells and bacterial residues (cell envelope fragments and cytosol) on the wettability of model mineral particles in a simplified laboratory system. We grew Pseudomonas putida cells in mineral medium either without (unstressed) or with additional 1.5 M NaCl (osmotically stressed). After 2 h of incubation, the cells were disintegrated by ultrasonic treatment. Different amounts of either intact cells, cell envelope fragments or cytosol (each corresponding to 108, 109, or 1010 cells per gram of mineral) were mixed with quartz sand, quartz silt or kaolinite. The bacteria-mineral associations were air-dried for 2 hours and analyzed for their contact angle. We found that the surfaces of osmotically stressed cells were more hydrophobic than the surfaces of unstressed cells and that the bacteria-mineral associations had higher contact angles than the pure minerals. A rather low surface coverage (~10%) of the mineral surfaces by bacteria was sufficient to increase the contact angle significantly, and the different wettabilities of stressed and unstressed cells were reflected in the contact angles of the bacteria-mineral associations. The increases in the contact angles were similar for intact cells and cell envelope fragments, whereas they were even more pronounced if the minerals interacted with the cytosol. Based on these results we conclude that bacterial cells and their residues play an important role in controlling soil particle surface properties, in particular wettability. This process can explain the development of water repellency in soils, which has a major impact on the distribution and availability of water in soils at the microscale.
High temperature and salinity enhance soil nitrogen mineralization in a tidal freshwater marsh.
Gao, Haifeng; Bai, Junhong; He, Xinhua; Zhao, Qingqing; Lu, Qiongqiong; Wang, Junjing
Soil nitrogen (N) mineralization in wetlands is sensitive to various environmental factors. To compare the effects of salinity and temperature on N mineralization, wetland soils from a tidal freshwater marsh locating in the Yellow River Delta was incubated over a 48-d anaerobic incubation period under four salinity concentrations (0, 10, 20 and 35ē) and four temperature levels (10, 20, 30 and 40░C). The results suggested that accumulated ammonium nitrogen (NH4+-N) increased with increasing incubation time under all salinity concentrations. Higher temperatures and salinities significantly enhanced soil N mineralization except for a short-term (?10 days) inhibiting effect found under 35ē salinity. The incubation time, temperature, salinity and their interactions exhibited significant effects on N mineralization (P<0.001) except the interactive effect of salinity and temperature (P>0.05), while temperature exhibited the greatest effect (P<0.001). Meanwhile, N mineralization processes were simulated using both an effective accumulated temperature model and a one-pool model. Both models fit well with the simulation of soil N mineralization process in the coastal freshwater wetlands under a range of 30 to 40░C (R2?=?0.88-0.99, P<0.01). Our results indicated that an enhanced NH4+-N release with increasing temperature and salinity deriving from the projected global warming could have profound effects on nutrient cycling in coastal wetland ecosystems. PMID:24733366
On the origin of superparamagnetic minerals of tropical soils and their impact on landmine detection
NASA Astrophysics Data System (ADS)
Igel, Jan; Preetz, Holger; Altfelder, Sven
Magnetic susceptibility of soils is mainly determined by their content of ferrimagnetic minerals whereas titanomagnetite, magnetite and maghemite being the most important ones. Titanomagnetite and magnetite are of magmatic origin, i.e. they crystallise during cooling of iron-rich magma and are part of many igneous rocks. Maghemite and sometimes magnetite are of pedogenic origin. They develop by crystallisation of dissolved iron during soil forming processes. Ferrimagnetic minerals that are smaller than some tens of nanometres are superparamagnetic (SP) and show frequency dependent susceptibility. SP minerals crystallise if magma cools down rapidly (e.g. volcanic magmas, glasses and ashes) and are frequently formed during pedogenesis. In order to investigate the origin and formation of SP minerals in tropical soils, we analyse magnetic properties of 594 samples from the entire tropics comprising the whole range of weathering states from unweathered rock to highly weathered soil. Tropical soils are subject to intense chemical weathering and are rich in ferrimagnetic and in particular SP minerals. The process leading to a high content of these minerals is either residual enrichment due to their weathering resistance or neo-formation. In this study we focus on the frequency dependent susceptibility (absolute and relative) of the samples and classify it according to the parent material and alteration. We observe that Ģ within each parent-material group, rock material shows in general lower susceptibility and absolute frequency dependence than soil material Ģ ultrabasic and basic/intermediate rocks and soils developed from these rocks show high absolute frequency dependent susceptibility and, in contrast, acid rocks and sediments show lower absolute frequency dependence Ģ absolute frequency dependence increases from unweathered rock to weathered rock, and from subsoil to topsoil material within every group of parent material Ģ relative frequency dependence rises successively with weathering for ultrabasic, basic/intermediate and acid igneous parent material, but, it tends to decrease for clay/clay slate and sandstone. Based on the above observations we conclude that the content of SP minerals depends on both: parent rock and alteration of the material. The total amount of SP minerals rises during weathering, regardless of the parent material. The process is either preferential accumulation of weathering resistant magnetic minerals, including the ultra-fine grained fraction, or neo-formation of new magnetic minerals. The increase of relative frequency dependence of igneous rocks is a clear indication that SP minerals are formed during soil genesis. However, for some sedimentary rocks, the amount of SP minerals is already high and is not subsequently increased further during weathering. Electromagnetic induction (EMI) based metal detectors are the most widely used sensing techniques in landmine clearance operations. They are negatively influenced by magnetic susceptibility and its frequency dependence. In particular tropical soils show to have a negative impact on EMI sensors. Besides, the tropics are the regions which are most affected by landmines where most of the humanitarian demining-activities concentrate. Currently, no soil classification system exists that helps to predict the influence of frequency dependent susceptibility on landmine detection. We deduce a system that can be used to predict the soil impact depending on parent material and weathering. Our system can be consulted by demining organisations to predict metal detector performance in tropical regions based on geologic and soil maps. Ultra-basic, basic and intermediate igneous rocks have a moderate influence on EMI detectors in average cases and a very severe influence in extreme cases. Soils developed from these rocks have a severe or very severe influence. In contrast, acid igneous rocks and sediments do not influence EMI detectors severely. Soils developed from these rocks have no influence in average cases; however, they may have a very severe infl
Microbes residing in young organic rich Alaskan soils contain older carbon than those residing in old mineral high Arctic soils
NASA Astrophysics Data System (ADS)
Ziolkowski, L. A.; Slater, G. F.; Onstott, T. C.; Whyte, L.; Townsend-Small, A.
Arctic soils range from very organic rich to low carbon and mineral-dominated soils. At present, we do not yet fully understand if all carbon in the Arctic is equally vulnerable to mineralization in a warmer climate. Many studies have demonstrated that ancient carbon is respired when permafrost has thawed, yet our understanding of the active layer and permafrost carbon dynamics is still emerging. In an effort to remedy this disconnect between our knowledge of surface fluxes and below ground processes, we used radiocarbon to examine the microbial carbon dynamics in soil cores from organic rich soils near Barrow, Alaska and mineral soils from the Canadian high Arctic. Specifically, we compared the microbial community using lipid biomarkers, the inputs of carbon using n-alkanes and measured the 14C of both the bulk organic carbon and of the microbial lipids. In theory, the microbial lipids (phospholipid fatty acids, PLFA) represent the viable microbial community, as these lipids are hydrolyzed quickly after cell death. Variations in the PLFA distributions suggested that different microbial communities inhabit organic rich Alaskan soils and those of the Canadian high Arctic. When the PLFA concentrations were converted to cellular concentration, they were within the same order of magnitude (1 to 5 x 108 cells/g dry soil) with slightly higher cell concentrations in the organic rich Alaskan soils. When these cellular concentrations were normalized to the organic carbon content, the Canadian high Arctic soils contained a greater proportion of microbes. Although bulk organic carbon 14C of Alaskan soils indicated more recent carbon inputs into the soil than the Canadian high Arctic soils, the 14C of the PLFA revealed the opposite. For corresponding depth horizons, microbes in Alaskan soils were consuming carbon 1000 to 1500 years older than those in the Canadian high Arctic. Differences between the 14C content of bulk organic carbon and the microbial lipids were much smaller in Alaskan soil than that of the Canadian high Arctic soil, indicating that Alaskan microbes were interacting with the bulk organic carbon pool and Canadian high Arctic soil microbes were disconnected from the bulk organic carbon pool. Additionally, dissimilarities in the n-alkane distributions suggest vastly different carbon sources to these different soils. Collectively, these results suggest that (a) these Arctic soils contain a comparable abundance of microbes, (b) the organic carbon being accumulated in the Alaskan soil is likely from recent biomass, (c) mineral soil accumulation in the Canadian high Arctic is likely due to erosional inputs of ancient carbon and (d) the carbon stocks in Alaskan soils are more bioavailable to the microbes than those in mineral soils of the Canadian high Arctic. Incubation studies that incorporate gas fluxes and proteomics may tease apart if the observed differences in bioavailability are a function of temperature, substrate availability or some other variable.
Forest type affects the coupled relationships of soil C and N mineralization in the temperate forests of northern China
NASA Astrophysics Data System (ADS)
Quan, Quan; Wang, Changhui; He, Nianpeng; Zhang, Zhen; Wen, Xuefa; Su, Hongxin; Wang, Qing; Xue, Jingyue
Decomposition of soil organic matter (SOM) is sensitive to vegetation and climate change. Here, we investigated the influence of changes in forest types on the mineralization of soil carbon (C) and nitrogen (N), and their temperature sensitivity (Q10) and coupling relationships by using a laboratory soil incubation experiments. We sampled soils from four forest types, namely, a primary Quercus liaotungensis forest (QL), Larix principis-rupprechtii plantation (LP), Pinus tabulaeformis plantation (PT), and secondary shrub forest (SS) in temperate northern China. The results showed that soil C and N mineralization differed significantly among forest types. Soil C and N mineralization were closely coupled in all plots, and C:N ratios of mineralized SOM ranged from 2.54 to 4.12. Forest type significantly influenced the Q10 values of soil C and N mineralization. The activation energy (Ea) of soil C and N mineralization was negatively related to the SOM quality index in all forest types. The reverse relationships suggested that the carbon quality-temperature (CQT) hypothesis was simultaneously applicable to soil C and N mineralization. Our findings show that the coupled relationships of soil C and N mineralization can be affected by vegetation change.
Forest type affects the coupled relationships of soil C and N mineralization in the temperate forests of northern China
Quan, Quan; Wang, Changhui; He, Nianpeng; Zhang, Zhen; Wen, Xuefa; Su, Hongxin; Wang, Qing; Xue, Jingyue
Decomposition of soil organic matter (SOM) is sensitive to vegetation and climate change. Here, we investigated the influence of changes in forest types on the mineralization of soil carbon (C) and nitrogen (N), and their temperature sensitivity (Q10) and coupling relationships by using a laboratory soil incubation experiments. We sampled soils from four forest types, namely, a primary Quercus liaotungensis forest (QL), Larix principis-rupprechtii plantation (LP), Pinus tabulaeformis plantation (PT), and secondary shrub forest (SS) in temperate northern China. The results showed that soil C and N mineralization differed significantly among forest types. Soil C and N mineralization were closely coupled in all plots, and C:N ratios of mineralized SOM ranged from 2.54 to 4.12. Forest type significantly influenced the Q10 values of soil C and N mineralization. The activation energy (Ea) of soil C and N mineralization was negatively related to the SOM quality index in all forest types. The reverse relationships suggested that the carbon quality-temperature (CQT) hypothesis was simultaneously applicable to soil C and N mineralization. Our findings show that the coupled relationships of soil C and N mineralization can be affected by vegetation change. PMID:25322802
NSDL National Science Digital Library
This site provides an in-depth look at mineral properties and identification. An alphabetical listing of common minerals allows the user to see a picture and view physical properties of the particular mineral. Properties of minerals are explained, including cleavage, hardness, crystal form, and luster. There are also downloadable labs for crystal models and mineral data sheets. Dichotomous and hardness keys are given for easier mineral identification.
Degradation of plant cuticles in soils: impact on formation and sorptive ability of humin-mineral matrices.
Olshansky, Yaniv; Polubesova, Tamara; Chefetz, Benny
Plant cuticles are important precursors for soil organic matter, in particular for soil humin, which is considered an efficient sorbent for organic pollutants. In this study, we examined degradation and transformation of cuticles isolated from fruit and leaves in loamy sand and sandy clay loessial arid brown soils. We then studied sorption of phenanthrene and carbamazepine to humin-mineral matrices isolated from the incubated soils. Low degradation (22%) was observed for agave cuticle in a sandy clay soil system, whereas high degradation (68-78%) was obtained for agave cuticle in a loamy sand soil system and for loamy sand and sandy clay soils amended with tomato cuticle. During incubation, most of the residual organic matter was accumulated in the humin fraction. Sorption of phenanthrene was significantly higher for humin-mineral matrices obtained from soils incubated with plant cuticles as compared with soils without cuticle application. Sorption of carbamazepine to humin-mineral matrices was not affected by cuticle residues. Cooperative sorption of carbamazepine on humin-mineral matrices isolated from sandy clay soil is suggested. Sorption-desorption hysteresis of both phenanthrene and carbamazepine was lower for humin-mineral matrices obtained from soils incubated with plant cuticles as compared with nonamended soils. Our results show that cuticle composition significantly affects the rate and extent of cuticle degradation in soils and that plant cuticle application influences sorption and desorption of polar and nonpolar pollutants by humin-mineral matrices. PMID:26024265
Effect of cyclodextrins on surface and pore properties of soil clay minerals.
Jozefaciuk, G; Muranyi, A; Fenyvesi, E
Although cyclodextrins are increasingly used in soil decontamination, little is known about their effects on soil physicochemical properties. In this work, the surface and pore properties of randomly methylated beta-cyclodextrin (RAMEB) and three typical clay minerals were characterized, and the effects of RAMEB concentrations on clay minerals were studied using water vapor adsorption-desorption and mercury intrusion porosimetry techniques. As compared to clay minerals, for pure RAMEB very large surface area and volume of nanometer-size pores (micropores) were determined. Energy of interaction with water vapor, volume of micrometer-size pores (mesopores), and fractal dimensions in both pore size ranges of RAMEB were lower than those of the minerals. When increasing amounts of RAMEB were added to the minerals, the surface area and micropore volume decreased and adsorption energy increased. The volume of mesopores decreased after RAMEB treatments for bentonite and kaolin and increased for illite. As deduced from the fractal dimensions increase, the pore structure of the minerals became more complex with RAMEB addition. The observed changes were in general contrary to these expected when RAMEB and minerals coexist as separate, nonreactive phases and suggested strong interaction of RAMEB with clay minerals. PMID:11775177
Persistence of Mineral-Associated Soil Organic Carbon in European Soil Profiles
NASA Astrophysics Data System (ADS)
Mayer, A.; Schrumpf, M.; Trumbore, S.
Soil Organic Carbon (SOC) is a heterogeneous mixture of components that are not equally biologically available, including light, plant derived material, dissolved organic carbon, and mineral-associated organic matter (MOM). Radiocarbon ages of bulk SOC average across this heterogeneity. Of particular interest is whether there are small amounts of very old OC (the so-called 'passive' pool) that can mask the fact that much of the OM is much younger. MOM has been shown to be older than the light fraction and DOC, but MOM is also a mixture of old and young material. This study seeks to clarify the quantity of C persisting on millennial time scales at different depths in the soil profile, and what factors allow this fraction to be more persistent than other fractions. We studied the fraction and age of C of the most chemically and physically stable fraction we could isolate from five European soils with differing land use, parent material, and soil type. First we isolated the MOM fraction by density, and then oxidized the MOM fraction with H2O2 to remove the labile C. The oxidation resistant residue was analyzed for C content and radiocarbon signature. The oxidation procedure removed 70-95% of the MOM fraction; the residue had a consistently older radiocarbon signature than the initial MOM, indicating that the C removed was younger than the bulk average. This stable fraction ranged from 100 radiocarbon years Before Present (BP) in the top 5 cm, to 10,000 years BP at the 30-40 cm depth. Non-crystalline iron concentrations were correlated with the absolute amount of SOC protected from oxidation, but not its proportion or age. With the exception of a tilled cropland site, all examined profiles exhibited a nearly linear depletion in radiocarbon signature with depth in both the protected and oxidizable MOM, confirming that the most chemically and physically stable C is oldest at the deepest point in a 50 cm profile. Ongoing work on this study will further elucidate how the origin of the MOM (microbe-, plant-, or parent material-derived) relates to the radiocarbon age along the soil depth profile.
Iron Redox Cycling Drives Decomposition of Mineral-Associated C in Humid Tropical Forest Soils
NASA Astrophysics Data System (ADS)
Hall, S. J.; Mcnicol, G.; Silver, W. L.
The stabilization of soil carbon (C) by reactive minerals and an inhibition of decomposition due to oxygen (O2) limitation (reducing conditions) have been proposed as drivers of the high soil C concentrations characteristic of humid tropical forests, which constitute a major terrestrial C reservoir. Here, we examined relationships between these factors and spatial patterns of C concentrations and C turnover (using radiocarbon modeling) in surface soils of the Luquillo Experimental Forest, Puerto Rico. We used concentrations of reduced iron (Fe(II)) as an index of reducing conditions given the importance of Fe reduction to anaerobic metabolism in these soils. Concentrations of Fe(II), reactive iron and aluminum (Al) minerals, interactions between Fe(II) and Al, and live fine root biomass explained most variation in C concentrations across the landscape (pseudo R2 = 0.84). Carbon increased with chelatable "poorly crystalline" Fe, in agreement with previous research, but C decreased with citrate/ascorbate extractable Fe, an index of Fe oxides susceptible to microbial reduction. We suggest that availability of Fe oxides to sustain anaerobic respiration partially offsets soil C accumulation in these ecosystems, despite the role of a subset of reactive Fe in promoting C stabilization. We estimated decomposition rates of mineral-associated C using 14C content of the heavy soil density fraction from a subset of samples. Turnover times averaged 108 years but decreased with Fe(II) concentrations. Thus, our data suggest that Fe redox cycling in soil microsites is associated with increased turnover of mineral-associated C in this fluctuating-oxygen environment, implying that the capacity of reactive metals to stabilize C may be partially contingent on O2 dynamics. Our results suggest a multifaceted role for reactive minerals in soil C cycling, emphasizing the importance of ecosystem-scale interactions among geochemical, physical, and biological factors.
Soil sorption and leaching of active ingredients of Lumax« under mineral or organic fertilization.
Pinna, Maria Vittoria; Roggero, Pier Paolo; Seddaiu, Giovanna; Pusino, Alba
The study describes the soil sorption of the herbicide Lumax«, composed of S-metolachlor (MTC), terbuthylazine (TBZ), and mesotrione (MST), as influenced by mineral and organic fertilizers. The investigation was performed on a sandy soil of an agricultural area designated as a Nitrate Vulnerable Zone, where mineral and organic fertilizers were applied for many years. Two organic fertilizers, cattle manure and slurry, respectively, and a mineral fertilizer with a nitrification inhibitor, Entec«, were compared. According to the experiments, performed with a batch method, the sorption conformed to Freundlich model. The extent of sorption of Lumax« ingredients was closely related to their octanol-water partition coefficient Kow. The respective desorption was hysteretic. Leaching trials were carried out by using water or solutions of DOM or Entec« as the eluants. Only the elution with the mineral fertilizer promoted the leaching of Lumax« active ingredients. PMID:24997942
Effects of amendment of different biochars on soil physical and biological properties related to carbon mineralization
NASA Astrophysics Data System (ADS)
Zhang, Renduo; Zhu, Shuzhi; Ouyang, Lei
Biochar addition to soils potentially affects various soil properties, and these effects are dependent on biochars derived from different feedstock materials and pyrolysis processes. The objective of this study was to investigate the effects of amendment of different biochars on soil physical and biological properties. Biochars were produced with dairy manure and woodchip at temperatures of 300, 500, and 700░C, respectively. Each biochar was mixed at 5% (w/w) with a forest soil and the mixture was incubated for 180 days, during which soil physical and biological properties, and soil respiration rates were measured. Results showed that the biochar addition significantly enhanced the formation of soil macroaggregates at the early incubation time. The biochar application significantly reduced soil bulk density, increased the amount of soil organic matter, and stimulated microbial activity and soil respiration rates at the early incubation stage. Biochar applications improved water retention capacity, with stronger effects by biochars produced at higher pyrolysis temperatures. At the same suction, the soil with woodchip biochars possessed higher water content than with the dairy manure biochars. Biochar addition significantly affected the soil physical and biological properties, which resulted in different soil carbon mineralization rates.
Dynamic role of ōillite-likeö clay minerals in temperate soils: facts and hypotheses
P. Barrķ; B. Velde; L. Abbadie
Analysis of new data and reinterpretation of published information for clay minerals found in temperate climate soil profiles\\u000a indicates that there is often a gradient of ōillite-likeö clay minerals with depth. We used the term ōillite-likeö because\\u000a these observations are based on X-Ray Diffractogram patterns and not on layer charge measurements which allow to define properly\\u000a illite. It appears that
The priming effect of soluble carbon inputs in organic and mineral soils from a temperate forest.
Wang, Hui; Xu, Wenhua; Hu, Guoqing; Dai, Weiwei; Jiang, Ping; Bai, Edith
The priming effect (PE) is one of the most important interactions between C input and output in soils. Here we aim to quantify patterns of PE in response to six addition rates of (13)C-labeled water-soluble C (WSC) and determine if these patterns are different between soil organic and mineral layers in a temperate forest. Isotope mass balance was used to distinguish WSC derived from SOC-derived CO2 respiration. The relative PE was 1.1-3.3 times stronger in the mineral layer than in the organic layer, indicating higher sensitivity of the mineral layer to WSC addition. However, the magnitude of cumulative PE was significantly higher in the organic layer than in the mineral layer due to higher SOC in the organic layer. With an increasing WSC addition rate, cumulative PE increased for both layers, but tended to level off when the addition rate was higher than 400Āmg C kg(-1) soil. This saturation effect indicates that stimulation of soil C loss by exogenous substrate would not be as drastic as the increase of C input. In fact, we found that the mineral layer with an WSC addition rate of 160-800Āmg C kg(-1) soil had net C storage although positive PE was observed. The addition of WSC basically caused net C loss in the organic layer due to the high magnitude of PE, pointing to the importance of the organic layer in C cycling of forest ecosystems. Our findings provide a fundamental understanding of PE on SOC mineralization of forest soils and warrant further in situ studies of PE in order to better understand C cycling under global climate change. PMID:25790803
Soil Genesis and Development, Lesson 1 - Rocks and Minerals
Technology Transfer Automated Retrieval System (TEKTRAN)
All soil ultimately forms from rocks or their weathering products. Geologists classify rocks according to their origins. General rock types can weather to give soils with distinctive properties. The objectives of this lesson are: 1. To be able to classify rocks based on visual characteristics accord...
Potassium Fixation and Supply by Soils with Mixed Clay Minerals.Ā
Hipp, Billy W.
OF THE SOILS USED IN THE STUDY were grown from 30 to 32 days, but plants of en all pots were allowed to grow the same length of crop was harvested at the end of the growth period i-: ting the entire plant at soil level. The plants merc rl;.. distilled...
Heavy metal linkages with mineral, organic and living soil compartments
Abdul Motalib M. Abdul Rida; Marcel B. Bouchķ
For soil ecotoxicological assessment, we can observe lethal effects (on organism as presence or absence) or sublethal effects due to bioconcentrations of contaminants in organisms. This paper deals with the analysis of seven heavy metals (Cd, Cu, Fe, Mn, Ni, Pb and Zn) and Ca: (i) in soils, by three chemical extraction techniques; (ii) in earthworm tissues; (iii) the relationships
The use of micro-FTIR to characterize soil minerals and Boron adsorption S. Pittiglio and H.E. Doner
(m-FTIR) is an appropriate method for identifying clay minerals in soil matrices. 2) Determine which the composition of the soil matrix and possibly the form and location of B in the soil matrix. METHODS Peds in order to retain soil aggregate structure. The resin was hardened by heating samples at 600 C for 48
Kinetics of carbon mineralization of biochars compared with wheat straw in three soils.
Qayyum, Muhammad Farooq; Steffens, Diedrich; Reisenauer, Hans Peter; Schubert, Sven
Application of biochars to soils may stabilize soil organic matter and sequester carbon (C). The objectives of our research were to study in vitro C mineralization kinetics of various biochars in comparison with wheat straw in three soils and to study their contribution to C stabilization. Three soils (Oxisol, Alfisol topsoil, and Alfisol subsoil) were incubated at 25░C with wheat straw, charcoal, hydrothermal carbonization coal (HTC), low-temperature conversion coal (LTC), and a control (natural organic matter). Carbon mineralization was analyzed by alkali absorption of CO released at regular intervals over 365 d. Soil samples taken after 5 and 365 d of incubation were analyzed for soluble organic C and inorganic N. Chemical characterization of biochars and straw for C and N bonds was performed with Fourier transformation spectroscopy and with the N fractionation method, respectively. The LTC treatment contained more N in the heterocyclic-bound N fraction as compared with the biochars and straw. Charcoal was highly carbonized when compared with the HTC and LTC. The results show higher C mineralization and a lower half-life of straw-C compared with biochars. Among biochars, HTC showed some C mineralization when compared with charcoal and LTC over 365 d. Carbon mineralization rates were different in the three soils. The half-life of charcoal-C was higher in the Oxisol than in the Alfisol topsoil and subsoil, possibly due to high Fe-oxides in the Oxisol. The LTC-C had a higher half-life, possibly due to N unavailability. We conclude that biochar stabilization can be influenced by soil type. PMID:22751064
Effects of temperature and amendments on nitrogen mineralization in selected Australian soils.
Thangarajan, Ramya; Bolan, Nanthi S; Naidu, Ravi; Surapaneni, Aravind
The effects of temperature (18, 24, and 37Ā░C) and form of nitrogen (N) input from various sources (organic-green waste compost, biosolids, and chicken manure; inorganic-urea) on N transformation in three different Australian soils with varying pH (4.30, 7.09, and 9.15) were examined. Ammonification rate (ammonium concentration) increased with increase in temperature in all soil types. The effect of temperature on nitrification rate (nitrate concentration) followed 24?>?37?>?18Ā░C. Nitrification rate was higher in neutral and alkaline soils than acidic soil. Mineral N (bioavailable N) concentration was high in urea treatments than in organic N source treatments in all soil types. Acidic soil lacked nitrification activity resulting in low nitrate (NO3) buildup in urea treatment, whereas a significant NO3 buildup was noticed in green waste compost treatment. In neutral and alkaline soils, the nitrification activity was low at 37Ā░C in urea treatment but with a significant NO3 buildup in organic amendment added soils. Addition of organic N sources supplied ammonia oxidizing bacteria thereby triggering nitrification in the soils (even at 37Ā░C). This study posits the following implications: (1) inorganic fertilizer accumulate high NO3 content in soils in a short period of incubation, thereby becoming a potential source of NO3 leaching; (2) organic N sources can serve as possible source of nitrifying bacteria, thereby increasing bioavailable N (NO3) in soils regardless of the soil properties and temperature. PMID:24114384
Limitations to carbon mineralization in litter and mineral soil of young and old ponderosa pine forests
F. m. Kelliher; D. j. Ross; B. e. Law; D. d. Baldocchi; N. j. Rodda
Summer drought is a feature of the semi-arid region of central Oregon, USA, where vegetation naturally develops into ponderosa pine (Pinus ponderosa var. Laws) forest. Forest management consists of clearcut harvest and natural regeneration. Soil microbial activity is interconnected with forest processes because substrate quality and availability can be important driving variables. Stand development influences the soil water regime, and
Organic matter mineralization in frozen boreal soils-environmental constraints on catabolic and anabolic microbial activity
NASA Astrophysics Data System (ADS)
Oquist, Mats G.; Sparrman, Tobias; Schleucher, J³rgen; Nilsson, Mats B.
Heterotrophic microbial mineralization of soil organic matter (SOM) and associated production and emission of atmospheric trace gases proceed during the winter months in the frozen soils of high latitude ecosystems. However, in what ways this microbial activity is constrained by the environmental conditions prevailing in a frozen soil matrix is uncertain. This presentation will address how temperature, water availability and substrate availability combine to regulate rates of microbial activity at below freezing temperatures and the implications of this activity for SOM mineralization in the surface layers of boreal forest soils experiencing seasonal freezing. We show that the amount and availability of liquid water is an integral factor regulating rates of microbial activity in the frozen soil matrix and can also explain frequently observed deviations in the temperature responses of biogenic CO2 production in frozen soils, as compared to unfrozen soils. Using stable isotope labeling (13C) we also show that the partitioning of substrate carbon, in the form of monomeric sugar (glucose), for catabolic and anabolic metabolism remain constant in the temperature range of -4C to 9C. This confirms that microbial growth may proceed even when soils are frozen. In addition we present corresponding data for organisms metabolizing polymeric substrates (cellulose) requiring exoenzymatic activity prior to substrate uptake. We conclude that the metabolic response of soil microorganism to controlling factors may change substantially across the freezing point of soil water, and also the patterns of interaction among controlling factors are affected. Thus, it is evident that metabolic response functions derived from investigations of unfrozen soils cannot be superimposed on frozen soils. Nonetheless, the soil microbial population appear very adapted to seasonal freezing with respect to their metabolic performance.
Mineral Transformations in Permafrost-Affected Soils, North Kolyma Lowland, Russia
A. Alekseev; T. Alekseeva; V. Ostroumov; C. Siegert; B. Gradusov
in composition and properties. At the interface between frozen and thawed soil, an increase in chemical poten- Soils in permafrost sediments were studied on the Kolyma Low- tials (i.e., possibility of elements to take part in chemical land, North-East Siberia. Mineral transformations were studied by comparing samples from different geochemical positions relative to reactions) of the pore-solution components is observed.
Microbial carbon mineralization in tropical lowland and montane forest soils of Peru
Whitaker, Jeanette; Ostle, Nicholas; McNamara, Niall P.; Nottingham, Andrew T.; Stott, Andrew W.; Bardgett, Richard D.; Salinas, Norma; Ccahuana, Adan J. Q.; Meir, Patrick
Climate change is affecting the amount and complexity of plant inputs to tropical forest soils. This is likely to influence the carbon (C) balance of these ecosystems by altering decomposition processes e.g., ōpositive priming effectsö that accelerate soil organic matter mineralization. However, the mechanisms determining the magnitude of priming effects are poorly understood. We investigated potential mechanisms by adding 13C labeled substrates, as surrogates of plant inputs, to soils from an elevation gradient of tropical lowland and montane forests. We hypothesized that priming effects would increase with elevation due to increasing microbial nitrogen limitation, and that microbial community composition would strongly influence the magnitude of priming effects. Quantifying the sources of respired C (substrate or soil organic matter) in response to substrate addition revealed no consistent patterns in priming effects with elevation. Instead we found that substrate quality (complexity and nitrogen content) was the dominant factor controlling priming effects. For example a nitrogenous substrate induced a large increase in soil organic matter mineralization whilst a complex C substrate caused negligible change. Differences in the functional capacity of specific microbial groups, rather than microbial community composition per se, were responsible for these substrate-driven differences in priming effects. Our findings suggest that the microbial pathways by which plant inputs and soil organic matter are mineralized are determined primarily by the quality of plant inputs and the functional capacity of microbial taxa, rather than the abiotic properties of the soil. Changes in the complexity and stoichiometry of plant inputs to soil in response to climate change may therefore be important in regulating soil C dynamics in tropical forest soils. PMID:25566230
Microbial carbon mineralization in tropical lowland and montane forest soils of Peru.
Whitaker, Jeanette; Ostle, Nicholas; McNamara, Niall P; Nottingham, Andrew T; Stott, Andrew W; Bardgett, Richard D; Salinas, Norma; Ccahuana, Adan J Q; Meir, Patrick
Climate change is affecting the amount and complexity of plant inputs to tropical forest soils. This is likely to influence the carbon (C) balance of these ecosystems by altering decomposition processes e.g., "positive priming effects" that accelerate soil organic matter mineralization. However, the mechanisms determining the magnitude of priming effects are poorly understood. We investigated potential mechanisms by adding (13)C labeled substrates, as surrogates of plant inputs, to soils from an elevation gradient of tropical lowland and montane forests. We hypothesized that priming effects would increase with elevation due to increasing microbial nitrogen limitation, and that microbial community composition would strongly influence the magnitude of priming effects. Quantifying the sources of respired C (substrate or soil organic matter) in response to substrate addition revealed no consistent patterns in priming effects with elevation. Instead we found that substrate quality (complexity and nitrogen content) was the dominant factor controlling priming effects. For example a nitrogenous substrate induced a large increase in soil organic matter mineralization whilst a complex C substrate caused negligible change. Differences in the functional capacity of specific microbial groups, rather than microbial community composition per se, were responsible for these substrate-driven differences in priming effects. Our findings suggest that the microbial pathways by which plant inputs and soil organic matter are mineralized are determined primarily by the quality of plant inputs and the functional capacity of microbial taxa, rather than the abiotic properties of the soil. Changes in the complexity and stoichiometry of plant inputs to soil in response to climate change may therefore be important in regulating soil C dynamics in tropical forest soils. PMID:25566230
Characterization of minerals: From the classroom to soils to talc deposits
NASA Astrophysics Data System (ADS)
McNamee, Brittani D.
This dissertation addresses different methods and challenges surrounding characterizing and identifying minerals in three environments: in the classroom, in soils, and in talc deposits. A lab manual for a mineralogy and optical mineralogy course prepares students for mineral characterization and identification by giving them the methods and tools to identify any mineral. Students begin with familiarizing themselves with the tools (e.g. Polarizing Light Microscope and refractive index liquids) and the methods (e.g. defining properties) needed to identify a mineral. Next, they work through characterizing the most common minerals to hone their skills. The students finish the semester with two projects: characterizing single mineral grains with a spindle stage and creating a mineral collection. Evaluation of mineralogical data from selected sand or silt fraction of soils from the USDA-NRCS National Cooperative Soil Survey database, show that soils in all states (except for Rhode Island) contain amphiboles. Forty-one of the fifty states had 10 % or more sampled pedons containing amphiboles. Overall, about 13 % of pedons sampled in the USA contained amphiboles. While amphibole asbestos deposits occur in mafic and ultramafic provinces, soil amphiboles occur evenly distributed across the USA. The majority of the amphiboles found in the soils would probably not meet the mineralogical definition of asbestos (i.e., they would not have been derived from asbestiform amphiboles); however, the majority would probably meet a commonly used regulatory definition to be considered a fiber (i.e., are over 5 microns in length with a greater that 3 to 1 aspect ratio). Furthermore, chemical and morphological characterization was done on minerals in talc deposits and R. T. Vanderbilt Co. processed talc products from the Gouverneur Mining District, New York. The main mineral phases detected within the samples are tremolite, anthophyllite, and talc. Compositional analyses were preformed by WDS via electron microprobe. Morphological analyses were done using the PLM and electron microprobe. Amounts of each mineralogical phase were calculated by the Reitveld method using X-ray diffraction scans.
A conceptual model of organo-mineral interactions in soils: self-assembly of organic molecular fragments into zonal structures on mineral surfaces
M. Kleber; P. Sollins; R. Sutton
In this paper, we propose a structure for organo-mineral associations in soils based on recent insights concerning the molecular\\u000a structure of soil organic matter (SOM), and on extensive published evidence from empirical studies of organo-mineral interfaces.\\u000a Our conceptual model assumes that SOM consists of a heterogeneous mixture of compounds that display a range of amphiphilic\\u000a or surfactant-like properties, and are
Adsorption of Trametes versicolor laccase to soil iron and aluminum minerals: enzyme activity, kinetics and stability studies.
Wu, Yue; Jiang, Ying; Jiao, Jiaguo; Liu, Manqiang; Hu, Feng; Griffiths, Bryan S; Li, Huixin
Laccases play an important role in the degradation of soil phenol or phenol-like substance and can be potentially used in soil remediation through immobilization. Iron and aluminum minerals can adsorb extracellular enzymes in soil environment. In the present study, we investigated the adsorptive interaction of laccase, from the white-rot fungus Trametes versicolor, with soil iron and aluminum minerals and characterized the properties of the enzyme after adsorption to minerals. Results showed that both soil iron and aluminum minerals adsorbed great amount of laccase, independent of the mineral specific surface areas. Adsorbed laccases retained 26-64% of the activity of the free enzyme. Compared to the free laccase, all adsorbed laccases showed higher Km values and lower Vmax values, indicating a reduced enzyme-substrate affinity and a lower rate of substrate conversion in reactions catalyzed by the adsorbed laccase. Adsorbed laccases exhibited increased catalytic activities compared to the free laccase at low pH, implying the suitable application of iron and aluminum mineral-adsorbed T. versicolor laccase in soil bioremediation, especially in acid soils. In terms of the thermal profiles, adsorbed laccases showed decreased thermal stability and higher temperature sensitivity relative to the free laccase. Moreover, adsorption improved the resistance of laccase to proteolysis and extended the lifespan of laccase. Our results implied that adsorbed T. versicolor laccase on soil iron and aluminum minerals had promising potential in soil remediation. PMID:24225344
Redistributed water by saprotrophic fungi triggers carbon mineralization in dry soils
NASA Astrophysics Data System (ADS)
Guhr, Alexander; Borken, Werner; Matzner, Egbert
Summer droughts are common in temperate forests and especially the upper soil horizons experience soil drought. Drought events can be accompanied by negative effects for forest ecosystems but many plants can reduce drought stress by hydraulic redistribution (HR). Similar processes were recently described for ectomycorrhizal networks but no information is available for mycelia networks of saprotrophic fungi. They strongly contribute to belowground nutrient cycling, C and N mineralization. We hypothesize that redistributed water by saprotrophic fungi triggers mineralization of organic matter in soils under drought conditions. The impact of HR by saprotrophic fungi on mineralization was determined using mesocosms comprising two chambers, separated by a 2 mm air gap to prevent bulk flow of water. After inoculation with fungal cultures and a growth phase, both chambers were desiccated. Subsequently, only chamber I was rewetted while chamber II was treated with 13C labelled plant material. CO2 samples were collected over 7 days after rewetting and analyzed for stable isotope ratio. In addition, enzymatic activity of chitinases and cellobiohydrolases in chamber II was determined after 7 days using the soil zymographie method with fluorogenic 4-Methylumbelliferyl-substrates. A negative control was provided by mesocosms in which hyphal connections between the chambers were severed before rewetting. Intact fungal connections between the chambers led to a strong increase in volumetric water content in chamber II after rewetting of chamber I and the CO2 had a higher enrichment in 13C than in the control mescosms with severed connections. Enrichment started 48 h after rewetting and continued for the rest of the experiment. This resulted in a more than two fold higher total carbon mineralization after 7 days in chamber II of mesocosms with intact hyphal connections. In addition, enzyme activities were also strongly increased compared to controls. In conclusion, mycelia networks of saprotrophic fungi contribute to redistribution of water from wet to dry soil and the redistributed water triggers carbon mineralization in dry soils.
Reactive Clay Minerals in a land use sequence of disturbed soils of the Belgian Loam Belt
NASA Astrophysics Data System (ADS)
Barao, Lucia; Vandevenne, Floor; Ronchi, Benedicta; Meire, Patrick; Govers, Gerard; Struyf, Eric
Clay minerals play a key role in soil biogeochemistry. They can stabilize organic matter, improve water storage, increase cation exchange capacity of the soil (CEC) and lower nutrient leaching. Phytoliths - the biogenic silica bodies (BSi) deposited in cell walls of plants - are important Si pools in soil horizons due to their higher solubility compared to minerals. They provide the source of Si for plant uptake in short time scales, as litter dissolves within soils. In a recent study, we analyzed the BSi pool differences across a set of different land uses (forests, pastures, croplands) in 6 long-term disturbed (multiple centuries) soil sites in the Belgium Loam Belt. Results from a simultaneous chemical extraction in 0.5M NaOH of Si and Al, showed that soils were depleted in the BSi pool while showing high levels of reactive secondary clay minerals, mainly in the deeper horizons and especially in the forests and the croplands. During the extraction, clays were similar in reactivity to the biogenic pool of phytoliths. In order to study the kinetics in a more natural environment, batch dissolution experiments were conducted. Samples from different soil depths for each land use site (0.5 g) were mixed with 0.5 L of demineralised water modified to pH 4, 7 and 10. Subsamples of 2 ml were taken during 3 months. In the end of the period, results for pH 7 showed that in the pastures, where reactive clays were almost absent, the ratio Si/RSi (defined as the Si concentration in the end of the batch experiment divided by the reactive silica extracted from the soil with the alkaline extraction) was lower than 0.005%. The same ratio was higher in the mineral horizons of forests (Si/RSi>0.01%) and croplands (0.005% < Si/RSi <0.01%) where clay minerals were the dominant fraction. These preliminary results highlight the clay minerals' strong potential for Si mobilization. More attention should be paid to this important fraction as it can contribute strongly to Si availability, in close competition with phytoliths and other soluble amorphous Si forms, strongly interfering with frequently applied methods to quantify biogenic Si in soils.
Nitrogen mineralization and nitrate leaching of a sandy soil amended with different organic wastes.
Burgos, Pilar; Madej¾n, Engracia; Cabrera, Francisco
Organic wastes can be recycled as a source of plant nutrients, enhancing crop production by improving soil quality. However, the study of the dynamic of soil nutrient, especially the N dynamic, after soil application of any organic material is vital for assessing a correct and effective use of the material, minimizing the losses of nitrate in leachates and avoiding the negative environmental effects that it may cause in groundwater. To estimate the effect of three organic materials, a municipal solid waste compost (MWC), a non-composted paper mill sludge (PS), and an agroforest compost (AC) on the N dynamic of a sandy soil two experiments were carried out: an incubation experiment and a column experiment. The incubation experiment was conducted to estimate the N mineralization rate of the different soil-amendment mixtures. The soil was mixed with the organic amendments at a rate equivalent to 50,000 kg ha(-1) and incubated during 40 weeks at constant moisture content (70% of its water-holding capacity) and temperature (28 degrees C) under aerobic conditions. Organic amendment-soil samples showed an immobilization of N during the first weeks, which was more noticeable and longer in the case of PS-treated soil compared to the other two amendments due to its high C/N ratio. After this immobilization stage, a positive mineralization was observed for all treatment, especially in MWC treated soil. Contemporaneously a 1-year column (19 cm diameter and 60 cm height) experiment was carried out to estimate the nitrate losses from the soil amended with the same organic materials. Amendments were mixed with the top soil (0-15 cm) at a rate equivalent to 50,000 kg ha(-1). The columns were periodically irrigated simulating rainfall in the area of study, receiving in total 415 mm of water, and the water draining was collected during the experimental period and analysed for NO3-N. At the end of the experimental period NO3-N content in soil columns at three depths (0-20, 20-35 and 35-50 cm) was determined. The nitrate concentration in drainage water confirmed the results obtained in the incubation experiment: nitrate leaching was higher in soil treated with MWC due to its higher N-mineralization rate. Nevertheless, the nitrate losses represented a low amount compared with the total nitrogen added to soil. No clear signs of water-draining contamination were observed during the first year after the application of AC and PS; however, the nitrate leaching in soil treated with MWC slightly exceeded the limit allowed for the Drinking Water Directive 98/83/CE. PMID:16634232
Clay mineral formation and transformation in rocks and soils
Eberl, D.D.
Three mechanisms for clay mineral formation (inheritance, neoformation, and transformation) operating in three geological environments (weathering, sedimentary, and diagenetic-hydrothermal) yield nine possibilities for the origin of clay minerals in nature. Several of these possibilities are discussed in terms of the rock cycle. The mineralogy of clays neoformed in the weathering environment is a function of solution chemistry, with the most dilute solutions favoring formation of the least soluble clays. After erosion and transportation, these clays may be deposited on the ocean floor in a lateral sequence that depends on floccule size. Clays undergo little reaction in the ocean, except for ion exchange and the neoformation of smectite; therefore, most clays found on the ocean floor are inherited from adjacent continents. Upon burial and heating, however, dioctahedral smectite reacts in the diagenetic environment to yield mixed-layer illite-smectite, and finally illite. With uplift and weathering, the cycle begins again. Refs.
Molecular-level analysis of organic matter structure and composition from different soil mineral fractions
NASA Astrophysics Data System (ADS)
Clemente, J. S.; Gregorich, E. G.; Simpson, A. J.; Simpson, M. J.
The formation and turnover of soil organic matter (SOM) depends on the inherent chemical characteristics of biomolecular inputs (lignin, proteins, carbohydrates, macromolecular lipids, etc.) as well as the interactions between biomolecules and soil mineral fractions. The objective of this study is to characterize organic matter associated with the light, sand, silt and clay fractions of a Canadian agricultural soil. And, because lignin is believed to be a major contributor in SOM formation and preservation, the oxidation state of lignin in the different mineral fractions was measured using mild alkaline copper oxidation and gas chromatography - mass spectrometery which releases lignin phenols that are indicative of lignin sources and stage of degradation. For example, an increase in the acid/aldehyde (Ad/Al) ratio of lignin phenols has been observed with increased lignin degradation (and oxidation). In this study, lignin phenols from organic matter associated with the clay fraction had higher Ad/Al ratios for both syringyl and vanillyl lignin monomers when compared to that associated with silt, sand and the whole soil. These results suggest that either lignin degradation is enhanced by SOM association with clay surfaces or that oxidized lignin is preserved on clay mineral surfaces via sorption after partial degradation has occurred. The structural characteristics of organic matter from the soil fractions will also be examined by solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. Organic matter associated with each mineral fraction will be extracted with NaOH for high resolution solution-state NMR spectroscopy. Results from NMR analysis will determine the relative abundance of functional groups (alkane, aromatic, carbonyl, alkoxy) in each of the soil fractions. Relative intensities of the functional groups are indicative of relative contributions of biomolecular classes such as lipids, lignin, fatty acids, and sugars to the organic matter associated with each fraction. The study comprises our initial steps in characterizing protection mechanisms responsible for the long-term retention and stability of biomolecules and their degradation intermediates in soil.
Molecular-Level Analysis of Organic Matter Structure and Composition from Different Soil Mineral Fractions
NASA Astrophysics Data System (ADS)
Clemente, J. S.; Gregorich, E. G.; Simpson, A. J.; Simpson, M. J.
The formation and turnover of soil organic matter (SOM) depends on the inherent chemical characteristics of biomolecular inputs (lignin, proteins, carbohydrates, macromolecular lipids, etc.) as well as the interactions between biomolecules and soil mineral fractions. The objective of this study is to characterize organic matter associated with the light, sand, silt and clay fractions of a Canadian agricultural soil. And, because lignin is believed to be a major contributor in SOM formation and preservation, the oxidation state of lignin in the different mineral fractions was measured using mild alkaline copper oxidation and gas chromatography - mass spectrometery which releases lignin phenols that are indicative of lignin sources and stage of degradation. For example, an increase in the acid/aldehyde (Ad/Al) ratio of lignin phenols has been observed with increased lignin degradation (and oxidation). In this study, lignin phenols from organic matter associated with the clay fraction had higher Ad/Al ratios for both syringyl and vanillyl lignin monomers when compared to that associated with silt, sand and the whole soil. These results suggest that either lignin degradation is enhanced by SOM association with clay surfaces or that oxidized lignin is preserved on clay mineral surfaces via sorption after partial degradation has occurred. The structural characteristics of organic matter from the soil fractions will also be examined by solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. Organic matter associated with each mineral fraction will be extracted with NaOH for high resolution solution-state NMR spectroscopy. Results from NMR analysis will determine the relative abundance of functional groups (alkane, aromatic, carbonyl, alkoxy) in each of the soil fractions. Relative intensities of the functional groups are indicative of relative contributions of biomolecular classes such as lipids, lignin, fatty acids, and sugars to the organic matter associated with each fraction. The study comprises our initial steps in characterizing protection mechanisms responsible for the long-term retention and stability of biomolecules and their degradation intermediates in soil.
Deuterium and oxygen-18 correlation: Clay minerals and hydroxides in Quaternary soils compared to meteoric waters
James R. Lawrence; Hugh P. Taylor Jr.
D and O 18 of clay minerals and hydroxides in Quaternary soils of the United States correlate directly with D and O 18 of corresponding present-day meteoric waters. Samples from Montana and Idaho are much lower in both D and O 18 than those from coastal areas. The Hawaiian and Gulf Coast samples are highest in D and O 18
Timber harvesting alters soil carbon mineralization and microbial community structure in coniferous forests
A. Chatterjee; G. F. Vance; E. Pendall; P. D. Stahl
Timber harvesting influences both above and belowground ecosystem nutrient dynamics. Impact of timber harvesting on soil organic matter (SOM) mineralization and microbial community structure was evaluated in two coniferous forest species, ponderosa pine (Pinus ponderosa) and lodgepole pine (Pinus contorta). Management of ponderosa pine forests, particularly even-aged stand practices, increased the loss of CO2-C and hence reduced SOM storage potential.
Modeling selenite adsorption envelopes on oxides, clay minerals, and soils using the triple layer model
Technology Transfer Automated Retrieval System (TEKTRAN)
Selenite adsorption behavior was investigated on amorphous aluminum and iron oxides, clay minerals: kaolinite, montmorillonite, and illite, and 45 surface and subsurface soil samples from the Southwestern and Midwestern regions of the USA as a function of solution pH. Selenite adsorption decreased ...
Adsorption of dissolved organic carbon to mineral soils: A comparison of four isotherm approaches
Moore, Tim
Adsorption of dissolved organic carbon to mineral soils: A comparison of four isotherm approaches D Langmuir Xi and Xf isotherms hold the advantage of estimating the maximum adsorption capacity, yet the Xf isotherm is a better reflection of adsorption processes. ┬® 2008 Elsevier B.V. All rights reserved. 1
Influence of sewage sludge compost stability and maturity on carbon and nitrogen mineralization in soil
M. P. Bernal; A. F. Navarro; M. A. Sßnchez-Monedero; A. Roig; J. Cegarra
Incubation experiments with soil were made to study C and N mineralization in a sewage sludge¢cotton waste mixture at different stages of the composting process performed by the Rutgers static pile system. Three composting samples were selected: initial mixture (I); the end of the active phase (E); and the mature compost (M). The CO2-C evolved (as % of added C)
Carbon and Nitrogen Mineralization Rates after Application of Organic Amendments to Soil
Tamara C. Flavel; Daniel V. Murphy
The objective of this study was to quantify C and N mineralization rates from a range of organic amendments that differed in their total C and N contents and C quality, to gain a better understanding of their influence on the soil N cycle. A pelletized poultry manure (PP), two green waste-based composts (GWCa, GWCb), a straw-based compost (SBC), and
W. L. Daniels; Z. W. Orndorff; P. D. Schroeder
Significant areas of prime farmland in the upper Coastal Plain of Virginia and North Carolina will be disturbed by heavy mineral sands (Ti\\/Zr- bearing ilmenite, rutile, zircon) mining over the next 20 years. The physical and chemical properties of mine soils that result from the mining and reclamation process were studied in a replicated small plot experimental setting between 1994
Z. W. Orndorff; W. L. Daniels; J. M. Galbraith
Significant areas of prime farmland in the upper Coastal Plain of Virginia have been disturbed by heavy mineral sands (Ti\\/Zr-bearing ilmenite, rutile, zircon) mining over the past 7 years. Previous work has shown that separation of sandy particles (tailings) from finer particles (slimes) in dewatering pits leads to significant lateral variability in the soils. The objectives of this study were
Bioremediation of experimental petroleum spills on mineral soils in the Vestfold Hills, Antarctica
Elizabeth Kerry
The effect of nutrient and water enhancement on the biodegradation of petroleum was tested in Antarctic mineral soils. Nitrogen, phosphorus and potassium were applied in solution, with or without gum xanthan or plastic covers, to sites artificially contaminated with distillate. The effectiveness of these procedures was assessed by measuring changes in total petroleum hydrocarbons; heptadecane\\/pristane and octadecane\\/phytane ratios; in concentrations
Sugarcane Genotype Selection Efficiency on Organic and Mineral Soils in Florida
Technology Transfer Automated Retrieval System (TEKTRAN)
Sugarcane (Saccharum spp.) genotype selection during the past 35 yrs has been more successful at developing cultivars for the organic (muck) than for the mineral (sand) soils in Florida, more likely a consequence of conducting the early and intermediate stages of selection exclusively on organic soi...
Distinguishing boron desorption from mineral dissolution in arid-zone soils
Technology Transfer Automated Retrieval System (TEKTRAN)
Boron release from six arid-zone soils from the San Joaquin Valley of California was investigated as a function of reaction time, solution pH, and suspension density. A multiple batch extraction experiment was carried out for 362 days to distinguish B desorption from mineral dissolution. Amounts o...
NSDL National Science Digital Library
Mrs. Walls
Create a poster about minerals! Directions: Make a poster about minerals. (20 points) Include at least (1) large picture (15 points) on your poster complete with labels of every part (10 points). (15 points) Include at least three (3) facts about minerals. (5 points each) (15 points) Write at ...
The Accumulation of Organic Carbon in Mineral Soils by Afforestation of Abandoned Farmland
Wei, Xiaorong; Qiu, Liping; Shao, Mingan; Zhang, Xingchang; Gale, William J.
The afforestation of abandoned farmland significantly influences soil organic carbon (OC). However, the dynamics between OC inputs after afforestation and the original OC are not well understood. To learn more about soil OC dynamics after afforestation of farmland, we measured the soil OC content in paired forest and farmland plots in Shaanxi Province, China. The forest plots had been established on farmland 18, 24, 48, 100, and 200 yr previously. The natural 13C abundance of soil organic matter was also analyzed to distinguish between crop- and forest-derived C in the afforested soils. We observed a nonlinear accumulation of total OC in the 0¢80 cm depth of the mineral soil across time. Total soil OC accumulated more rapidly under forest stands aged 18 to 48 yr than under forest stands aged 100 or 200 yrs. The rate of OC accumulation was also greater in the 0¢10 cm depth than in the 10¢80 cm depth. Forest-derived OC in afforested soils also accumulated nonlinearly across time, with the greatest increase in the 0¢20 cm depth. Forest-derived OC in afforest soils accounted for 52¢86% of the total OC in the 0¢10 cm depth, 36¢61% of the total OC in the 10¢20 cm depth, and 11¢50% of the total OC in the 20¢80 cm depth. Crop-derived OC concentrations in the 0¢20 cm depth decreased slightly after afforestation, but there was no change in crop-derived OC concentrations in the 20¢80 cm depth. The results of our study support the claim that afforestation of farmland can sequester atmospheric CO2 by increasing soil OC stocks. Changes in the OC stocks of mineral soils after afforestation appear to be influenced mainly by the input of forest-derived C rather than by the loss of original OC. PMID:22412854
Passive sequestration of atmospheric CO2 through coupled plant-mineral reactions in urban soils.
Manning, David A C; Renforth, Phil
Photosynthetic removal of CO(2) from the atmosphere is an important planetary carbon dioxide removal mechanism. Naturally, an amount equivalent to all atmospheric carbon passes through the coupled plant-soil system within 7 years. Plants cycle up to 40% of photosynthesized carbon through their roots, providing a flux of C at depth into the soil system. Root-exuded carboxylic acids have the potential to supply 4-5 micromoles C hr(-1)g(-1) fresh weight to the soil solution, and enhance silicate mineral weathering. Ultimately, the final product of these root-driven processes is CO(2), present in solution as bicarbonate. This combines with Ca liberated by corrosion associated with silicate mineral weathering to enter the soil-water system and to produce pedogenic calcium carbonate precipitates. Combining understanding of photosynthesis and plant root physiology with knowledge of mineral weathering provides an opportunity to design artificial soils or to plan land use in ways that maximize removal and sequestration of atmospheric CO(2) through artificially enhanced pedogenic carbonate precipitation. This process requires relatively low energy and infrastructure inputs. It offers a sustainable carbon dioxide removal mechanism analogous to the use of constructed wetlands for the passive remediation of contaminated waters, and is likely to achieve wide public acceptance. PMID:22616942
Kinetics of Ion Exchange on Clay Minerals and Soil: II. Elucidation of Rate-limiting Steps1 R. A. OGWADA ANDD. L. SPARKS2
Sparks, Donald L.
Kinetics of Ion Exchange on Clay Minerals and Soil: II. Elucidation of Rate-limiting Steps1 R. A of this study was to elucidate the rate- limiting steps for K+ adsorption on the clay minerals and soil. We.L. Sparks. 1986. Kinetics of ion exchange on clay minerals and soil: II. Elucidation of rate-limiting steps
Kinetics of Ion Exchange on Clay Minerals and Soil: I. Evaluation of Methods1 R. A. OGWADA AND D. L. SPARKS2
Sparks, Donald L.
Kinetics of Ion Exchange on Clay Minerals and Soil: I. Evaluation of Methods1 R. A. OGWADA AND D. L,vermiculite. Ogwada, R.A., and D.L. Sparks. 1986. Kinetics of ion exchangeon clay minerals and soil: I. Evaluation displacement or flow techniques to investigate kinetics of ion exchange on soils and clay minerals (Sparks
The soluble organic acids in soils consist largely of complex mixtures of polymeric compounds referred to collectively as fluvic and humic acids. These compounds are relatively refactory, and are broken down only slowly by bacteria. ow-molecular-mass acids (e.g., acetic, oxalic, ...
Ethylene Dibromide Mineralization in Soils under Aerobic Conditions
Pignatello, Joseph J.
1,2-Dibromoethane (EDB), which is a groundwater contaminant in areas where it was once used as a soil fumigant, was shown to be degraded aerobically by microorganisms in two types of surface soils from an EDB-contaminated groundwater discharge area. At initial concentrations of 6 to 8 ?g/liter, EDB was degraded in a few days to near or below the detection limit of 0.02 ?g/liter. At 15 to 18 mg/liter, degradation was slower. Bromide ion release at the higher concentrations was 1.4 ▒ 0.3 and 2.1 ▒ 0.2 molar equivalents for the two soils. Experiments with [14C]EDB showed that EDB was converted to approximately equal amounts of CO2 and apparent cellular carbon; only small amounts of added 14C were not attributable to these products or unreacted EDB. These results are encouraging, because they indicate that groundwater bacteria may hasten the removal of EDB from contaminated aerobic groundwater supplies. This report also provides evidence for soil-mediated chemical transformations of EDB. PMID:16347020
The biological factors influence on the conversion of mineral components of Extremely Arid Desert Soils (Kazakhstan)
NASA Astrophysics Data System (ADS)
Kutovaya, Olga; Vasilenko, Elena; Lebedeva, Marina; Tkhakakhova, Azida
Extremely arid soils of stony deserts (hamadas) along the southern periphery of the Ili Depression are considered to be analogous to extremely arid soils of Mongolia, also named as "ultra-arid primitive gray-brown soils." In general, the morphology of extremely arid soils of hamadas in the Ili Depression is similar to that of the soils of stony deserts in other parts of the world, including the Gobi, Atacama, and Tarim deserts. The diagnostics of the active communities of microorganisms were performed according to the method of Rybalkina-Kononenko. The exact identification of the living forms of microorganisms to the species level is not always possible with the use of this method. However, it allows us to study the physiological role of the microorganisms and their ecological functions, including the relationships with the soil matrix and other organisms. In particular, it is possible to estimate the contribution of the microorganisms to the transformation of mineral soil components. The obtained materials allow us to conclude that the extremely arid desert soils are characterized by the very high biological activity during short periods of the increased soil moistening after rare and strong rains. The diversity of living forms is very considerable; both prokaryotes (cyanobacteria, actinomycetes, and iron bacteria) and protists (green algae, diatoms, and dinoflagellates) are developed in the soil. Thus, during a short period after the rains, these microorganisms pass from the stage of anabiosis to the stage of active growth and reproduction. Then, upon drying of the soil, the biotic activity of the soil slows down and, finally, terminates. The organisms remain in the state of anabiosis until the next rain. During the period of active growth, the microorganisms compose a specific consortium of different species and exert a profound impact on the soil properties. They participate in the transformation of the soil minerals with the formation of amorphous substances that are clearly seen in biofilms on the surface of gravels of the desert pavement and on the walls of vesicular pores in the crust and subcrust (AKL) horizons of the soil. The organomineral compounds are accumulated in the vesicular pores due to the synthesis and mineralization of the microbial biomass. This is a specific feature of the humus-accumulative process in the extremely arid desert soils. The biogenic transformation of iron-containing minerals, the mobility of iron, and its accumulation in films and coagulated microforms is largely due to the living activity of iron bacteria. These iron pedofeatures are specific of the extremely arid desert soils. We suppose that some part of vesicular pores in the AKL horizon has a microbiological origin, because separate bacterial cells may form intracellular gas vacuoles and extracellular gas bulbs, as well as membrane sacs and cell dilatations that can shape the vesicular pores. In general, our data indicate that soils, including extremely arid desert soils, serve as reservoirs of the microbial diversity and ensure the development and preservation of diverse microorganisms with specific mechanisms of adaptation to the sharp changes in the environmental conditions. This biota-protecting role of soils is particularly well pronounced during the climatic pessimum. This study was supported by the Russian Foundation for Basic Research, project no. 12-04-00990a.
Microbial Mineralization of Soil Organic Matter: Role of Chemical Composition and Structural Organization
NASA Astrophysics Data System (ADS)
Khalaf, M. M. R.; Chilom, G.; Rice, J. A.
The purpose of this study is to quantitatively assess the effect of organic matter self-assembly on its resistance to microbial mineralization. Humic acids isolated from leonardite, two peats and a mineral soil were used as organic matter samples because they provide a broad range of variability in terms of the origin and nature of their organic components. Using a solvent-based fractionation method, humic acid samples were disassembled into a humic-like component and a humic-lipid composite. The humic-lipid composite was further disassembled into an amphiphilic and a lipid component using an alkaline aqueous solution. Mixtures that reproduced the composition of self-assembled samples were prepared by mixing the solid individual fractions in the exact proportions that they were present in the original material. The original humic acids or their corresponding mixtures were added as the sole carbon source in separate aerobic cultures containing a microbial consortium isolated from a mineral soil. After incubation for 125 days mineralization of the self-assembled samples was shown to be higher by as much as 70% compared to their corresponding physical mixtures. The extent of mineralization of the self-assembled samples was not correlated to the material's chemical composition or hydrophobicity index obtained from their 13C solid-state NMR spectra. In contrast, mineralization of the physical mixtures and the individual fractions did vary with chemical composition and was accompanied by preferential mineralization of alkyl carbon. These results suggest the microbial mineralization of humic acids is related to their self-assembly.
Cadmium, copper, lead, and zinc in secondary sulfate minerals in soils of mined areas in Southeast Spain
D. M. Carmona; ┴. Faz Cano; J. M. Arocena
Soils in mined areas in southeastern Spain are commonly characterized by extreme acidity, high salinity, and metals. These present challenges to establish vegetation as a management option for these environmentally-problematic landscapes. We collected salt efflorescence and the corresponding soil materials to better understand the geochemical cycling of Cd, Cu, Pb, and Zn in soils of mined areas. Mineral composition was
Influence of edaphic factors on the mineralization of neem oil coated urea in four Indian soils.
Kumar, Rajesh; Devakumar, C; Kumar, Dinesh; Panneerselvam, P; Kakkar, Garima; Arivalagan, T
The utility of neem (Azadirachta indica A Juss) oil coated urea as a value-added nitrogenous fertilizer has been now widely accepted by Indian farmers and the fertilizer industry. In the present study, the expeller grade (EG) and hexane-extracted (HE) neem oils, the two most common commercial grades, were used to prepare neem oil coated urea (NOCU) of various oil doses, for which mineralization rates were assessed in four soils at three incubation temperatures (20, 27, and 35 degrees C). Neem oil dose-dependent conservation of ammonium N was observed in NOCU treatments in all of the soils. However, a longer incubation period and a higher soil temperature caused depletion of ammonium N. Overall, the nitrification in NOCU treatment averaged 56.6% against 77.3% for prilled urea in four soils. NOCU prepared from EG neem oil was consistently superior to that derived from hexane-extracted oil. The performance of NOCUs was best in coarse-textured soil and poorest in sodic soil. The nitrification rate (NR) of the NOCUs in the soils followed the order sodic > fine-textured > medium-textured > coarse-textured. The influence of edaphic factors on NR of NOCUs has been highlighted. The utility of the present study in predicting the performance of NOCU in diverse Indian soils was highlighted through the use of algorithms for computation of the optimum neem oil dose that would cause maximum inhibition of nitrification in any soil. PMID:18841982
Mineralization of 13C glucose in three fine textured soils from the western boreal forest
NASA Astrophysics Data System (ADS)
Norris, C. E.; Quideau, S. A.; Macey, D. E.
Microbial composition is known, on similar soil types, to vary based on differing organic matter inputs, or stand composition. Dominating western upland boreal forests are fine textured soils with a canopy cover of aspen (Populus tremuloides Michx.), white spruce (Picea glauca (Moench) Voss or a mixture of the two. These soils then reflect different belowground biogeochemical processing of organic matter. Anthropogenic soils, formed from a combination of peat litter and fine textured mineral soil, are now also a part of the landscape in the western boreal. This study set out to determine if a simple labelled compound (13C glucose) was processed differently between soils from the two dominant stand types (aspen and spruce) and a soil from an anthropogenic (constructed) site. Results indicate that while all three soils rapidly incorporated, and respired, the labelled carbon each maintained a distinct microbial community structure (as evidenced by phospholipid fatty acid analysis) throughout the 300 hour experiment. Therefore soils with different microbial communities from varied organic matter inputs decompose organic carbon by different processes, even in the case of simple labile compounds.
Ectomycorrhizal Influence on Particle Size, Surface Structure, Mineral Crystallinity, Functional Groups, and Elemental Composition of Soil Colloids from Different Soil Origins
Li, Yanhong; Wang, Huimei; Wang, Wenjie; Yang, Lei; Zu, Yuangang
Limited data are available on the ectomycorrhizae-induced changes in surface structure and composition of soil colloids, the most active portion in soil matrix, although such data may benefit the understanding of mycorrhizal-aided soil improvements. By using ectomycorrhizae (Gomphidius viscidus) and soil colloids from dark brown forest soil (a good loam) and saline-alkali soil (heavily degraded soil), we tried to approach the changes here. For the good loam either from the surface or deep soils, the fungus treatment induced physical absorption of covering materials on colloid surface with nonsignificant increases in soil particle size (P > 0.05). These increased the amount of variable functional groups (O¢H stretching and bending, C¢H stretching, C=O stretching, etc.) by 3¢26% and the crystallinity of variable soil minerals (kaolinite, hydromica, and quartz) by 40¢300%. However, the fungus treatment of saline-alkali soil obviously differed from the dark brown forest soil. There were 12¢35% decreases in most functional groups, 15¢55% decreases in crystallinity of most soil minerals but general increases in their grain size, and significant increases in soil particle size (P < 0.05). These different responses sharply decreased element ratios (C?:?O, C?:?N, and C?:?Si) in soil colloids from saline-alkali soil, moving them close to those of the good loam of dark brown forest soil. PMID:23766704
Sorption and Transport of Pharmaceutical chemicals in Organic- and Mineral-rich Soils
NASA Astrophysics Data System (ADS)
Vulava, V. M.; Schwindaman, J.; Murphey, V.; Kuzma, S.; Cory, W.
Pharmaceutical, active ingredients in personal care products (PhACs), and their derivative compounds are increasingly ubiquitous in surface waters across the world. Sorption and transport of four relatively common PhACs (naproxen, ibuprofen, cetirizine, and triclosan) in different natural soils was measured. All of these compounds are relatively hydrophobic (log KOW>2) and have acid/base functional groups, including one compound that is zwitterionic (cetirizine.) The main goal of this study was to correlate organic matter (OM) and clay content in natural soils and sediment with sorption and degradation of PhACs and ultimately their potential for transport within the subsurface environment. A- and B-horizon soils were collected from four sub-regions within a pristine managed forested watershed near Charleston, SC, with no apparent sources of anthropogenic contamination. These four soil series had varying OM content (fOC) between 0.4-9%, clay mineral content between 6-20%, and soil pH between 4.5-6. The A-horizon soils had higher fOC and lower clay content than the B-horizon soils. Sorption isotherms measured from batch sorption experimental data indicated a non-linear sorption relationship in all A- and B-horizon soils - stronger sorption was observed at lower PhAC concentrations and lower sorption at higher concentrations. Three PhACs (naproxen, ibuprofen, and triclosan) sorbed more strongly with higher fOC A-horizon soils compared with the B-horizon soils. These results show that soil OM had a significant role in strongly binding these three PhACs, which had the highest KOW values. In contrast, cetirizine, which is predominantly positively charged at pH below 8, strongly sorbed to soils with higher clay mineral content and least strongly to higher fOC soils. All sorption isotherms fitted well to the Freundlich model. For naproxen, ibuprofen, and triclosan, there was a strong and positive linear correlation between the Freundlich adsorption constant, Kf, and fOC, again indicating that these PhACs preferentially partition into the soil OM. Such a correlation was absent for cetirizine. Breakthrough curves of PhACs measured in homogeneous packed soil columns indicated that PhAC transport was affected by chemical nonequilibrium processes depending on the soil and PhAC chemistry. The shape of the breakthrough curves indicated that there were two distinct sorption sites - OM and clay minerals - which influence nonequilibrium transport of these compounds. The retardation factor estimated using the distribution coefficient, Kd, measured from the sorption experiments was very similar to the measured value. While the sorption and transport data do not provide mechanistic information regarding the nature of PhAC interaction with chemical reactive components within geological materials, they do provide important information regarding potential fate of such compounds in the environment. The results also show the role that soil OM and mineral surfaces play in sequestering or transporting these chemicals. These insights have implications to the quality of the water resources in our communities.
Fire effects on peat and organo-mineral soils of Meshchera plain
NASA Astrophysics Data System (ADS)
Tsibart, Anna; Koshovskii, Timur; Gamova, Natalia; Kovach, Roman
The fire effects the soil properties depend on soil type and on their vulnerability to fires. The most of available data is devoted to changes in organo-mineral soils. But the peat fires can cause deeper changes in soil profiles, especially in case of drained peat soils. Now the lack of information exists in the sphere of the comparison of these fire types on soil cover. Meshchera plain (Moscow and Ryazan Regions, Russia) has different soil types. Moreover peatlands were partly drained, and the plain was affected by numerous fires of different time. So there is a need of detailed post-fire soil investigations in this region. During current research the soils Meshchera plain subjected by wildfires of 2002, 2007, 2010 and 2012 were studied. A total of 32 profiles including background and post-fire histosols, histic and sod podzols were investigated. Moreover the detailed description of vegetation cover was conducted. The samples were taken from genetic horizons. The morfological properties of soil profiles were sudied and the samples were analysed on organic carbon, pH, macroelements, magnetic susceptibility. After the wildfires changes in morfological and physico-chemical properties of soils were detected in most cases. The formation of ash and charry horizons was observed only in cases of peat soils affecetd by intense fires, and all post-fire drained peat soils had thick ash horizons even after 10 years after the fires. The significant loss of organic matter took place after burning. But almost immediately after the fires new stage of humus formation usually started. For instance, in post-fire histosols in 2 years after the burning the content of organic carbon reached to 10-12 % in upper horizons. ph values in background histosols were approximately 4-5. After the fire pH increased in these soil type to 8, and two years after the fire event pH decreased to 6-7. In podzols pH values returned to the pre-fire level 4-5 in two years. The magnetic susceptibility of soil samples in background histosols was 2-40 ū10-6 cm3/g. After the fires it increased in ash horizons up to 250 ū10-6 cm3/g. In sod podzols the changes also occurred. Background podzols had 2- 5ū10-6 cm3/g. Post-fire horizons had up to 50- 60ū10-6 cm3/g after the fires. And even 10 years later the differences between post-fire and background soils preserved. So this parameter could be used as an indicator of fire events in soil profiles. After the fire the significant changes occurred in horizon mineral composition. Ash horizons had elevated concentrations of Al2O3 (9-17%), Fe2O3 (4-11%), P2O3 (1-1,8 %), CaO (1,9-2,8 %) and K2O (0,1-1,9%). The observed trends were similar for histosols and for histic podzols. And the changes in horizon mineral composition remained 2 and 10 years after the fire. So the more significant morphological and chemical changes occurred in the profiles of histosols, especially fire altered the soils of drained peatlands. These soil type keeps changes even 10 years after the fires.
Influence of soil properties on the toxicity of TiO? nanoparticles on carbon mineralization and bacterial abundance.
Simonin, Marie; Guyonnet, Julien P; Martins, Jean M F; Ginot, Morgane; Richaume, AgnĶs
Information regarding the impact of low concentration of engineered nanoparticles on soil microbial communities is currently limited and the importance of soil characteristics is often neglected in ecological risk assessment. To evaluate the impact of TiO2 nanoparticles (NPs) on soil microbial communities (measured on bacterial abundance and carbon mineralization activity), 6 agricultural soils exhibiting contrasted textures and organic matter contents were exposed for 90 days to a low environmentally relevant concentration or to an accidental spiking of TiO2-NPs (1 and 500mgkg(-1) dry soil, respectively) in microcosms. In most soils, TiO2-NPs did not impact the activity and abundance of microbial communities, except in the silty-clay soil (high OM) where C-mineralization was significantly lowered, even with the low NPs concentration. Our results suggest that TiO2-NPs toxicity does not depend on soil texture but likely on pH and OM content. We characterized TiO2-NPs aggregation and zeta potential in soil solutions, in order to explain the difference of TiO2-NPs effects on soil C-mineralization. Zeta potential and aggregation of TiO2-NPs in the silty-clay (high OM) soil solution lead to a lower stability of TiO2-NP-aggregates than in the other soils. Further experiments would be necessary to evaluate the relationship between TiO2-NPs stability and toxicity in the soil. PMID:25464292
Linking annual N2O emission in organic soils to mineral nitrogen input as estimated by heterotrophic respiration and soil C/N ratio.
Mu, Zhijian; Huang, Aiying; Ni, Jiupai; Xie, Deti
Organic soils are an important source of N2O, but global estimates of these fluxes remain uncertain because measurements are sparse. We tested the hypothesis that N2O fluxes can be predicted from estimates of mineral nitrogen input, calculated from readily-available measurements of CO2 flux and soil C/N ratio. From studies of organic soils throughout the world, we compiled a data set of annual CO2 and N2O fluxes which were measured concurrently. The input of soil mineral nitrogen in these studies was estimated from applied fertilizer nitrogen and organic nitrogen mineralization. The latter was calculated by dividing the rate of soil heterotrophic respiration by soil C/N ratio. This index of mineral nitrogen input explained up to 69% of the overall variability of N2O fluxes, whereas CO2 flux or soil C/N ratio alone explained only 49% and 36% of the variability, respectively. Including water table level in the model, along with mineral nitrogen input, further improved the model with the explanatory proportion of variability in N2O flux increasing to 75%. Unlike grassland or cropland soils, forest soils were evidently nitrogen-limited, so water table level had no significant effect on N2O flux. Our proposed approach, which uses the product of soil-derived CO2 flux and the inverse of soil C/N ratio as a proxy for nitrogen mineralization, shows promise for estimating regional or global N2O fluxes from organic soils, although some further enhancements may be warranted. PMID:24798347
Linking Annual N2O Emission in Organic Soils to Mineral Nitrogen Input as Estimated by Heterotrophic Respiration and Soil C/N Ratio
Mu, Zhijian; Huang, Aiying; Ni, Jiupai; Xie, Deti
Organic soils are an important source of N2O, but global estimates of these fluxes remain uncertain because measurements are sparse. We tested the hypothesis that N2O fluxes can be predicted from estimates of mineral nitrogen input, calculated from readily-available measurements of CO2 flux and soil C/N ratio. From studies of organic soils throughout the world, we compiled a data set of annual CO2 and N2O fluxes which were measured concurrently. The input of soil mineral nitrogen in these studies was estimated from applied fertilizer nitrogen and organic nitrogen mineralization. The latter was calculated by dividing the rate of soil heterotrophic respiration by soil C/N ratio. This index of mineral nitrogen input explained up to 69% of the overall variability of N2O fluxes, whereas CO2 flux or soil C/N ratio alone explained only 49% and 36% of the variability, respectively. Including water table level in the model, along with mineral nitrogen input, further improved the model with the explanatory proportion of variability in N2O flux increasing to 75%. Unlike grassland or cropland soils, forest soils were evidently nitrogen-limited, so water table level had no significant effect on N2O flux. Our proposed approach, which uses the product of soil-derived CO2 flux and the inverse of soil C/N ratio as a proxy for nitrogen mineralization, shows promise for estimating regional or global N2O fluxes from organic soils, although some further enhancements may be warranted. PMID:24798347
Temperature effect on mineralization of SOM, plant litter and priming: modified by soil type?
NASA Astrophysics Data System (ADS)
Azzaroli Bleken, Marina; Berland Fr°seth, Randi
The purpose of this study was to provide improved temperature response functions to be used in models of soil organic carbon (SOC) and litter mineralization, with focus on the winter period. Our working hypothesis were: 1) decomposition of SOM and plant residue occurs also at temperature close to the freezing point; 2) the effect of temperature on SOC decomposition is stronger in clayey than in sandy soil; 3) decomposition and response to temperature of added plant litter is not affected by soil type. A silty clay loam (27% clay, 3% sand) and a sandy loam (6% clay, 51% sand) with similar weather and cultivation history were pre-incubated at about 15░ C for about 4.5 months. Clover leaves labelled with 13C were added to half of the samples, and soil with and without clover was incubated for 142 days at 0, 4, 8.5 or 15 ░C. Mineralization of SOC and clover leaves was observed also at 0░ C. In the absence of added plant material, SOC decomposition followed a first order reaction which was twice as fast in the sandy soil as in the clay soil. The decomposition rate of clover leaves was also higher in the sandy soil than in the clay soil. However, the influence of temperature on SOC and on clover decomposition was the same in both soils. In presence of plant material, there was a positive priming effect on SOC, which initially correlated with decomposition of plant litter. There was a progressively lower priming effect at higher temperatures, particularly in the sandy soil, that could be understood as substrates exhaustion in a restricted volume of influence around the added clover leaves. We provide parameterised Arrhenius and alternative modifying linear temperature functions together with decay rates at reference temperature, which can be used for predicting decay rates of SOC per se and of the labile pool of clover leaves. We also show the superiority of these functions compared to the use of Q10 as temperature factor. Further, we suggest approaches for modelling the priming effect caused by plant litter. Reference: Fr°seth RB, Bleken MA(2015) Effect of low temperature and soil type on the decomposition rate of soil organic carbon and clover leaves, and related priming effect. Soil Biology and Biochemistry 80:156-166.
Organic nitrogen storage in mineral soil: implications for policy and management
NASA Astrophysics Data System (ADS)
Bingham, A. H.; Cotrufo, M. F.
Nitrogen is one of the most important ecosystem nutrients and often its availability limits net primary production as well as stabilization of soil organic matter. The long-term storage of nitrogen-containing organic matter in soils was classically attributed to chemical complexity of plant and microbial residues that retarded microbial degradation. Recent advances have revised this framework, with the understanding that persistent soil organic matter consists largely of chemically labile, microbially processed organic compounds. Chemical bonding to minerals and physical protection in aggregates are more important to long-term (i.e., centuries to millennia) preservation of these organic compounds that contain the bulk of soil nitrogen rather than molecular complexity, with the exception of nitrogen in pyrogenic organic matter. This review examines the factors and mechanisms that influence the long-term sequestration of organic nitrogen in mineral soils. It examines the policy and management implications which stem from this newly accepted paradigm, such as critical loads considerations and nitrogen saturation and mitigation consequences. Finally, it emphasizes how essential it is for this important but underappreciated pool to be better quantified and incorporated into policy and management decisions.
Pathogenic prion protein is degraded by a manganese oxide mineral found in soils
Russo, F.; Johnson, C.J.; McKenzie, D.; Aiken, Judd M.; Pedersen, J.A.
Prions, the aetiological agents of transmissible spongiform encephalopathies, exhibit extreme resistance to degradation. Soil can retain prion infectivity in the environment for years. Reactive soil components may, however, contribute to the inactivation of prions in soil. Members of the birnessite family of manganese oxides (MnO2) rank among the strongest natural oxidants in soils. Here, we report the abiotic degradation of pathogenic prion protein (PrPTSE) by a synthetic analogue of naturally occurring birnessite minerals. Aqueous MnO2 suspensions degraded the PrPTSE as evidenced by decreased immunoreactivity and diminished ability to seed protein misfolding cyclic amplification reactions. Birnessite-mediated PrPTSE degradation increased as a solution's pH decreased, consistent with the pH-dependence of the redox potential of MnO2. Exposure to 5.6 mg MnO2 ml-1 (PrPTSE:MnO2=1 : 110) decreased PrPTSE levels by ???4 orders of magnitude. Manganese oxides may contribute to prion degradation in soil environments rich in these minerals. ?? 2009 SGM.
A field method for the determination of nitrogen mineralization in forest soils
NASA Astrophysics Data System (ADS)
Razgulin, S. M.
The mineralization of nitrogen in forest soils, one of the processes that provides forest ecosystems with nitrogen, has practically not been studied in Russia. A variant of the method used for the measurement of the nitrogen mineralization in forest soils is proposed, and a description of its field and laboratory stages is given. At the field stage, as the ammonium concentrations are determined in the soil horizons, eight soil samples free of plants and plant roots are recommended to be exposed in a uniform forest area in order to provide a 10% error of the average. The results obtained in a laboratory by the traditional method of measuring the ammonium content in litter extracts may be overstated by 5 times (on the average, by 1.7 times) as compared to the results obtained by the diffusion-isothermic method proposed. The source of errors in the former method is the specific features of NesslerÆs reagent, which forms colored complexes with metals and organic compounds. In addition, extracts from loamy soils often grow turbid and opalescent at the addition of NesslerÆs reagent, which makes the measurement of the optical density impossible. A highly sensitive and well-reproducible method is recommended for the reduction of nitrates to nitrites in a column with coppered cadmium. The methods proposed are simple and reliable and do not require the expensive autoanalyzers that are used abroad.
The use of volcanic soil as mineral landfill liner--III. Heavy metals retention capacity.
Navia, Rodrigo; Fuentes, Bßrbara; Diez, MarĒa C; Lorber, Karl E
The volcanic soil of Southern Chile was tested for its heavy metal retention capacity. The maximum uptakes for CrO4(2-) (CrVI), Cu(2+), Zn(2+) and Pb(2+) were determined to be 2.74, 5.32, 5.86 and 7.44 mg g(-1), respectively. At a slightly alkaline pH value (7.5), it seems that a precipitation-adsorption process was responsible for the Cu(2+) and Zn(2+) uptake onto volcanic soil. All the determined values are of the same order of magnitude as natural zeolites heavy metals adsorption capacities. In addition, the heavy metals diffusion model through a 1 m volcanic soil mineral liner shows breakthrough times of 21.6, 10.2 and 8.9 years, for Pb(2+), Zn(2+) and Cu(2+), respectively, confirming the trend obtained in the adsorption isotherms. The natural volcanic soil of Southern Chile is an interesting material for possible use as landfill mineral basal sealing. It has an appropriate sealing potential (average Kf value of 5.85 x 10(-9) m s(-1)) and a heavy metals retention capacity comparable with natural zeolites. About two-thirds of the agricultural land in Chile (approximately 0.4 million km2) is derived from volcanic ash, suggesting an important soil volume for future landfill projects, that could be obtained in sufficient quantities from urban building activities. PMID:15988945
Mineral control of soil carbon storage with reforestation of abandoned pastures
NASA Astrophysics Data System (ADS)
MarĒn-Spiotta, E.; Silver, W. L.; Swanston, C. W.; Torn, M. S.; Burton, S. D.
We applied CP MAS 13C-NMR spectroscopy and radiocarbon modeling to soil C density fractions to track changes in the quality and turnover of C with forest regrowth on former pasturelands. Our results showed that inter-aggregate, unattached particulate organic C (free light fraction) and C located inside soil aggregates (occluded light fraction) represent distinct soil C pools. The signal intensity of the O-alkyl region, representing cellulose, decreased with mineral-association, while alkyl C, attributed to waxy compounds and microbially resynthesized lipids, increased from the free to the occluded light fractions. The alkyl/O-alkyl ratio changed consistently with changes in C-to-N and ?15N across different land cover types, and thus appears to be a reliable index of humification. In contrast to cellulose, proteins, lipids and lignin did not show any consistent trends, suggesting different controls on their decomposition. Greater variability in the chemical makeup of the occluded light fraction suggests that it represents material in different stages of decay. Mean residence times (MRT) of the free light C were significantly shorter (4.3 ▒ 0.5 yrs) than for the occluded fraction (7.3 ▒ 0.8 yrs). The occluded fraction in active pastures and secondary forests in the earliest stage of succession had shorter MRT than in primary forests and older secondary forests, which would be explained by lower aggregate stability and faster cycling rates in disturbed versus undisturbed soils. The mineral associated C in the disturbed soils had slower cycling C (MRT = 98.9 ▒ 10.6 yrs) than the undisturbed sites (65.8 ▒ 2.1 yrs), most likely due to a preferential loss of labile C in the first. Incorporation of C into soil aggregates afforded some protection from decomposition, but the main mechanism of stabilization was direct mineral association. As the sorptive capacity of a soil is dependent on its mineral composition, it appears that the Oxisols at our sites have reached their maximum C storage capacity. This may explain their resiliency to land-use change and why we have observed no significant accumulation of soil C despite large increases in aboveground biomass with reforestation.
Rebuilding Peatlands on Mineral Soils Utilizing Lessons Learned from Past Peatland Initiation
NASA Astrophysics Data System (ADS)
Vitt, D. H.; Koropchak, S. C.; Xu, B.; Bloise, R.; Wieder, R.; Mowbray, S.
Recent surveys of peatland initiation during the past 10,000 years in northeastern Alberta have revealed that nearly all peatlands, regardless of whether they are currently bogs and fens, were initiated by paludification, or swamping of upland soils. Terrestrialization (or infilling of water bodies) rarely if ever was involved in the initiation of peatlands across the mid boreal of Canada. Although the importance of paludification as a significant natural process in the initiation of peatland ecosystems has long been known by peatland ecologists, this knowledge has not been transferred to peatland and wetland restoration methodologies. We initiated this study to determine if wetland structure and function could be re-established on mineral gas/oil pads that were originally placed on organic soils. We have attempted to emulate the paludification process by removing mineral material to near the surrounding peatland natural water level and introducing a suite of wetland plants to the rewetted mineral soils. The experimental design comprised two well sites at the Shell Carmon Creek in situ plant near Peace River, Alberta. We placed 292 2 x 2 m plots over a series of fertilizer, water level, cultivation, and amendment treatments. In this presentation, we address four questions: 1) Will locally available peatland vascular plant species establish on these wet, compacted, mineral soils? If so; 2) Are species responses affected by water level, amendment, cultivation, and fertilization treatments, 3) Are invasive weeds a concern in these re-establishment trials, and 4) Will the surrounding bog water chemistry have an effect on water in contact with the mineral soils? Results after three growing season are: 1) All three species originally planted (a sedge, a willow, and tamarack) have successfully established at both well sites; 2) Carex aquatilis has performed well and responses to differing water levels and cultivation are not significant; 3) The plant responses to amendments are, in general, not different from the control plots; 4) The abundance of weeds is significantly different among some of the amendment types; and 5) Water chemistry (pH and electrical conductivity) of the ditches is affected by the surrounding bog waters. In addition, a fifth question was asked: Can Carex aquatilis establish by seed and if so, do C. aquatilis seeds require a peat amendment? In May 2009, three blank 4 m2 plots were selected on each of the experimental well site reclamations. Half of each plot was covered with approximately 4 cm of peat and the other half remained a mineral soil substrate. Each plot half was divided into 2 halves (1 m2); one that had approximately 600 Carex aquatilis seeds scattered across it and one that had no seeds added. Results from reassessment in July 2010 showed that subplots with added seeds had more seedlings than the subplots without added seeds. There was no difference between the number of seedlings between the peat and mineral soil subplots on either site, but on one of the sites, the subplots with peat had much higher percent cover of weeds than the mineral soil subplots.
Soil Phosphorus Stoichiometry Drives Carbon Turnover Along a Soil C Gradient Spanning Mineral and Organic Soils Under Rice Cultivation
NASA Astrophysics Data System (ADS)
Hartman, W.; Ye, R.; Horwath, W. R.; Tringe, S. G.
Soil carbon (C) cycling is linked to the availability of nutrients like nitrogen (N) and phosphorus (P). However, the role of soil P in influencing soil C turnover and accumulation is poorly understood, with most models focusing on C:N ratios based on the assumption that terrestrial ecosystems are N limited. To determine the effects of N and P availability on soil C turnover, we compared soil respiration over the course of a growing season in four adjacent rice fields with 5%, 10%, 20% and 25% soil C. In each of these fields, plots were established to test the effect of N additions on plant growth, using control and N addition treatments (80 kg N/ha urea). Although soil P was not manipulated in parallel, prior work has shown soil P concentrations decline markedly with increasing soil C content. Soil CO2 flux was monitored using static chambers at biweekly intervals during the growing season, along with porewater dissolved organic C and ammonium. Soils were collected at the end of the growing season, and tested for total C, N, and P, extractable N and P, pH, base cations and trace metals. Soil DNA was also extracted for 16S rRNA sequencing to profile microbial communities. Soil N additions significantly increased CO2 flux and soil C turnover (seasonal CO2 flux per unit soil C) in 5% and 10% C fields, but not in 20% or 25% C fields. Soil C content was closely related to soil N:P stoichiometry, with N:P ratios of ca. 12, 16, 24, and 56 respectively in the 5, 10, 20 and 25% C fields. Seasonal CO2 fluxes (per m2) were highest in 10% C soils. However, soil C turnover was inversely related to soil C concentrations, with the greatest C turnover at the lowest values of soil C. Soil C turnover showed stronger relationships with soil chemical parameters than seasonal CO2 fluxes alone, and the best predictors of soil C turnover were soil total and extractable N:P ratios, along with extractable P alone. Our results show that soil P availability and stoichiometry influence the turnover of soil C, even where primary producers are clearly limited by N. Prior work has suggested these contrasting patterns in nutrient limitation may arise due to stoichiometric differences among plants and soil microbes. We hypothesize that differences in soil carbon turnover may in part reflect shifts in metabolism of microbial communities associated with stoichiometric variation in soils.
Can 15 N profiles in forest soils predict loss and net N mineralization rates?
H. Vervaet; P. Boeckx; V. Unamuno; O. Van Cleemput; G. Hofman
This paper studies changes of 15N signatures (ཋN, ?) and total N (TN, %) in soil profiles among forest stands with different $$ {\\\\rm NO}_3^ - $$ losses within the same climatic zone. An additional aim was to investigate whether the change of ཋN ((ཋN) within the 0-10, 10-20 and 20-30 cm depths of the mineral layer could be linked
Rare earth elements in forest-floor herbs as related to soil conditions and mineral nutrition
Germund Tyler; Tommy Olsson
Mixtures of rare earth elements (REEs) in fertilizers are widely used in Chinese agriculture to improve crop nutrition. REE\\u000a concentrations in wild-growing plants, especially herbs, are little known. This study describes differences in the concentrations\\u000a and proportions of REEs in eight forest-floor herbaceous plants and relates these differences to soil and mineral nutrient\\u000a conditions. REEs studied were yttrium (Y), lanthanum
Comparison of thermal signatures of a mine buried in mineral and organic soils
NASA Astrophysics Data System (ADS)
Lamorski, K.; Pregowski, Piotr; Swiderski, Waldemar; Usowicz, B.; Walczak, R. T.
Values of thermal signature of a mine buried in soils, which ave different properties, were compared using mathematical- statistical modeling. There was applied a model of transport phenomena in the soil, which takes into consideration water and energy transfer. The energy transport is described using Fourier's equation. Liquid phase transport of water is calculated using Richard's model of water flow in porous medium. For the comparison, there were selected two soils: mineral and organic, which differs significantly in thermal and hydrological properties. The heat capacity of soil was estimated using de Vries model. The thermal conductivity was calculated using a statistical model, which incorprates fundamental soil physical properties. The model of soil thermal conductivity was built on the base of heat resistance, two Kirchhoff's laws and polynomial distribution. Soil hydrological properties were described using Mualem-van Genuchten model. The impact of thermal properties of the medium in which a mien had been placed on its thermal signature in the conditions of heat input was presented. The dependence was stated between observed thermal signature of a mine and thermal parameters of the medium.
Net nitrogen mineralization and net nitrification rates in soils following deforestation for pasture across the southwestern Brazilian Amazon Basin landscape
Christopher Neill; Marisa C. Piccolo; Carlos C. Cerri; Paul A. Steudler; Jerry M. Melillo; Marciano Brito
Previous studies of the effect of tropical forest conversion to cattle pasture on soil N dynamics showed that rates of net\\u000a N mineralization and net nitrification were lower in pastures compared with the original forest. In this study, we sought\\u000a to determine the generality of these patterns by examining soil inorganic N concentrations, net mineralization and nitrification\\u000a rates in 6
An improved radiative transfer model for estimating mineral abundance of immature and mature lunar soils
NASA Astrophysics Data System (ADS)
Liu, Dawei; Li, Lin; Sun, Ying
An improved Hapke's radiative transfer model (RTM) is presented to estimate mineral abundance for both immature and mature lunar soils from the Lunar Soil Characterization Consortium (LSCC) dataset. Fundamental to this improved Hapke's model is the application of an alternative equation to describe the effects of larger size submicroscopic metallic iron (SMFe) (>50 nm) in the interior of agglutinitic glass that mainly darken the host material, contrasting to the darkening and reddening effects of smaller size SMFe (<50 nm) residing in the rims of mineral grains. Results from applying a nonlinear inversion procedure to the improved Hapke's RTM show that the average mass fraction of smaller and larger size SMFe in lunar soils was estimated to be 0.30% and 0.31% respectively, and the particle size distribution of soil samples is all within their measured range. Based on the derived mass fraction of SMFe and particle size of the soil samples, abundances of end-member components composing lunar soil samples were derived via minimizing the difference between measured and calculated spectra. The root mean square error (RMSE) between the fitted and measured spectra is lower than 0.01 for highland samples and 0.005 for mare samples. This improved Hapke's model accurately estimates abundances of agglutinitic glass (R-squared = 0.88), pyroxene (R-squared = 0.69) and plagioclase (R-squared = 0.95) for all 57 samples used in this study including both immature and mature lunar soils. However, the improved Hapke's RTM shows poor performance for quantifying abundances of olivine, ilmenite and volcanic glass. Improving the model performance for estimation of these three end-member components is the central focus for our future work.
Effects of CO[sub 2], temperature, and seedlings on soil organic matter contents, and C and N mineralization, in forest soils
Perry, D.A.; Gillham, M.L.; Homann, P.; Griffiths, R. (Oregon State Univ., Corvallis, OR (United States))
Soils from 500-year-old old-growth Douglas-fir forests in the Oregon Cascade Mtns. (900 m and 1200 m sites) were [open quote]incubated[close quote] for 32 weeks in controlled-environment chambers. This factorial experiment had two levels each of atmospheric CO[sub 2] (350-700 ppm), soil temperature (13/17[degrees]C), soil N (1200 m soils contained twice as much C and N than soils from 900 m), and vegetation (with/without seedlings). Exchangeable NH[sub 4] was greater in the 900 m soils than in the 1200 m soils for all treatments except elevated CO[sub 2], and net mineralized NH[sub 4] was greater in 900 m soils for all treatments. Extractable NO[sub 3] decreased from ambient (350 ppm CO[sub 2], 13[degrees]C) in all treatments and in both soil types, and was greater in 1200 m soils. Total net N mineralized was greater in the 1200 a m soils at higher CO[sub 2], temperature, or both. These results suggest greater proportional NO[sub 3] uptake in seedlings grown in the lower elevation, N-limited soils, and/or that soil C quality is higher in 900 m soils.
Pristine soils mineralize 3-chlorobenzoate and 2,4-dichlorophenoxyacetate via different microbial populations.
Fulthorpe, R R; Rhodes, A N; Tiedje, J M
Biodegradation of two chlorinated aromatic compounds was found to be a common capability of the microorganisms found in the soils of undisturbed, pristine ecosystems. We used 2,4-dichlorophenoxyacetate (2,4-D) and 3-chlorobenzoate (3CBA) as enrichment substrates to compare populations of degrading bacteria from six different regions making up two ecosystems. We collected soil samples from four Mediterranean (California, central Chile, the Cape region of South Africa, and southwestern Australia) and two boreal (northern Saskatchewan and northwestern Russia) ecosystems that had no direct exposure to pesticides or to human disturbance. Between 96 and 120 samples from each of the six regions were incubated with 50 ppm of [U-14C]2,4-D or [U-14C]3CBA. Soils from all regions samples mineralized both 2,4-D and 3CBA, but 3CBA was mineralized without a lag period, while 2,4-D was generally not mineralized until the second week. 3CBA degradative capabilities were more evenly distributed spatially than those for 2,4-D. The degradative capabilities of the soils were readily transferred to fresh liquid medium. 3CBA degraders were easily isolated from most soils. We recovered 610 strains that could release carbon dioxide from ring-labeled 3CBA. Of these, 144 strains released chloride and degraded over 80% of 1 mM 3CBA in 3 weeks or less. In contrast, only five 2,4-D degraders could be isolated, although a variety of methods were used in an attempt to culture the degraders. The differences in the distribution and culturability of the bacteria responsible for 3CBA and 2,4-D degradation in these ecosystems suggest that the two substrates are degraded by different populations. We also describe a 14C-based microtiter plate method that allows efficient screening of a large number of samples for biodegradation activity. PMID:8919776
Carbon Mineralization of Soils from Native Evergreen Broadleaf Forest and Three Plantations in Mid?subtropic China
Jian Zhang
Mineralization of soil organic carbon (C) plays a key role in supplying nutrient elements essential to plant growth. Changes of C mineralization of mixed stands of Chinese fir and Michelia macclurei (a broadleaf tree), pure M. macclurei stands, and pure Chinese fir (Cunninghamia lanceolata) stands established in 1983 after clear?felling of a first?generation Chinese fir forest were analyzed in Huitong,
Determination of the N mineralization potential of different soils by anaerobic incubation as calibrated in a pot-experiment
G. Dersch; M. Pfeffer; O. H. Danneberg
Summary In a pot experiment with Italian raygrass as testplant and at optimal conditions for N mineralization from the organic N pool (adequate water supply, no relevant mineral N content in the soil\\/sand substrate) about 70 % of the N uptake variation from the above ground grass vegetation could be explained by the biological parameter \\
Minerals vs. Microbes: Biogeochemical Controls on Carbon Storage in Humid Tropical Forest Soils
NASA Astrophysics Data System (ADS)
Hall, S. J.; Silver, W. L.
Humid tropical forest soils contain a substantial portion (~500 Pg) of the terrestrial carbon (C) pool, yet their response to climate change remains unclear due to mechanistic uncertainty in the biogeochemical controls on soil C storage in these ecosystems. Poorly-crystalline minerals have long been known to stabilize soil C, but few studies have explored their relative importance in comparison with other likely controls such as rhizosphere processes, oxygen deficiency (anaerobiosis), and C quality. We examined relationships among soil C and a suite of biogeochemical variables measured in 162 samples from surface soils (ultisols and oxisols) collected over scales of landforms to landscapes (m - km) in the Luquillo Experimental Forest, Puerto Rico. We measured iron (Fe), aluminum (Al), and manganese (Mn) oxides in 0.5M hydrochloric acid (HCl), sodium citrate/ascorbic acid (CA), and citrate/dithionite (CD) extractions, along with clay content, root biomass, C quality (C/N ratios), and anaerobiosis using HCl-extractable reduced iron (Fe(II)) concentrations as a proxy. We used mixed-effects models to compare the relative importance of the above variables (normalized by mean and standard deviation) as predictors of soil C, with random effects to account for spatial structure. Poorly-crystalline Al oxide concentrations (CA extraction), soil C/N ratio, and Fe(II) concentrations each had highly significant (p < 0.0001) positive relationships with soil C concentrations that conveyed equivalent explanatory power, assessed by comparing standardized regression coefficients. The optimal mixed model explained 82 % of the variation of the residual sum of squares of soil C concentrations, which varied between 2 - 20 % C among samples. Fine root biomass had a weak but significantly positive association with soil C concentrations (p < 0.05), while crystalline Fe oxide concentrations (CD extraction) displayed a negative correlation (p < 0.01), and clay contents had no significant relationship. The latter results are surprising given the documented role of Fe oxides and clay minerals in C stabilization, yet may indicate the importance of C supply via roots in controlling C concentrations in humid tropical ecosystems. Samples associated with high concentrations of crystalline Fe and high clay contents may represent soils from deeper in the soil profile exposed by landslides, characterized by poorly-developed aggregate structure and fewer C inputs since disturbance. Our optimal mixed model suggested an equivalent importance of soil mineralogy, anaerobiosis, and C quality as correlates of soil C concentrations across tropical forest ecosystems varying in temperature, precipitation, and community composition. Whereas soil mineralogy may be relatively static over timescales of years to decades, O2 availability and the chemical composition of soil C inputs and can potentially vary more rapidly. Our model suggests that changes in temperature and precipitation regimes that alter O2 availability and/or increase the lability of C inputs may lead to decreased soil C storage in humid tropical forest soils.
Modeling mineral dust emissions from the Sahara desert using new surface properties and soil database
NASA Astrophysics Data System (ADS)
Laurent, B.; Marticorena, B.; Bergametti, G.; LķOn, J. F.; Mahowald, N. M.
The present study investigates the mineral dust emissions and the occurrence of dust emission events over the Sahara desert from 1996 to 2001. Mineral dust emissions are simulated over a region extending from 16░N to 38░N and from 19░W to 40░E with a ?░ ū ?░ spatial resolution. The input parameters required by the dust emission model are surface features data (aerodynamic roughness length, dry soil size distribution and texture for erodible soils), and meteorological surface data (mainly surface wind velocity and soil moisture). A map of the aerodynamic roughness lengths is established based on a composition of protrusion coefficients derived from the POLDER-1 surface products. Soil dry size distribution and texture are derived from measurements performed on soil samples from desert areas, and from a soil map derived from a geomorphologic analysis of desert landscapes. Surface re-analyzed meteorological databases (ERA-40) of the European Centre for Medium range Weather Forecasts (ECMWF) are used. The influence of soil moisture on simulated dust emissions is quantified. The main Saharan dust sources identified during the 6-year simulated period are in agreement with the previous studies based on in situ or satellite observations. The relevance of the simulated large dust sources and point sources ("hot spots") is tested using aerosol indexes derived from satellite observations (TOMS Absorbing Aerosol Index and Infrared Dust Difference Index Meteosat). The Saharan dust emissions simulated from 1996 to 2001 range from 585 to 759 Tg a-1. The simulations show marked seasonal cycles with a maximum in summer for the western Sahara and in spring for the eastern Sahara. The interannual variability of dust emissions is pronounced in the eastern part of the Sahara while the emissions from the western Sahara are more regular over the studied period. The soil moisture does not noticeably affect the Saharan dust emissions, their seasonal cycle or their interannual variability, but it can partly control and limit the dust emissions in some parts of the northern desert margin, where the precipitation rates are higher. Our simulations also tend to confirm that the Sahara is the major terrestrial source of mineral dust.
Bioremediation of experimental petroleum spills on mineral soils in the Vestfold Hills, Antarctica
Kerry, E. (Univ. of Tasmania (Australia))
The effect of nutrient and water enhancement on the biodegradation of petroleum was tested in Antarctic mineral soils. Nitrogen, phosphorus and potassium were applied in solution, with or without gum xanthan or plastic covers, to sites artificially contaminated with distillate. The effectiveness of these procedures was assessed by measuring changes in total petroleum hydrocarbons; heptadecane/pristane and octadecane/phytane ratios; in concentrations of major hydrocarbon components and in microbial numbers and activity. Significantly lower hydrocarbon concentration were recorded after one year in soils treated with fertilizer solutions, but only in the surface 3 cm. These soils also showed lowered heptadecane/pristane and octadecane/phytane ratios and had the highest levels of microbial activity relative to other plots. Soils treated with gum xanthan or covered with plastic had the highest residual hydrocarbon levels. Both treatments inhibited evaporative loss of hydrocarbon, and there were indications that gum xanthan was utilized by the microbiota as an alternative carbon source to distillate. Higher temperatures were recorded under the plastic but no stimulation of biodegradation was detected. Estimated numbers of metabolically active bacteria were in the range 10[sup 7] to 10[sup 8] g[sup [minus]1] dry weight of soil, with an estimated biomass of 0.03 to 0.26 mg g[sup [minus]1] soil. Estimated numbers of amoebae were in the range 10[sup 6] 10[sup 7] g[sup [minus]1] soil (biomass of 2 to 4 mg g[sup [minus]1]). The highest populations were recorded in fertilized, contaminated soils, the only soils where petroleum degradation was demonstrated. 23 refs., 1 fig., 4 tabs.
Response of maize yield, nitrate leaching, and soil nitrogen to pig slurry combined with mineral nitrogen.
Yag³e, MarĒa R; QuĒlez, Dolores
The application of pig (Sus scrofa) slurry (PS) is a common fertilization practice that may affect nitrate concentrations and loads in drainage and receiving water bodies. To protect water resources, many agricultural areas are being designated as vulnerable to nitrate contamination, and there is a need for scientific data aiming at reducing nitrate exports from these vulnerable zones by optimizing N fertilization strategies. The objective of this work, conducted in drainage lysimeters in a 4-yr monoculture maize (Zea mays L.) crop, is to assess the effects of four fertilization strategies combining PS (30, 60, 90, and 120 t ha(-1)) and mineral N on yield, changes in soil mineral N, and concentration and mass of nitrate in drainage waters. Grain yield was not affected by treatments in the four experimental years, nor was the soil mineral N at the end of the experiment. Effects of fertilization strategies on nitrate concentration and mass in drainage waters were detected only after 3 yr of repeated PS applications. The mass of nitrate leached over the 4 yr was positively related to the total amount of N applied, either organic or mineral. In year 2003, precipitation in spring reduced N availability for the crop in treatments with rates > or = 60 t PS ha(-1). The N-budget revealed that the transport pathways for 25% of N inputs to the system are unknown. The presowing application of pig slurry at 30 t ha(-1) complemented with mineral N at side-dressing, was the most efficient from an environmental standpoint (4-yr average of 145 kg grain yield kg(-1) N leached). PMID:20176841
Beryllium geochemistry in soils: Evaluation of 10Be/9Be ratios in authigenic minerals as a basis for age models
Barg, E.; Lal, D.; Pavich, M.J.; Caffee, M.W.; Southon, J.R.
Soils contain a diverse and complex set of chemicals and minerals. Being an 'open system', both in the chemical and nuclear sense, soils have defied quantitative nuclear dating. However, based on the published studies of the cosmogenic atmospheric 10Be in soils, its relatively long half-life (1.5 Ma), and the fact that 10Be gets quickly incorporated in most soil minerals, this radionuclide appears to be potentially the most useful for soil dating. We therefore studied the natural variations in the specific activities of 10Be with respect to the isotope 9Be in mineral phases in eight profiles of diverse soils from temperate to tropical climatic regimes and evaluated the implications of the data for determining the time of formation of soil minerals, following an earlier suggestion [Lal et al., 1991. Development of cosmogenic nuclear methods for the study of soil erosion and formation rates. Current Sci. 61, 636-639.]. We find that the 10Be/9Be ratios in both bulk soils and in the authigenic mineral phases are confined within a narrower range than in 10Be concentrations. Also, the highest 10Be/9Be ratios in authigenic minerals are observed at the soil-rock interface as predicted by the model. We present model 10Be/9Be ages of the B-horizon and the corresponding soil formation rates for several soil profiles. The present study demonstrates that the 10Be/9Be ratios in the authigenic phases, e.g. clay and Fe-hydroxides, can indeed be used for obtaining useful model ages for soils younger than 10-15 Ma. However, the present work has to be pushed considerably further, to take into account more realistic age models in which, for instance, downward transport of 10Be and clays, and in-situ dissolution of clay minerals at depths, altering the 10Be/9Be ratios of the acidic solutions, are included. We show that in the case of younger soils (< 1 Ma) studied here, their 10Be inventories and 10Be/9Be ratios have been significantly disturbed possibly by mixing with transported soils. ?? 1997 Elsevier Science B.V.
Nitrous oxide emissions respond differently to mineral and organic nitrogen sources in contrasting soil types.
Pelster, David E; Chantigny, Martin H; Rochette, Philippe; Angers, Denis A; Rieux, Christine; Vanasse, Anne
The use of various animal manures for nitrogen (N) fertilization is often viewed as a viable replacement for mineral N fertilizers. However, the impacts of amendment type on NO production may vary. In this study, NO emissions were measured for 2 yr on two soil types with contrasting texture and carbon (C) content under a cool, humid climate. Treatments consisted of a no-N control, calcium ammonium nitrate, poultry manure, liquid cattle manure, or liquid swine manure. The N sources were surface applied and immediately incorporated at 90 kg N ha before seeding of spring wheat ( L.). Cumulative NO-N emissions from the silty clay ranged from 2.2 to 8.3 kg ha yr and were slightly lower in the control than in the fertilized plots ( = 0.067). The 2-yr mean NO emission factors ranged from 2.0 to 4.4% of added N, with no difference among N sources. Emissions of NO from the sandy loam soil ranged from 0.3 to 2.2 kg NO-N ha yr, with higher emissions with organic than mineral N sources ( = 0.015) and the greatest emissions with poultry manure ( < 0.001). The NO emission factor from plots amended with poultry manure was 1.8%, more than double that of the other treatments (0.3-0.9%), likely because of its high C content. On the silty clay, the yield-based NO emissions (g NO-N kg grain yield N) were similar between treatments, whereas on the sandy loam, they were greatest when amended with poultry manure. Our findings suggest that, compared with mineral N sources, manure application only increases soil NO flux in soils with low C content. PMID:22370405
Mineral?nutrient concentrations in the mountain mahogany species Cercocarpus montanus and Cercocarpus intricatus and in their associated soils
Jack D. Brotherson
Data taken from study sites in northeastern Utah and northeastern Arizona were used to describe the mineral?nutrient relationships of C. montanus and C. intricatus. General habitat and soil relationships are discussed as well as nutrient dynamics with respect to beneath and between plants, uptake patterns ?soil to plant, transfer within the plant and ideas of leaf duration (evergreen vs. deciduous)
Technology Transfer Automated Retrieval System (TEKTRAN)
Our objective was to determine the effects of swine lagoon effluent (SLE)and ammonium nitrate (AN) on soil N supplying capacity and microbial functional groups of N mineralizers and nitrifiers in a forage production system. We collected soils at 0 ¢ 7.5 cm depth in 2004 from field plots planted with...
Biochar and manure effects on net nitrogen mineralization and greenhouse gas emissions from calcareous soil under corn
Technology Transfer Automated Retrieval System (TEKTRAN)
Few multiyear field studies have examined the impacts of a one-time biochar application on net N mineralization and greenhouse gas emissions in an irrigated, calcareous soil; yet such applications are hypothesized as a means of sequestering atmospheric CO2 and improving soil quality. We fall-applie...
Accumulation and turnover of carbon in organic and mineral soils of the BOREAS northern study area
Trumbore, S.E.; Harden, J.W.
Rates of input, accumulation, and turnover of C differ markedly within soil profiles and in soils with different drainage in the BOREAS northern study area. Soil C storage increases from ???3 kg C m-2 in well-drained, sandy soils to greater than 100 kg C m-2 in wetlands. Two modes of C accumulation were observed in upland soil profiles. Large annual C inputs (0.06-0.1 kg C m-2 yr-1) and slow decomposition (turnover times of 6-250 years) lead to rapid C accumulation in regrowing surface moss and detrital layers following fire. Deep organic layers that have accumulated over the millennia since the initiation of soil development, and are located below the most recent charred horizon, show slower rates of input (0.015-0.03 kg C m-2 yr-1) and turnover (100-1600 years) and accumulate C about 10 times slower than surface detrital layers. Rates of C input to soils derived from C and 14C data were in accord with net primary production estimates, with highest rates of input (0.14-0.6 kg C m-2 yr-1) in wetlands. Turnover times for C in surface detrital layers were 6-15 years for well-drained sand soils that showed highest soil temperatures in summer, 30-40 years for wetlands, and 36-250 years for uplands with thick moss cover and black spruce trees. Long (>100 years) turnover times in upland black spruce/clay soils most likely reflect the influence of woody debris incorporated into detrital layers. Turnover times for deep organic and mineral layer C were controlled by drainage, with fastest turnover (80-130 years) in well-drained sand soils and slowest turnover (>3000 years) in wetlands. Total C accumulation rates, which account for C losses from both deep organic and surface detrital layers, are close to zero for sand/jack pine soils, 0.003-0.01 kg C m-2 yr-1 for moderately to poorly drained sites in mature forest stands, and 0.03 kg C m-2 yr-1 for a productive fen. Decomposition of organic matter more than several decades old accounts for 9-22% of total heterotrophic respiration at these sites. The rates of C accumulation derived here are decadal averages for specific stands and will vary as stands age or undergo disturbance. Extrapolation to larger regions and longer timescales, where burning offsets C gains in moss layers, will yield smaller rates of C storage.
Native CaCO3 Mineral Dissolution and Its Contribution to Sodic Calcareous Soil Reclamation Under Laboratory Conditions
Fahu Li; Rami Keren
Efficient and sustainable reclamation of sodic soils is important to agricultural production. With the help of a peristaltic pump, laboratory-leaching experiments for sodic calcareous soils with exchangeable sodium percentage (ESP) of 1, 12.5, and 19 were conducted under atmospheric CO2 partial pressure to investigate native CaCO3 mineral dissolution and its contribution to the rehabilitation of moderate sodium-affected soils at the
A mineral support and biotic catalyst are essential in the formation of highly polymeric soil humic substances
NASA Astrophysics Data System (ADS)
Zavarzina, A. G.
The hypothesis was proposed that highly polymeric humic substances in the mineral horizons of soils in a temperate humid climate originate from polymerization of water-soluble structural precursors directly on mineral surfaces under the catalytic effect of immobilized phenoloxidases (heterophasic biocatalysis). This hypothesis was confirmed by a laboratory experiment using a mixture of monomeric phenols and nitrogenous compounds as structural precursors, fungal laccase as a biotic catalyst, and a hydroxyaluminum-kaolinite complex as a mineral support. Enzymic oxidation of phenolic precursors on the mineral surface was substantially more rapid than abiotic oxidation and led to synthesis of a highly polymeric fraction with a molecular weight over 75 kDa. These products were not produced on the mineral with an absence of laccase (abiotic catalysis) or in solution without the mineral matrix (homogeneous catalysis).
Measurement of net nitrogen and phosphorus mineralization in wetland soils using a modification of the resin-core technique
Noe, Gregory B.
A modification of the resin-core method was developed and tested for measuring in situ soil N and P net mineralization rates in wetland soils where temporal variation in bidirectional vertical water movement and saturation can complicate measurement. The modified design includes three mixed-bed ion-exchange resin bags located above and three resin bags located below soil incubating inside a core tube. The two inner resin bags adjacent to the soil capture NH4+, NO3-, and soluble reactive phosphorus (SRP) transported out of the soil during incubation; the two outer resin bags remove inorganic nutrients transported into the modified resin core; and the two middle resin bags serve as quality-control checks on the function of the inner and outer resin bags. Modified resin cores were incubated monthly for a year along the hydrogeomorphic gradient through a floodplain wetland. Only small amounts of NH4+, NO3-, and SRP were found in the two middle resin bags, indicating that the modified resin-core design was effective. Soil moisture and pH inside the modified resin cores typically tracked changes in the surrounding soil abiotic environment. In contrast, use of the closed polyethylene bag method provided substantially different net P and N mineralization rates than modified resin cores and did not track changes in soil moisture or pH. Net ammonification, nitrifi cation, N mineralization, and P mineralization rates measured using modified resin cores varied through space and time associated with hydrologic, geomorphic, and climatic gradients in the floodplain wetland. The modified resin-core technique successfully characterized spatiotemporal variation of net mineralization fluxes in situ and is a viable technique for assessing soil nutrient availability and developing ecosystem budgets.
Biodegradability of nonaqueous-phase liquids affects the mineralization of phenanthrene in soil because of microbial competition
Morrison, D.E.; Alexander, M. [Cornell Univ., Ithaca, NY (United States)
A study was conducted to determine the effects of biodegradability of nonaqueous-phase liquids (NAPLs) and microbial competition on the biodegradation in soil of a constituent of the NAPLs. The rates of mineralization of phenanthrene dissolved in 8 mg of 2,2,4,4,6,8,8-heptamethylnonane (HMN), di(2-ethylhexyl) phthalate (DEHP), or pristane per g of soil were faster than the rates when the compound was dissolved in hexadecane or dodecane. Addition of inorganic N and P to the soil increased the mineralization rate in the first two but not the last two NAPLs. N and P addition did not enhance mineralization of phenanthrene when added in 500 {micro}g of hexadecane, pristane, or HMN per g of soil. Hexadecane was rapidly degraded, pristane was slowly metabolized, DEHP was still slower, and HMN was not mineralized in the test period. Mixing the soil stimulated mineralization of phenanthrene dissolved in HMN but not in hexadecane. Mineralization of phenanthrene dissolved in HMN was the same if the gas phase contained 21%, 2.1%, or traces of O{sub 2}. In contrast, the biodegradation of phenanthrene dissolved in hexadecane, although the same at 21 and 2.1% O{sub 2}, was not observed if traces of O{sub 2} were present. The mineralization was slower in unshaken soil-water mixtures if phenanthrene was added in hexadecane than in HMN or pristane, but the rates with the 3 NAPLs were increased by shaking the suspensions. The authors suggest that the biodegradability of major components of NAPLs and microbial competition for N, P, or O{sub 2} will have a major impact on the rate of transformation of minor constituents of NAPLs.
Cd Mobility in Anoxic Fe-Mineral-Rich Environments - Potential Use of Fe(III)-Reducing Bacteria in Soil Remediation
NASA Astrophysics Data System (ADS)
Muehe, E. M.; Adaktylou, I. J.; Obst, M.; Schr÷der, C.; Behrens, S.; Hitchcock, A. P.; Tylsizczak, T.; Michel, F. M.; Krõmer, U.; Kappler, A.
Agricultural soils are increasingly burdened with heavy metals such as Cd from industrial sources and impure fertilizers. Metal contaminants enter the food chain via plant uptake from soil and negatively affect human and environmental health. New remediation approaches are needed to lower soil metal contents. To apply these remediation techniques successfully, it is necessary to understand how soil microbes and minerals interact with toxic metals. Here we show that microbial Fe(III) reduction initially mobilizes Cd before its immobilization under anoxic conditions. To study how microbial Fe(III) reduction influences Cd mobility, we isolated a new Cd-tolerant, Fe(III)-reducing Geobacter sp. from a heavily Cd-contaminated soil. In lab experiments, this Geobacter strain first mobilized Cd from Cd-loaded Fe(III) hydroxides followed by precipitation of Cd-bearing mineral phases. Using M÷ssbauer spectroscopy and scanning electron microscopy, the original and newly formed Cd-containing Fe(II) and Fe(III) mineral phases, including Cd-Fe-carbonates, Fe-phosphates and Fe-(oxyhydr)oxides, were identified and characterized. Using energy-dispersive X-ray spectroscopy and synchrotron-based scanning transmission X-ray microscopy, Cd was mapped in the Fe(II) mineral aggregates formed during microbial Fe(III) reduction. Microbial Fe(III) reduction mobilizes Cd prior to its precipitation in Cd-bearing mineral phases. The mobilized Cd could be taken up by phytoremediating plants, resulting in a net removal of Cd from contaminated sites. Alternatively, Cd precipitation could reduce Cd bioavailability in the environment, causing less toxic effects to crops and soil microbiota. However, the stability and thus bioavailability of these newly formed Fe-Cd mineral phases needs to be assessed thoroughly. Whether phytoremediation or immobilization of Cd in a mineral with reduced Cd bioavailability are feasible mechanisms to reduce toxic effects of Cd in the environment remains to be determined.
Temporal dynamics of available and microbial phosphorus and organic phosphorus mineralization in a grassland soil
NASA Astrophysics Data System (ADS)
Liebisch, Frank; Keller, Fabrizio; Frossard, Emmanuel; Huguenin-Elie, Olivier; Oberson, Astrid; B³nemann, Else
Turnover of phosphorus (P) through the microbial biomass and P mineralization have been reported as two main biological factors controlling P availability in soils. This is particularly true for grassland soils where organic matter is accumulated in the topsoil and microbial activity is high. The amounts of plant available inorganic P and microbial P can fluctuate over the season, but their interaction and responses to changes in environmental conditions, fertilization and cutting are not yet well understood. Also, gross P mineralization has not yet been measured in grassland soils. We studied P mineralization and immobilization in a species rich grassland managed at low intensity (with three harvests per season) under different P inputs. The trial was established in 1992 in Watt (Switzerland). Three different P input treatments were selected: no P (NK), mineral P (NPK) and organic P (NPKorg) fertilization, with 17 kg P ha-1yr-1 applied as superphosphate and slurry, respectively (rates according to Swiss fertilizer recommendations). We used two different approaches. Firstly, available (anion exchange resin extractable) and microbial P (hexanol labile P) were measured in fresh samples periodically taken throughout the vegetation period. Secondly, an isotopic dilution technique was applied on composite topsoil samples (0-5 cm) to determine rates of basal P mineralization and microbial immobilization of P in an incubation experiment. During the season available P ranged from 0.9-3.5, 5.3-11.2 and 1.9-6.7 mg kg-1 soil-1 and microbial P from 20-44, 43-59 and 61-93 mg kg-1 soil-1 in NK, NPK and NPKorg, respectively. Thus, microbial P was highest in NPKorg whereas available P was highest in NPK. Both P pools were lowest in NK. Average annual yield was lowest in NK (4.5 t ha-1), NPKorg (6.5 kg ha-1) and highest in NPK (7.5 t ha-1). However, no consistent relationship between changes in microbial and available P and plant productivity was found. Changes in weather conditions were reflected by changes in available and microbial P measured in the field. Phosphorus flushes were observed after dry periods (microbial P reduced and available P increased). Whereas fluctuations show microbial P release and P immobilization, an expected counteraction of microbial and available P could not be fully confirmed. In the incubation experiment microbial and available P were similar to average values in the field. A higher respiration rate measured in NPKorg indicated a higher microbial activity than in the other two treatments. Despite the differences in microbial P and respiration, the 33P recovery in the microbial biomass between 3 and 30 days of incubation was about 30% in all treatments. In conclusion we found complex interactions of available and microbial P with climate, fertilization, sward cutting and plant growth. An increased immobilization of P indicated by higher microbial P in the organic fertilized treatment was not confirmed in the isotope study. Gross and net mineralization data are still under analysis and will be presented at the conference.
Sol-Gel Precursors for Ceramics from Minerals Simulating Soils from the Moon and Mars
NASA Technical Reports Server (NTRS)
Sibille, Laurent; Gavira-Gallardo, Jose-Antonio; Hourlier-Bahloul, Djamila
Recent NASA mission plans for the human exploration of our Solar System has set new priorities for research and development of technologies necessary to enable a long-term human presence on the Moon and Mars. The recovery and processing of metals and oxides from mineral sources on other planets is under study to enable use of ceramics, glasses and metals by explorer outposts. We report some preliminary results on the production of sol-gel precursors for ceramic products using mineral resources available in Martian or Lunar soil. The presence of SiO2, TiO2, and A12O3 in both Martian (44 wt.% SiO2, 1 wt.% TiO2, 7 wt.% Al2O3) and Lunar (48 wt.% SiO2, 1.5 wt.% TiO2, 16 wt.% Al2O3) soils and the recent developments in chemical processes to solubilize silicates using organic reagents and relatively little energy indicate that such an endeavor is possible. In order to eliminate the risks involved in the use of hydrofluoric acid to dissolve silicates, two distinct chemical routes are investigated to obtain soluble silicon oxide precursors from Lunar and Martian simulant soils. Clear sol-gel precursors have been obtained by dissolution of silica from Lunar simulant soil in basic ethylene glycol (C2H4(OH)2) solutions to form silicon glycolates. Thermogravimetric Analysis and X-ray Photoelectron Spectroscopy were used to characterize the elemental composition and structure of the precursor molecules. Further concentration and hydrolysis of the products was performed to obtain gel materials for evaluation as ceramic precursors. In the second set of experiments, we used the same starting materials to synthesize silicate esters in acidified alcohol mixtures. Preliminary results indicate the presence of silicon alkoxides in the product of distillation.
The use of volcanic soil as mineral landfill liner--I. Physicochemical characterization and comparison with zeolites.
Navia, Rodrigo; Hafner, Georg; Raber, Georg; Lorber, Karl E; Sch÷ffmann, Elke; Vortisch, Walter
The main physicochemical characteristics of the volcanic soil of Southern Chile, with allophane as the main pedogenic mineral phase were analysed and compared with common zeolites (clinoptilolite) of the European market. The ultimate goal of this study was to test volcanic soil for the use as mineral landfill liner. The main results indicated that the clay and silt fractions together of the volcanic soil were between 38 and 54%. The buffering capacity of the volcanic soil was higher compared with the studied zeolites, whereas the cationic exchange capacity of the volcanic soil (between 5.2 and 6.5 cmol + kg(-1)) is of the same order of magnitude of the studied zeolites (between 9.7 and 11.4 cmol + kg(-1)). Moreover, the anionic exchange capacity of the volcanic soil was higher compared to the zeolites analysed. The hydraulic conductivity of the volcanic soil, measured in the laboratory at maximum proctor density, ranges between 5.16 x 10(-9) and 6.48 x 10(-9) m s(-1), a range that is comparable to the value of 4.51 x 10(-9) m s(-1) of the studied zeolite. The Proctor densities of the volcanic soil are in a lower range (between 1.11 and 1.15 g ml(-1)) compared with zeolites (between 1.19 and 1.34 g ml(-1)). The volcanic soil physicochemical characteristics are comparable to all the requirements established in the Austrian landfill directive (DVO, 2000). Therefore, the use as mineral landfill basal sealing of the analysed volcanic soil appears reasonable, having a pollutant adsorption capacity comparable to zeolites. It is of special interest for Southern Chile, because there are no alternative mineral raw materials for basal liners of landfills. PMID:15988944
Impact of Surface Roughness and Soil Texture on Mineral Dust Emission Fluxes Modeling
NASA Technical Reports Server (NTRS)
Menut, Laurent; Perez, Carlos; Haustein, Karsten; Bessagnet, Bertrand; Prigent, Catherine; Alfaro, Stephane
Dust production models (DPM) used to estimate vertical fluxes of mineral dust aerosols over arid regions need accurate data on soil and surface properties. The Laboratoire Inter-Universitaire des Systemes Atmospheriques (LISA) data set was developed for Northern Africa, the Middle East, and East Asia. This regional data set was built through dedicated field campaigns and include, among others, the aerodynamic roughness length, the smooth roughness length of the erodible fraction of the surface, and the dry (undisturbed) soil size distribution. Recently, satellite-derived roughness length and high-resolution soil texture data sets at the global scale have emerged and provide the opportunity for the use of advanced schemes in global models. This paper analyzes the behavior of the ERS satellite-derived global roughness length and the State Soil Geographic data base-Food and Agriculture Organization of the United Nations (STATSGO-FAO) soil texture data set (based on wet techniques) using an advanced DPM in comparison to the LISA data set over Northern Africa and the Middle East. We explore the sensitivity of the drag partition scheme (a critical component of the DPM) and of the dust vertical fluxes (intensity and spatial patterns) to the roughness length and soil texture data sets. We also compare the use of the drag partition scheme to a widely used preferential source approach in global models. Idealized experiments with prescribed wind speeds show that the ERS and STATSGO-FAO data sets provide realistic spatial patterns of dust emission and friction velocity thresholds in the region. Finally, we evaluate a dust transport model for the period of March to July 2011 with observed aerosol optical depths from Aerosol Robotic Network sites. Results show that ERS and STATSGO-FAO provide realistic simulations in the region.
Effects of Soil Management on N Mineralization and Nitrification Rates in Soybean Fields of the Amazon, Brazil
NASA Astrophysics Data System (ADS)
Figueira, M.; Mitsuya, M.; Moura, J. M. S.
The biological nitrogen fixation (BNF) promoted by the cultivation of soybean [Glycine max. (L.) Merrill], consists in a significant input of reactive nitrogen (N) in the system. The availability of this nutrient to plants occurs through the mineralization of organic-N of the soil, conducted by soil organic matter and / or crop residues. Thus, understanding the fate of this increased supply, as well as changes in the dynamics of N in the system is essential in the context of the recent expansion of soybean in the Amazon. This work aims to understand the dynamics of N in the soil cultivated with soybean, through the determination of ammonium and nitrate concentrations, as well as, mineralization and nitrification rates in soybean fields under till and no-till systems in the municipality of Santarķm, Brazil. We collected 12 soil samples (0-10cm depth) in each crop and the extractions were done in 2M KCl solution using 10 g of soil. The samples were incubated for 7 days when new extractions were done to determine the rates of mineralization and nitrification. The till system showed higher concentrations of nitrate (0.82 ▒ 0.13 mg kg-1) and ammonium (8.15 ▒ 0.54 mg kg-1) compared to the results found in no-till system (0.59 ▒ 0.09 mg kg-1 and 5.25 ▒ 0.28 mg kg-1 for nitrate and ammonium respectively). The mineralization rates were negative in the till system, indicating possible immobilization of N in the soil during that period. In contrast, no-till system showed higher rates of mineralization in the soil. Although there is a great removal of N by grain harvest, it is possible to infer that no-till system has higher nitrogen availability to soybean and that this management could contribute to an increased productivity mainly due to deposition of crop residues enriched in N on the soil.
Soil solid materials affect the kinetics of extracellular enzymatic reactions
NASA Astrophysics Data System (ADS)
Lammirato, C.; Miltner, A.; Kõstner, M.
INTRODUCTION Soil solid materials affect the degradation processes of many organic compounds by decreasing the bioavailability of substrates and by interacting with degraders. The magnitude of this effect in the environment is shown by the fact that xenobiotics which are readily metabolized in aquatic environments can have long residence times in soil. Extracellular enzymatic hydrolysis of cellobiose (enzyme: beta-glucosidase from Aspergillus niger) was chosen as model degradation process since it is easier to control and more reproducible than a whole cell processes. Furthermore extracellular enzymes play an important role in the environment since they are responsible for the first steps in the degradation of organic macromolecules; beta-glucosidase is key enzyme in the degradation of cellulose and therefore it is fundamental in the carbon cycle and for soil in general. The aims of the project are: 1) quantification of solid material effect on degradation, 2) separation of the effects of minerals on enzyme (adsorption ?change in activity) and substrate (adsorption ?change in bioavailability). Our hypothesis is that a rate reduction in the enzymatic reaction in the presence of a solid phase results from the sum of decreased bioavailability of the substrate and decreased activity of enzyme molecules. The relative contribution of the two terms to the overall effect can vary widely depending on the chemical nature of the substrate, the properties of the enzyme and on the surface properties of the solid materials. Furthermore we hypothesize that by immobilizing the enzyme in an appropriate carrier the adsorption of enzymes to soil materials can be eliminated and that therefore immobilization can increase the overall reaction rate (activity loss caused by immobilization < activity loss caused by adsorption to soil minerals). MATERIALS AND METHODS Enzymatic kinetic experiments are carried out in homogeneous liquid systems and in heterogeneous systems where solid materials (bentonite, kaolinite, goethite, activated charcoal) are suspended in a mixed liquid (standard experimental conditions: 66 mM phosphate buffer, pH 5, 25░C, 20 mg solid/ml buffer). The enzyme in an immobilized form (covalent bonding to oxirane groups on the surfaces of macroporous Eupergit« C particles) is used to exclude a direct effect of soil solid materials on the enzyme without excluding their effect on the availability of the substrate.The progress of the reactions is determined by measuring the accumulation of the product (i.e. glucose) in the systems at different times (after destroying enzymatic activity by boiling the samples) with a coupled enzymatic assay and an automatic microplate spectrophotometer. A regression analysis on the data points is performed to calculate the initial reaction rates, which is the parameter that allows to compare the different systems. RESULTS AND DISCUSSION The results show that, under the standard experimental conditions, cellobiose is not adsorbed by the clay minerals bentonite and kaolinite and by the iron oxyhydroxide goethite. In the case of activated charcoal a rapid adsorption phase in the first 20' is followed by a much slower process; after 4h 30' approximately 98% of cellobiose was adsorbed. The results from the adsorption experiments of beta-glucosidase to bentonite, kaolinite, goethite and activated charcoal show that, under the standard experimental conditions, the adsorption process is rapid in all cases (more than 80% of the adsorption takes place in the first 20 minutes). After 1h 20min the following fractions of enzyme were adsorbed: 30 % to bentonite, 60% to kaolinite, 67% to goethite, 100% to activated charcoal. The effect of kaolinite on the reaction rate was quantified: under the standard experimental conditions the initial reaction rate in presence of the mineral was 22% less then in the control. The fraction of enzyme molecules which are adsorbed to kaolinite (60%) loses 37% of its activity. CONCLUSIONS The results from the adsorption experiments lead to the conclusion that, among the sol
NASA Astrophysics Data System (ADS)
Wildner, Manfred; Giester, Gerald; Kersten, Monika; Langer, Klaus
Polarized electronic absorption spectra of colourless chalcocyanite, CuSO4, have been measured using microscope-spectrometric techniques. The spectra are characterized by a structured and clearly polarized band system in the near-infrared spectral range with components centred at 11,720, 10,545, 9,100, and 7,320 cm-1, which have been assigned to crystal field d- d transitions of Cu2+ cations in pseudo-tetragonally elongated CuO6 polyhedra with point symmetry C i (). The polarization behaviour is interpreted based on a D 2( C 2?) pseudo-symmetry. Crystal field calculations were performed for the actual triclinic point symmetry by applying the Superposition Model of crystal fields, as well as in terms of a `classic' pseudo-tetragonal crystal field approach yielding the parameters Dq (eq) = 910, Dt = 395, and Ds = 1,336 cm-1, corresponding to a cubically averaged Dq cub = 679 cm-1. A comparative survey on crystal fields in Cu2+ minerals shows that the low overall crystal field strength in chalcocyanite, combined with a comparatively weak pseudo-tetragonal splitting of energy levels, is responsible for its unique colourless appearance among oxygen-based Cu2+ minerals. The weak crystal field in CuSO4 can be related to the lower position of the SO4 2- anion compared to, e.g. the H2O molecule in the spectrochemical series of ligands.
Patterns of spatial distribution of mineral components of the complex of gray forest soils Vladimir opolye
NASA Astrophysics Data System (ADS)
Karpova, Dina; Chizhikova, Natalya; Starokozhko, Natalya; Hadyushina, Viktorya; Korotaeva, Valentina
The aim of the work is the analysis of spatial distribution of soil fundamental characteristics - fine fractions content (less than 1, 1-5, 5-10 and more than 10 mkm) and their mineralogical composition. The experiments were carried out on the experimental field in Suzdal region in a trench (22 m length and 2 m depth) laid in upland, well-drained conditions. Soil samples from 5 different soil profiles were collected. Fractions were obtained by Gorbunov method. Mineralogical analysis were carried out by universal X-ray diffractometer (Carl Zeiss Jena, Germany). The dominant fraction is a coarse silt fraction, the sand fraction content is negligible. The soil is characterized by medium-textured loam composition from the above and a sandy loam composition in the bottom. Textural differentiation occured due to the distribution of clay fraction. The content of this fraction in plough horizons varies depending on addition of part of other horizons during plowing. The plogh-layer of the residual-carbonate agrogrey soil is characterized by higher (20-23 %) amount of fraction less than 1 mkm, in comparison with plough horizon above the second humus horizon (SHH ), where the amount of silt is 15-16 %. The main components of the fraction derived from the rock are complex mixed- lattice formations dominated by mica - smectite with a high proportion of smectite packages, mica - smectites with low content of smectite packages were in subordinate quantity. The next component is hydromica - a mixture of dioctahedral and trioctahedral varieties. Smectite phase and hydromica add up to 85-90 % of the silt component. The amount of kaolinite and chlorite usually range in 7-13 %. Kaolinite is generally imperfect, chlorite is magnesia-ferric. The presence of fine quartz and feldspars (less amount) is revealed. During the soil formation the redistribution of the above minerals whose behavior is caused by the type of soil is occurring. Agrogrey heavy-textured soils are characterized by textural differentiation of the profile. The main carrier of this differentiation is the silt fraction, mainly its component - the swelling phase. Smectite phase dominates in silt fraction and it is eluvially distributed within the soil profile. Silty fraction of loess loam contains 72 % of the smectite phase. Behavior of minerals constituting the sum of kaolinite and chlorite content indicates its relatively uniform distribution. A slight increase in their content is noted in the eluvial part of the profile, mainly due to increasing in the proportion of kaolinite. The amount of hydromica reduces down the profile from 44.2 % to 19.8% in loess loam (soil-forming rock). The ratio of dioctahedral structures of hydromica to trioctahedral changes within the soil profile: trioctahedral varieties are more abundant in the upper part of the profile.
Linking dynamics of soil microbial phospholipid fatty acids to carbon mineralization in a 13C natural abundance experiment: Impact of heavy metals and acid rain
Michael Stemmer; Andrea Watzinger; Karl Blochberger; Georg Haberhauer; Martin H. Gerzabek
A 13C natural abundance experiment including GC-c-IRMS analysis of phospholipid fatty acids (PLFAs) was conducted to assess the temporal dynamics of the soil microbial community and carbon incorporation during the mineralization of plant residues under the impact of heavy metals and acid rain. Maize straw was incorporated into (i) control soil, (ii) soil irrigated with acid rain, (iii) soil amended
Long Term Effect of Land Reclamation from Lake on Chemical Composition of Soil Organic Matter and Its Mineralization
He, Dongmei; Ruan, Honghua
Since the late 1950s, land reclamation from lakes has been a common human disturbance to ecosystems in China. It has greatly diminished the lake area, and altered natural ecological succession. However, little is known about its impact on the carbon (C) cycle. We conducted an experiment to examine the variations of chemical properties of dissolved organic matter (DOM) and C mineralization under four land uses, i.e. coniferous forest (CF), evergreen broadleaf forest (EBF), bamboo forest (BF) and cropland (CL) in a reclaimed land area from Taihu Lake. Soils and lake sediments (LS) were incubated for 360 days in the laboratory and the CO2 evolution from each soil during the incubation was fit to a double exponential model. The DOM was analyzed at the beginning and end of the incubation using UV and fluorescence spectroscopy to understand the relationships between DOM chemistry and C mineralization. The C mineralization in our study was influenced by the land use with different vegetation and management. The greatest cumulative CO2-C emission was observed in BF soil at 0¢10 cm depth. The active C pool in EBF at 10¢25 cm had longer (62 days) mean residence time (MRT). LS showed the highest cumulative CO2-C and shortest MRT comparing with the terrestrial soils. The carbohydrates in DOM were positively correlated with CO2-C evolution and negatively correlated to phenols in the forest soils. Cropland was consistently an outlier in relationships between DOM chemistry and CO2-evolution, highlighting the unique effects that this land use on soil C cycling, which may be attributed the tillage practices. Our results suggest that C mineralization is closely related to the chemical composition of DOM and sensitive to its variation. Conversion of an aquatic ecosystem into a terrestrial ecosystem may alter the chemical structure of DOM, and then influences soil C mineralization. PMID:24905998
Interactive control of minerals, wildfire, and erosion on soil carbon stabilization in conifer ecosystems of the western U.S.
NASA Astrophysics Data System (ADS)
Rasmussen, C.
Answering the question of what controls the fate and stabilization of organic carbon in forest soils is central to understanding the role of western US ecosystems in mitigating climate change, optimizing forest management, and quantifying local and regional terrestrial carbon budgets. Over half of forest soil C is stored belowground, stabilized by a number of separate, but interacting physical, chemical and biological mechanisms. Here we synthesize data from a series of field and laboratory studies focused on identifying mineral, physical, and landscape position controls on belowground C stabilization mechanisms in western U.S. conifer ecosystems. Results from these studies demonstrate an important for role for short-range-order Fe- and Al-oxyhydroxides and Al-humus complexes in C stabilization, and that the soil mineral assemblage moderates C cycling via control on partitioning of C into physical fractions ("free", "occluded", "mineral") with varying MRT and chemistry. Measures of occluded fraction chemical composition by 13C-NMR indicate this fraction is 2-5 times more enriched in pyrogenic C than the bulk soil and that this fraction is on the order of ~25 to 65% charred materials. Radiocarbon analyses of a large set of conifer soil samples from California and Arizona further indicate the occluded fraction is generally older than either the free light or mineral fraction. In particular, soil C in convergent, water and sediment gathering portions of the landscape are enriched in long MRT charred materials. These results indicate an important role for the interaction of soil mineral assemblage, wildfire, and erosion in controlling belowground C storage and stabilization in western conifer forests. Drought and wildfire are expected to increase with climate change and thus may exert significant control on belowground C storage directly through biochemical and physical changes in aboveground biomass, production of charred materials, and indirectly via post-fire physical erosion and redistribution of C-rich sediment across the landscape.
Clay fractions from a soil chronosequence after glacier retreat reveal the initial evolution of organo-mineral associations
NASA Astrophysics Data System (ADS)
D³mig, Alexander; Hõusler, Werner; Steffens, Markus; K÷gel-Knabner, Ingrid
Interactions between organic and mineral constituents prolong the residence time of organic matter in soils. However, the structural organization and mechanisms of organic coverage on mineral surfaces as well as their development with time are still unclear. We used clay fractions from a soil chronosequence (15, 75 and 120 years) in the foreland of the retreating Damma glacier (Switzerland) and from mature soils outside the proglacial area (>700 and <3000 years) to elucidate the evolution of organo-mineral associations during initial soil formation. The chemical composition of the clay-bound organic matter (OM) was assessed by solid-state 13C NMR spectroscopy while the quantities of amino acids and neutral sugar monomers were determined after acid hydrolysis. The mineral phase was characterized by X-ray diffraction, oxalate extraction, specific surface area by N2 adsorption (BET approach), and cation exchange capacity at pH 7 (CECpH7). The last two methods were applied before and after H2O2 treatment. We found pronounced shifts in quantity and quality of OM during aging of the clay fractions, especially within the first one hundred years of soil formation. The strongly increasing organic carbon (OC) loading of clay-sized particles resulted in decreasing specific surface areas (SSA) of the mineral phases and increasing CECpH7. Thus, OC accumulation was faster than the supply of mineral surfaces and cation exchange capacity was mainly determined by the OC content. Clay-bound OC of the 15-year-old soils showed high proportions of carboxyl C and aromatic C. This may point to remnants of ancient OC which were inherited from the recently exposed glacial till. With increasing age (75 and 120 years), the relative proportions of carboxyl and aromatic C decreased. This was associated with increasing O-alkyl C proportions, whereas accumulation of alkyl C was mainly detected in clay fractions from the mature soils. These findings from solid-state 13C NMR spectroscopy are in line with the increasing amounts of microbial-derived carbohydrates with soil age. The large accumulation of proteins, which was comparable to those of carbohydrates, and the very low C/N ratios of H2O2-resistant OM indicated strong and preferential associations between proteinaceous compounds and mineral surfaces. In the acid soils, poorly crystalline Fe oxides were the main providers of mineral surface area and important for the stabilization of OM during aging of the clay fractions. This was indicated by (I) the strong correlations between oxalate soluble Fe and both, SSA of H2O2-treated clay fractions and OC content, and (II) the low formation of expandable clays due to small extents of mineral weathering. Our chronosequence approach provided new insights into the evolution of organo-mineral interactions in acid soils. The formation of organo-mineral associations started with the sorption of proteinaceous compounds and microbial-derived carbohydrates on mineral surfaces which were mainly provided by ferrihydrite. The sequential accumulation of different organic compounds and the large OC loadings point to multiple accretion of OM in distinct zones or layers during the initial evolution of clay fractions.
Storage and stability of organic carbon in soils as related to depth, occlusion within aggregates, and attachment to minerals
NASA Astrophysics Data System (ADS)
Schrumpf, M.; Kaiser, K.; Guggenberger, G.; Persson, T.; K÷gel-Knabner, I.; Schulze, E.-D.
Conceptual models suggest that stability of organic carbon (OC) in soil depends on the source of plant litter, occlusion within aggregates, incorporation in organo-mineral complexes, and location within the soil profile. Density fractionation is a useful tool to study the relevance of OC stabilization in aggregates and in association with minerals, but it has rarely been applied to full soil profiles. We aim to determine factors shaping the depth profiles of physically unprotected and mineral associated OC and test their relevance for OC stability across a range of European soils that vary in vegetation, soil types, parent material, and land use. At each of the 12 study sites, 10 soil cores were sampled to 60 cm depth and subjected to density separation. Bulk soil samples and density fractions (free light fractions - fLF, occluded light fractions - oLF, heavy fractions - HF) were analysed for OC, total nitrogen (TN), ?14C, and ?14C. Bulk samples were also incubated to determine CO2 evolution per g OC in the samples (specific mineralization rates) as an indicator for OC stability. Depth profiles of OC in the light fraction (LF-OC) matched those of roots for undisturbed grassland and forest sites, suggesting that roots are shaping the depth distribution of LF-OC. Organic C in the HF declined less with soil depth than LF-OC and roots, especially at grassland sites. The decrease in ?14C (increase in age) of HF-OC with soil depth was related to soil pH as well as to dissolved OC fluxes. This indicates that dissolved OC translocation contributes to the formation of subsoil HF-OC and shapes the ?14C profiles. The LF at three sites were rather depleted in 14C, indicating the presence of fossil material such as coal and lignite, probably inherited from the parent material. At the other sites, modern ?14C signatures and positive correlations between specific mineralization rates and fLF-OC indicate the fLF is a potentially available energy and nutrient source for subsurface microorganisms throughout the profile. Declining specific mineralization rates with soil depth confirm greater stability of OC in subsoils across sites. The overall importance of OC stabilization by binding to minerals was demonstrated by declining specific mineralization rates with increasing contributions of HF-OC to bulk soil OC, and the low ?14C values of HF-OC. The stability of HF-OC was greater in subsoils than in topsoils; nevertheless, a portion of HF-OC was active throughout the profile. While quantitatively less important than OC in the HF, consistent older ages of oLF-OC than fLF-OC suggest that occlusion of LF-OC in aggregates also contributes to OC stability in subsoils. Overall, our results indicate that association with minerals is the most important factor in stabilization of OC in soils, irrespective of vegetation, soil type, and land use.
Characterization of mineral phosphate solubilization traits from a barley rhizosphere soil functional metagenome
Chhabra, Sagar; Brazil, Dina; Morrissey, John; Burke, James I; O'Gara, Fergal; N Dowling, David
Mineral phosphate solubilization (MPS) microorganisms are important for their provision of orthophosphate anions for plant growth promotion activity in soil. In this study, we applied a functional metagenomic approach to identify this trait directly from the microbiome in barley rhizosphere soil that had not received P fertilizer over a 15-year period. A fosmid system was used to clone the metagenome of which 18,000 clones (?666 Mb of DNA) was screened for MPS. Functional assays and High Performance Liquid Chromatography analysis recognized gluconic acid production and MPS activity in the range 24.8¢77.1 mmol/L and 27.6¢38.16 ?g/mL, respectively, when screened in an Escherichia coli host (at frequency of one MPS-positive clone hit per 114 Mb DNA tested). The MPS clones (with average insert size of ?37 kb) were analysed by 454 Roche sequencing and annotated. A number of genes/operons with homology to Phosphorous (P) uptake, regulatory and solubilization mechanisms were identified, linking the MPS function to the uncultivated microbiome present in barley rhizosphere soil. PMID:23894099
Characterization of mineral phosphate solubilization traits from a barley rhizosphere soil functional metagenome.
Chhabra, Sagar; Brazil, Dina; Morrissey, John; Burke, James I; O'Gara, Fergal; N Dowling, David
Mineral phosphate solubilization (MPS) microorganisms are important for their provision of orthophosphate anions for plant growth promotion activity in soil. In this study, we applied a functional metagenomic approach to identify this trait directly from the microbiome in barley rhizosphere soil that had not received P fertilizer over a 15-year period. A fosmid system was used to clone the metagenome of which 18,000 clones (~666 Mb of DNA) was screened for MPS. Functional assays and High Performance Liquid Chromatography analysis recognized gluconic acid production and MPS activity in the range 24.8-77.1 mmol/L and 27.6-38.16 ?g/mL, respectively, when screened in an Escherichia coli host (at frequency of one MPS-positive clone hit per 114 Mb DNA tested). The MPS clones (with average insert size of ~37 kb) were analysed by 454 Roche sequencing and annotated. A number of genes/operons with homology to Phosphorous (P) uptake, regulatory and solubilization mechanisms were identified, linking the MPS function to the uncultivated microbiome present in barley rhizosphere soil. PMID:23894099
Isolation from Agricultural Soil and Characterization of a Sphingomonas sp. Able To Mineralize the Phenylurea Herbicide Isoproturon
S. R. Sorensen; ZEEV RONEN; JENS AAMAND
A soil bacterium (designated strain SRS2) able to metabolize the phenylurea herbicide isoproturon, 3-(4- isopropylphenyl)-1,1-dimethylurea (IPU), was isolated from a previously IPU-treated agricultural soil. Based on a partial analysis of the 16S rRNA gene and the cellular fatty acids, the strain was identified as a Sphingomonas sp. within the -subdivision of the proteobacteria. Strain SRS2 was able to mineralize IPU
Thallium speciation and extractability in a thallium- and arsenic-rich soil developed from mineralized carbonate rock.
Voegelin, Andreas; Pfenninger, Numa; Petrikis, Julia; Majzlan, Juraj; Pl÷tze, Michael; Senn, Anna-Caterina; Mangold, Stefan; Steininger, Ralph; G÷ttlicher, J÷rg
We investigated the speciation and extractability of Tl in soil developed from mineralized carbonate rock. Total Tl concentrations in topsoil (0-20 cm) of 100-1000 mg/kg are observed in the most affected area, subsoil concentrations of up to 6000 mg/kg Tl in soil horizons containing weathered ore fragments. Using synchrotron-based microfocused X-ray fluorescence spectrometry (?-XRF) and X-ray absorption spectroscopy (?-XAS) at the Tl L3-edge, partly Tl(I)-substituted jarosite and avicennite (Tl2O3) were identified as Tl-bearing secondary minerals formed by the weathering of a Tl-As-Fe-sulfide mineralization hosted in the carbonate rock from which the soil developed. Further evidence was found for the sequestration of Tl(III) into Mn-oxides and the uptake of Tl(I) by illite. Quantification of the fractions of Tl(III), Tl(I)-jarosite and Tl(I)-illite in bulk samples based on XAS indicated that Tl(I) uptake by illite was the dominant retention mechanism in topsoil materials. Oxidative Tl(III)uptake into Mn-oxides was less relevant, probably because the Tl loadings of the soil exceeded the capacity of this uptake mechanism. The concentrations of Tl in 10 mM CaCl2-extracts increased with increasing soil Tl contents and decreasing soil pH, but did not exhibit drastic variations as a function of Tl speciation. With respect to Tl in contaminated soils, this study provides first direct spectroscopic evidence for Tl(I) uptake by illite and indicates the need for further studies on the sorption of Tl to clay minerals and Mn-oxides and its impact on Tl solubility in soils. PMID:25885948
Clay minerals and metal oxides strongly influence the structure of alkane-degrading microbial communities during soil maturation.
Steinbach, Annelie; Schulz, Stefanie; Giebler, Julia; Schulz, Stephan; Pronk, Geertje J; K÷gel-Knabner, Ingrid; Harms, Hauke; Wick, Lukas Y; Schloter, Michael
Clay minerals, charcoal and metal oxides are essential parts of the soil matrix and strongly influence the formation of biogeochemical interfaces in soil. We investigated the role of these parental materials for the development of functional microbial guilds using the example of alkane-degrading bacteria harbouring the alkane monooxygenase gene (alkB) in artificial mixtures composed of different minerals and charcoal, sterile manure and a microbial inoculum extracted from an agricultural soil. We followed changes in abundance and community structure of alkane-degrading microbial communities after 3 and 12 months of soil maturation and in response to a subsequent 2-week plant litter addition. During maturation we observed an overall increasing divergence in community composition. The impact of metal oxides on alkane-degrading community structure increased during soil maturation, whereas the charcoal impact decreased from 3 to 12 months. Among the clay minerals illite influenced the community structure of alkB-harbouring bacteria significantly, but not montmorillonite. The litter application induced strong community shifts in soils, maturated for 12 months, towards functional guilds typical for younger maturation stages pointing to a resilience of the alkane-degradation function potentially fostered by an extant 'seed bank'. PMID:25535940
Interactions between arsenic and iron oxyhydroxides in lacustrine sediments
N. Belzile; A. Tessier
Arsenic and iron concentrations were measured in surficial sediments and in interstitial and overlying waters at 22 littoral stations of 16 lakes. The lakes were chosen to cover values of pH between 4.0 and 8.4 and various As concentrations. Depth-distributions of dissolved As and Fe concentrations suggest a close association of both elements in a dissolution-diffusion-precipitation cycle for Fe and
Interactions between arsenic and iron oxyhydroxides in lacustrine sediments
Belzile, N.; Tessier, A. (Univ. du Quebec (Canada))
Arsenic and iron concentrations were measured in surficial sediments and in interstitial and overlying waters at 22 littoral stations of 16 lakes. The lakes were chosen to cover values of pH between 4.0 and 8.4 and various As concentrations. Depth-distributions of dissolved As and Fe concentrations suggest a close association of both elements in a dissolution-diffusion-precipitation cycle for Fe and adsorbed As. Using a simplified version of the surface complexation model, apparent adsorption constants of As onto natural Fe oxyhydroxides have been calculated from the concentrations of As and Fe determined in leachates of surficial lake sediments and the in situ measurement of dissolved As in their respective overlying waters. These calculations assume, based on thermodynamic considerations and experimental evidence, that only As(V) is associated with the natural Fe oxyhydroxides. The binding intensity values obtained from these lakes are compared to those obtained for the adsorption of As(V) onto various synthetic Fe oxyhydroxides in well-defined media. The binding constants derived from field measurements agree well with those obtained from laboratory experiments performed with amorphous Fe oxyhydroxides.
[Relationships of microbial biomass carbon and nitrogen with particle composition and nitrogen mineralization potential in calcareous soil].
Jin, Fa-Hui; Li, Shi-Qing; Lu, Hong-Ling; Li, Sheng-Xiu
Taking 25 surface soil samples of calcareous soil with greater difference in fertility on Loess Plateau as test materials, this paper studied the relationships of soil microbial biomass carbon (B(C)) and nitrogen (B(N)) with soil nitrogen mineralization potential (N(0)), total nitrogen (TN), organic carbon (OC), and particle composition. The results showed that B(C) and B(N) had significant positive correlations with TN and OC, suggesting that B(C) and B(N) were highly related with soil fertility and could be used as biological indices of soil quality. B(C) and B(N) were highly correlated with N(0), with the correlation coefficient being 0.741 and 0.665, respectively (P < 0.01). B(C), B(N), TN, OC and N(0) all had significant positive correlations with physical clay (< 0.01 mm) but negative correlations with physical sand (> 0.01 mm), and had significant positive correlations with the ratio of physical clay to physical sand, indicating that soil organic matter was mainly combined with physical clay to form soil organic-mineral complexes. PMID:18335620
Storage and stability of organic carbon in soils as related to depth, occlusion within aggregates, and attachment to minerals
NASA Astrophysics Data System (ADS)
Schrumpf, M.; Kaiser, K.; Guggenberger, G.; Persson, T.; K÷gel-Knabner, I.; Schulze, E.-D.
Conceptual models suggest that stability and age of organic carbon (OC) in soil depends on the source of plant litter, occlusion within aggregates, incorporation in organo-mineral complexes, and location within the soil profile. Various tools like density fractionation, mineralization experiments, and radiocarbon analyses have been used to study the importance of these mechanisms. We systematically apply them to a range of European soils to test whether general controls emerge even for soils that vary in vegetation, soil types, parent material, and land use. At each of the 12 study sites, 10 soil cores were sampled in 10 cm depth intervals to 60 cm depth and subjected to density separation. Bulk soil samples and density fractions (free light fractions - fLF, occluded light fractions - oLF, heavy fractions - HF) were analysed for OC, total nitrogen (TN), ?13C, and ?14C. Bulk samples were also incubated to determine mineralizable OC. Declining OC-normalized CO2 release and increasing age with soil depth confirm greater stability of OC in subsoils across sites. Depth profiles of LF-OC matched those of roots, which in turn reflect plant functional types in soil profiles not subject to ploughing. Modern ?14C signatures and positive correlation between mineralizable C and fLF-OC indicate the fLF is an easily available energy and nutrient source for subsurface microbes. Fossil C derived from the geogenic parent material affected the age of OC especially in the LF at three study sites. The overall importance of OC stabilization by binding to minerals was demonstrated by declining OC-normalized CO2 release rates with increasing contributions of HF-OC to bulk soil OC and the low ?14C values of HF-OC. The stability of HF-OC was greater in subsoils than in topsoils; nevertheless, a portion of HF-OC was active throughout the profile. The decrease in ?14C (increase in age) of HF-OC with soil depth was related to soil pH as well as to dissolved OC fluxes. This indicates that dissolved OC translocation contributes to the formation of subsoil HF-OC and shapes the ?14C profiles. While quantitatively less important than OC in the HF, consistent older ages of oLF-OC than fLF-OC indicate that occlusion of LF-OC in aggregates also contributes to OC stability in subsoils. Overall, our results showed that association with minerals is the most important factor in stabilization of OC in soils.
Genetically biodiverse potato cultivars grown on a suitable agricultural soil under compost amendment or mineral fertilization: yield, quality, genetic and epigenetic variations, soil properties.
Cicatelli, Angela; Baldantoni, Daniela; Iovieno, Paola; Carotenuto, Maurizio; Alfani, Anna; De Feis, Italia; Castiglione, Stefano
The use of compost for soil amendment is a promising agricultural practice environmentally and economically viable. In the framework of a wide research project designed to evaluate the effects of soil amendment with municipal solid waste compost in comparison with traditional mineral fertilization practices, 54 different cultivars (Cvs) of potatoes were AFLP (amplified fragment length polymorphism) molecularly fingerprinted. The seven most genetically biodiverse potato Cvs were used to establish an experimental field in southern Italy. The field area was divided into two portions fertilized with compost (20 Mg ha(-1)) or with ammonium sulphate (200 kg ha(-1)). No significant differences in productivity, organoleptic characteristics and element concentrations were observed between the potato tubers obtained with both kinds of soil fertilization, while the tubers grown on compost amended soil showed, on average, higher K concentrations with respect to those grown on mineral fertilised soil. cDNA-AFLP (complementary DNA-AFLP) and MSAP (methylation sensitive amplified polymorphism) analyses were carried out on both leaves and tubers of one selected Cv to estimate if any transcriptome alterations or epigenetic modifications were induced by the two kinds of fertilization, however no variations were detected. Chemical and biological soil qualities (i.e., microbial respiration, FDA hydrolysis, alkaline and acid phosphatase) were assessed on soil samples at the start of the experiment and at the end of potato crop cycle. No significant differences in soil pH and limited ones, in the available fraction of some trace elements, were observed; while conductivity was much higher for the compost amended portion of the experimental field. Microbial respiration, FDA hydrolysis and acid phosphatase activities were significantly increased by compost amendment, in comparison with mineral fertilization. Finally, a sensory panel of potato Cvs detected no significant differences among qualitative descriptors and among potatoes coming from the two differently fertilized soils. PMID:25016108
Seasonal Soil Nitrogen Mineralization within an Integrated Crop and Livestock System in Western North Dakota, USA
NASA Astrophysics Data System (ADS)
Landblom, Douglas; Senturklu, Songul; Cihacek, Larry; Pfenning, Lauren; Brevik, Eric C.
Protecting natural resources while maintaining or maximizing crop yield potential is of utmost importance for sustainable crop and livestock production systems. Since soil organic matter and its decomposition by soil organisms is at the very foundation of healthy productive soils, systems research at the North Dakota State University Dickinson Research Extension Center is evaluating seasonal soil nitrogen fertility within an integrated crop and livestock production system. The 5-year diverse crop rotation is: sunflower (SF) - hard red spring wheat (HRSW) - fall seeded winter triticale-hairy vetch (THV; spring harvested for hay)/spring seeded 7-species cover crop (CC) - Corn (C) (85-90 day var.) - field pea-barley intercrop (PBY). The HRSW and SF are harvested as cash crops and the PBY, C, and CC are harvested by grazing cattle. In the system, yearling beef steers graze the PBY and C before feedlot entry and after weaning, gestating beef cows graze the CC. Since rotation establishment, four crop years have been harvested from the crop rotation. All crops have been seeded using a JD 1590 no-till drill except C and SF. Corn and SF were planted using a JD 7000 no-till planter. The HRSW, PBY, and CC were seeded at a soil depth of 3.8 cm and a row width of 19.1 cm. Seed placement for the C and SF crops was at a soil depth of 5.1 cm and the row spacing was 0.762 m. The plant population goal/ha for C, SF, and wheat was 7,689, 50,587, and 7,244 p/ha, respectively. During the 3rd cropping year, soil bulk density was measured and during the 4th cropping year, seasonal nitrogen fertility was monitored throughout the growing season from June to October. Seasonal nitrate nitrogen (NO3-N), ammonium nitrogen (NH4-N), total season mineral nitrogen (NO3-N + NH4-N), cropping system NO3-N, and bulk density were measured in 3 replicated non-fertilized field plot areas within each 10.6 ha triple replicated crop fields. Within each plot area, 6 - 20.3 cm x 0.61 m aluminum irrigation pipes were pressed into the soil as enclosures to restrict root access to soil nitrogen. Soil samples were taken as close to 2-week intervals as possible from both inside and outside the enclosures. The crop rotation N values were also compared to triple replicated perennial native grassland plot areas (predominate sp. Western wheatgrass - Pascopyrum smithii, Blue grama - Bouteloua gracilis, Little bluestem - Schizachyrium scoparium, Switchgrass - Panicum virgatum). Trends identified for both NH4-N and NO3-N indicate that the values are relatively similar with respect to seasonal change over time. There was a greater amount of soil nitrogen accumulation inside the enclosures indicating that outside the enclosures roots scavenge nitrogen for plant growth and production. Seasonally, comparing the cropping system crops, NO3-N declined mid-July and then rebounded by mid-August and continued to increase until leveling off in September. Corn NO3-N, however, did not follow this pattern, but increased from early June to the end of June and remained high until the first of September. We will present the results of bulk density data and seasonal N fertility data providing evidence for the impact of previous CC on corn production. Probable explanation for the mid-summer nitrogen decline will be presented and justification for reduced fertilizer application will be discussed.
Rare earth elements in forest-floor herbs as related to soil conditions and mineral nutrition.
Tyler, Germund; Olsson, Tommy
Mixtures of rare earth elements (REEs) in fertilizers are widely used in Chinese agriculture to improve crop nutrition. REE concentrations in wild-growing plants, especially herbs, are little known. This study describes differences in the concentrations and proportions of REEs in eight forest-floor herbaceous plants and relates these differences to soil and mineral nutrient conditions. REEs studied were yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). Leaf concentrations of sum REEs differed more than one order of magnitude between species, being highest in Anemone nemorosa (10.1 nmol/g dry mass) and lowest in Convallaria majalis (0.66 nmol/g) from the same site. Leaf concentrations of all REEs correlated positively (p < 0.001), as did sum REE with calcium (Ca) and strontium (Sr) concentrations (p < 0.001). A negative relationship (r = -0.83, (p < 0.001) was measured between phosphorus (P) concentrations and sum REE concentrations in leaves. However, the proportions of the single REEs in the REE sum differed among species. In A. nemorosa, 57% of the molar REE sum was taken by Y + La, and only 21% by Ce. The other extreme was Maianthemum bifolium, with 37% La + Y and 41% Ce. These two species had 2.7-3.0% of the REE sum as heavier lanthanides, compared to 4.1-5.2% in the six other species. No clear relationship between soil properties or REE contents and leaf REE concentrations was detected. For La, however, an overrepresentation in leaves prevailed throughout all species compared to soils, whereas particularly Nd, Sm, and Tb had a lower proportion in the leaves of all species than in their soils. Possible uptake mechanisms of REEs in plants are discussed. PMID:16116249
Metagenomes from Thawing Low-Soil-Organic-Carbon Mineral Cryosols and Permafrost of the Canadian High Arctic
Chauhan, Archana; Layton, Alice C.; Vishnivetskaya, Tatiana A.; Williams, Daniel; Pfiffner, Susan M.; Rekepalli, Bhanu; Stackhouse, Brandon; Lau, Maggie C. Y.; Phelps, Tommy J.; Mykytczuk, Nadia; Ronholm, Jennifer; Whyte, Lyle; Onstott, Tullis C.
Microbial release of greenhouse gases from thawing permafrost is a global concern. Seventy-six metagenomes were generated from low-soil-organic-carbon mineral cryosols from Axel Heiberg Island, Nunavut, Canada, during a controlled thawing experiment. Permafrost thawing resulted in an increase in anaerobic fermenters and sulfate-reducing bacteria but not methanogens. PMID:25414511
Effect of zinc and boron interaction on growth and mineral composition of lemon seedlings in a calcareous soil
M. Rajaie; A. k. Ejraie; H. r. Owliaie; A. r. Tavakoli
Abstract The impact ,of different ,concentration ,of zinc (Zn) and ,boron (B) on growth ,and mineral composition,of lemon ,seedlings (Citrus Aurantifolia L.) was studied under greenhouse ,conditions. We used five concentration levelsof B (0, 2.5, 5, 10 and 20 Ąg g, of soil. In above mentioned B levels, lemon seedlings displayed slight to severe B toxicity symptoms. ,Zn treatments ,reduced
The effect of increasing salinity and forest mortality on soil nitrogen and phosphorus mineralization in tidal freshwater forested wetlands
Noe, Gregory B.; Krauss, Ken W.; Lockaby, B. Graeme; Conner, William H.; Hupp, Cliff R.
Tidal freshwater wetlands are sensitive to sea level rise and increased salinity, although little information is known about the impact of salinification on nutrient biogeochemistry in tidal freshwater forested wetlands. We quantified soil nitrogen (N) and phosphorus (P) mineralization using seasonal in situ incubations of modified resin cores along spatial gradients of chronic salinification (from continuously freshwater tidal forest to salt impacted tidal forest to oligohaline marsh) and in hummocks and hollows of the continuously freshwater tidal forest along the blackwater Waccamaw River and alluvial Savannah River. Salinification increased rates of net N and P mineralization fluxes and turnover in tidal freshwater forested wetland soils, most likely through tree stress and senescence (for N) and conversion to oligohaline marsh (for P). Stimulation of N and P mineralization by chronic salinification was apparently unrelated to inputs of sulfate (for N and P) or direct effects of increased soil conductivity (for N). In addition, the tidal wetland soils of the alluvial river mineralized more P relative to N than the blackwater river. Finally, hummocks had much greater nitrification fluxes than hollows at the continuously freshwater tidal forested wetland sites. These findings add to knowledge of the responses of tidal freshwater ecosystems to sea level rise and salinification that is necessary to predict the consequences of state changes in coastal ecosystem structure and function due to global change, including potential impacts on estuarine eutrophication.
Can differences in soil community composition after peat meadow restoration lead to different decomposition and mineralization rates?
Jerry van Dijk; Wim A. M. Didden; Frans Kuenen; Peter M. van Bodegom; Herman A. Verhoef; Rien Aerts
Reducing decomposition and mineralization of organic matter by increasing groundwater levels is a common approach to reduce plant nutrient availability in many peat meadow restoration projects. The soil community is the main driver of these processes, but how community composition is affected by peat meadow restoration is largely unknown. Furthermore, it is unclear whether restoration induced changes could lead to
Microbiological quality of organic vegetables produced in soil treated with different types of manure and mineral fertilizer
Dķbora Cabral Machado; Carla Marques Maia; Isabel Dias Carvalho; Natan Fontoura da Silva; Maria Clßudia Dantas PorfĒrio Borge Andrķ; ┴lvaro Bisol Serafini
An attempt was made to evaluate microbiological quality of horticultural crops grown organically. Three species of vegetables were used, lettuce (Lactuva sativa), radish (Raphanus sativus) and spinach (Tetragonia expansa), grown organically, in fertile soil. Six different treatments were applied: mineral fertilizer, chicken, cow, and pig manure, chicken litter and cow manure, in association with a liquid foliar biofertilizer. These crops
Metagenomes from thawing low-soil-organic-carbon mineral cryosols and permafrost of the canadian high arctic.
Chauhan, Archana; Layton, Alice C; Vishnivetskaya, Tatiana A; Williams, Daniel; Pfiffner, Susan M; Rekepalli, Bhanu; Stackhouse, Brandon; Lau, Maggie C Y; Phelps, Tommy J; Mykytczuk, Nadia; Ronholm, Jennifer; Whyte, Lyle; Onstott, Tullis C; Sayler, Gary S
Microbial release of greenhouse gases from thawing permafrost is a global concern. Seventy-six metagenomes were generated from low-soil-organic-carbon mineral cryosols from Axel Heiberg Island, Nunavut, Canada, during a controlled thawing experiment. Permafrost thawing resulted in an increase in anaerobic fermenters and sulfate-reducing bacteria but not methanogens. PMID:25414511
DRIFT and HR MAS NMR characterization of humic substances from a soil treated with different organic and mineral fertilizers
NASA Astrophysics Data System (ADS)
Ferrari, Erika; Francioso, Ornella; Nardi, Serenella; Saladini, Monica; Ferro, Nicola Dal; Morari, Francesco
In this study, using DRIFT and HR MAS NMR, we analyzed the humic substances isolated from a soil treated, over 40 years, with different organic, mineral and organic plus mineral treatments and cultivated with maize as the main crop. As expected, the structure of humic substances was very complex but by combining both techniques (DRIFT and HR MAS NMR) additional information was obtained on aromatic and aliphatic components, the most recalcitrant parts of these macromolecules. In so doing we wanted to investigate the relationship between HS structure and long-term management practices. An elevated content of lignin, aminoacids, peptides and proteins was observed mainly for farmyard manure treatments with respect to mineral or liquid manure amendments; this supports how the different management practices have greatly influenced the humification process of cultivated soils.
Impact of soil primary size fractions on sorption and desorption of atrazine on organo-mineral fractions.
Huang, Yufen; Liu, Zhongzhen; He, Yan; Li, Yanliang
In the current study, a mechanical dispersion method was employed to separate clay (<2 ?m), silt (2-20 ?m), and sand (20-50 ?m) fraction in six bulk soils. Batch equilibrium method was used to conduct atrazine sorption and desorption experiments on soil organo-mineral fractions with bulk soils and their contrasting size fractions separately. The potential contribution of total organic carbon (TOC) for atrazine retention in different fractions was further investigated. It was found that clay fraction had the highest adsorption but the least desorption capacities for atrazine, while sand fraction had the lowest adsorption but the highest desorption capacities for atrazine. The adsorption percentage of atrazine, as compared with adsorption by the corresponding bulk soils, ranged from 53.6 to 80.5%, 35.7 to 56.4%, and 0.2 to 4.5% on the clay, silt, and sand fractions, respectively. TOC was one of the key factors affecting atrazine retention in soils, with the exact contribution dependent on varying degree of coating with mineral component in different soil size fractions. The current study may be useful to predict the bioavailability of atrazine in different soil size fractions. PMID:25300187
Evolution of soil organic matter changes using pyrolysis and metabolic indices: a comparison between organic and mineral fertilization.
Marinari, S; Masciandaro, G; Ceccanti, B; Grego, S
The aim of this study was to evaluate chemical and biochemical changes of organic matter in fertilized (ammonium nitrate) and amended (vermicompost and manure) soils using pyrolysis and metabolic indices. The metabolic potential [dehydrogenase (DH-ase)/water soluble organic carbon (WSOC)], the metabolic quotient (qCO2) and the microbial quotient (Cmic:Corg) were calculated as indices of soil organic matter evolution. Pyrolysis-gas chromatography (Py-GC) was used to study structural changes in the organic matter. Carbon forms and microbial biomass have been measured by dichromate oxidation and fumigation-extraction methods, respectively. Dehydrogenase activity has been tested using INT (p-Iodonitrotetrazolium violet) as substrate. The results showed that organic amendment increased soil microbial biomass and its activity which were strictly related to pyrolytic mineralization and humification indices (N/O, B/E3). Mineral fertilization caused a greater alteration of native soil organic matter than the organic amendments, in that a high release of WSOC and relatively large amounts of aliphatic pyrolytic products, were observed. Therefore, the pyrolysis and metabolic indices provided similar and complementary information on soil organic matter changes after mineral and organic fertilization. PMID:17067793
The content of available mineral phosphorus compounds in chestnut soils of Northern Mongolia upon application of different forms of phosphorite
NASA Astrophysics Data System (ADS)
Ubugunov, L. L.; Enkhtuyaa, B.; Merkusheva, M. G.
The effect of different forms of phosphorite (activated and crude ground) of the Burenkhansk deposit on the phosphate status of chestnut soils and the productivity of spring wheat was studied in Northern Mongolia. It was found that the transformation of mineral soil phosphates upon the application of activated phosphorite (together with NK) is similar to that upon superphosphate application, and the available phosphorus concentration is even a gradation higher. The application of crude ground phosphorite helped to preserve the content of mineral phosphates in the soil at the initial level. Optimum concentrations of available phosphorus and the sum of loosely bound and calcium phosphates in the plow horizon were estimated 33-35 mg/kg) and 16-18 mg/100 g, respectively. Under these concentrations, high and sustainable yields of spring wheat were obtained upon application of activated phosphorite.
Mineral cycling in soil and litter arthropod food chains. Progress report, November 1, 1980-October 31, 1981
Crossley, D.A. Jr.
Progress and current status are reported for research projects concerned with mineral element and nutrient dynamics in soil arthropod food chains. Research is performed within the larger context of terrestrial decomposition, in which soil arthropods may act as regulators of nutrient dynamics during decomposition. Research is measuring rates of nutrient accumulation and excretion by using radioactive tracer analogs of nutrients. This year, emphasis has been placed on field work in which soil arthropod population size and nutrients inputs were varied experimentally. The presence of microarthropods in field microcosms increased the mineralization of N and P in each case, but rates were not correlated with arthropod densities. Experiments recently started are using both arthropod and microfloral inhibitors, in open systems on the forest floor, with the objective of quantifying arthropod enhancement of microbial immobilization of nutrients.
Alaska Geochemical Database (AGDB)-Geochemical data for rock, sediment, soil, mineral, and concentrate sample media
Granitto, Matthew; Bailey, Elizabeth A.; Schmidt, Jeanine M.; Shew, Nora B.; Gamble, Bruce M.; Labay, Keith A.
The Alaska Geochemical Database (AGDB) was created and designed to compile and integrate geochemical data from Alaska in order to facilitate geologic mapping, petrologic studies, mineral resource assessments, definition of geochemical baseline values and statistics, environmental impact assessments, and studies in medical geology. This Microsoft Access database serves as a data archive in support of present and future Alaskan geologic and geochemical projects, and contains data tables describing historical and new quantitative and qualitative geochemical analyses. The analytical results were determined by 85 laboratory and field analytical methods on 264,095 rock, sediment, soil, mineral and heavy-mineral concentrate samples. Most samples were collected by U.S. Geological Survey (USGS) personnel and analyzed in USGS laboratories or, under contracts, in commercial analytical laboratories. These data represent analyses of samples collected as part of various USGS programs and projects from 1962 to 2009. In addition, mineralogical data from 18,138 nonmagnetic heavy mineral concentrate samples are included in this database. The AGDB includes historical geochemical data originally archived in the USGS Rock Analysis Storage System (RASS) database, used from the mid-1960s through the late 1980s and the USGS PLUTO database used from the mid-1970s through the mid-1990s. All of these data are currently maintained in the Oracle-based National Geochemical Database (NGDB). Retrievals from the NGDB were used to generate most of the AGDB data set. These data were checked for accuracy regarding sample location, sample media type, and analytical methods used. This arduous process of reviewing, verifying and, where necessary, editing all USGS geochemical data resulted in a significantly improved Alaska geochemical dataset. USGS data that were not previously in the NGDB because the data predate the earliest USGS geochemical databases, or were once excluded for programmatic reasons, are included here in the AGDB and will be added to the NGDB. The AGDB data provided here are the most accurate and complete to date, and should be useful for a wide variety of geochemical studies. The AGDB data provided in the linked database may be updated or changed periodically. The data on the DVD and in the data downloads provided with this report are current as of date of publication.
Characterization of ^{239,240}Pu Radionuclide Adsorption to Soil Particles and Mineral Dust Aerosols
NASA Astrophysics Data System (ADS)
Tatro, D. P.; Arimoto, R.; McMillan, N. J.; Barnes, M.
The release of ^{239,240}Pu into the environment by nuclear weapons testing 50 years ago initiated the cyclic mobilization of Pu-contaminated soil particles via the resuspension of dust resulting in a widespread distribution of Pu and other radionuclides. It is unclear what enables the aeolian transport of Pu in the environment; plausible hypotheses of Pu binding to dust and soil particles include Pu adsorption to iron oxides/hydroxides, organic acids, or silicate minerals such as clays. To investigate the connections between surface soils, dust and radionuclides, samples of soil and/or dust were collected from the Project Gnome Site in Eddy County, NM, the Jemez Mountains near Los Alamos, NM, and two 50-year old attics and wind-blown dust in Big Spring, TX. This study tests the hypothesis that Pu is adsorbed onto Fe oxides and hydroxides that coat dust/soil particles. The samples are generally low in organic carbon (0.2 - 4.8%, except for the unburned Los Alamos sample at 9.4%), as measured by LOI (Loss On Ignition) at 360 ░C. The citrate-bicarbonate-dithionite method (CDB) of Fe oxide removal, first proposed by Mehra and Jackson in 1960, was used to selectively extract Fe oxides from the samples while leaving silicate Fe intact. Chemical digestion of each sample creates two fractions, the extracted supernatant and a solid pellet residue. If the Pu were associated with Fe oxides, then Fe and Pu should both be selectively removed from the bulk sample during the CBD process, leaving the pellet depleted in Fe and Pu and the supernatant enriched. For Fe, this was confirmed by scanning electron microscope and petrographic analyses. Preliminary radiochemical analyses of Pu activity also verify this hypothesis. Pu activity is significantly lower in pellets than bulk samples (Pu activitypellet/Pu activitybulk average = 0.07, range 0.02-0.12); Pu activity in supernatants is significantly higher than in bulk samples (Pu activitysupernatant/Pu activitybulk average = 4.45, range 2.53-6.92). The Big Springs wind-blown dust sample is an outlier; further analyses are in progress to evaluate its composition.
Modeling of pH-dependent adsorption and leaching of MCPA in profiles of Polish mineral soils.
Paszko, Tadeusz
This study aimed to determine the leaching potential of MCPA and the contribution of major soil components to its retention in 27 profiles of common Polish arable soils. Results of experiments and modeling of the pH-dependent adsorption indicated that the adsorption of the neutral and anionic forms of MCPA on soil organic matter are the predominant adsorption mechanisms, even in soil horizons with very low organic matter contents. The third most important mechanism was the adsorption of MCPA anions, most likely through the water bridging mechanism on sorption sites created by exchangeable Fe cations adsorbed in soil. It was found that in acidic soils with very low organic matter contents, the neutral form of MCPA was also adsorbed on the quartz and silica sorption sites of silt and sand. The value of r(2) was 78% when it was assumed that MCPA was adsorbed only on organic matter and 93% when all indicated mechanisms of adsorption on mineral soil components were included in the model fitted to data from all soil profiles. Simulations using FOCUS PELMO indicated that in two profiles, the 80th percentiles of the average yearly concentrations of MCPA in the leachate exceeded the European Union (EU) contamination limit of 0.1 ?gL(-1). It was shown that when an assumption was made in the model of pH-dependent adsorption that MCPA was adsorbed only on organic matter, the leaching potential of MCPA was overestimated in the examined soils. Much better predictions were obtained when adsorption on mineral soil components was also included in the model. PMID:25051325
Effect of cadmium on fungi and on interactions between fungi and bacteria in soil: influence of clay minerals and pH
H. Babich; G. Stotzky
Fungi (Rhizopus stolonifer, Trichoderma viride, Fusarium oxysporum f. sp. conglutinans, Cunninghamella echinulata, and several species of Aspergillus and Penicillium) tolerated higher concentrations of cadmium (Cd) when grown in soil than when grown on laboratory media, indicating that soil mitigated the toxic effects of Cd. In soil amended with clay minerals, montmorillonite provided partial or total protection against fungistatic effects of
Immediate Effects of Time and Method of Alfalfa Termination on Soil Mineral Nitrogen, Moisture, Weed Control, and Seed Yield, Quality, and Nitrogen Uptake
S. S. Malhi; A. M. Johnston; H. Loeppky; C. L. Vera; H. J. Beckie; P. M. S. Bandara
Three field experiments were conducted on Gray Luvisol (Typic Cryoboralf) soils in northeastern Saskatchewan to compare the effects of alfalfa (Medicago sativa Leyss) stand termination with tillage and herbicides at different times on mineral nitrogen (N) (ammonium-N and nitrate-N) and moisture content of soil in spring (experiments 1 and 2), soil moisture, volunteer alfalfa and dandelion control, plant density, seed
A novel method for soil aggregate stability measurement by laser granulometry with sonication
NASA Astrophysics Data System (ADS)
Rawlins, B. G.; Lark, R. M.; Wragg, J.
Regulatory authorities need to establish rapid, cost-effective methods to measure soil physical indicators - such as aggregate stability - which can be applied to large numbers of soil samples to detect changes of soil quality through monitoring. Limitations of sieve-based methods to measure the stability of soil macro-aggregates include: i) the mass of stable aggregates is measured, only for a few, discrete sieve/size fractions, ii) no account is taken of the fundamental particle size distribution of the sub-sampled material, and iii) they are labour intensive. These limitations could be overcome by measurements with a Laser Granulometer (LG) instrument, but this technology has not been widely applied to the quantification of aggregate stability of soils. We present a novel method to quantify macro-aggregate (1-2 mm) stability. We measure the difference between the mean weight diameter (MWD; ?m) of aggregates that are stable in circulating water of low ionic strength, and the MWD of the fundamental particles of the soil to which these aggregates are reduced by sonication. The suspension is circulated rapidly through a LG analytical cell from a connected vessel for ten seconds; during this period hydrodynamic forces associated with the circulating water lead to the destruction of unstable aggregates. The MWD of stable aggregates is then measured by LG. In the next step, the aggregates - which are kept in the vessel at a minimal water circulation speed - are subject to sonication (18W for ten minutes) so the vast majority of the sample is broken down into its fundamental particles. The suspension is then recirculated rapidly through the LG and the MWD measured again. We refer to the difference between these two measurements as disaggregation reduction (DR) - the reduction in MWD on disaggregation by sonication. Soil types with more stable aggregates have larger values of DR. The stable aggregates - which are resistant to both slaking and mechanical breakdown by the hydrodynamic forces during circulation - are disrupted only by sonication. We used this method to compare macro-aggregate (1-2 mm) stability of air-dried agricultural topsoils under conventional tillage developed from two contrasting parent material types and compared the results with an alternative sieve-based technique. The first soil from the Midlands of England (developed from sedimentary mudstone; mean soil organic carbon (SOC) 2.5%) contained a substantially larger amount of illite/smectite (I/S) minerals compared to the second from the Wensum catchment in eastern England (developed from sands and glacial deposits; mean SOC=1.7%). The latter soils are prone to large erosive losses of fine sediment. Both sets of samples had been stored air-dried for 6 months prior to aggregate analyses. The mean values of DR (n=10 repeated subsample analyses) for the Midlands soil was 178?m; mean DR (n=10 repeat subsample analyses) for the Wensum soil was 30?m. The large difference in DR is most likely due to differences in soil mineralogy. The coefficient of variation of mean DR for duplicate analyses of sub-samples from the two topsoil types is around 10%. The majority of this variation is likely to be related to the difference in composition of the sub-samples. A standard, aggregated material could be included in further analyses to determine the relative magnitude of sub-sampling and analytical variance for this measurement technique. We then used the technique to investigate whether - as previously observed - variations (range 1000 - 4000 mg kg-1) in the quantity of amorphous (oxalate extractable) iron oxyhydroxides in a variety of soil samples (n=30) from the Wensum area (range SOC 1 - 2%) could account for differences in aggregate stability of these samples.
Recent (<4 year old) Leaf Litter is Not a Major Source of Microbial Carbon in a Temperate Forest Mineral Soil
Kramer, Christiane [University of California, Irvine; Trumbore, Susan E. [University of California, Irvine; Froberg, Mats J. [Sveriges Lantbruksuniversitet; Cisneros dozal, Luz Maria [Los Alamos National Laboratory (LANL); Zhang, Dachun [University of California, Irvine; Xu, Xiamei [University of California, Irvine; Santos, Guaciara [University of California, Irvine; Hanson, Paul J [ORNL
Microbial communities in soil A horizons derive their carbon from several potential sources: organic carbon (C) transported down from overlying litter and organic horizons, root-derived C, or soil organic matter. We took advantage of a multi-year experiment that manipulated the {sup 14}C isotope signature of surface leaf litter inputs in a temperate forest at the Oak Ridge Reservation, Tennessee, USA, to quantify the contribution of recent leaf litter C to microbial respiration and biomarkers in the underlying mineral soil. We observed no measurable difference (< {approx}40{per_thousand} given our current analytical methods) in the radiocarbon signatures of microbial phospholipid fatty acids (PLFA) isolated from the top 10 cm of mineral soil in plots that experienced 3 years of litterfall that differed in each year by {approx}750{per_thousand} between high-{sup 14}C and low-{sup 14}C treatments. Assuming any difference in {sup 14}C between the high- and low-{sup 14}C plots would reflect C derived from these manipulated litter additions, we estimate that <6% of the microbial C after 4 years was derived from the added 1-4-year-old surface litter. Large contributions of C from litter < 1 year (or >4 years) old (which fell after (or prior to) the manipulation and therefore did not differ between plots) are not supported because the {sup 14}C signatures of the PLFA compounds (averaging 200-220{per_thousand}) is much higher that of the 2004-5 leaf litter (115{per_thousand}) or pre-2000 litter. A mesocosm experiment further demonstrated that C leached from {sup 14}C-enriched surface litter or the O horizon was not a detectable C source in underlying mineral soil microbes during the first eight months after litter addition. Instead a decline in the {sup 14}C of PLFA over the mesocosm experiment likely reflected the loss of a pre-existing substrate not associated with added leaf litter. Measured PLFA {Delta}{sup 14}C signatures were higher than those measured in bulk mineral soil organic matter in our experiments, but fell within the range of {sup 14}C values measured in mineral soil roots. Together, our experiments suggest that root-derived C is the major (>60%) source of C for microbes in these temperate deciduous forest soils.
Quantification of the effects of various soil fumigation treatments on nitrogen mineralization and nitrification in laboratory incubation and field studies.
Yan, Dongdong; Wang, Qiuxia; Mao, Liangang; Li, Wei; Xie, Hongwei; Guo, Meixia; Cao, Aocheng
Better quantification of nitrogen mineralization and nitrification after fumigation would indicate if any adjustment is needed in fertilizer application. The effects of chloropicrin (Pic), 1,3-dichloropropene (1,3-D), dimethyl disulfide (DMDS) and metham sodium (MS) fumigation on soil nitrogen dynamics were evaluated in lab incubation and field studies. Although some differences were observed in NH(4)(+)-N and NO(3)(-)-N concentrations in lab incubation and field experiments, both studies led to the same conclusions: (1) Soil fumigation was shown to increase soil mineral nitrogen only during the first 2 weeks after fumigation (WAF). In particular, Pic significantly increased soil mineral nitrogen in both studies at 1 WAF. However, for all fumigant treatments the observed effect was temporary; the soil mineral content of treated samples recovered to the general level observed in the untreated control. (2) All the fumigation treatments depressed nitrification temporarily, although the treatments exhibited significant differences in the duration of nitrification inhibition. In both studies, for a limited period of time, Pic showed a stronger inhibitory effect on nitrification compared to other fumigant treatments. An S-shaped function was fitted to the concentrations of NO(3)(-)-N in lab incubation samples. The times of maximum nitrification (t(max)) in DMDS and MS treatments were 0.97 week and 1.03 week, which is similar to the untreated control (t(max)=1.02 week). While Pic has the longest effect on nitrifying bacteria, nitrification appears to restart at a later time (t(max)=14.37 week). PMID:23062947
Changes in the biological diversity and concentration of total DNA under the influence of mineral fertilizers in agrochernozemic soils
NASA Astrophysics Data System (ADS)
Tkhakakhova, Azida; Kutovaya, Olga; Ivanova, Ekaterina; Pavlyuchenko, Anatoly
Chernozems represent the most valuable soil resource for Russian agriculture. Their sustainable use in intensive farming systems with preservation of the biological diversity and biological activity of these soils is of crucial importance for the agri-environmental security of Russia. We studied the influence of different rates of mineral fertilizers on the biological activity of chernozems on experimental fields of the Dokuchaev Research Institute of Agriculture in Kamennaya Steppe (Voronezh oblast). Soil samples were taken at the end of April 2013 from the plow horizon on trials with different rates of fertilization: NPK-0, NPK-60, and NPK-120 (kg/ha); a long-term fallow plot was used as an absolute control. The biological activity was analyzed by routine inoculation methods and by the molecular biology techniques based on DNA isolation from the soil samples. Quantitative parameters of the isolated and purified DNA were determined by measuring the fluorescence of the DNA preparations with added intercalating dyes; GelDoc XR system and Image Lab and TotalLab Quant. software were used. Microbiological studies showed the high biological activity of the chernozems soil in all the trials. No significant differences were found between the trials for the microbiological processes of the carbon cycle. There was a weakly expressed tendency for an increase in the activity of actinomycetes from the soil with zero fertilization (5.11 log10CFU/g) to the soil with maximum (NPK-120) fertilization (5.69 log10CFU/g) and the fallow soil (5.73 log10CFU/g); the number of cultivated micromycetes decreased from the soil with zero fertilization (4.76 log10CFU/g) to the soil with maximum fertilization (4.14 log10CFU/g) and to the fallow soil (4.1 log10CFU/g). A less equilibrium state is typical of the microorganisms participating in the nitrogen cycle. The number of cultivated aerobic and anaerobic nitrogen-fixing bacteria somewhat increased in the fertilized trials (NPK-60, NPK-120). The most active development of denitrifiers was in the fallow soil. It is known that cultivated forms comprise only about 1 to 10% of the total number of soil microorganisms. Quantitative analysis by the methods of molecular biology makes it possible to consider the full range of microorganisms. The concentration of extracted DNA can serve as an indicator of the total "biogenity" of the soil, as we isolated the genetic material of all organisms living in the soil. The highest concentration of DNA found in the samples from the fallow soil. Much lower values were found in the soils treated with mineral fertilizers: 38.9% in trial NPK-60 and 53.3% in trials NPK-120 and NPK-0. Thus, to sustain biota in cultivated chernozems and to improve the ecological state of the fields, the rates of mineral fertilizers have to be properly controlled. Moderate rates can be recommended. Features of the soil microbiome can serve as universal and sensitive indicators of the state of the soils under different farming systems. The quantitative analysis of isolated total DNA is an efficient tool to control the ecological state of the soils, especially those involved in agriculture.
Photocatalytic atrazine degradation by synthetic minerals, atmospheric aerosols, and soil particles.
Lackhoff, Marion; Niessner, Reinhard
In this work, the photocatalytic atrazine degradation by seven synthetic minerals and five environmental particle samples was examined to investigate a possible contribution of photocatalysis to the abiotic degradation of atrazine in the environment. Particle suspensions containing 500 ng/L atrazine were irradiated with a sun simulator, and the atrazine degradation was monitored by enzyme-linked immunosorbent assay (ELISA). Atrazine detection by ELISA proved to be an useful analytical tool because of low cross-reactivity of atrazine metabolites and high sensitivity with detection limits in the lower nanograms per liter range. The atrazine degradation followed first-order kinetics, and the obtained rate coefficients were compared with the rate of direct photolysis. Known photocatalysts, such as TiO2 and ZnO, showed the expected fast photocatalytic degradation (k = 27-327 x 10(-3) min(-1)) of atrazine. The degradation rates detected upon irradiation of titanium-, zinc-, or iron-containing minerals were orders of magnitudes lower (k = 0.15-0.70 x 10(-3) min(-1)) but still significantly faster than direct photolysis without particles (k = 0.10 x 10(-3) min(-1)). With environmental particle samples (soot, fly ash, sand, road dust, and volcanic ash), however, no significant photocatalytic activity was observed (k = 0.07-0.16 x 10(-3) min(-1)). The atrazine degradation rates were in the range of direct photolysis. Thus photocatalysis by aerosol or soil particles appears not to enhance abiotic atrazine degradation in the environment. PMID:12521159
Net mineralization of N at deeper soil depths as a potential mechanism for sustained forest production under elevated [CO2
Iversen, Colleen M [ORNL; Hooker, Toby [Utah State University (USU); Classen, Aimee T [University of Tennessee, Knoxville (UTK); Norby, Richard J [ORNL
Elevated atmospheric [CO2] is projected to increase forest production, which could increase ecosystem carbon (C) storage. However, sustained forest production will depend on the nutrient balance of the forested ecosystem. Our aim was to examine the causes and consequences of increased fine-root production and mortality throughout the soil profile under elevated CO2 with respect to potential gross nitrogen (N) cycling rates. Our study was conducted in a CO2-enriched sweetgum (Liquidambar styraciflua L.) plantation in Oak Ridge, TN, USA. We used isotope pool dilution methodology to measure potential gross N cycling rates in laboratory incubations of soil from four depth increments to 60 cm. Our objectives were two-fold: (1) determine whether N is available for root acquisition in deeper soil, and (2) determine whether increased inputs of labile C from greater fine-root mortality at depth under elevated [CO2] had altered N cycling rates. While gross N fluxes declined with soil depth, we found that N is potentially available for roots to access, especially below 15 cm depth where microbial consumption of mineral N was reduced. Overall, up to 60% of potential gross N mineralization, and 100% of potential net N mineralization, occurred below 15-cm depth at this site. This finding was supported by in situ measurements from ion-exchange resins, where total inorganic N availability at 55 cm depth was equal to or greater than N availability at 15 cm depth. While it is likely that trees grown under elevated [CO2] are accessing a larger pool of inorganic N by mining deeper soil, we found no effect of elevated [CO2] on potential gross or net N cycling rates. Thus, increased root exploration of the soil volume under elevated [CO2] may be more important than changes in potential gross N cycling rates in sustaining forest responses to rising atmospheric CO2.
Competition between trees and grasses for both soil water and mineral nitrogen in dry savannas.
Donzelli, D; De Michele, C; Scholes, R J
The co-existence of trees and grasses in savannas in general can be the result of processes involving competition for resources (e.g. water and nutrients) or differential response to disturbances such as fire, animals and human activities; or a combination of both broad mechanisms. In moist savannas, the tree-grass coexistence is mainly attributed to of disturbances, while in dry savannas, limiting resources are considered the principal mechanism of co-existence. Virtually all theoretical explorations of tree-grass dynamics in dry savannas consider only competition for soil water. Here we investigate whether coexistence could result from a balanced competition for two resources, namely soil water and mineral nitrogen. We introduce a simple dynamical resource-competition model for trees and grasses. We consider two alternative hypotheses: (1) trees are the superior competitors for nitrogen while grasses are superior competitors for water, and (2) vice-versa. We study the model properties under the two hypotheses and test each hypothesis against data from 132 dry savannas in Africa using Kendall's test of independence. We find that Hypothesis 1 gets much more support than Hypothesis 2, and more support than the null hypothesis that neither is operative. We further consider gradients of rainfall and nitrogen availability and find that the Hypothesis 1 model reproduces the observed patterns in nature. We do not consider our results to definitively show that tree-grass coexistence in dry savannas is due to balanced competition for water and nitrogen, but show that this mechanism is a possibility, which cannot be a priori excluded and should thus be considered along with the more traditional explanations. PMID:23639405
Influence of Environmental Factors on Antagonism of Fungi by Bacteria in Soil: Clay Minerals and pH
Rosenzweig, William D.; Stotzky, G.
The soil replica plating technique was used to evaluate the influence of clay minerals and pH on antagonistic interactions between fungi and bacteria in soil. In general, the antagonistic activity of bacteria towards filamentous fungi was greater in soil than on agar. The spread of Aspergillus niger through soil was inhibited by Serratia marcescens when the organisms were inoculated into separate sites in soil, and this antagonistic effect was maintained when the soil was amended with 3, 6, 9, or 12% (vol/vol) montmorillonite, whereas the addition of kaolinite at a concentration of 3% reduced the antagonism and at 6, 9, or 12% totally eliminated it. Similar results were obtained with the inhibition of A. niger by Agrobacterium radiobacter and of Penicillium vermiculatum by either S. marcescens or Nocardia paraffinae. When A. niger and S. marcescens were inoculated into the same soil site, A. niger was inhibited in all soils, regardless of clay content, although the extent of inhibition was greater as the concentration of montmorillonite, but not of kaolinite, increased. A. niger was inhibited more when inoculated as spores than as mycelial fragments and when inoculated 96 h after S. marcescens, but a 1% glucose solution reduced the amount of inhibition when the fungus was inoculated 96 h after the bacterium. When the pH of the soil-clay mixtures was altered, the amount of antagonism usually increased as the pH increased. Antagonism appeared to be related to the cation-exchange capacity and the pH of the soil-clay mixtures. Bacillus cereus and another species of Bacillus showed no activity in soil towards A. niger under any of the environmental conditions tested, even though the Bacillus sp. significantly inhibited A. niger and seven other fungi on agar. PMID:16345477
Arsenic binding to iron(II) minerals produced by an iron(III)-reducing Aeromonas strain isolated from paddy soil.
Wang, Xin-Jun; Chen, Xue-Ping; Kappler, Andreas; Sun, Guo-Xin; Zhu, Yong-Guan
An iron reducing bacterial strain was isolated from a paddy soil and identified as a member of the Aeromonas group by 16S rRNA gene sequence analysis. When the cells were growing with dissolved Fe(III) as electron acceptor in the presence of As(V), Fe(II) minerals (siderite and vivianite) were formed and dissolved As was removed efficiently from solution. When the cells were growing with the Fe(III) hydroxide mineral (ferrihydrite) as electron acceptor in the presence of As(V), ferrihydrite was reduced and dissolved As(V) concentrations decreased sharply. Our results demonstrated firstly that members of the Aeromonas group can reduce Fe(III) in paddy soils, and secondly that iron reduction does not necessarily lead to arsenic mobilization. However, As immobilization can occur in environments that contain significant concentrations of counter ions such as bicarbonate and phosphate. PMID:19572768
Visible spectrophotometric determination of tantalum in soil, sediment, minerals, and alloys.
Patel, K S; Shukla, A; Agarwal, N; Hoffmann, P
A new, sensitive, and selective method is described for the spectrophotometric determination of Ta(V). The method is based on the extraction of the Ta(V)-F-CV+ complex (CV+ = crystal violet cation) with a benzene solution of imidoyl derivatives (ID), i.e., N,N'-diphenylbenzamidine (DPBA), N-hydroxy-N,N'-diphenylbenzamidine, and N-(2,5-dimethyl)phenyl-p-tolylimidoylphenylhydrazine, from sulfuric acid solution; DPBA was selected for detailed study. The molar absorptivities of the Ta(V)-F-CV+-ID complexes in the benzene solution were in the range of (1.00-1.65) x 10(5) L/mol x cm at 600 nm. The limit of detection was 7 ng Ta/mL (which had an absorbance greater than that of the blank + 3 standard deviations). The optimization of the analytical variables, the composition of the complex, and the effect of diverse ions in the determination of Ta are discussed. The present method was applied to the determination of Ta in environmental samples, i.e., soil, sediment, minerals, and alloys. PMID:11324604
Fungal role in the movement, leaching and deposition of minerals across leaf litter and soil
NASA Astrophysics Data System (ADS)
Pinzari, Flavia; Maggi, Oriana; Persiani, Anna Maria
A considerable number of fungi have been described as having the power to translocate nutrients, but little is known about this role in the leaf litter-soil interface food web. A technique for evaluating the mechanisms of cellulose colonization by fungi and the changes in elemental composition of cellulose during its exploitation was set up. Ten sheets of pure cellulose (cotton linter) filter paper (10cm2) were layered to form a pad which was then inserted into a square-shaped terylene netting bag (15cm2), with a mesh size of 1mm2 . This package was then incubated for 6 months under leaf litter originating from an area of a low mixed Mediterranean maquis located in southern Italy (408570N; 138550E). Four different sites as field replicates were considered along three sampling times. The analysis of cellulose sheets by means of Scanning electron microscopy and EDS (Energy Dispersive X-ray spectroscopy) after 45, 180 and 600 days of field incubation has provided evidence of a progressive increase in the fragmentation of the niche represented by the cellulose itself in the course of proceeding of the decomposition. A clear change occurred in the content of trace elements during decomposition: two groups of elements were observed that seemed to have behaved differently over time. A larger group whose average concentration has been increasing with field incubation time was composed by Si, Fe, Al K, Cl, Mg. A second group of three elements (Ca, P and S) instead has followed a very different trend, increasing in some cases significantly and almost logarithmically between the first and the second sampling, and then remaining constant or even decreased (as in the case of Ca) between the second and the third sampling. The first group of microelements is clearly linked to the contribution of the soil (sandy), while the elements of the second group appeared correlated to biological activity. During the decomposition of cellulose Ca enters into fungal enzymatic mechanisms related to the tricarboxylic acid cycle (i.e. accumulation or precipitation of calcium oxalate in the environment); this can explain the peculiar behaviour of this element across the incubation time. The P and S are biogenic elements that enter directly in the composition of proteins and nucleic acids and other fundamental biological molecules (ATP , co-enzymes, structural proteins), and could be associated to the extent of fungal colonisation of cellulosic material. The results of the study provided evidence of a functional role of fungal hyphae and rhizomorphs in the movement, leaching and deposition of minerals across soil and leaf litter layers. (417 words)
Glycine mineralization in situ closely correlates with soil carbon availability across six North American forest
Wagner, Diane
-weight substrates by soil microorganisms may be governed as much by the overall decomposability of soil C as by N limitation to microbial growth. Keywords Soil free amino acid ┴ Glycine ┴ 13 C ┴ Soil C and N ┴ Mineralizable-009-9400-2 #12;Introduction Free amino acids (FAA) represent a labile pool of soil nitrogen (N) for plant
Glycine mineralization in situ closely correlates with soil carbon availability across six North American forest
Ruess, Roger W.
and FAA-N. This suggests the consumption of these low-molec- ular-weight substrates by soil microorganisms growth. Keywords Soil free amino acid ┴ Glycine ┴ 13 C ┴ Soil C and N ┴ Mineralizable C ┴ Forest soils J amino acids (FAA) represent a labile pool of soil nitrogen (N) for plant and microbial uptake and play
Mineralization and Nutrient Release of an Organic Fertilizer Made by Flour, Meat, and Crop Residues in Two Vineyard Soils with Different pH Levels
E. Garz¾n; F. Gonzßlez-Andrķs; V. M. GarcĒa-MartĒnez; J. M. de Paz
The mineralization and nutrient evolution of an organic fertilizer compost of flour, meat, and crop residues was evaluated in two vineyard soils. A lysimetric testing, using 2.2-L B³chner funnels, was carried out to study the evolution of pH, electrical conductivity, and nutrients during the 400-day experiment. The net mineralization for two different doses of the fertilizer mixed with the soils
Soil carbon sequestration and mineralization potential in an old-field revegetated with shrubs in semi-arid climate conditions
NASA Astrophysics Data System (ADS)
de Dato, G.; Lagomarsino, A.; Abou Jaoudķ, R.; De Angelis, P.
Revegetation and afforestation of abandoned fields can modify mineralisation processes of soil organic matter and, as a consequence, the potential for C sequestration. Our work aimed to analyse these changes identifying C fractions with different degrees of physical protection and potential mineralization, in a old-field revegetated with shrubby species in a Mediterranean semi-arid area. A multi-specific plantation was made up in February 2006, by planting Juniperus phoenicea L. (JP), Pistacia lentiscus L. (PL) and Rosmarinus officinalis L. (RO). The area has a typical Mediterranean climate with an average temperature of 16.8 ░C and a total annual precipitation of 643 mm. Soil cores were collected in three plots with a mixed specific composition, and in one plot used as control (grass cover). Soil cores (0 - 20 cm depth) were sampled in April 2010 at two distances (30 and 60 cm) from the centre of shrub crown cover in revegetated plots, and randomly in the control. The following variables were examined: soil aggregates (macro- > 250 Ąm and micro-aggregates between 53 and 250 Ąm), fine particulate organic matter (F-POM) and its C and N content, microbial respiration after 28 days at 24 ░C, and mineralization rate of labile and stable C. In the short period, no variation in soil C accumulation induced by the plantation was detected. On the other hand, C input from the different soil covers had a distinct pattern: in revegetated plots it was mainly made up by POM, while fine roots represented the major C input in the control. Macro- and micro-aggregates distribution differed in the control and revegetated plots, allowing a higher physical protection of organic carbon in the control. Nevertheless, more recalcitrant organic matter inputs in the plantation can likely determine a more robust soil C accumulation in the long term.
Rain Basin Design Implications for Soil Microbial Activity and N-mineralization in a Semi-arid Environment
NASA Astrophysics Data System (ADS)
Stern, C.; Pavao-Zuckerman, M.
Rain basins have been an increasingly popular Green Infrastructure (GI) solution to the redistribution of water flow caused by urbanization. This study was conducted to examine how different approaches to basin design, specifically mulching (gravel vs. compost and gravel), influence the water availability of rain basins and the effects this has on the soil microbial activity of the basins. Soil microbes are a driving force of biogeochemical process and may impact the carbon and nitrogen dynamics of rain basin GI. In this study we sampled 12 different residential-scale rain basins, differing in design established at Biosphere 2, Arizona in 2013. Soil samples and measurements were collected before and after the onset of the monsoon season in 2014 to determine how the design of basins mediates the transition from dry to wet conditions. Soil abiotic factors were measured, such as moisture content, soil organic matter (SOM) content, texture and pH, and were related to the microbial biomass size within the basins. Field and lab potential N-mineralization and soil respiration were measured to determine how basin design influences microbial activity and N dynamics. We found that pre-monsoon basins with compost had higher moisture contents and that there was a positive correlation between the moisture content and the soil microbial biomass size of the basins. Pre-monsoon data also suggests that N-mineralization rates for basins with compost were higher than those with only gravel. These design influences on basin-scale biogeochemical dynamics and nitrogen retention may have important implications for urban biogeochemistry at neighborhood and watershed scales.
Technology Transfer Automated Retrieval System (TEKTRAN)
The 13C natural abundance approach for determining soil organic C (SOC) stability and turnover has been used to determine SOC mineralization kinetics. These calculations often assume that 13C fractionation during relic SOC and non-harvested biomass mineralization is insignificant. The objective of t...
Crop rotations with annual and perennial forages under no-till soil management: soil attributes, soybean mineral nutrition, and yield
Technology Transfer Automated Retrieval System (TEKTRAN)
Extensive use of sustainable and intensive agricultural systems would result in profitable farms producing greater yields while maintaining or enhancing natural resources. Development of sustainable crop and soil management systems depends on understanding complex relationships between soil managem...
Crop rotations with annual and perennial forages under no-till soil management: soil attributes, soybean mineral nutrition, and yield
Technology Transfer Automated Retrieval System (TEKTRAN)
Extensive use of sustainable crop and soil management systems would result in profitable farms producing greater yields while maintaining or enhancing natural resources. Development of sustainable agricultural systems depends on understanding complex relationships between soil management, crop mana...
Development and application of a soil organic matter based soil quality index in mineralized terrane of the Western US
Technology Transfer Automated Retrieval System (TEKTRAN)
Soil quality indices provide a means of distilling large amounts of data into a single metric that evaluates the soilÆs ability to carry out key ecosystem functions. Primarily developed in agroecosytems, then forested ecosystems, we set out to develop and apply an index using the relation between so...
Mineral content of grasses and grasslands of the Himalayan region: 1. Trace element distribution in soil profiles and their concentrations in surface soils
Singh, B.R.; Mishra, V.K.; Tripathi, B.R.
Researchers analyzed soil samples, collected from naturally occurring grasslands of the Himalayan region, to investigate trace element distribution in soil profiles and their concentrations in surface soils, as well as to examine frequency and geographical distribution of low and high levels of trace elements. Both chemical and radiochemical analytical techniques were employed to determine the trace elements. This study was part of a research project on the evaluation of mineral content of natural grasslands and grasses and the relationship between the mineral contents in grasses and grasslands. Little or no variation in the content of total Zn, Mn, Cu, Cd, Ni, Pb, Co, and I from surface to subsurface horizons in the soil profiles was observed. However, the concentrations of extractable Zn, Mn, Cu, and B in the surface horizons were higher than in the subsurface horizons. The variations among the profiles were primarily related to the geological material from which the soils derived. Means and ranges of trace elements are given for particular locations and for the whole sample area. Concentrations of most of the trace elements varied greatly among sites at the same location and among locations. There were highly significant correlations between the contents of trace elements, especially total Zn and Mn, and extractable Zn, Fe, Ni, Co, B, and I, and the soil chemical properties, elevation, rainfall, and temperature. Rainfall and temperature showed negative correlations for almost all the trace elements. A number of the trace elements were interrelated in their geochemical origin. On the basis of the critical levels suggested for trace element deficiencies, proportions of the samples that may be considered deficient were about 28% for Zn, 50% for Mn, 20-30% for Cu, 4% for Fe, 56-87% for B, 77% for Mo, and 5-10% for Co.
Mineral Occurrence, Translocation, and Weathering in Soils Developed on Four Types of Carbonate and Non-carbonate Alluvial Fan Deposits in Mojave Desert, Southeastern California
NASA Astrophysics Data System (ADS)
Deng, Y.; McDonald, E. V.
Soil geomorphology and mineralogy can reveal important clues about Quaternary climate change and geochemical process occurring in desert soils. We investigated (1) the mineral transformation in desert soils developed on four types of alluvial fans (carbonate and non-carbonate) under the same conditions of climate and landscape evolution; and (2) the effects of age, parent materials, and eolian processes on the transformation and translocation of the minerals. Four types of alluvial-fan deposits along the Providence Mountains piedmonts, Mojave Desert, southeastern California, USA were studied: (1) carbonate rocks, primarily limestone and marble (LS), (2) fine-grained rhyodacite and rhyolitic tuff mixed with plutonic and carbonate rocks (VX), (3) fine- to coarse- grained mixed plutonic (PM) rocks, and (4) coarse-grained quartz monzonite (QM). These juxtaposed fan deposits are physically correlated in a small area (about 20 km by 15 km) and experienced the same climatic changes in the late Pleistocene and Holocene. The soils show characteristic mineral compositions of arid/semiarid soils: calcite is present in nearly all of the samples, and a few of the oldest soils contain gypsum and soluble salts. Parent material has profound influence on clay mineral composition of the soils: (1) talc were observed only in soils developed on the volcanic mixture fan deposits, and talc occurs in all horizons; (2) palygorskite occur mainly in the petrocalcic (Bkm) of old soils developed on the LS and VX fan deposits, indicating pedogenic origin; (3) chlorite was observed mainly in soils developed on VX fan deposits (all ages) and on some LS deposits, but it is absent in soils developed on PM and QM fan deposits; and (4) vermiculite was common throughout soils developed on plutonic rock fan deposits. These mineralogical differences suggest that minerals in the soils are primarily inherited from their parent materials and that mineral weathering in this area was weak. Except the abundance of palygorskite, soils developed on alluvial fans with different ages (4,000 to 200,000 yrs old) did not show other distinct mineralogy difference as a function of age or soil development, which supports the weak weathering of the soils. The results suggest that the clays in the argillic horizons are primarily derived from the accumulation of desert dust, and with time, are translocated into subsoil horizons. The pedogenic accumulation of dust is a soil-geomorphic process common to the Mojave Desert, as well as other deserts in the world.
The role of reaction affinity and secondary minerals in regulating chemical weathering rates at the Santa Cruz Soil Chronosequence, California
Maher, K.; Steefel, Carl; White, A.F.; Stonestrom, D.A.
In order to explore the reasons for the apparent discrepancy between laboratory and field weathering rates and to determine the extent to which weathering rates are controlled by the approach to thermodynamic equilibrium, secondary mineral precipitation, and flow rates, a multicomponent reactive transport model (CrunchFlow) was used to interpret soil profile development and mineral precipitation and dissolution rates at the 226 ka Marine Terrace Chronosequence near Santa Cruz, CA. Aqueous compositions, fluid chemistry, transport, and mineral abundances are well characterized [White A. F., Schulz M. S., Vivit D. V., Blum A., Stonestrom D. A. and Anderson S. P. (2008) Chemical weathering of a Marine Terrace Chronosequence, Santa Cruz, California. I: interpreting the long-term controls on chemical weathering based on spatial and temporal element and mineral distributions. Geochim. Cosmochim. Acta 72 (1), 36-68] and were used to constrain the reaction rates for the weathering and precipitating minerals in the reactive transport modeling. When primary mineral weathering rates are calculated with either of two experimentally determined rate constants, the nonlinear, parallel rate law formulation of Hellmann and Tisserand [Hellmann R. and Tisserand D. (2006) Dissolution kinetics as a function of the Gibbs free energy of reaction: An experimental study based on albite feldspar. Geochim. Cosmochim. Acta 70 (2), 364-383] or the aluminum inhibition model proposed by Oelkers et al. [Oelkers E. H., Schott J. and Devidal J. L. (1994) The effect of aluminum, pH, and chemical affinity on the rates of aluminosilicate dissolution reactions. Geochim. Cosmochim. Acta 58 (9), 2011-2024], modeling results are consistent with field-scale observations when independently constrained clay precipitation rates are accounted for. Experimental and field rates, therefore, can be reconciled at the Santa Cruz site. Additionally, observed maximum clay abundances in the argillic horizons occur at the depth and time where the reaction fronts of the primary minerals overlap. The modeling indicates that the argillic horizon at Santa Cruz can be explained almost entirely by weathering of primary minerals and in situ clay precipitation accompanied by undersaturation of kaolinite at the top of the profile. The rate constant for kaolinite precipitation was also determined based on model simulations of mineral abundances and dissolved Al, SiO2(aq) and pH in pore waters. Changes in the rate of kaolinite precipitation or the flow rate do not affect the gradient of the primary mineral weathering profiles, but instead control the rate of propagation of the primary mineral weathering fronts and thus total mass removed from the weathering profile. Our analysis suggests that secondary clay precipitation is as important as aqueous transport in governing the amount of dissolution that occurs within a profile because clay minerals exert a strong control over the reaction affinity of the dissolving primary minerals. The modeling also indicates that the weathering advance rate and the total mass of mineral dissolved is controlled by the thermodynamic saturation of the primary dissolving phases plagioclase and K-feldspar, as is evident from the difference in propagation rates of the reaction fronts for the two minerals despite their very similar kinetic rate laws. ?? 2009 Elsevier Ltd.
Temperature Effects on Soil Mineralization of Polylactic Acid Plastic in Laboratory Respirometers
Kai-Lai G. Ho; Anthony L. Pometto III
A respirometric system was used to analyze the biodegradation of high molecular weight (120,000 to 200,000 g mol-1) polylactic acid (PLA) plastic films in soil under laboratory conditions. The respirometric system consisted of air-conditioning pretraps, a soil reactor, and a carbon dioxide (CO2) posttrap. A 200-g homogeneous soil mixture of all-purpose potting soil : manure soil : sand [1 :
Effect of pyrochar and hydrochar amendments on the mineralization of the herbicide isoproturon in an agricultural soil.
Eibisch, Nina; Schroll, Reiner; Fu▀, Roland
Carbon (C)-rich, solid products from pyrolysis (pyrochars) and hydrothermal carbonization (HTC, hydrochars) are expected to reduce the bioavailability and bioaccessibility of pesticides as side effect of soil addition. To compare effects of different feedstocks (digestate, miscanthus, woodchips) and production processes (pyrolysis at 750░C, HTC at 200░C and 250░C), (14)C-labeled isoproturon (IPU) was applied at 0.75kgha(-)(1) to loamy sand amended either with 0.5% or 5% pyrochars or hydrochars, which was then incubated for 50d. Mineralization of IPU was measured as (14)C-CO2 released from soil-char composites. Pore-water and methanol extractable (14)C-IPU was quantified as well as non-extractable (14)C-residues (NER). Furthermore, C mineralization of pyrochars, hydrochars and feedstocks was studied to assess the relationship between IPU bioaccessibility and char decomposability. In pure soil, 8.1% of applied IPU was mineralized after 50d. This was reduced more strongly in pyrochar treatments (81▒6% reduction) than in hydrochar treatments (56▒25% reduction). Different feedstocks had no significantly different effect when 5% char was added, but their effect was significant and dependent on the production process in 0.5% amendments. Pesticide binding can occur by surface sorption as well as by diffusion and subsequent occlusion in micropores. The latter can be expected to result in high amounts of NER, as it was observed in the pyrochar treatments. Hydrochars were less stable than pyrochars and contained lower amounts of NER. Thus, in hydrochar amended soils, better accessibility of IPU to microbial degradation may be a result of full char decomposition within decades ensuring controlled pesticide degradation. PMID:25543158
A study was conducted of the influence of the rate of application of simulated acid rain on N mineralization and nitrification in a forest soil. The rates were varied by applying different quantities of simulated rain for varying periods of time. The soil was exposed in the labor...
Mineral ecophysiological evidence for microbial activity in banded iron formation
Li, Dr. Yi-Liang [University of Tennessee, Knoxville (UTK); Konhauser, Dr, Kurt [University of Alberta; Cole, David R [ORNL; Phelps, Tommy Joe [ORNL
The phosphorus composition of banded-iron formations (BIFs) has been used as a proxy for Precambrian seawater composition and the paleoeredox state of Earth's surface environment. However, it is unclear whether the phosphorus in BIFs originally entered the sediment as a sorbed component of the iron oxyhydroxide particles, or whether it was incorporated into the biomass of marine phytoplankton. We conducted high-resolution mineral analyses and report here the first detection of an Fe(III) acetate salt, as well as nanocrystals of apatite in association with magnetite, in the 2.48 Ga Dales Gorge Member of the Brockman Iron Formation (a BIF), Hamersley, Western Australia. The clusters of apatite are similar in size and morphology to biogenic apatite crystals resulting from biomass decay in Phanerozoic marine sediments, while the formation of an Fe(III) acetate salt and magnetite not only implies the original presence of biomass in the BIF sediments, but also that organic carbon likely served as an electron donor during bacterial Fe(III) reduction. This study is important because it suggests that phytoplankton may have played a key role in the transfer of phosphorus (and other trace elements) from the photic zone to the seafloor.
Resources for a lunar base: Rocks, minerals, and soil of the Moon
Lawrence A. Taylor
The rocks and minerals of the Moon will be included among the raw materials used to construct a lunar base. The lunar regolith, the fragmental material present on the surface of the Moon, is composed mostly of disaggregated rocks and minerals, but also includes glassy fragments fused together by meteorite impacts. The finer fraction of the regolith (i.e., less than
Temperature effects on soil organic sulphur mineralization and elemental sulphur oxidation in subtropical soils of varying pH
Milkha S. Aulakh; Randhir Sharma
The increasing sulphur (S) deficiency in soils of several parts of world has led to the use of fertilizer S, an important factor in enhancing the production and quality of crops. Very limited information is available on the use of elemental sulphur (S0) as a fertilizer, its oxidation into SO42- and transformation into organic S in semiarid subtropical soils. We
Microbial biomass and mineral N transformations in soil planted with barley, ryegrass, pea or turnip
Ron Wheatley; Karl Ritz; Bryan Griffiths
Plants of barley (Hordeum vulgare), ryegrass (Lolium perenne), pea (Pisum sativum) or turnip (Brassica campestris rapifera) were grown in pots of unfertilised soil for 10 weeks together with unplanted control pots. A wide range of soil microbiological parameters was measured on bulk soil samples 2, 4, 7 and 10 weeks after seedlings were transplanted. There was no effect of planting
Nitrogen mineralization in lowland rice soils: The role of organic matter quantity and quality
Kanwar Lal Sahrawat
Ammonium production in wetland soils and sediments is the key process that impacts nitrogen (N) availability, wetland productivity and environmental quality. Significant relationships between organic matter content and mineralizable N have been reported for diverse groups of wetland rice soils. However, recent research also showed that in soils under intensified wetland rice production systems, the relationships between organic matter and
Root-Parasitic Nematodes Enhance Soil Microbial Activities and Nitrogen Mineralization
C. Tu; S. R. Koenning; S. Hu
Obligate root-parasitic nematodes can affect soil microbes positively by enhancing C and nutrient leakage from roots but negatively by restricting total root growth. However, it is unclear how the resulting changes in C availability affect soil microbial activities and N cycling. In a microplot experiment, effects of root-parasitic reniform nematodes (Rotylenchulus reniformis) on soil microbial biomass and activities were examined
Soil is an extremely complex habitat for microbes because of the heterogeneity of soil particulates, the constantly changing water and gas regimes, the discontinuity between microhabitats, the intermittent supply of nutrients, etc. The complexity of soil is reflected in the heter...
Manure and mineral fertilizer effects on seasonal dynamics of bioactive soil phosphorus fractions
Technology Transfer Automated Retrieval System (TEKTRAN)
Seasonal fluctuations in bioavailable soil phosphorus can influence soil test results and associated assessment of off-site transport risk. Our objective was to evaluate changes in soil P speciation and availability with time following applications of grain fed cattle (Bos taurus) manure or monoamm...
Effects of a municipal solid waste compost and mineral fertilization on plant growth in two tropical agricultural soils of Mali
M Soumarķ; F. M. G Tack; M. G Verloo
A pot experiment was conducted to compare the effects of compost and mineral fertilization on the growth and chemical composition of ryegrass (Lolium perenne L.) in two Malian agricultural soils (Baguinķda, abbreviated as Bgda, 12░23? S, 7░45? W and Gao, 16░18? N, 0░ GM). Treatments included: control, NPK alone, NPK+C25, NPK+C50, NPK+C100, PK+C50, NK+C50, NP+C50, K+C50, P+C50, N+C50 and C50
Comparison of manure compost and mineral fertilizer for hybrid poplar plantation establishment on boreal heavy clay soils
Marie Larcheveque; Annie Desrochers; Guy R. Larocque
Ģ Introduction\\u000a ĀĀ Clay soils are typically rich in nutrients but are often compact and hard during summer increasing planting shock by limiting\\u000a root development. Recycling farm manure in hybrid poplar plantations may offer additional benefits to mineral fertilizer as\\u000a organic amendment can create better conditions for the early development of roots in addition to nutrient release.\\u000a \\u000a \\u000a \\u000a \\u000a Ģ Material and
Estimation of the efficiency of hydrocarbon mineralization in soil by measuring CO2-emission and variations in the isotope composition of carbon dioxide
NASA Astrophysics Data System (ADS)
Dubrovskaya, Ekaterina; Turkovskaya, Olga
Estimation of the efficiency of hydrocarbon mineralization in soil by measuring CO2-emission and variations in the isotope composition of carbon dioxide E. Dubrovskaya1, O. Turkovskaya1, A. Tiunov2, N. Pozdnyakova1, A. Muratova1 1 - Institute of Biochemistry and Physiology of Plants and Microorganisms, RAS, Saratov, 2 - A.N. Severtsov Institute of Ecology and Evolution, RAS, Moscow, Russian Federation Hydrocarbon mineralization in soil undergoing phytoremediation was investigated in a laboratory experiment by estimating the variation in the 13?/12? ratio in the respired ??2. Hexadecane (HD) was used as a model hydrocarbon pollutant. The polluted soil was planted with winter rye (Secale cereale) inoculated with Azospirillum brasilense strain SR80, which combines the abilities to promote plant growth and to degrade oil hydrocarbon. Each vegetated treatment was accompanied with a corresponding nonvegetated one, and uncontaminated treatments were used as controls. Emission of carbon dioxide, its isotopic composition, and the residual concentration of HD in the soil were examined after two and four weeks. At the beginning of the experiment, the CO2-emission level was higher in the uncontaminated than in the contaminated soil. After two weeks, the quantity of emitted carbon dioxide decreased by about three times and did not change significantly in all uncontaminated treatments. The presence of HD in the soil initially increased CO2 emission, but later the respiration was reduced. During the first two weeks, nonvegetated soil had the highest CO2-emission level. Subsequently, the maximum increase in respiration was recorded in the vegetated contaminated treatments. The isotope composition of plant material determines the isotope composition of soil. The soil used in our experiment had an isotopic signature typical of soils formed by C3 plants (?13C,-22.4ē). Generally, there was no significant fractionation of the carbon isotopes of the substrates metabolized by the soil microbiota. The plants and microorganisms used had the isotopic signatures similar to that of the soil, whereas the ?13C of HD was -47.9ē. The HD mineralization level was assessed by determining the difference between the isotopic compositions of soil CO2 immediately after pollution and during remediation. In the unvegetated soil, about 13% of initially added HD was mineralized, the phytoremediation increased the total decomposition of the contaminant to 19%, and an additional plant inoculation with strain SR80 raised it to 33%. The GC analysis of soil demonstrated that contaminant loss in the plant treatments and in the inoculated plant treatment was 71 and 72%, respectively, whereas in the nonvegetated treatments, it was 64 and 66%, respectively. Thus, the elimination of the contaminant resulted from its total mineralization (CO2 emission) and partial chemical transformation.
Influence of mineral characteristics and long-term arable and forest land use on stocks, composition, and stability of soil organic matter
NASA Astrophysics Data System (ADS)
Kaiser, Michael; Ellerbrock, Ruth H.; Wulf, Monika; Dultz, Stefan; Hierath, Christina; Michael, Sommer
A land use change from arable to forest is discussed as an option to sequester carbon and mitigate climate change but land use specific mechanisms responsible for soil organic matter stabilization are still poorly understood. In this study we aimed to analyze the impact of soil mineral characteristics on organic carbon (OC) stocks and on the composition as well as on the stability of mineral associated organic matter (OM) of arable and forest topsoils. We selected seven soil types of different mineral characteristics. Topsoil samples of each soil type were taken from a deciduous forest and an adjacent arable site, which have been continuously used for more than 100 years. The sequentially extracted Na-pyrophosphate soluble OM fractions (OM(PY)), representing mineral associated OM, were analyzed on their OC and 14C content and characterized by infrared spectroscopy. We found land use effects on the soil OC stocks and OC amounts separated by OM(PY) (OCPY) (forest > arable) as well as on the stability of OM(PY) (arable > forest). For the forest and arable topsoils, a linear relationship was found between the stocks of OC and exchangeable Ca. Only for the near neutral arable topsoils, correlation analyses indicate increasing OCPY contents with an increase in oxalate soluble Fe and Al, exchangable Ca, and Na-pyrophosphate soluble Mg and Fe contents. The stability of OM(PY) of the arable topsoils seems to increase with the specific surface area of the mineral phase and the content of exchangeable Ca. For the acidic forest topsoils, the stability of OM(PY) seems to increase with increasing pH, the C=O group content of OM(PY) and, the Na-pyrophosphate soluble Mg contents. The results indicate cation bridging of OM to mineral surfaces in near neutral arable soils and OM-crosslinking in acidic forest soil as important mechanisms for the stabilization of OM(PY).
Multiscale Assessment of Methylarsenic Reactivity in Soil. 2. Distribution and Speciation in Soil
M Shimizu; Y Arai; D Sparks
Methylated forms of arsenic (As), monomethylarsenate (MMA) and dimethylarsenate (DMA), have historically been used as herbicides and pesticides. Because of their large application to agriculture fields and the toxicity of MMA and DMA, the distribution, speciation, and sorption of methylated As to soils requires investigation. Monomethylarsenate and DMA were reacted with a soil up to one year under aerobic and anaerobic conditions. Microsynchrotron based X-ray fluorescence ({mu}-SXRF) mapping studies showed that MMA and DMA were heterogeneously distributed in the soil and were mainly associated with iron oxyhydroxides, e.g., goethite, in the soil. Micro-X-ray absorption near edge structure (XANES) spectra collected from As hotspots showed MMA and DMA were demethylated to arsenate over one year incubation under aerobic conditions. Monomethylarsenate was methylated to DMA, and DMA was maintained as DMA over a 3 month incubation under anaerobic conditions. Arsenic-iron precipitation, such as the formation of scorodite (FeAsO{sub 4} {center_dot} 2H{sub 2}O), was not observed, indicating that MMA and DMA were mainly associated with Fe-oxyhydroxides as sorption complexes.
Enumeration and characterization of the soil microflora from hydrocarbon-contaminated soil sites able to mineralize polycyclic aromatic hydrocarbons (PAH)
M. Kõstner; M. Breuer-Jammali; B. Mahro
The use of a plate screening technique allowed the direct isolation and quantification of polycylic aromatic hydrocarbon (PAH)-degrading bacteria from different soil sites. Bacteria that were able to grow on anthracene, phenanthrene, fluoranthene or pyrene as a sole carbon source were found with numbers between 103 and 105 colony-forming units (cfu)\\/g of soil dry weight, but only in samples that
Minerals Masquerading As Enzymes: Abiotic Oxidation Of Soil Organic Matter In An Iron-Rich Humid Tropical Forest Soil
NASA Astrophysics Data System (ADS)
Hall, S. J.; Silver, W. L.
Oxidative reactions play an important role in decomposing soil organic matter fractions that resist hydrolytic degradation, and fundamentally affect the cycling of recalcitrant soil carbon across ecosystems. Microbial extracellular oxidative enzymes (e.g. lignin peroxidases and laccases) have been assumed to provide a dominant role in catalyzing soil organic matter oxidation, while other potential oxidative mechanisms remain poorly explored. Here, we show that abiotic reactions mediated by the oxidation of ferrous iron (Fe(II)) could explain high potential oxidation rates in humid tropical forest soils, which often contain high concentrations of Fe(II) and experience rapid redox fluctuations between anaerobic and aerobic conditions. These abiotic reactions could provide an additional mechanism to explain high rates of decomposition in these ecosystems, despite frequent oxygen deficits. We sampled humid tropical forest soils in Puerto Rico, USA from various topographic positions, ranging from well-drained ridges to riparian valleys that experience broad fluctuations in redox potential. We measured oxidative activity by adding the model humic compound L-DOPA to soil slurries, followed by colorimetric measurements of the supernatant solution over time. Dilute hydrogen peroxide was added to a subset of slurries to measure peroxidative activity. We found that oxidative and peroxidative activity correlated positively with soil Fe(II) concentrations, counter to prevailing theory that low redox potential should suppress oxidative enzymes. Boiling or autoclaving sub-samples of soil slurries to denature any enzymes present typically increased peroxidative activity and did not eliminate oxidative activity, further suggesting the importance of an abiotic mechanism. We found substantial differences in the oxidation products of the L-DOPA substrate generated by our soil slurries in comparison with oxidation products generated by a purified enzyme (mushroom tyrosinase). Tyrosinase generated a red compound (dopachrome) that is the target analyte of the traditional L-DOPA oxidative enzyme assay, whereas our soil slurries generated purple melanin-like compounds that were likely generated by more extensive oxidation. To investigate the importance of Fe(II) for L-DOPA oxidation, we added realistic concentrations of Fe(II) (equivalent to 10 - 500 ?g Fe g-1 soil) to an L-DOPA buffer solution under oxic conditions, and found rates of L-DOPA oxidation comparable to those from soil slurries. Molecular oxygen and Fe(II) are known to generate strong oxidants via Fenton reactions. We decreased L-DOPA oxidation rates in soil slurries by adding catalase and superoxide-dismutase enzymes to scavenge reactive oxygen species, suggesting that a free-radical mechanism contributed to L-DOPA oxidation. We obtained similar results using another humic model compound, tetramethylbenzidine (TMB). Although abiotic oxidative reactions involving iron have been employed to degrade anthropogenic organic contaminants, this study is among the first to demonstrate their potential importance for oxidizing organic matter in natural ecosystems. In soils rich in Fe(II), abiotic reactions could complement, or even obviate, the role of microbial oxidative enzymes in degrading recalcitrant organic compounds.
Usefulness of NIR spectroscopy for the estimation of the mineral composition and texture of soils and heavy metal uptake
NASA Astrophysics Data System (ADS)
Soriano-Disla, J. M.; G¾mez, I.; Jordßn, M. M.; Guerrero, C.; Navarro-Pedre±o, J.; Meseguer, S.; Sanfeliu, T.
The accumulation of heavy metals in soils from different sources (atmospheric deposition, agricultural practices, urban-industrial activities, etc.) is of a great environmental concern. In this sense, there is a consensus in the literature that the total heavy metals in soil are not a suitable tool for risk assessment regarding heavy metal mobility and bioavailability. Several approaches have been proposed to estimate this bioavailability but controversy exists to define an universal method. The bioavailability is influenced, apart from other properties like pH, organic matter, etc., by the mineral fraction and texture of a soil. However, the determination of these parameters, especially the mineral composition, is laborious, expensive, and time consuming. Thus, the objectives of this work are the estimation of the texture and mineral components of contrasting soils and the heavy metal uptake (Cu, Zn, Pb, Ni, Cr, Cd) by barley after sewage sludge application using NIR spectroscopy. A set of 70 contrasting soils from different parts of Spain were used for the analysis of the texture and mineral composition. The mineralogical characterization of soil samples was carried out by X-ray diffraction (XRD) using whole soil random powder, oriented clay on ceramic plates, and clay random powder. Chung method was used for semi-quantitative interpretation of X-ray diffraction patterns of soils, obtaining the percentage of Calcite (Ca), Quartz (Q), Albite (Ab), Potassium Feldspar (FK), phyllosilicates (PS). For the prediction of heavy metal uptake, the 70 soils were divided in two separate sets of 36 (experiment 1) and 34 (experiment 2) soils. The methodology for both experiments, separated in time, was the same. The soils were amended with the same dose of sewage sludge (15.71 g dry weight kg-1) and placed in pots. In these pots, a bioassay with barley, under greenhouse conditions, was carried out. Eight weeks after sowing, the plants were harvested. Roots were dried in an oven at 65░C for 2 days, and total heavy metals were determined. The soil samples (air-dried and ground to pass through 2-mm sieve) were placed in glass Petri-dishes, and scanned on reflectance mode from 12000 to 3800 cm-1. For these measurements, a Fourier-Transform near infrared (FT-NIR) spectrophotometer (MPA, Bruker Optik GmbH, Germany) was used. Partial least squares (PLS) regressions were performed to relate the spectral information with the studied parameters. For the mineral parameters and texture, and according to the RPD value, the following models were obtained: excellent for Ca (R2=90.33; RPD=3.24) and Ab (R2=86.03; RPD=2.70), very good (where quantitative predictions are possible) for silt (R2=77.61; RPD=2.13), sand (R2=75.46; RPD=2.03), Q (R2=75.72; RPD=2.04) and FK (R2=78.97; RPD=2.20), and fair models which may be used for assessment and correlation for clay (R2=68.19; RPD=1.78) and PS (R2=67.63; RPD=1.77). For the case of the estimation of the heavy metal uptake, and using the results obtained in the experiment 1, very good models were obtained for Pb (R2=80.75; RPD=2.31), fair, where only high and low values are distinguishable, Ni (R2=50.13; RPD=1.43) and Cd (R2=57.65; RPD=1.56), and poor for Cu (R2=21.94; RPD=1.15), Zn (R2=1.03; RPD=1.02) and Cr (R2=46.01; RPD=1.38). The models developed with the results obtained in the experiment 2 were classified as follows: excellent for Zn (R2=87.62; RPD=2.89) and Ni (R2=85.67; RPD=2.68), very good for Pb (R2=75.08; RPD=2.04) and Cd (R2=77.37; RPD=2.13), good for Cu (R2=72.54; RPD=1.94), and fair for Cr (R2=54.9; RPD=1.51). Although satisfactory results were found for Cu and Zn in the experiment 2 (surprisingly, after the bad results of the experiment 1), they seemed not to be useful, since they were influenced by just one high value, very different to the rest. However, this was not the case of the rest of studied metals, which seemed to have similar patterns in both experiments, with logical differences due to the different ranges, soils, etc. The results indicate that NIR spectroscopy can be a very usef
Analysis of mineral matrices of planetary soil analogues from the Utah Desert
NASA Astrophysics Data System (ADS)
Kotler, J. M.; Quinn, R. C.; Foing, B. H.; Martins, Z.; Ehrenfreund, P.
Phyllosilicate minerals and hydrated sulphate minerals have been positively identified on the surface of Mars. Studies conducted on Earth indicate that micro-organisms influence various geochemical and mineralogical transitions for the sulphate and phyllosilicate minerals. These minerals in turn provide key nutrients to micro-organisms and influence microbial ecology. Therefore, the presence of these minerals in astrobiology studies of Earth-Mars analogue environments could help scientists better understand the types and potential abundance of micro-organisms and/or biosignatures that may be encountered on Mars. Bulk X-ray diffraction of samples collected during the EuroGeoMars 2009 campaign from the Mancos Shale, the Morrison and the Dakota formations near the Mars Desert Research Station in Utah show variable but common sedimentary mineralogy with all samples containing quantities of hydrated sulphate minerals and/or phyllosilicates. Analysis of the clay fractions indicate that the phyllosilicates are interstratified illite-smectites with all samples showing marked changes in the diffraction pattern after ethylene glycol treatment and the characteristic appearance of a solvated peak at ś17 ┼. The smectite phases were identified as montmorillonite and nontronite using a combination of the X-ray diffraction data and Fourier-Transform Infrared Spectroscopy. The most common sulphate mineral in the samples is hydrated calcium sulphate (gypsum), although one sample contained detectable amounts of strontium sulphate (celestine). Carbonates detected in the samples are variable in composition and include pure calcium carbonate (calcite), magnesium-bearing calcium carbonate (dolomite), magnesium, iron and manganese-bearing calcium carbonate (ankerite) and iron carbonate (siderite). The results of these analyses when combined with organic extractions and biological analysis should help astrobiologists and planetary geologists better understand the potential relationships between mineralogy and microbiology for planetary missions.
Depth-Related Changes in Community Structure of Culturable Mineral Weathering Bacteria and in Weathering Patterns Caused by Them along Two Contrasting Soil Profiles
Huang, Jing; Xi, Jun; Huang, Zhi; Wang, Qi; Zhang, Zhen-Dong
Bacteria play important roles in mineral weathering and soil formation. However, few reports of mineral weathering bacteria inhabiting subsurfaces of soil profiles have been published, raising the question of whether the subsurface weathering bacteria are fundamentally distinct from those in surface communities. To address this question, we isolated and characterized mineral weathering bacteria from two contrasting soil profiles with respect to their role in the weathering pattern evolution, their place in the community structure, and their depth-related changes in these two soil profiles. The effectiveness and pattern of bacterial mineral weathering were different in the two profiles and among the horizons within the respective profiles. The abundance of highly effective mineral weathering bacteria in the Changshu profile was significantly greater in the deepest horizon than in the upper horizons, whereas in the Yanting profile it was significantly greater in the upper horizons than in the deeper horizons. Most of the mineral weathering bacteria from the upper horizons of the Changshu profile and from the deeper horizons of the Yanting profile significantly acidified the culture media in the mineral weathering process. The proportion of siderophore-producing bacteria in the Changshu profile was similar in all horizons except in the Bg2 horizon, whereas the proportion of siderophore-producing bacteria in the Yanting profile was higher in the upper horizons than in the deeper horizons. Both profiles existed in different highly depth-specific culturable mineral weathering community structures. The depth-related changes in culturable weathering communities were primarily attributable to minor bacterial groups rather than to a change in the major population structure. PMID:24077700
Role of soil mineral components in the stabilization of organic matter in Umbric Ferralsols of South Brazil
NASA Astrophysics Data System (ADS)
Velasco-Molina, Marta; Berns, Anne E.; Macias, Felipe; Knicker, Heike
Climatic conditions of subtropical and tropical regions support fast carbon (C) mineralization, and thus an accelerated degradation of soil organic matter (SOM) if compared to temperate region (Sßnchez & Logan, 1992). However, even in those regions, there are still soil horizons that show notable C accumulation. Examples for the latter are umbric horizons in typical tropical soils, such as Ferralsols. The occurrence of this soils with thick umbric epipedons (ū 100 cm thickness) in areas of South Brazil is a paradox, that still needs a better understanding (Marques et al., 2011), in particular since the processes that are responsible for the thickness and darkness of the umbric horizons are of special interest with respect to the role of soils as carbon sink. One major contributor to SOM stabilization represents the soil mineral phase. Therefore the main goal of this work its to study the impact of this factor on the SOM sequestration in Umbric Ferralsols from Atibaia, Campinas (SŃo Paulo State) and Chapec¾ (Santa Catarina State) developed under different environmental conditions. With this objective the mineral fractions have been isolated by selective extraction of iron and aluminium oxides with different extracting solutions (sodium pyrophosphate, ammonium oxalate and dithionite-citrate-bicarbonate solution) and related to SOM quality and quantity. The latter was studied by the use of solid-state cross polarisation (CPMAS) 13C NMR spectroscopy after demineralization with hydrofluoric acid (Gonńalves et al., 2003). Quantification of the NMR spectra was performed by integration of the respective chemical shift regions under consideration of the contribution of spinning side bands. For our study the following regions were distinguished (Knicker & L³demann, 1995): alkyl C (0-45 ppm), N-alkyl C (45-60ppm), O-alkyl C (60-110 ppm), aryl C (110-160 ppm), carbonyl C (160-245 ppm). Preliminary results show that, the minimum vertical variation of total Fe into the profile is classical in Ferralsols and the behavior of Al points to the high presence of gibbsite in the clay fractions of the deeper horizon of the Campinas soils. The (AlP+FeP)/C ratios, obtained after extraction of the Al and Fe forms with a sodium pyrophosphate solution, were above 0.03 throughout the studied profile. According to Nierop et al. (2002) this points towards the existence of organic-metallic compounds. Most tentatively, they precipitated due to saturation of adsorption site. The solid-state 13C NMR spectra of the Chapec¾ samples showed that the preserved organic C is dominated by a alkyl C in lipids and amino acids (45 - 0 ppm). Other major intensities are observed between 110 and 45 ppm, in the region of O/N-alkyl C (carbohydrates, amino acids) and carboxyl C (220 to 160 ppm). The missing of a clear signal in the region between 160 and 110 ppm (signal derives from aromatic or olefinic C) indicates that in this soil lignin has minor contributions to its aromatic C content.
Complementary Enzymes Activities in Organic Phosphorus Mineralization and Cycling by Phosphohydrolases in Soils
Technology Transfer Automated Retrieval System (TEKTRAN)
Inorganic and organic phosphates react strongly with soil constituents, resulting in relatively low concentrations of soluble phosphates in the soil solution. Multiple competing reactions control the solution-phase concentration and the cycling of phosphorus-containing organic substrates and the re...
Globally soils are an important terrestrial reservoir of carbon, storing approximately 3 times the carbon held in vegetation and 2 times the amount contained in the atmosphere. With the potential for global climate change it is imperative that world soils continue to be a sink f...
To determine the possible microbiological changes in soil resulting from acid rain, columns containing samples of forest soils were leached with either a continuous application of 100cm of simulated acid rain (pH3.2-4.1) at 5 cm/hour or an intermittent 1.5-hour application of 1.2...
The effect of mineral-ion interactions on soil hydraulic conductivity
Technology Transfer Automated Retrieval System (TEKTRAN)
The reuse of winery wastewater (WW) for irrigation could provide an alternative water source for wine production. The shift of many wineries and other food processing industries to K+-based cleaners requires studies on the effects of K+ on soil hydraulic conductivity (HC). Soils of contrasting mine...
Intense forest wildfire sharply reduces mineral soil C and N: the first direct evidence
Bernard T. Bormann; Peter S. Homann; Robyn L. Darbyshire; Brett A. Morrissette
Direct evidence of the effects of intense wildfire on forest soil is rare because reliable prefire data are lacking. By chance, an established large-scale experiment was partially burned in the 2002 Biscuit fire in southwestern Oregon. About 200 grid points were sampled across seven burned and seven unburned stands before and after the fire. Fire-related soil changes Ś including losses
Assessing indices for predicting potential N mineralization in pedogenically distinct soils under different tillage management systems
Technology Transfer Automated Retrieval System (TEKTRAN)
A reliable laboratory index of nitrogen availability would be useful for making N recommendations but no single approach has received broad acceptance across a wide range of soils. We compared several indices over a range of soil conditions to test the possibility of determining the best combination...
In search of a better approach to predict phosphorus movement in soils from applied wastewaters, reactions of added orthophosphates were studied in 9 different soils with widely varying physical and chemical properties. Information obtained on the nature and rate of P reaction wi...
Carbon, Nitrogen and Fungal mycelium in the organic and in the mineral soil layers across a chronosequence of Stone pine Forest on Mount Vesuvius
NASA Astrophysics Data System (ADS)
de Marco, Anna; Giordano, Maria; Esposito, Fabrizio; Virzo de Santo, Amalia
Forest ecosystems act as a substantial carbon sink and store about 20% of all soil C. The amount of organic matter sequestered in the soil is dependent on the quantity of plant litter delivered to the soil as well as to the extent of litter decomposition. Stone pine forests are common in the Mediterranean areas of southern Italy, were this tree has been largely used for afforestation of volcanic substrates on Mount Vesuvius. Nevertheless, very little is known about carbon accumulation in Stone pine soil as well as about soil organic matter turnover in the organic and in the mineral soil layers. The aim of this study was to assess, along the whole soil profile, the concentration of C and N and the amount of fungal mycelium across a chronosequence encompassing a 36y, a 66y and a 96y old Stone pine forest within the National Park of Vesuvius. The chronosequence allows to estimate the changes with forest age in C and N concentration and the allocation of organic matter below-ground. The amount of fungal mycelium, particularly the active mycelium, at different depth along the soil profile is an indicator of the organic matter turn-over. The forest stands had been implanted on the same type of parent material, i.e. on lava. The sandy mineral soil was 15 cm deep in the youngest forest and reached a maximum depth of 37 cm in the two older forests. Litter fall (2006-2009) steadily increased from the youngest to the oldest forest stand (3828, 6144 and 7831 Kg/ha/y, respectively) and was positively related to tree basal area. C and N concentration in the organic soil layers (litter and humus) of the three stands did not change remarkably with forest age. In contrast, in the 0-15 cm mineral layer, C and N concentrations were about threefold higher in the 66y old compared to the 36y old forest stand. A further increase (by 2,4 for C and by 1,5 for N) was observed in the 96y old compared to the 66y old forest stand. In the deeper (15-37 cm) mineral soil of the two older forest stands, C concentration was 6 times higher and N concentration 3 times higher in the 96y old forest. The values of the C/N ratio decreased with depth in all stands; C/N values in the mineral soil, were higher in the oldest forest stand, consistently with the lower increase of N compared to C concentration. The results indicate that C and N accrual in the soil of the chronosequence derives from a combination of aboveground (mainly needle litter) and belowground (mainly roots) litter inputs whose different quality is mirrored by the different C/N ratio along the soil profile. The amount of active fungal mycelium was related mainly to soil water content and was highest in the humus layer. Though the active mycelium was present all over the whole profile of both the older forest stands, even in the deepest layers, its amount decreased with depth likely due to resource shortage. When referred to soil organic matter, fungal mycelium was most abundant in the mineral soil layers from 5 to 15 cm where it constituted up to 11% and 7% of the organic matter, respectively in the 66y and the 96y old forest; in contrast in the organic soil layers fungal mycelium reached a maximum of 2 % of the organic matter. This suggests that organic matter turnover is more active in the upper mineral soil layers and decreases with depth and forest age favouring a major accumulation in the deepest layers of the oldest forest stand.
Methane oxidation in an intensively cropped tropical rice field soil under long-term application of organic and mineral fertilizers.
Nayak, D R; Babu, Y Jagadeesh; Datta, A; Adhya, T K
Methane (CH4) oxidation is the only known biological sink process for mitigating atmospheric and terrestrial emissions of CH4, a major greenhouse gas. Methane oxidation in an alluvial soil planted to rice (Oryza sativa L.) under long-term application of organic (compost with a C/N ratio of 21.71), and mineral fertilizers was measured in a field-cum-laboratory incubation study. Oxidation rates were quantified in terms of decrease in the concentration of CH4 in the headspace of incubation vessels and expressed as half-life (t(1)2) values. Methane oxidation rates significantly differed among the treatments and growth stages of the rice crop. Methane oxidation rates were high at the maximum tillering and maturity stages, whereas they were low at grain-filling stage. Methane oxidation was low (t(1)2) = 15.76 d) when provided with low concentration of CH4. On the contrary, high concentration of CH4 resulted in faster oxidation (t(1)2) = 6.67 d), suggesting the predominance of "low affinity oxidation" in rice fields. Methane oxidation was stimulated following the application of mineral fertilizers or compost implicating nutrient limitation as one of the factors affecting the process. Combined application of compost and mineral fertilizer, however, inhibited CH4 oxidation probably due to N immobilization by the added compost. The positive effect of mineral fertilizer on CH4 oxidation rate was evident only at high CH4 concentration (t(1)2 = 4.80 d), while at low CH4 concentration their was considerable suppression (t(1) = 17.60 d). Further research may reveal that long-term application of fertilizers, organic or inorganic, may not inhibit CH4 oxidation. PMID:17940256
Data compilation, synthesis, and calculations used for organic-carbon storage and inventory estimates for mineral soils of the Mississippi River Basin
Buell, Gary R.; Markewich, Helaine W.
U.S. Geological Survey investigations of environmental controls on carbon cycling in soils and sediments of the Mississippi River Basin (MRB), an area of 3.3 x 106 square kilometers (km2), have produced an assessment tool for estimating the storage and inventory of soil organic carbon (SOC) by using soil-characterization data from Federal, State, academic, and literature sources. The methodology is based on the linkage of site-specific SOC data (pedon data) to the soil-association map units of the U.S. Department of Agriculture State Soil Geographic (STATSGO) and Soil Survey Geographic (SSURGO) digital soil databases in a geographic information system. The collective pedon database assembled from individual sources presently contains 7,321 pedon records representing 2,581 soil series. SOC storage, in kilograms per square meter (kg/m2), is calculated for each pedon at standard depth intervals from 0 to 10, 10 to 20, 20 to 50, and 50 to 100 centimeters. The site-specific storage estimates are then regionalized to produce national-scale (STATSGO) and county-scale (SSURGO) maps of SOC to a specified depth. Based on this methodology, the mean SOC storage for the top meter of mineral soil in the MRB is approximately 10 kg/m2, and the total inventory is approximately 32.3 Pg (1 petagram = 109 metric tons). This inventory is from 2.5 to 3 percent of the estimated global mineral SOC pool.
Effects of aluminosilicate minerals in clay soil fractions on pore water hydroxide ion concentrations in soil/cement matrices
Cook, Evan Russell
form of montmorillonite, with 0. 5, 10, 20, and 40 percent bentonite by total, air-dry weight were mixed with Type I Portland cement at 10, 20, and 30 percent cement by weight of air-dry soil. Pore water was expressed and analyzed for hydroxide, calcium...
Changes in hot water soil extracts brought about by nitrogen immobilization and mineralization processes during incubation of amended soils
G. Redl; C. H³bner; F. Wurst
During incubation of an acid cambisol and an alkaline fluvisol, amended with glucose and nitrate, hot water soil extracts were analysed for N content, ultraviolet absorption, and fluorescence. Humic substances in the hot water extracts and in a neutral sodium pyrophosphate extract were fractionated on polyvinylpyrrolidone and measured spectroscopically. Changes in the hot water and pyrophosphate extract compositions were related
The impact of mineral fertilizers and lime on the transformation of humic acids in a soddy-podzolic heavy loamy soil of the Cis-Ural region
NASA Astrophysics Data System (ADS)
Zav'yalova, N. E.
The composition and structure of humic acids in a soddy-podzolic heavy loamy soil (Retisol) of the Cis-Ural region after the long-term application of mineral fertilizers and lime was studied by the methods of elemental analysis, infrared spectroscopy, and thermogravimetry. It was found that mineral fertilizers and lime did not change the ranges of C, H, O, and N contents and general structure typical of humic acids in soddy-podzolic soils. The long-term anthropogenic impact on the soil resulted in some transformation of the composition and properties of humic acids. Clear absorption bands in the area of 1700 cm-1 (C=O of carbonyl group) and 1620 cm-1 (C=C of aromatic rings), which characterize the benzenoid structures of molecules, were found in the infrared spectra of humic acids from the soil treated with lime at the rate to compensate for the total acidity. Soil liming favored the accumulation of thermodynamically stable fragments of the central part of humic acid molecules and the destruction of peripheral radicals. The application of mineral fertilizers resulted in the enrichment of humic acids with aliphatic fragments. The combined application of mineral fertilizers and lime increased the portion of aromatic structures and, at the same time, enriched humic acids in aliphatic fragments less resistant to pyrolysis. These fragments are biologically and chemically active and can be readily involved in the element turnover processes, thus protecting the stable part of humus from the biological destruction.
Eucalyptus development in degraded soil fertilized with sewage sludge and mineral fertilizer
NASA Astrophysics Data System (ADS)
Rodrigues, R. A. F.; Santos, E. B.; Alves, M. C.; Arruda, O. G.
The aim of this study was to compare the development of eucalyptus in a degraded Oxisol with mineral fertilizer and sewage sludge. The study was conducted in Selviria, Mato Grosso do Sul, Brasil. The culture of eucalyptus was planted in 2003 at 2.0 m x 1.5 m spacing, with application of 60 Mg ha-1 of sewage sludge (dry basis) and mineral fertilizer. After five years (2008) the area received biosolids and mineral fertilizer, and after five months, were evaluated for height and diameter at breast height of Eucalyptus. The experimental design was randomized blocks with four treatments: T1 - control (without addition of inputs), T2 - Mineral fertilization (30 kg ha-1 N, 90 kg ha-1 of P2O5 and 60 kg ha-1 K2O), T3 - Reapplication of 4.64 Mg ha-1 of sewage sludge, dry basis, T4 - Reapplication of 9.28 Mg ha-1 of sewage sludge, dry basis. Before reapplication the biosolids plant height was higher in the eucalyptus with treatment 9.28 Mg ha-1 of sewage sludge (8.03 m) compared to control (5.75 m) and mineral fertilizer (5.91 m) and that treatment 4.64 Mg ha-1 of sewage sludge (6.34 m) did not differ from the previous three. For the diameter at breast height was the highest value for treatment with 9.28 Mg ha-1 (7.78 cm) compared to control (5.23 cm) and 4.64 Mg ha-1 (5.03 cm), and that of mineral fertilizer (5.96 cm) did not differ from all treatments. After reapplication of sludge plant height was higher in the eucalyptus treatment with 9.28 Mg ha-1 of sewage sludge (11.21 m) compared with control (7.51 m), mineral fertilizer (7.77 m) and 4 64 Mg ha-1 (8.07 m), which did not differ. The diameter at breast height had the same behavior before the application of biosolids in the highest value observed being 9.28 Mg ha-1 (8.46 cm) compared with control (5.75 cm) and 4.64 Mg ha-1 (5.03 cm) and that of mineral fertilizer (6.34 cm) did not differ from the others. Reapplication of the dose of 9.28 Mg ha-1 of sewage sludge in degraded Oxisol provided greater height and diameter at breast height from eucalyptus trees.
Thermal Analyzer for Planetary Soil (TAPS): an in Situ Instrument for Mineral and Volatile-element Measurements
NASA Technical Reports Server (NTRS)
Gooding, J. L.; Ming, D. W.; Gruener, J. E.; Gibbons, F. L.; Allton, J. H.
Thermal Analyzer for Planetary Soil (TAPS) offers a specific implementation for the generic thermal analyzer/evolved-gas analyzer (TA/EGA) function included in the Mars Environmental Survey (MESUR) strawman payload; applications to asteroids and comets are also possible. The baseline TAPS is a single-sample differential scanning calorimeter (DSC), backed by a capacitive-polymer humidity sensor, with an integrated sampling mechanism. After placement on a planetary surface, TAPS acquires 10-50 mg of soil or sediment and heats the sample from ambient temperature to 1000-1300 K. During heating, DSC data are taken for the solid and evolved gases are swept past the water sensor. Through ground based data analysis, multicomponent DSC data are deconvolved and correlated with the water release profile to quantitatively determine the types and relative proportions of volatile-bearing minerals such as clays and other hydrates, carbonates, and nitrates. The rapid-response humidity sensors also achieve quantitative analysis of total water. After conclusion of soil-analysis operations, the humidity sensors become available for meteorology. The baseline design fits within a circular-cylindrical volume less than 1000 cm(sup 3), occupies 1.2 kg mass, and consumes about 2 Whr of power per analysis. Enhanced designs would acquire and analyze multiple samples and employ additional microchemical sensors for analysis of CO2, SO2, NO(x), and other gaseous species. Atmospheric pumps are also being considered as alternatives to pressurized purge gas.
Natural immobilization of uranium by phosphate mineralization in an oxidizing saprolite¢soil profile: chemical weathering of the Coles Hill uranium deposit, Virginia
J. L Jerden; A. K Sinha; L Zelazny
Geochemical and mineralogical studies of the 15- to 20-m-thick soil and saprolite profile developed over the Coles Hill uranium deposit demonstrate that uranium transport may be inhibited or naturally attenuated by the precipitation of U(VI) phosphate minerals in oxidizing and saturated soil environments. This study examines geochemical conditions in which these secondary uranium phosphates are formed and remain stable for
Urea-nitrogen transformation and compost-nitrogen mineralization in three different soils as affected by the interaction between both nitrogen inputs
Kyung-Hwa Han; Woo-Jung Choi; Gwang-Hyun Han; Seok-In Yun; Sun-Ho Yoo; Hee-Myong Ro
Interactive effects of a combined application of urea and compost on the fates of urea-N and net mineralization of compost-N in three soils with different contents of organic-C and inorganic-N were examined through an aerobic 6-week incubation study. Soils were each subjected to four treatments of urea and compost applied at rates of 0 and 0Āmg N kg -1 (control),
Nitrogen mineralization in riparian soils along a river continuum within a multi-landuse basin
Nitrogen dynamics in riparian systems are often addressed within one landuse type and are rarely studied on watershed scales involving multiple land uses. This study tested for both temporal trends and watershed-wide spatial patterns in N mineralization and identified site fact...
Point of zero charge determination in soils and minerals via traditional methods and detection
Ma, Lena
) potentiometric titration measuring the adsorption of H+ and OH└ on amphoteric surfaces in solutions of varying possessing amphoteric surfaces. This poses far-reaching implications for soil management in agriculture
Mineral-Induced Formation of Free Radicals: A Plausible Mechanism for Anoxic Oxidation in Martian Soils
NASA Astrophysics Data System (ADS)
Gil-Lozano, C.; Losa-Adams, E.; Davila, A. F.; Fairen, A. G.; Gago-Duport, L.
We investigated the kinetic of free radical generation by aqueous pyrite slurries under anoxic conditions as a possible explanation for the oxidative reactivity of martian soils today and in the past.
Fate of gram-negative bacterial biomass in soilŚmineralization and contribution to SOM
Reimo Kindler; Anja Miltner; Hans-Hermann Richnow; Matthias Kõstner
Soil microorganisms contribute to the formation of non-living soil organic matter (SOM) by metabolic transformation of plant-derived material. After cell death, their biomass components with a specific molecular character become incorporated into SOM imprinting its chemical properties, although this process has not yet been quantified. In order to elucidate the contribution to SOM formation, we investigated the fate of gram-negative
After exposure of samples of three forest soils(pH 3.4 and 3.9) from the Adirondacks region of New York to 60, 230, or 400 cm of simulated rain of pH 3.5 or 5.6 in 4, 14 or 24 weeks, respectively, the soil samples were seperated into the 0 to 2 and 2 to 5 cm organic layers and fu...
Impact of Organic Amendments with and Without Mineral Fertilizers on Soil Microbial Respiration
NASA Astrophysics Data System (ADS)
Gilani, S. S.; Bahmanyar, M. A.
A field experiment was conducted to study the effects of Sewage Sludge (SS), Municipal Waste Compost (MWC) and Vermicompost (VC) with and without chemical fertilizer (Urea, 50 kg ha-1 + Potassium sulfate, 100 kg ha-1 + Triple super phosphate, 127.5 kg ha-1) on Soil Microbial Respiration (SMR) and Total Organic Carbon (TOC) in a soil cropped to soybean. Experiment was arranged in a complete block design with three replications. Organic amendments were added to soil at rate of 0 (control treatment), 20 and 40 Mg ha-1. Furthermore each level of organic fertilizers with Į normal of chemical fertilizer was also enriched. Soil samples were taken after one year of fertilization. Results illustrated that application of organic amendments increased TOC and SMR and soybean yield compared to control and chemical fertilizer treatments. Sewage sludge amended soils showed higher SMR, TOC and soybean yield than that of other organic amendment treatments. An increasing trend was observed in all studied parameters, as rates of application increased. All parameters were greater in treatments receiving a combination of chemical fertilizers and organic amendments (enriched treatments) compared to soils receiving organic amendments alone. Results obtained by discriminate analysis indicated that rates of application were more effective to create discriminating among treatments. This study showed that TOC was significantly correlated with SMR. Significant correlation was also observed between SMR and soybean yield.
Integrating plant-microbe interactions to understand soil C stabilization with the MIcrobial-MIneral Carbon Stabilization model (MIMICS)
NASA Astrophysics Data System (ADS)
Grandy, Stuart; Wieder, Will; Kallenbach, Cynthia; Tiemann, Lisa
If soil organic matter is predominantly microbial biomass, plant inputs that build biomass should also increase SOM. This seems obvious, but the implications fundamentally change how we think about the relationships between plants, microbes and SOM. Plant residues that build microbial biomass are typically characterized by low C/N ratios and high lignin contents. However, plants with high lignin contents and high C/N ratios are believed to increase SOM, an entrenched idea that still strongly motivates agricultural soil management practices. Here we use a combination of meta-analysis with a new microbial-explicit soil biogeochemistry model to explore the relationships between plant litter chemistry, microbial communities, and SOM stabilization in different soil types. We use the MIcrobial-MIneral Carbon Stabilization (MIMICS) model, newly built upon the Community Land Model (CLM) platform, to enhance our understanding of biology in earth system processes. The turnover of litter and SOM in MIMICS are governed by the activity of r- and k-selected microbial groups and temperature sensitive Michaelis-Menten kinetics. Plant and microbial residues are stabilized short-term by chemical recalcitrance or long-term by physical protection. Fast-turnover litter inputs increase SOM by >10% depending on temperature in clay soils, and it's only in sandy soils devoid of physical protection mechanisms that recalcitrant inputs build SOM. These results challenge centuries of lay knowledge as well as conventional ideas of SOM formation, but are they realistic? To test this, we conducted a meta-analysis of the relationships between the chemistry of plant liter inputs and SOM concentrations. We find globally that the highest SOM concentrations are associated with plant inputs containing low C/N ratios. These results are confirmed by individual tracer studies pointing to greater stabilization of low C/N ratio inputs, particularly in clay soils. Our model and meta-analysis results suggest that current ideas about plant-microbe-SOM relationships are unraveling. If so, our reconsideration of the mechanisms stabilizing SOM will also challenge long-held views about how to optimize plant community management to increase SOM.
The impact of farming practice on soil microorganisms and arbuscular mycorrhizal fungi: Crop type versus long-term mineral and organic fertilization
Christopher Ngosong; Mareike Jarosch; Joachim Raupp; Elke Neumann; Liliane Ruess
This study investigates an arable field soil with long-term (27 and 28 years) mineral (NPK) and organic (cattle manure, cattle manure with biodynamic preparations) fertilizer amendments at low, medium and high amounts. Arbuscular mycorrhizal (AM) fungi host plant wheat was cultivated in the first vegetation period and non-host amaranth in the second. Phospholipid fatty acids (PLFA) were used to assess
The accumulation of heavy metals in plants (Lactuca sativa L., Fragaria vesca L.) after the amelioration of coalmine tailing soils with different organo-mineral amendments
Vlado Licina; Svetlana Antic-Mladenovic; Mirjana Kresovic
The investigation was based on two pot experiments with lettuce and strawberry, aiming to assess the uptake of heavy metals (cobalt [Co], chromium [Cr], lead [Pb], cadmium [Cd], nickel [Ni], arsenic [As]) from coalmine tailing soils subjected to different amelioration measures (application of liquid fertilizers combined with different organo-mineral materialsĀ¢Āzeolite material, peat material, coal dust and poultry manure processed by
Effect of wet and dry cycles in calcareous soil on mineral nutrient uptake of two grasses, Agrostis stolonifera L. and Festuca ovina L
Aparna Misra; Germund Tyler
Shoot uptake of mineral nutrients (Ca, Cu, Fe, K, mg, Mn, P, S, Zn) by Agrostis stolonifera L. was compared with Festuca ovina L. under wet and dry cycles. Such conditions are typical for A. stolonifera sites, whereas F. ovina is growing mostly on consistently drier and better-drained soils. Plants were grown in a glasshouse, at controlled temperature and light
Mineralization of 2,4-dichlorophenoxyacetic acid in soil simultaneously enriched with saccharides
F. Kunc; J. Rybß?ovß; J. LasĒk
Detoxication of 2,4-dichlorophenoxyacetic acid (2,4-D) in samples of chernozem soil was determined by a biological test and\\u000a the time course of production of14CO2 a product of microbial degradation of 2-14C-2,4-D, was measured during 38-d incubation at 28░C in the dark. Enrichment of the soil with glucose (1000 ppm), two exocellular\\u000a bacterial glucan and glucomannan polysaccharides (750 ppm), or a mixture
Phosphate-Solubilizing and Mineralizing Abilities of Bacteria Isolated from Soils 1 1 Project supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, the Ministry of Education of the P.R. China
Guang-Can TAO; Shu-Jun TIAN; Miao-Ying CAI; Guang-Hui XIE
Microorganisms capable of solubilizing and mineralizing phosphorus (P) pools in soils are considered vital in promoting P bioavailability. The study was conducted to screen and isolate inorganic P-solubilizing bacteria (IPSB) and organic P-mineralizing bacteria (OPMB) in soils taken from subtropical flooded and temperate non-flooded soils, and to compare inorganic P-solubilizing and organic P-solubilizing abilities between IPSB and OPMB. Ten OPMB
Effect of iron oxide reductive dissolution on the transformation and immobilization of arsenic in soils: New insights from X-ray photoelectron and X-ray absorption spectroscopy.
Fan, Jian-Xin; Wang, Yu-Jun; Liu, Cun; Wang, Li-Hua; Yang, Ke; Zhou, Dong-Mei; Li, Wei; Sparks, Donald L
The geochemical behavior and speciation of arsenic (As) in paddy soils is strongly controlled by soil redox conditions and the sequestration by soil iron oxyhydroxides. Hence, the effects of iron oxide reductive dissolution on the adsorption, transformation and precipitation of As(III) and As(V) in soils were investigated using batch experiments and synchrotron based techniques to gain a deeper understanding at both macroscopic and microscopic scales. The results of batch sorption experiments revealed that the sorption capacity of As(V) on anoxic soil was much higher than that on control soil. Synchrotron based X-ray fluorescence (?-XRF) mapping studies indicated that As was heterogeneously distributed and was mainly associated with iron in the soil. X-ray absorption near edge structure (XANES), micro-X-ray absorption near edge structure (?-XANES) and X-ray photoelectron spectroscopy (XPS) analyses revealed that the primary speciation of As in the soil is As(V). These results further suggested that, when As(V) was introduced into the anoxic soil, the rapid coprecipitation of As(V) with ferric/ferrous ion prevented its reduction to As(III), and was the main mechanism controlling the immobilization of As. This research could improve the current understanding of soil As chemistry in paddy and wetland soils. PMID:25064258
Soil profiles as indicators of mineral weathering rates and organic interactions for a Pennsylvania diabase
E. M. Hausrath; A. K. Navarre-Sitchler; P. B. Sak; J. Z. Williams; S. L. Brantley
Basaltic bedrock dissolves quickly, and its weathering rate is therefore important towards controlling the composition of natural waters, soil formation, and CO2 concentrations in the atmosphere. Despite its importance, however, few reports of basalt or diabase and gabbro weathering rates exist in the literature, and most have been measured in laboratory dissolution experiments or based on watershed studies. Here, using
Mineralization of the Bacillus thuringiensis Cry1Ac endotoxin in soil
Technology Transfer Automated Retrieval System (TEKTRAN)
Despite a number of studies describing the fate of Bacillus thuringiensis insecticidal endotoxins in soil have been conducted in the past decade, conflicting information on persistence of this class of insecticidal toxins exists. In the present experiment, 14C from glucose was incorporated into the ...
Technology Transfer Automated Retrieval System (TEKTRAN)
The Maillard reaction, as an alternative theory for soil organic matter (SOM) formation, has not been investigated under conditions relevant for SOM formation. This research was conducted to investigate the distribution of newly formed humic materials into mineralogical distinct clay-size fractions...
Carbon mineralization from organic wastes at different composting stages during their incubation with soil
M. P. Bernal; M. A. Sßnchez-Monedero; C. Paredes; A. Roig
The decomposition of seven different organic waste mixtures prepared with sewage sludges, animal manures, city refuse and industrial and plant residues, was studied during their aerobic incubation with soil. The waste mixtures were composted by the Rutgers static pile system, and four samples of each mixture were collected at various composting stages: the initial mixture, and samples taken during the
Altered Snow Density and Chemistry Change Soil Nitrogen Mineralization and Plant Growth
Christian Rixen; Michele Freppaz; Veronika Stoeckli; Christine Huovinen; Kai Huovinen; Sonja Wipf
Snow properties such as snow density will likely change in a warmer climate. Changes in depth and extent of snow cover have been shown to affect soil nutrient dynamics and plant growth; however, effects of a changed snow density have so far not been explicitly tested. We altered snow properties (especially depth and density according to those found on ski
Peatland establishment on mineral soils: Effects of water level, amendments, and species after two growing seasons
Dale H. Vitt; R. Kelman Wieder; Bin Xu; Molly Kaskie; Sara Koropchak
Recent surveys of peatland initiation that occurred over the past 10,000 years in northeastern Alberta have revealed that most peatlands initiated by paludification, or swamping of upland soils. Peatland ecologists have long known the importance of the paludification process, but it has not been transferred to peatland restoration methodologies. We initiated this study to determine if wetland structure and function
Rebuilding Peatlands on Mineral Soils Utilizing Lessons Learned from Past Peatland Initiation
D. H. Vitt; S. C. Koropchak; B. Xu; R. Bloise; R. Wieder; S. Mowbray
Recent surveys of peatland initiation during the past 10,000 years in northeastern Alberta have revealed that nearly all peatlands, regardless of whether they are currently bogs and fens, were initiated by paludification, or swamping of upland soils. Terrestrialization (or infilling of water bodies) rarely if ever was involved in the initiation of peatlands across the mid boreal of Canada. Although
Concentrations of Major and Minor Mineral Elements in Different Organs of Kosteletzkya virginica and Saline Soils
C. J. Ruan; P. Qin; Z. X. He; M. Xie
Kosteletzkya virginica (L.) Presl. is a perennial dicot halophytic species that grows in brackish portions of coastal tidal marshes of the mid-Atlantic and southeastern United States. It was introduced into Northern Jiangsu, China, by the Halophyte Biotechnology Center (University of Delaware, Newark, DE) as a species with potential to improve the soil and develop ecologically sound saline agriculture. Fifteen major
Identification of Mn-oxide minerals in some soils from Devon, UK, and their varying capacity to adsorb Co and Cu.
Lidiard, H M; Rae, J E; Parker, A
A number of Mn-oxide minerals in soils from a farm in North Devon have been tentatively identified using a combination of advanced analytical techniques: scanning electron microscopy (SEM), scanning electron microprobe (SEMP), X-ray diffraction (XRD) and bulk chemical analysis by wet digestion followed by inductively-coupled plasma spectrometry (ICP). The minerals lithiophorite and hollandite are thought to occur throughout the study area although there is considerable geographical variation in the proportions of minerals present. Bimessite, vernadite, romanechite, todorokite and cryptomelane may also be present, although in smaller amounts.The use of SEMP, together with a simple sorption experiment, has allowed a study of the extent of uptake of Co and Cu by different Mn-oxide minerals. Lithiophorite appears to take up Co and Cu more effectively than hollandite within a pH range of 4-6. PMID:24198105
An investigation of groundwater organics, soil minerals, and activated carbon on the complexation, adsorption, and separation of technetium-99
Gu, B. [Oak Ridge National Lab., TN (United States). Environmental Sciences Div.; Dowlen, K.E. [Oak Ridge Associated Universities, TN (United States)
This report summarizes studies on the interactions of technetium-99 (Tc) with different organic compounds and soil minerals under both oxidizing and reducing conditions. The report is divided into four parts and includes (1) effect of natural organic matter (NOM) on the complexation and solubility of Tc, (2) complexation between Tc and trichloroethylene (TCE) in aqueous solutions, (3) adsorption of Tc on soil samples from Paducah Gaseous Diffusion Plant (PGDP), and (4) adsorption and separation of Tc on activated carbon. Various experimental techniques were applied to characterize and identify Tc complexation with organic compounds and TCE, including liquid-liquid extraction, membrane filtration, size exclusion, and gel chromatography. Results indicate, within the experimental error, Tc (as pertechnetate, TcO{sub 4}) did not appear to form complexes with groundwater or natural organic matter under both atmospheric and reducing conditions. However, Tc can form complexes with certain organic compounds or specific functional groups such as salicylate. Tc did not appear to form complexes with TCE in aqueous solution.Both liquid-liquid extraction and high performance liquid chromatography (HPLC) gave no indication Tc was complexed with TCE. The correlations between Tc and TCE concentrations in monitoring wells at PGDP may be a coincidence because TCE was commonly used as a decontamination reagent. Once TCE and Tc entered the groundwater, they behaved similarly because both TcO{sub 4}{sup {minus}} and TCE are poorly adsorbed by soils. An effective remediation technique to remove TcO{sub 4}{sup {minus}} from PGDP contaminated groundwater is needed. One possibility is the use of an activated carbon adsorption technique developed in this study.
Reactivity of Primary Soil Minerals and Secondary Precipitates Beneath Leaking Hanford Waste Tanks
Nagy, Kathryn L.; Sturchio, Neil C.
This project, renewal of a previous EMSP project of the same title, is in its first year of funding at the University of Illinois at Chicago. The purpose is to continue investigating rates and mechanisms of reactions between primary sediment minerals found in the Hanford subsurface and leaked waste tank solutions. The goals are to understand processes that result in (1) changes in porosity and permeability of the sediment and resultant changes in flow paths of the contaminant plumes, (2) formation of secondary precipitates that can take up contaminants in their structures, and (3) release of mineral components that can drive redox reactions affecting dissolved contaminant mobility. A post-doctoral scientist, Dr. Sherry Samson, has been hired and two masters of science students are beginning to conduct experimental research. One research project that is underway is focused on measurement of the dissolution rates of plagioclase feldspar in high pH, high nitrate, high Al-bearing solutions characteristic of the BX tank farms. The first set of experiments is being conduced at room temperature. Subsequent experiments will examine the role of temperature because tank solutions in many cases were near boiling when leakage is thought to have occurred and temperature gradients have been observed beneath the SX and BX tank farms. The dissolution experiments are being conducted in stirred-flow kinetic reactors using powdered labradorite feldspar from Pueblo Park, New Mexico.
Effect of pH on carbon dioxide hydrate formation in mixed soil mineral suspensions.
Lamorena, Rheo B; Lee, Woojin
We investigated the effect of pH on CO2 hydrate formation in the presence of phyllosilicate mixtures. Different pH conditions of phyllosilicate suspensions (Na-montmorillonite-rich and phyllosilicate-rich suspensions) with and without NaCl (3.5%) were prepared and controlled by the addition of an acid or base before the dissolution of CO2. The formation of CO2 hydrates was observed in all phyllosilicate suspensions (30 bar and 273.45 K). The temperature-time plot results showed that hydrate formations were suppressed more in acidic mineral suspensions than in basic suspensions. The fastest hydrate induction time can be observed in Na-montmorillonite-rich and phyllosilicate-rich suspensions with and without NaCl at near neutral conditions (pH 6-8), followed by basic (approximately pH 12.0) and acidic (approximately pH 2.0) pHs. Hydrate induction time can be significantly affected by various chemical species forming under different suspension pHs. The distribution of chemical species in each mineral suspension was estimated by a chemical equilibrium model, PHREEOC, and used for the identification of hydrate formation characteristics in the suspension. Particle-particle and particle-water interactions may possibly contribute to the delay of hydrate formation. NaCl was not an efficient inhibitor but a possible promoter for hydrate formation when pH-dependent solid surfaces were present in the system. PMID:19731696
Mineralogical and Chemical Analysis of Fracture and Matrix Minerals in Selected Samples of the Culebra Dolomite
Bryan, C.R.; Siegel, M.D.; Krumhansl, J.L.
Contaminant release scenarios proposed for the Waste Isolation Pilot Plant (WIPP) repository suggest that the Culebra Dolomite member of the Rustler Formation could be an important radionuclide release path. This thin, vuggy, highly fractured unit is the most transmissive geologic unit overlying the WIPP. Many of the samples obtained from drill cores in the Culebra exhibit fractures that are lined with iron-oxyhydroxide-rich and clay-rich mineral coatings. The coatings are mineralogically distinct from the rock matrix, and may have sorptive characteristics that are different from a clay-poor dolomite matrix. Where locally abundant, such coatings could affect advective/diffusive exchange between matrix blocks and fractures and the accessible mineral surface area available for radionuclide adsorption. Clay minerals are present in the matrix and as fracture coatings in the samples from all the drill core locations examined in this study. Visual examination of rock sample surfaces in the H -19b7 core suggests that at least 7% of the total fracture surface area is coated with iron oxhydroxides or clays. In the samples from H-19b7, the amount of clay disseminated in the matrix varies from <1% to {approx}12 % by weight, and generally increases with stratigraphic height within the unit. In a suite of samples obtained from 12 other locations in the vicinity of the WIPP site, matrix samples from the Culebra contain 0.6--7% clay. These samples were taken from the more transmissive lower two-thirds of the unit (Culebra Units 2-4) which was considered to be the accessible portion of the unit in the WIPP Compliance Certification Application (CCA). Clay minerals also occur as clay-rich laminae and partings with the geometries of primary sedimentary structures and dissolution residues. Such partings are the loci of bedding plane fractures, and have the heaviest clay coatings found in the unit. Crosscutting fractures also commonly exhibit clay mineral coatings, but these are generally discontinuous and much thinner.
Influence of nitrogen on cellulose and lignin mineralization in blackwater and redwater forested wetland soils
J. A. Entry
Microcosms were used to determine the influence of N additions on active bacterial and active fungal biomass, cellulose degradation\\u000a and lignin degradation at 5, 10 and 15?weeks in soils from blackwater and redwater wetlands in the northern Florida panhandle.\\u000a Blackwater streams contain a high dissolved organic C concentration which imparts a dark color to the water and contain low\\u000a concentrations
Impact of two different types of grassland-to-cropland-conversion on dynamics of soil organic matter mineralization and N2O emission
NASA Astrophysics Data System (ADS)
Roth, G.; Flessa, H.; Helfrich, M.; Well, R.
Conversion of grassland to arable land often causes a decrease of soil organic matter stocks and it increases nitrate leaching and the emission of the greenhouse gases CO2 and N2O. Conversion methods which minimize the mechanical impact on the surface soil may reduce mineralization rates and greenhouse gas emissions. We determined the effect of two different types of grassland to maize conversion (a) plowing of the sward followed by seeding of maize and (b) chemical killing of the sward by glyphosate followed by direct seed of maize) on the mineralization of grassland derived organic matter, the release of nitrate and the emission of N2O. The field experiment was carried out at the research station Kleve which is located in North Rhine-Westphalia, Germany. A four times replicated plot experiment with the following treatments was set up in April 2010: (i) mechanical conversion of grassland to maize (ii) chemical conversion grassland to maize and (iii) continuous grassland as reference. Nitrogen fertilization was 137 kg N ha-1 for maize and 250 kg N ha-1 for grassland. Soil respiration and emission of N2O were measured weekly for one year using manual closed chambers and gas chromatography. Emission of CO2 from mineralization of grassland-derived organic matter was determined from the ?13C signature of soil respiration. Soil respiration was mainly fueled by mineralization of grassland-derived organic carbon. There was no effect of the type of grassland conversion on total mineralization of organic matter originating from grassland. Both grassland to maize conversion treatments exhibited very high soil nitrate concentrations one year after grassland conversion (about 250 kg NO3-N in 0 - 90 cm). Total N2O emission decreased in the order chemical conversion of grassland (25.5) > mechanical conversion of grassland (20.1) > permanent grassland (10.8). Emissions were highest after harvest of maize when soil moisture increased. The results show that both types of grassland-to-maize conversion resulted in a large surplus of soil nitrate which promotes nitrate leaching to the groundwater and indirect N2O emissions. In addition, it caused high direct N2O emissions. We found no evidence that grassland conversion without mechanical plowing is an option to reduce groundwater contamination and greenhouse gas emission to the atmosphere.
Oligotyping reveals stronger relationship of organic soil bacterial community structure with N-amendments and soil chemistry in comparison to that of mineral soil at Harvard Forest, MA, USA.
Turlapati, Swathi A; Minocha, Rakesh; Long, Stephanie; Ramsdell, Jordan; Minocha, Subhash C
The impact of chronic nitrogen amendments on bacterial communities was evaluated at Harvard Forest, Petersham, MA, USA. Thirty soil samples (3 treatments ū 2 soil horizons ū 5 subplots) were collected in 2009 from untreated (control), low nitrogen-amended (LN; 50 kg NH4NO3 ha(-1) yr(-1)) and high nitrogen-amended (HN; 150 kg NH4NO3 ha(-1) yr(-1)) plots. PCR-amplified partial 16S rRNA gene sequences made from soil DNA were subjected to pyrosequencing (Turlapati et al., 2013) and analyses using oligotyping. The parameters M (the minimum count of the most abundant unique sequence in an oligotype) and s (the minimum number of samples in which an oligotype is expected to be present) had to be optimized for forest soils because of high diversity and the presence of rare organisms. Comparative analyses of the pyrosequencing data by oligotyping and operational taxonomic unit clustering tools indicated that the former yields more refined units of taxonomy with sequence similarity of ?99.5%. Sequences affiliated with four new phyla and 73 genera were identified in the present study as compared to 27 genera reported earlier from the same data (Turlapati et al., 2013). Significant rearrangements in the bacterial community structure were observed with N-amendments revealing the presence of additional genera in N-amended plots with the absence of some that were present in the control plots. Permutational MANOVA analyses indicated significant variation associated with soil horizon and N treatment for a majority of the phyla. In most cases soil horizon partitioned more variation relative to treatment and treatment effects were more evident for the organic (Org) horizon. Mantel test results for Org soil showed significant positive correlations between bacterial communities and most soil parameters including NH4 and NO3. In mineral soil, correlations were seen only with pH, NH4, and NO3. Regardless of the pipeline used, a major hindrance for such a study remains to be the lack of reference databases for forest soils. PMID:25762982
Oligotyping reveals stronger relationship of organic soil bacterial community structure with N-amendments and soil chemistry in comparison to that of mineral soil at Harvard Forest, MA, USA
Turlapati, Swathi A.; Minocha, Rakesh; Long, Stephanie; Ramsdell, Jordan; Minocha, Subhash C.
The impact of chronic nitrogen amendments on bacterial communities was evaluated at Harvard Forest, Petersham, MA, USA. Thirty soil samples (3 treatments ū 2 soil horizons ū 5 subplots) were collected in 2009 from untreated (control), low nitrogen-amended (LN; 50 kg NH4NO3 ha-1 yr-1) and high nitrogen-amended (HN; 150 kg NH4NO3 ha-1 yr-1) plots. PCR-amplified partial 16S rRNA gene sequences made from soil DNA were subjected to pyrosequencing (Turlapati et al., 2013) and analyses using oligotyping. The parameters M (the minimum count of the most abundant unique sequence in an oligotype) and s (the minimum number of samples in which an oligotype is expected to be present) had to be optimized for forest soils because of high diversity and the presence of rare organisms. Comparative analyses of the pyrosequencing data by oligotyping and operational taxonomic unit clustering tools indicated that the former yields more refined units of taxonomy with sequence similarity of ?99.5%. Sequences affiliated with four new phyla and 73 genera were identified in the present study as compared to 27 genera reported earlier from the same data (Turlapati et al., 2013). Significant rearrangements in the bacterial community structure were observed with N-amendments revealing the presence of additional genera in N-amended plots with the absence of some that were present in the control plots. Permutational MANOVA analyses indicated significant variation associated with soil horizon and N treatment for a majority of the phyla. In most cases soil horizon partitioned more variation relative to treatment and treatment effects were more evident for the organic (Org) horizon. Mantel test results for Org soil showed significant positive correlations between bacterial communities and most soil parameters including NH4 and NO3. In mineral soil, correlations were seen only with pH, NH4, and NO3. Regardless of the pipeline used, a major hindrance for such a study remains to be the lack of reference databases for forest soils. PMID:25762982
High gradient magnetic separation of iron oxide minerals from soil claysĀ
Schulze, Darrell Gene
steel wool, placed in a strong magnetic field (1. 6 Tesla), provides the magnetic field and magnetic field gradients necessary to trap weakly magnetic, clay size particles flowing through the filter as a dilute suspension in pH 10. 5 Na C03 solution.... Of the total dithionite-citrate-bicarbonate extractable Fe 0 in 2 3 the 2-0. 2 um size fraction of six soils, 70 to 94X was recovered in the magnetic fraction which consisted of 1. 6 to 27. 7X Fe 0 by weight. For the &0. 2 pm size fraction, 11 to 40X...
The Impact of Afforestation on the Carbon Stocks of Mineral Soils Across the Republic of Ireland.
NASA Astrophysics Data System (ADS)
Wellock, M.; Laperle, C.; Kiely, G.; Reidy, B.; Duffy, C.; Tobin, B.
At the beginning of the twentieth century forests accounted for only 1% of the total Irish land cover (Pilcher & Mac an tSaoir, 1995). However, due to the efforts of successive governments there has been rapid afforestation since the 1960s resulting in a 10.0% forest land cover as of 2007 (The Department of Agriculture, Fisheries, and Food, 2007). A large proportion of this afforestation took place after the mid-1980s and was fueled by government grant incentive schemes targeted at private landowners (Renou & Farrell 2005). Consequently, 54% of forests are less than 20 years old (Byrne, 2006). This specific land use change provides an opportunity for Ireland to meet international obligations set forth by the United Nations Framework Convention on Climate Change (UNFCCC, 1992). These obligations include the limitation of greenhouse gas emissions to 13% above 1990 levels. In order to promote accountability for these commitments, the UNFCCC treaty and the Kyoto Protocol (Kyoto Protocol, 1997) mandate signatories to publish greenhouse gas (GHG) emissions inventories for both greenhouse gas sources and removals by sinks. Article 3.3 of the Kyoto Protocol allows changes in C stocks due to afforestation, reforestation, and deforestation since 1990 to be used to offset inventory emissions. Therefore, due to the rapid rate of afforestation and its increased carbon sequestration since 1990, Ireland has the potential to significantly offset GHG emissions. There is little known as to the impacts of afforestation on the carbon stocks in soils over time, and even less known about the impact on Irish soils. The FORESTC project aims to analyse this impact by undertaking a nationwide study using a method similar to that of the paired plot method in Davis and Condron, 2002. The study will examine 42 forest sites across Ireland selected randomly from the National Forest Inventory (National Forest Inventory, 2007). These 42 sites will be grouped based on the forest type which includes conifer, broadleaf, and mixed (broadleaf and conifer) and soil type: brown earth, podzol, brown podzolic, gley and brown earth. The paired plot method involves selecting a second site that represents the same soil type and physical characteristics as the forest site. The only difference between the two sites should be the current land-use of the pair site, which should represent the pre-afforestation land-use of the forest site. Each forest site and its pair site will be sampled in the top 30 cm of soil for bulk density and organic carbon %, while litter and F/H layer samples will be taken and analysed for carbon. This data should provide an analysis of the carbon stocks of the soil and litter of both the forest site and its pair site allowing for comparison and thus the impact of afforestation on carbon stocks. References. Byrne, K.A., & Milne, R. (2006). Carbon stocks and sequestration in plantation forests in the Republic of Ireland. Forestry, 79, no. 4: 361. Davis, M.R., & Condron, L.M. (2002). Impact of grassland afforestation on soil carbon in New Zealand: a review of paired-site studies. Australian Journal of Soil Research, 40, no. 4: 675-690. Kyoto Protocol. 1997 Kyoto Protocol to the United Nations Framework Convention on Climate Change. FCCC/CP/1997/7/Add.1, Decision 1/CP.3, Annex 7. UN. National Forest Inventory: NFI Methodology. (2007). Forest Service, The Department of Agriculture, Fisheries, and Food, Wexford, Ireland. Pilcher, J.R. & Mac an tSaoir, S. (1995). Wood, Trees and Forests in Ireland. (Royal Irish Academy, Dublin. Renou, F. & Farrell, E.P. (2005). Reclaiming peatlands for forestry: the Irish experience. In: Stanturf, J.A. and Madsen, P.A. (eds.). Restoration of boreal and temperate forests. CRC Press, Boca Raton. p.541-557. UNFCCC. 1992 United Nations Framework Convention on Climate Change. Palais des Nations, Geneva. http://www.unfccc.de/index.html
Effects of Mineral Phosphorous Fertilization and cd Loading on cd Translocation from Soil to Corn (Zea mays L.)
NASA Astrophysics Data System (ADS)
Lßszl¾, Mßrton, ,, Dr.
During the last fifty years phenomenal progress has been made in several areas of ecology of different toxic elements in soils. Concerns regarding heavy metals contamination in the environment affecting all ecosystem componets, including "soil-plant-animal-human" chain (SPAHC), have been identified with increasing efforts on limiting their bioavailability. Many sites have been identified as hazardous (H) waste (W) sites (S)(HWS) because of the presence of elevated concentrations of these elements. In 2000, the main cadmium actual transfer index ("ATI" by Mßrton 2004) maximum and minimum values in the case of maize 4-6 foliaged phenophase ranged between +22.0- -89.2%. compared with control soils. The grain "ATI" maximum and minimum values changed between +14.4- -89.2% as opposed to unterated plants. The highest yields reached around 10 t* ha-1. These study shows maize has ability to a different degree to cadmium bioaccumulation from soil to corn and by these way for "FOOD CHAIN". Key words: Phosphorous, Fertilization, Cadmium, Translocation, Corn Introduction Nowadays, sustainable (S) precision (P) agricultural (A) production (P)(SPAP) has become the major issue following global changes in all the world over. It is well known that it has strongly established on soils. The functioning and their ability to supply nutrients, store water, release gases, modify pollutants, decrease physical degradation and produce crops is profundly influenced by their fertiliy. During the last fifty years phenomenal progress has been made in several areas of ecology of different toxic elements in soils (ATSDR 1997, 1999; ANZECC 1992; CWP 1995; COC 2004; DEFRA 2002; EDF 1998; HSC 2005; IARC 1993; ). Concerns regarding heavy metals contamination in the environment affecting all ecosystem componets, including "soil-plant-animal-human" chain (SPAHC), have been identified with increasing efforts on limiting their bioavailability (Magher 1991; NEPC 1998; NDH 1986; NTP 1991). Many sites have been identified as hazardous (H) waste (W) sites (S)(HWS) because of the presence of elevated concentrations of these elements. They will remain a threat to the environment until they are removed or immobilized. We can test and improve these situation by using different plant species, as corn (Zea mays L.) x macro nutrients as phosphorous experimental methods. Maize has a very great biomass (B) production (P) potential (P)(BPP) and important role in soil fertility by the design of plant rotation to field plant production, the animal foraging as a fodder-crop with a high carbohydrate (70%) and protein (10%) content (70%) and via pytoremediation possibilities. Cd is considered to be a nonessential element for maize, it is effectively absorbed by both the root and leaf system. By these ways a great proportion of the cadmium is to be accumulated in root tissues, even when Cd enters the plant via foliar system from the polluted air and precipitation. The most chief geobiochemical property of cadmium ions is their strong affinity for sulfhydryl groups of several compounds (OSHA 1992; Richardson 1992; RAIS 1991; Sittig 1991; TAP 1999; WA 1996; WHO 1992, 2001). Furthermore Cd shows an affinity for other side chains of protein and for phosphate groups too. The Cd content of maize is of the highest concern as a Cd reservoir and as the patway of cadmium to soil-plant-animal-man chain (FOOD CHAIN). Thus, tolerance and adaptation of corn to higher Cd levels, although important from the environmental poin of view, create a helth risc. Material and Method The phosphorus (P2O5) mineral fertilization and cadmium loading effects were studied in a long-term field experiment set up at Experimental Station of the Research Institute for Soil Science and Agricultural Chemistry of the Hungarian Academy of Sciences on a calcareous chernozem soil at Nagyh÷rcs÷k in 1977. The soil had the following agrogeochemical characteristics: pH (KCl) 7.3, humus 3.0%, ammonlactate (AL) soluble-P2O5 60-80 mg*kg-1, AL-K2O 180-200 mg*kg-1 in the plowed
Crenarchaeota affiliated with group 1.1b are prevalent in coastal mineral soils of the Ross Sea region of Antarctica.
Ayton, J; Aislabie, J; Barker, G M; Saul, D; Turner, S
The objective of this study was to examine the presence and diversity of Archaea within mineral and ornithogenic soils from 12 locations across the Ross Sea region. Archaea were not abundant but DNA sufficient for producing 16S rRNA gene clone libraries was extracted from 18 of 51 soil samples, from four locations. A total of 1452 clones were analysed by restriction fragment length polymorphism and assigned to 43 operational taxonomic units from which representatives were sequenced. Archaea were primarily restricted to coastal mineral soils which showed a predominance of Crenarchaeota belonging to group 1.1b (> 99% of clones). These clones were assigned to six clusters (A through F), based on shared identity to sequences in the GenBank database. Ordination indicated that soil chemistry and water content determined archaeal community structure. This is the first comprehensive study of the archaeal community in Antarctic soils and as such provides a reference point for further investigation of microbial function in this environment. PMID:20002141
Fire, temperature and nutrient responses on the C balance of arctic tundra soils from surface, mineral horizons and permafrost
NASA Astrophysics Data System (ADS)
De Baets, S. L.; Lewis, R.; van de Weg, M. J.; Quine, T. A.; Shaver, G. R.; Hartley, I. P.
Models predict substantial release of carbon (C) from thawing permafrost as the climate warms. Therefore, determining how the decomposition of the organic matter stored in near surface permafrost is controlled represents a key research priority. Important questions remain regarding how readily decomposable the organic matter may be, as well as the extent to which microbial activity is limited by the low temperatures, the rate of new labile C inputs, and/or nitrogen (N) availability. Accurate model predictions require that these questions are addressed.Disturbances, including fire, which is becoming increasingly common in the tundra biome, may promote rates of permafrost thaw. In 2007, the Anaktuvuk River fire burned over 1,000 km2 of tundra on the North Slope of the Brooks Range, Alaska, USA, doubling the cumulative area burned in this region over the past 50 years. This fire enhanced active layer thickness by removing insulating plant biomass and exposing surfaces with low albedo. In this study we investigated how temperature, N and labile C additions affected rates of CO2 production over a one-year incubation of samples collected from different depths (topsoil, mineral horizons and near-surface permafrost) in burnt and unburnt sites within the Anaktuvik river catchment. The results show that respiration rates did not decline substantially during the 1-year incubation, indicating there were relatively large amounts of readily decomposable C present. However, decomposition rates per gram of C did decline with depth, especially in the burnt sites where some of the surface soil may have been lost. This indicates that the C present in the near surface permafrost may be less labile than C nearer the soil surface. In addition, respiration rates in the deeper horizons were more temperature sensitive, potentially reflecting the lower lability of the C present. Against expectations, N addition inhibited respiration in the deeper layers, especially at low temperatures. Labile C additions promoted the decomposition of soil organic matter in the deep soil samples, but not in the surface samples, with the positive priming effect being lost following N addition. This study indicates that there is the potential for considerable loss of C following the thaw of near-surface permafrost in Alaskan tussock tundra, although the C present may be slightly less readily decomposable than C stored nearer the surface. The decomposition of near-surface permafrost C was shown to be highly temperature sensitive and thus accurately simulating the soil thermal regime post-thaw is likely to be important in predicting rates of C release. In addition, root colonisation of previously frozen horizons may stimulate decomposition if labile C inputs increase. On the other hand, the inhibition of activity by N addition suggests that the positive feedback associated with reduced microbial N limitation in a warming Arctic may not be ubiquitous.
The impact of biotic/abiotic interfaces in mineral nutrient cycling: A study of soils of the Santa Cruz chronosequence, California
NASA Astrophysics Data System (ADS)
White, Art F.; Schulz, Marjorie S.; Vivit, Davison V.; Bullen, Tomas D.; Fitzpatrick, John
Biotic/abiotic interactions between soil mineral nutrients and annual grassland vegetation are characterized for five soils in a marine terrace chronosequence near Santa Cruz, California. A Mediterranean climate, with wet winters and dry summers, controls the annual cycle of plant growth and litter decomposition, resulting in net above-ground productivities of 280-600 g m-2 yr-1. The biotic/abiotic (A/B) interface separates seasonally reversible nutrient gradients, reflecting biological cycling in the shallower soils, from downward chemical weathering gradients in the deeper soils. The A/B interface is pedologically defined by argillic clay horizons centered at soil depths of about one meter which intensify with soil age. Below these horizons, elevated solute Na/Ca, Mg/Ca and Sr/Ca ratios reflect plagioclase and smectite weathering along pore water flow paths. Above the A/B interface, lower cation ratios denote temporal variability due to seasonal plant nutrient uptake and litter leaching. Potassium and Ca exhibit no seasonal variability beneath the A/B interface, indicating closed nutrient cycling within the root zone, whereas Mg variability below the A/B interface denotes downward leakage resulting from higher inputs of marine aerosols and lower plant nutrient requirements. The fraction of a mineral nutrient annually cycled through the plants, compared to that lost from pore water discharge, is defined their respective fluxes Fj,plants = qj,plants/(qj,plants + qj,discharge) with average values for K and Ca (FK,plants = 0.99; FCa,plants = 0.93) much higher than for Mg and Na (FMg,plants 0.64; FNa,plants = 0.28). The discrimination against Rb and Sr by plants is described by fractionation factors (KSr/Ca = 0.86; KRb/K = 0.83) which are used in Rayleigh fractionation-mixing calculations to fit seasonal patterns in solute K and Ca cycling. KRb/K and K24Mg/22Mg values (derived from isotope data in the literature) fall within fractionation envelopes bounded by inputs from rainfall and mineral weathering. KSr/Ca and K44Ca/40Ca fractionation factors fall outside these envelopes indicating that Ca nutrient cycling is closed to these external inputs. Small net positive K and Ca fluxes (6-14 mol m-2 yr-1), based on annual mass balances, indicate that the soils are accumulating mineral nutrients, probably as a result of long-term environmental disequilibrium.
Effect of cadmium on fungi and on interactions between fungi and bacteria in soil: influence of clay minerals and pH.
Babich, H; Stotzky, G
Fungi (Rhizopus stolonifer, Trichoderma viride, Fusarium oxysporum f. sp. conglutinans, Cunninghamella echinulata, and several species of Aspergillus and Penicillium) tolerated higher concentrations of cadmium (Cd) when grown in soil than when grown on laboratory media, indicating that soil mitigated the toxic effects of Cd. In soil amended with clay minerals, montmorillonite provided partial or total protection against fungistatic effects of Cd, whereas additions of kaolinite provided little or no protection. Growth rates of Aspergillus niger were inhibited to a greater extent by 100 or 250 mug of Cd per g in soil adjusted to pH 7.2 than in the same soil at its natural pH of 5.1. However, there were no differences in the growth rates of Aspergillus fischeri with 100 or 250 mug of Cd per g in the same soil, whether at pH 5.1 or adjusted to pH 7.2. Growth of A. niger and A. fischeri in a soil contaminated with a low concentration of Cd (i.e., 28 mug/g), obtained from a site near a Japanese smelter, did not differ significantly from growth in a soil collected some distance away and containing 4 mug of Cd per g. Growth of A. niger in sterile soil amended with 100 mug of Cd per g and inoculated with Bacillus cereus or Agrobacterium tumefaciens was reduced to a greater extent than in the same soil containing 100 mug of Cd per g but no bacteria. The inhibitory effects of Agrobacterium radiobacter to A. niger were slightly reduced in the presence of 100 mug of Cd per g, whereas the inhibitory effects of Serratia marcescens were enhanced. PMID:18085
Arthrobacter nanjingensis sp. nov., a mineral-weathering bacterium isolated from forest soil.
Huang, Zhi; Bao, Yuan Yuan; Yuan, Tong Tong; Wang, Guo Xiang; He, Lin Yan; Sheng, Xia Fang
A Gram-stain-positive, non-motile, rod- or coccoid-shaped actinobacterium, designated strain A33(T), was isolated from a forest soil sample from Nanjing, Jiangsu Province, PR China. The strain grew optimally at 30 ░C, pH 7.0 and with 3 % NaCl (w/v). Phylogenetic analysis of the strain, based on 16S rRNA gene sequences, showed that it was most closely related to Arthrobacter woluwensis (98.4 % sequence similarity), Arthrobacter humicola (97.5 %), Arthrobacter globiformis (97.4 %), Arthrobacter oryzae (97.3 %) and Arthrobacter cupressi (97.0 %). The major cellular fatty acids were anteiso-C15 : 0, anteiso-C17 : 0 and iso-C15 : 0; MK-9(H2) was the predominant respiratory quinone. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and three glycolipids. Cell-wall analysis revealed that the peptidoglycan type was A3?, based on l-lysine-l-alanine; the cell-wall sugars were galactose and mannose. The genomic G+C content of strain A33(T) was 66.8 mol%. The low DNA-DNA relatedness values between strain A33(T) and recognized species of the genus Arthrobacter and many phenotypic properties supported the classification of strain A33(T) as a representative of a novel species of the genus Arthrobacter, for which the name Arthrobacter nanjingensis sp. nov. is proposed. The type strain is A33(T) (?= CCTCC AB 2014069(T)?= DSM 28237(T)). PMID:25358511
Bioaccessible arsenic in soils of former sugar cane plantations, Island of Hawaii.
Cutler, William G; Brewer, Roger C; El-Kadi, Aly; Hue, Nguyen V; Niemeyer, Patrick G; Peard, John; Ray, Chittaranjan
Arsenical herbicides were used extensively for emergent weed control in Hawaiian sugar cane cultivation from 1913 to about 1950. As a result, surface soil arsenic concentrations average 280 mg kg(-1) across more than 60 km(2) of former sugar plantation land in the eastern portion of the Island of Hawaii. This study was conducted to elucidate the relationship between soil properties and arsenic bioaccessibility in the iron-rich volcanic soils. Soils are predominantly Andisols, formed by weathering of basaltic lava and tephra, with pedogenic solid phases consisting of short-range order iron oxyhydroxides, allophane-like aluminosilicates, and metal-humus compounds. These reactive solid phases strongly adsorb oxyanions, such as phosphate and arsenite/arsenate. High arsenic sorption capacity limits desorption and vertical migration within the soil column and prevents contamination of the underlying groundwater aquifer, despite high arsenic loading and precipitation rates. In vitro arsenic bioaccessibility, as measured by the SBRC gastric-phase test, ranges from 2% to 35% and averages 9% of total arsenic. Bioaccessible arsenic is higher in less weathered soils (Udifolists, Typic and Lithic Hydrudands) and lower in more weathered ash-dominant soils (Acrudoxic Hydrudands). Soil weathering indicators, such as reactive iron content, are strong predictors of arsenic bioaccessibility. Based on evidence from soil mineralogy, geochemistry and arsenic speciation, as well as limited soil arsenic bioavailability/bioaccessibility comparisons, risks to human health from direct contact (soil ingestion) are significantly reduced by low arsenic bioaccessibility. Nonetheless, some soils within former sugar cane cultivation areas contain bioaccessible arsenic concentrations exceeding Hawaii Department of Health risk-based action levels, and will require mitigating actions. Even higher levels of soil arsenic contamination have been identified at former pesticide storage and mixing areas, but are generally of localized extent. PMID:23178778
Mineral ecophysiological evidence for biogeochemical cycles in 2461-2495 million year old banded iron formations (BIF).
Li, Y [Argonne National Laboratory (ANL); Konhauser, Dr, Kurt [University of Alberta; Cole, David [Ohio State University; Mildner, David [ORNL; Phelps, Tommy Joe [ORNL
The phosphorus composition of banded-iron formations (BIFs) has been used as a proxy for Precambrian seawater composition and the paleoeredox state of Earth's surface environment. However, it is unclear whether the phosphorus in BIFs originally entered the sediment as a sorbed component of the iron oxyhydroxide particles, or whether it was incorporated into the biomass of marine phytoplankton. We conducted high-resolution mineral analyses and report here the first detection of an Fe(III) acetate salt, as well as nanocrystals of apatite in association with magnetite, in the 2.48 Ga Dales Gorge Member of the Brockman Iron Formation (a BIF), Hamersley, Western Australia. The clusters of apatite are similar in size and morphology to biogenic apatite crystals resulting from biomass decay in Phanerozoic marine sediments, while the formation of an Fe(III) acetate salt and magnetite not only implies the original presence of biomass in the BIF sediments, but also that organic carbon likely served as an electron donor during bacterial Fe(III) reduction. This study is important because it suggests that phytoplankton may have played a key role in the transfer of phosphorus (and other trace elements) from the photic zone to the seafloor.
Effect of species composition on carbon and nitrogen stocks in forest floor and mineral soil in Norway spruce and European beech mixed forests
NASA Astrophysics Data System (ADS)
Andivia, Enrique; Rolo, VĒctor; Jonard, Mathieu; Formßnek, Pavel; Ponette, Quentin
Management of existing forests has been identified as the main strategy to enhance carbon sequestration and to mitigate the impact of climate change on forest ecosystems. In this direction, the conversion of Norway spruce monospecific stands into mixed stands by intermingling individuals of European beech is an ongoing trend in adaptive forest management strategies, especially in Central Europe. However, studies assessing the effect of changes in tree species composition on soil organic carbon (SOC) and nitrogen stocks are still scarce and there is a lack of scientific evidence supporting tree species selection as a feasible management option to mitigate the effects of predicted future climatic scenarios. We compared C and N stocks in the forest floor (litter and humus) and the top 10 cm of mineral soil in two monospecific stands of Norway spruce and European beech and in a mixed stand of both species. The effect of tree species composition on the C and N stocks and its spatial distribution was evaluated based on litterfall, root production, elevation and canopy opening, and by using a combination of modelling and geostatistical techniques. C stock was highest in the Norway spruce and the mixed stands, while N stock was highest in the mixed stand and lowest under European beech, with intermediate values in the Norway spruce stand. Each forest type showed differences in forest floor properties, suggesting that species composition is an important factor governing forest floor characteristics, including C and N stocks. The distribution of C and N stocks between forest soil layers was different for each forest type. C and N stocks were highest in the hummus layer under Norway spruce, whereas both stocks were lowest in the European beech stand. On the other hand, the mixed stand showed the highest C and N accumulation in the uppermost mineral soil layer, while the monospecific stands showed similar values. Litterfall was the main contribution to C and N stocks of the humus layer in monospecific stands. Forest floor stocks were also influenced by microelevation and canopy opening in the European beech stand and by microelevation in the Norway spruce stand. Root turnover and Norway spruce litterfall proportion directly increased C stocks in the mineral soil of the mixed stand. Additionally, N stock in the forest floor of the mixed stand was positively correlated with the Norway spruce litterfall proportion. Spatial analyses further confirmed that species composition was the main source of spatial variability of SOC stock in mixed stands. These results suggest that the admixture of individuals of European beech and Norway spruce may lead to a translocation of SOC from the forest floor to the better protected mineral soil layer, which might be beneficial for long term SOC sequestration.
Effect of basic slag addition on soil properties, growth and leaf mineral composition of beans in a Cu-contaminated soil
Paris-Sud XI, Universitķ de
in a Cu-contaminated soil NEGIM O.1 , ELOIFI B.1 , MENCH M.2 , BES C.2 , GASTE H.2 , MOTELICA-HEINO M.3 in contaminated soils. The BS effects on soil pH, soil conductivity, growth and chemical composition of beans were Contamination 19, 2 (2010) 174 - 187" #12;2 the Cu-contaminated soil promoted bean growth with the lowest foliar
Effects of CO[sub 2], temperature, and seedlings on soil organic matter contents, and C and N mineralization, in forest soils
D. A. Perry; M. L. Gillham; P. Homann; R. Griffiths
Soils from 500-year-old old-growth Douglas-fir forests in the Oregon Cascade Mtns. (900 m and 1200 m sites) were [open quote]incubated[close quote] for 32 weeks in controlled-environment chambers. This factorial experiment had two levels each of atmospheric CO[sub 2] (350-700 ppm), soil temperature (13\\/17[degrees]C), soil N (1200 m soils contained twice as much C and N than soils from 900 m),
Influence of residue and nitrogen fertilizer additions on carbon mineralization in soils with different texture and cropping histories.
Chen, Xianni; Wang, Xudong; Liebman, Matt; Cavigelli, Michel; Wander, Michelle
To improve our ability to predict SOC mineralization response to residue and N additions in soils with different inherent and dynamic organic matter properties, a 330-day incubation was conducted using samples from two long-term experiments (clay loam Mollisols in Iowa [IAsoil] and silt loam Ultisols in Maryland [MDsoil]) comparing conventional grain systems (Conv) amended with inorganic fertilizers with 3 yr (Med) and longer (Long), more diverse cropping systems amended with manure. A double exponential model was used to estimate the size (Ca, Cs) and decay rates (ka, ks) of active and slow C pools which we compared with total particulate organic matter (POM) and occluded-POM (OPOM). The high-SOC IAsoil containing highly active smectite clays maintained smaller labile pools and higher decay rates than the low-SOC MDsoil containing semi-active kaolinitic clays. Net SOC loss was greater (2.6 g kg(-1); 8.6%) from the IAsoil than the MDsoil (0.9 g kg(-1), 6.3%); fractions and coefficients suggest losses were principally from IAsoil's resistant pool. Cropping history did not alter SOC pool size or decay rates in IAsoil where rotation-based differences in OPOM-C were small. In MDsoil, use of diversified rotations and manure increased ka by 32% and ks by 46% compared to Conv; differences mirrored in POM- and OPOM-C contents. Residue addition prompted greater increases in Ca (340% vs 230%) and Cs (38% vs 21%) and decreases in ka (58% vs 9%) in IAsoil than MDsoil. Reduced losses of SOC from residue-amended MDsoil were associated with increased OPOM-C. Nitrogen addition dampened CO2-C release. Clay type and C saturation dominated the IAsoil's response to external inputs and made labile and stable fractions more vulnerable to decay. Trends in OPOM suggest aggregate protection influences C turnover in the low active MDsoil. Clay charge and OPOM-C contents were better predictors of soil C dynamics than clay or POM-C contents. PMID:25078458
Influence of Residue and Nitrogen Fertilizer Additions on Carbon Mineralization in Soils with Different Texture and Cropping Histories
Chen, Xianni; Wang, Xudong; Liebman, Matt; Cavigelli, Michel; Wander, Michelle
To improve our ability to predict SOC mineralization response to residue and N additions in soils with different inherent and dynamic organic matter properties, a 330-day incubation was conducted using samples from two long-term experiments (clay loam Mollisols in Iowa [IAsoil] and silt loam Ultisols in Maryland [MDsoil]) comparing conventional grain systems (Conv) amended with inorganic fertilizers with 3 yr (Med) and longer (Long), more diverse cropping systems amended with manure. A double exponential model was used to estimate the size (Ca, Cs) and decay rates (ka, ks) of active and slow C pools which we compared with total particulate organic matter (POM) and occluded-POM (OPOM). The high-SOC IAsoil containing highly active smectite clays maintained smaller labile pools and higher decay rates than the low-SOC MDsoil containing semi-active kaolinitic clays. Net SOC loss was greater (2.6 g kg?1; 8.6%) from the IAsoil than the MDsoil (0.9 g kg?1, 6.3%); fractions and coefficients suggest losses were principally from IAsoilÆs resistant pool. Cropping history did not alter SOC pool size or decay rates in IAsoil where rotation-based differences in OPOM-C were small. In MDsoil, use of diversified rotations and manure increased ka by 32% and ks by 46% compared to Conv; differences mirrored in POM- and OPOM-C contents. Residue addition prompted greater increases in Ca (340% vs 230%) and Cs (38% vs 21%) and decreases in ka (58% vs 9%) in IAsoil than MDsoil. Reduced losses of SOC from residue-amended MDsoil were associated with increased OPOM-C. Nitrogen addition dampened CO2-C release. Clay type and C saturation dominated the IAsoilÆs response to external inputs and made labile and stable fractions more vulnerable to decay. Trends in OPOM suggest aggregate protection influences C turnover in the low active MDsoil. Clay charge and OPOM-C contents were better predictors of soil C dynamics than clay or POM-C contents. PMID:25078458
Mineralization and plant uptake of 14C-labeled nonylphenol, nonylphenol tetraethoxylate, and nonylphenol nonylethoxylate in biosolids/soil systems planted with crested wheatgrass.
Dettenmaier, Erik; Doucette, William J
Microcosm experiments (duration, 150 d) were conducted to evaluate the mineralization and plant uptake of [14C]nonylphenol (NP), [14C]nonylphenol tetraethoxylate (NPE4), and [14C]nonylphenol nonylethoxylate (NPE9) in a soil/biosolids (99.5:0.5 w/w) environment planted with crested wheatgrass (Agropyron cristatum). Three initial nominal concentrations (6, 24, and 47 mg/kg dry wt) each of NP, NPE4, and NPE9 were examined along with unplanted and unplanted poisoned controls. Phenol (22 mg/kg) also was evaluated as a more degradable reference compound. The biosolids were obtained from a municipal treatment plant, and the loamy sand soil was freshly collected. Mineralization ranged from 7% for NP to 53% for phenol, and no enhancement was observed in the planted systems. For NP, NPE4, and NPE9, 14C foliar tissues concentrations were proportional to exposure concentrations but were 10-fold lower than the root concentrations and two- to threefold lower than the soil concentrations. Bioconcentration factors (BCFs) based on 14C measurements ranged from 0.31 (mg compound/kg dry plant/ mg compound/kg dry soil) for systems spiked with NP to 0.52 for systems spiked with NPE9. Results of the NP analysis (initial concentration, 47 mg/ kg) showed a 90% decrease in the soil concentration and an average BCF of 1.0. The lower BCF calculated from the 14C analysis likely resulted from the presence of NP transformation products in the soil that are less available or are translocated by the plants but quantified by the combustion/liquid scintillation counting procedure. PMID:17713204
Accumulation of polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs (OPAHs) in organic and mineral soil horizons from four U.S. remote forests.
Obrist, Daniel; Zielinska, Barbara; Perlinger, Judith A
We characterized distributions of 23 polycyclic aromatic hydrocarbons (?23PAH) and nine oxygenated PAHs (?9OPAH) in four remote forests. We observed highest ?23PAH and ?9OPAH concentrations in a coniferous forest in Florida, particularly in organic layers which we attributed to frequent prescribed burning. Across sites, ?23PAH and ?9OPAH concentrations strongly increased from surface to humidified organic layers (+1626%) where concentrations reached up to 584ngg(-1). Concentrations in mineral soils were lower (average 37▒8ngg(-1)); but when standardized per unit organic carbon (OC), PAH/OC and OPAH/OC ratios were at or above levels observed in organic layers. Accumulation in litter and soils (i.e., enrichment factors with depth) negatively correlated with octanol-water partition coefficients (Kow) and therefore was linked to water solubility of compounds. Concentrations of ?9OPAHs ranged from 6▒6ngg(-1) to 39▒25ngg(-1) in organic layers, and from 3▒1ngg(-1) to 11▒3ngg(-1) in mineral soils, and were significantly and positively correlated to ?23PAHs concentrations (r(2) of 0.90) across sites and horizons. While OPAH concentrations generally decreased from organic layers to mineral soil horizons, OPAH/OC ratios increased more strongly with depth compared to PAHs, in particular for anthrone, anthraquinone, fluorenone, and acenaphthenequinone. The strong vertical accumulation of OPAH relative to OC was exponentially and negatively correlated to C/N ratios (r(2)=0.67), a measure that often is used for tissue age. In fact, C/N ratios alone explained two-thirds of the variability in OPAH/OC ratios suggesting particularly high retention, sorption, and persistency of OPAHs in old, decomposed carbon fractions. PMID:25929871
Effects of Plant Leachates from Four Boreal Understorey Species on Soil N Mineralization, and White Spruce (Picea glauca) Germination and Seedling Growth
CASTELLS, EVA; PEčUELAS, JOSEP; VALENTINE, DAVID W.
Ģ Background and Aims Natural regeneration of white spruce (Picea glauca) after disturbance has been reported to be very poor. Here a study was made to determine whether C compounds released from understorey species growing together with white spruce could be involved in this regeneration failure, either by (1) changing soil nutrient dynamics, (2) inhibiting germination, and/or (3) delaying seedling growth. Ģ Methods Foliage leachates were obtained from two shrubs (Ledum palustre and Empetrum hermaphroditum) and one bryophyte (Sphagnum sp.) with high phenolic compound concentrations that have been reported to depress growth of conifers in boreal forests, and, as a comparison, one bryophyte (Hylocomium splendens) with negligible phenolic compounds. Mineral soil from a white spruce forest was amended with plant leachates to examine the effect of each species on net N mineralization. Additionally, white spruce seeds and seedlings were watered with plant leachates to determine their effects on germination and growth. Ģ Key Results Leachates from the shrubs L. palustre and E. hermaphroditum contained high phenolic compound concentrations and dissolved organic carbon (DOC), while no detectable levels of C compounds were released from the bryophytes Sphagnum sp. or H. splendens. A decrease in net N mineralization was determined in soils amended with L. palustre or E. hermaphroditum leachates, and this effect was inversely proportional to the phenolic concentrations, DOC and leachate C/N ratio. The total percentage of white spruce germination and the growth of white spruce seedlings were similar among treatments. Ģ Conclusions These results suggest that the shrubs L. palustre and E. hermaphroditum could negatively affect the performance of white spruce due to a decrease in soil N availability, but not by direct effects on plant physiology. PMID:15802310
Bogs are a specialized wetland community with saturated, acidic, peat soils that have low concentra-tions of minerals (e.g., calcium, magnesium) and essential nutrients (phosphorus, nitrogen). They
US Army Corps of Engineers
, acidic, peat soils that have low concentra- tions of minerals (e.g., calcium, magnesium) and essential of living Sphagnum mosses growing over a layer of saturated, acidic peat. Sedges, forbs and/or the low), pitcher plant (Sarracenia purpurea) and sundew (Drosera rotundifolia). SOILS: Fibric peat (Histosols
Changes in plant functional groups, litter quality, and soil carbon and nitrogen mineralization with sheep grazing in an Inner Mongolian Grassland
Barger, N.N.; Ojima, D.S.; Belnap, J.; Shiping, W.; Yanfen, W.; Chen, Z.
This study reports on changes in plant functional group composition, litter quality, and soil C and N mineralization dynamics from a 9-year sheep grazing study in Inner Mongolia. Addressed are these questions: 1) How does increasing grazing intensity affect plant community composition? 2) How does increasing grazing intensity alter soil C and N mineralization dynamics? 3) Do changes in soil C and N mineralization dynamics relate to changes in plant community composition via inputs of the quality or quantity of litter? Grazing plots were set up near the Inner Mongolia Grassland Ecosystem Research Station (IMGERS) with 5 grazing intensities: 1.3, 2.7, 4.0, 5.3, and 6.7 sheep ha -1??yr-1. Plant cover was lower with increasing grazing intensity, which was primarily due to a dramatic decline in grasses, Carex duriuscula, and Artemisia frigida. Changes in litter mass and percentage organic C resulted in lower total C in the litter layer at 4.0 and 5.3 sheep ha-1??yr-1 compared with 2.7 sheep ha -1??yr-1. Total litter N was lower at 5.3 sheep ha-1??yr-1 compared with 2.7 sheep ha -1??yr-1. Litter C:N ratios, an index of litter quality, were significantly lower at 4.0 sheep ha-1??yr -1 relative to 1.3 and 5.3 sheep ha-1??yr -1. Cumulative C mineralized after 16 days decreased with increasing grazing intensity. In contrast, net N mineralization (NH4+ + NO3-) after a 12-day incubation increased with increasing grazing intensity. Changes in C and N mineralization resulted in a narrowing of CO2-C:net Nminratios with increasing grazing intensity. Grazing explained 31% of the variability in the ratio of CO 2-C:net Nmin. The ratio of CO2-C:net N min was positively correlated with litter mass. Furthermore, there was a positive correlation between litter mass and A. frigida cover. Results suggest that as grazing intensity increases, microbes become more C limited resulting in decreased microbial growth and demand for N.
Warming-enhanced preferential microbial mineralization of humified boreal forest soil organic matter: Interpretation of soil profiles along a climate transect using laboratory incubations
Li, Jianwei; Ziegler, Susan; Lane, Chad S.; Billings, Sharon A.
Humified soil organic matter storage in boreal forests is large, and its responses to warming over relatively long timescales is critical for predicting soil feedbacks to climate change. To derive information relevant across decades to centuries...
Mineralization of melamine and cyanuric acid as sole nitrogen source by newly isolated Arthrobacter spp. using a soil-charcoal perfusion method.
Hatakeyama, Takashi; Takagi, Kazuhiro; Yamazaki, Kenichi; Sakakibara, Futa; Ito, Koji; Takasu, Eiichi; Naokawa, Takuji; Fujii, Kunihiko
Melamine belongs to the s-triazine family, and industrially used as raw product in many ways all over the world. Melamine has been reported for human harmful effects and detected from some crops, soil and water. To remove melamine from the polluted environment, the efficient melamine-mineralizing microorganisms have been needed. We newly isolated three melamine-degrading bacteria from the same upland soil sample using soil-charcoal perfusion method. These bacteria were classified as Arthrobacter sp. MCO, Arthrobacter sp. CSP and Microbacterium sp. ZEL by 16S rRNA genes sequencing analysis. Both Arthrobacter species completely degraded melamine within 2 days, and consumed melamine as a sole nitrogen source. Both strains also grew in cyanuric acid as sole nitrogen source, and released small quantities of ammonium ions. These strains are the first identified bacteria that can mineralize both melamine and cyanuric acid as sole initial nitrogen source in Arthrobacter sp. Although ammeline and ammelide intermediates were detected, these strains possess none of the known genes encoding melamine degrading enzymes. Since the Arthrobacter strains also degraded melamine in a high pH liquid medium, they present as potential bioremediation agents in melamine-polluted environments. PMID:25752233
Residual effect of pre-emergence herbicides on microbial activities in relation to mineralization of C, N and P in the Gangetic alluvial soil of West Bengal, India.
Barman, Saurav; Das, Amal Chandra
An experiment has been conducted under laboratory conditions to investigate the residual effect of three pre-emergence herbicides (thiobencarb, pendimethalin and pretilachlor) at fivefold field application rates (7.5, 10.0 and 2.5Ākg a.i.?ha(-1), respectively), on the changes of microbial activities and some biochemical processes in the Gangetic alluvial soil of West Bengal. Application of herbicides in general significantly increased microbial biomass resulting in greater mineralization of C, N and P in soil. The highest stimulation of microbial biomass C was recorded with thiobencarb (24.4Ā%) followed by pendimethalin (23.4Ā%). Microbial biomass N was highly induced under pretilachlor (54.5Ā%) and thiobencarb (52.7Ā%), while the stimulation of microbial biomass P was at par in the herbicide-treated soils. Compared to untreated control, the highest amount of organic C was retained with thiobencarb followed by pendimethalin. A similar trend was recorded with thiobencarb for total N, while pendimethalin induced exchangeable NH4 (+) and soluble NO3 (-) to the highest extent (42.2 and 34.5Ā%, respectively). Regarding the availability of P in soil, pretilachlor manifested greater stimulation (33.1Ā%) than thiobencarb (21.6Ā%) and pendimethalin (11.4Ā%). As compared to untreated control, thiobencarb harboured maximum number of bacteria (107.9Ā%), while pretilachlor exerted the highest stimulations towards the proliferations of actinomycetes (132.6Ā%) and fungi (149.5Ā%) in soil. PMID:26113205
Effect of Ground Rubber vs. ZnSO4 on Spinach Accumulation of Cd from Cd-Mineralized California Soil
Technology Transfer Automated Retrieval System (TEKTRAN)
Certain soils derived from marine shale in Salinas Valley, CA, USA, contain significant levels of natural Cd but normal levels of Zn, all derived from the soil parent materials. Crops grown on these soils contain high levels of Cd, and because of the high Cd:Zn, this Cd is highly bioavailable and a...
Mineral cycling in soil and litter arthropod food chains. Three-year progress report, November 1, 1980-January 31, 1984
Crossley, D.A. Jr.
This report summarizes our analysis of trophic dynamics in soil fauna including their impact on the decomposition process, investigation of relationships between soil fauna and microflora, development and testing of models describing these processes, and documentation of rates of movement of nutrients along soil arthropod food chains.
Mid-infrared soil spectral changes due to cultivation, C mineralization, and short-term substrate utilization
Technology Transfer Automated Retrieval System (TEKTRAN)
Mid infrared diffuse reflectance spectroscopy is a valuable technique for the study of the C quantity and quality of soils. We analyzed soils from two sites (Hoytville, OH, and Akron, CO), under different managements (native, vs. different levels of cultivation). Each soil was also analyzed before a...
Chemical composition of dissolved organic matter in agroecosystems: Correlations with soil enzyme activity and carbon and nitrogen mineralization
Lei Tian; Emily Dell; Wei Shi
Soil enzyme-catalyzed depolymerization of organic matter results in the production of low molecular weight and dissolved organic compounds. This fraction of soil organic matter is the immediate energy, carbon and other nutrient substrates for microbial catabolic pathways and thus likely plays an important role in soil processes. The purpose of this study was to elucidate interrelationships among dissolved organic matter,
Soil organic matter accumulation and its implications for nitrogen mineralization and plant species composition during succession in coastal dune slacks
F. Berendse; E. J. Lammerts; H. Olff
Vegetation and soil development during succession in coastal dune slacks on Terschelling island, the Netherlands, was investigated, by comparing neighbouring ecosystems on similar substrates that had been developing for 1, 5, 35 and 76 years since the vegetation and organic soil layer had been removed. In this successional sequence, soil organic matter accumulated rapidly due to the production of litter
Epigeal fauna of a degraded soil treated with mineral fertilizer and compound cellulose cultivated of tree species
NASA Astrophysics Data System (ADS)
Gißcomo, R. G.; de Arruda, O. G.; Souto Filho, S. N.; Alves, M. C.; Pereira, M. G.; Frigķrio, G. C.
The aim of this study was to investigate the behavior of the epigeal fauna in a degraded soil in the recovery process after one year of cultivated with tree species. The experiment was established in February 2010 in Mato Grosso do Sul, Brazil. The experimental design was randomized blocks in split plots with five treatments and four replications. In the main plots, pure cultivation of Eucalyptus urograndis (exotic species - hybrids) and Mabea fistulifera Mart. (native species) and the subplot treatments: Control; D0 - without fertilization; DM - mineral fertilizer according to crop need; DC - with compost manure according to crop need (10 t ha-1); D15 - 15 t ha-1 and D20 - 20 t ha-1 of the compound. In February of the years 2010 and 2011 were installed in the central region of each treatment two traps "pitt fall" which remained for seven days in the field. We calculated Shannon diversity and Pielou evenness indices, and richness of wildlife activity groups. The results were analyzed by ANOVA and Scott Knott test at 5% significance level. In 2010, the area with M. fistulifera, was captured a total of 2697 organisms distributed mainly in: Hymenoptera with 45.83% of the total collected, Collembola (36.93%), Hemiptera Heteroptera (6.56%). In the area with E. urograndis, 1938 organisms were captured, being 50.67% of the order Hymenoptera, Collembola 26.83%, 7.59% Hemiptera Heteroptera. It was found that there was no significant difference between treatments and between species for all variables. Collected in 2011 were 4970 organisms in 56.22% of the order Hymenoptera, Collembola 18.49% and 7.12% beetle in the area of M. fistulifera. In the area of E. urograndis were 4200 organisms, 55.29% (Hymenoptera), 23.79% (Collembola) and 5.86% (Coleoptera). It appears that the activity values and richness of the fauna groups were significantly higher in treatments with organic fertilization in both cultive. It is concluded that after one year there was a variation of the dominant groups and an increase in the activity and the orders number epigeal fauna in the treatments with application of organic compost.
NSDL National Science Digital Library
Humans use soil for their daily needs but do not sufficiently take account of its slow formation and fast loss. Discover the amazing geology of soil formation and the basic rock and soil types.Although soil seems the end product from weathering rocks, it is merely a stage in the gigantic cycle of mineral recycling by the movement of tectonic plates.
NSDL National Science Digital Library
Scott Bauer (USDA-ARS; )
Soil is an example of a non-living thing. Soil contains nutrients and living organisms, but the soil itself is not alive. Soil is important in plant growth because soil gives plants a place to anchor their roots and it also provides the plant with essential nutrients.
Magnetic properties of alluvial soils polluted with heavy metals
NASA Astrophysics Data System (ADS)
Dlouha, S.; Petrovsky, E.; Boruvka, L.; Kapicka, A.; Grison, H.
Magnetic properties of soils, reflecting mineralogy, concentration and grain-size distribution of Fe-oxides, proved to be useful tool in assessing the soil properties in terms of various environmental conditions. Measurement of soil magnetic properties presents a convenient method to investigate the natural environmental changes in soils as well as the anthropogenic pollution of soils with several risk elements. The effect of fluvial pollution with Cd, Cu, Pb and Zn on magnetic soil properties was studied on highly contaminated alluvial soils from the mining/smelting district (P?Ēbram; CZ) using a combination of magnetic and geochemical methods. The basic soil characteristics, the content of heavy metals, oxalate, and dithionite extractable iron were determined in selected soil samples. Soil profiles were sampled using HUMAX soil corer and the magnetic susceptibility was measured in situ, further detailed magnetic analyses of selected distinct layers were carried out. Two types of variations of magnetic properties in soil profiles were observed corresponding to indentified soil types (Fluvisols, and Gleyic Fluvisols). Significantly higher values of topsoil magnetic susceptibility compared to underlying soil are accompanied with high concentration of heavy metals. Sequential extraction analysis proved the binding of Pb, Zn and Cd in Fe and Mn oxides. Concentration and size-dependent parameters (anhysteretic and isothermal magnetization) were measured on bulk samples in terms of assessing the origin of magnetic components. The results enabled to distinguish clearly topsoil layers enhanced with heavy metals from subsoil samples. The dominance of particles with pseudo-single domain behavior in topsoil and paramagnetic/antiferromagnetic contribution in subsoil were observed. These measurements were verified with room temperature hysteresis measurement carried out on bulk samples and magnetic extracts. Thermomagnetic analysis of magnetic susceptibility measured on magnetic extracts indicated the presence of magnetite/maghemite in the uppermost layers, and strong mineralogical transformation of iron oxyhydroxides during heating. Magnetic techniques give valuable information about the soil Fe oxides, which are useful for investigation of the environmental effects in soil. Key words: magnetic methods, Fe oxides, pollution, alluvial soils.
Combining Organic and Mineral Fertilizers for Integrated Soil Fertility Management in Smallholder Farming Systems of Kenya: Explorations Using the Crop-Soil Model FIELD
P. A. Tittonell; M. Corbeels; Wijk van M. T; B. Vanlauwe; K. E. Giller
Integrated soil fertility management (ISFM) technologies for African smallholders should consider (i) within-farm soil heterogeneity; (ii) long-term dynamics and variability; (iii) manure quality and availability; (iv) access to fertilizers; and (v) competing uses for crop residues. We used the model FIELD (Field-scale resource Interactions, use Efficiencies and Long term soil fertility Development) to explore allocation strategies of manure and fertilizers.
Technology Transfer Automated Retrieval System (TEKTRAN)
Soil is a diverse natural material characterized by solid, liquid, and gas phases that impart unique chemical, physical, and biological properties. Soil provides many key functions, including supporting plant growth and providing environmental remediation. Monitoring key soil properties and processe...
Sequential extractions for the study of radiocesium and radiostrontium dynamics in mineral and organic soils from Western Europe and Chernobyl areas
Rigol, A.; Roig, M.; Vidal, M.; Rauret, G. [Univ. de Barcelona (Spain). Dept. Quimica Analitica] [Univ. de Barcelona (Spain). Dept. Quimica Analitica
To study radiostrontium (RSr) and radiocesium (RCs) aging in soils, three sequential extraction schemes were used on Mediterranean loamy and loam-sandy soils, podsols and peaty podsols from the area near Chernobyl, and peats from Western Europe. Aging was quantified by changes in radionuclide distribution. Two factors were thought to affect radionuclide distribution: time elapsed since contamination and drying-wetting cycles. Changes in radionuclide distribution were of low significance in Mediterranean loamy and loam-sandy soils in the short term, even after drying-wetting cycles. In the short term, podsols and peaty podsols showed a decrease in the RSr exchangeable fraction in the laboratory samples, whereas samples taken 6 years after contamination did not show any further decrease. For RCs in podsols and peaty-podsols, the application of drying-wetting cycles for 9 months led to observe a 2--3-fold decrease in the exchangeable fraction, whereas time alone did not lead to any change. No RCs aging was observed in peats with a low or almost negligible content of mineral matter, low base saturation and low interception potential for RCs, even after drying-wetting cycles. Finally, changes in the radionuclide exchangeable fraction over time in these soils corresponded to changes in transfer factors over a similar period.
Decoupling of soil C and N mineralization by labile C inputs explain high C sequestration rates in response to N fertilization
NASA Astrophysics Data System (ADS)
Bengtson, Per; Ehtesham, Emad
During the last decade there have been an ongoing controversy regarding the extent to which N fertilization can increase C sequestration in forest ecosystems by stimulating primary production. There is also evidence that N fertilization commonly results in reduced soil respiration rates that cannot be fully explained by lower root respiration. Several hypotheses aimed at explaining the phenomenon have been proposed, but the mechanism remains elusive. The aim of this study was to examine if decreased decomposition and respiration of soil organic matter (SOM) in response to N fertilization can be explained by diminishing priming effects, and to determine to which extent priming of SOM decomposition is manifested as C or N mineralization under different loadings of labile C and N. We also aimed at determining if any changes that occur in response to N fertilization are long-term effects dependent on a shift in e.g. microbial community composition, or an immediate effect caused by increased N availability and decreased N mining. To achieve these aims we designed an experiment where the potential priming of microbial C and N mineralization was studied in a Norway spruce forest. SOM derived respiration, gross N mineralization and 13C-incorporation into microbial biomarker lipids (PLFA's) were measured 4 and 24 hours after addition of 13C-enriched glucose. Field treatments included control, N fertilization, and two levels of tree density. We also included a treatment where the control soil received inorganic N, at the same level as in the field N fertilization treatment, in addition to glucose. Glucose additions in most cases caused a significant reduction in microbial respiration of SOM, resulting in what is commonly referred to as "negative priming". In contrast, gross N mineralization rates generally increased in response to the glucose additions. Glucose additions, therefore, appeared to result in a decoupling of microbial respiration of SOM and gross N mineralization, possibly because of preferential glucose use by the microbial community. The decoupling was most pronounced in the N-fertilized plot with high tree density, where an up to 30 percent decrease in microbial respiration of SOM coincided with a more than 7-fold increase in gross N mineralization. A PLSR-analysis of 13C incorporation into microbial biomarker lipids (PLFA's) suggest that fungi was mediating this response, since the proportion of glucose derived 13C that was recovered in the fungal biomarker PLFA 18:2?6,9 was negatively correlated to respiration of SOM and C priming, and positively to gross N mineralization and N priming. The results suggest that labile C inputs can contribute to C sequestration above as well as below ground, since microbial immobilization of the labile C may result in decreased microbial respiration of SOM that coincides with a strong increase in the production of plant available N. Tree density and N fertilization appear to be important mediators of the response, which could potentially explain the strong effect of N fertilization on net ecosystem exchange that have previously been reported.
Reconstruction of the long-term fire history of an old-growth deciduous forest in Southern Quķbec, Canada, from charred wood in mineral soils
NASA Astrophysics Data System (ADS)
Talon, Brigitte; Payette, Serge; Filion, Louise; Delwaide, Ann
Charcoal particles are widespread in terrestrial and lake environments of the northern temperate and boreal biomes where they are used to reconstruct past fire events and regimes. In this study, we used botanically identified and radiocarbon-dated charcoal macrofossils in mineral soils as a paleoecological tool to reconstruct past fire activity at the stand scale. Charcoal macrofossils buried in podzolic soils by tree uprooting were analyzed to reconstruct the long-term fire history of an old-growth deciduous forest in southern Quķbec. Charcoal fragments were sampled from the uppermost mineral soil horizons and identified based on anatomical characters. Spruce ( Picea spp.) fragments dominated the charcoal assemblage, along with relatively abundant wood fragments of sugar maple ( Acer saccharum) and birch ( Betula spp.), and rare fragments of pine ( Pinus cf. strobus) and white cedar ( Thuja canadensis). AMS radiocarbon dates from 16 charcoal fragments indicated that forest fires were widespread during the early Holocene, whereas no fires were recorded from the mid-Holocene to present. The paucity of charcoal data during this period, however, does not preclude that a fire event of lower severity may have occurred. At least eight forest fires occurred at the study site between 10,400 and 6300 cal yr B.P., with a dominance of burned conifer trees between 10,400 and 9000 cal yr B.P. and burned conifer and deciduous trees between 9000 and 6300 cal yr B.P. Based on the charcoal record, the climate at the study site was relatively dry during the early Holocene, and more humid from 6300 cal yr B.P. to present. However, it is also possible that the predominance of conifer trees in the charcoal record between 10,400 and 6300 cal yr B.P. created propitious conditions for fire spreading. The charcoal record supports inferences based on pollen influx data (Labelle, C., Richard, P.J.H. 1981. Vķgķtation tardiglaciaire et postglaciaire au sud-est du Parc des Laurentides, Quķbec. Gķographie Physique et Quaternaire 35, 345-359) of the early arrival of spruce and sugar maple in the study area shortly after deglaciation. We conclude that macroscopic charcoal analysis of mineral soils subjected to disturbance by tree uprooting may be a useful paleoecological tool to reconstruct long-term forest fire history at the stand scale.
Usefulness of NIR spectroscopy for the estimation of the mineral composition and texture of soils and heavy metal uptake
J. M. Soriano-Disla; I. G¾mez; M. M. Jordßn; C. Guerrero; J. Navarro-Pedre±o; S. Meseguer; T. Sanfeliu
The accumulation of heavy metals in soils from different sources (atmospheric deposition, agricultural practices, urban-industrial activities, etc.) is of a great environmental concern. In this sense, there is a consensus in the literature that the total heavy metals in soil are not a suitable tool for risk assessment regarding heavy metal mobility and bioavailability. Several approaches have been proposed to
Sorption of N2 and EGME vapors on some soils, clays, and mineral oxides and determination of sample surface areas by use of sorption data
Chiou, C.T.; Rutherford, D.W.; Manes, M.
Vapor sorption isotherms of ethylene glycol monoethyl ether (EGME) at room temperature and isotherms of N2 gas at liquid nitrogen temperature were determined for various soils and minerals. The N2 monolayer capacities [Qm (N2)] were calculated from the BET equation and used to determine the surface areas. To examine whether EGME is an appropriate adsorbate for determination of surface areas, the apparent EGME monolayer capacities [Qm (EGME)ap] were also obtained by use of the BET equation. For sand, aluminum oxide, kaolinite, hematite, and synthetic hydrous iron oxide, which are relatively free of organic impurity and expanding/solvating minerals, the Qm (EGME)ap values are in good conformity with the corresponding Qm (N2) values and would give surface areas consistent with BET (N2) values. For other samples (Woodburn soil, a natural hydrous iron oxide, illite, and montmorillonite), the Qm (EGME)ap values overestimate the Qm (N2) values from a moderate to a large extent, depending on the sample. A high-organic-content peat shows a very small BET (N2) surface area; the EGME/ peat isotherm is linear and does not yield a calculation of the surface area. Large discrepancies between results of the two methods for some samples are attributed to the high solubility of polar EGME in soil organic matter and/ or to the cation solvation of EGME with solvating clays. The agreement for other samples is illustrative of the consistency of the BET method when different adsorbates are used, so long as they do not exhibit bulk penetration and/or cation solvation. ?? 1993 American Chemical Society.
NSDL National Science Digital Library
Pamela Gore
The purpose of the handout is to identify the three major types of soils: pedalfer, pedocal, and laterite, and to understand the soil profile. This is accomplished with brief descriptions of the soil horizons and the designation of common elements to pedalfers, pedocals, and laterite soils. The handout is concluded with a discussion of soil erosion. Links are provided to the online Physical Geology resources at Georgia Perimeter College.
Transformations of mercury, iron, and sulfur during the reductive dissolution of iron oxyhydroxide by sulfide
Aaron J. Slowey; Gordon E. Brown
Methylmercury can accumulate in fish to concentrations unhealthy for humans and other predatory mammals. Most sources of mercury (Hg) emit inorganic species to the environment. Therefore, ecological harm occurs when inorganic Hg is converted to methylmercury. Sulfate- and iron-reducing bacteria (SRB and FeRB) methylate Hg, but the effects of processes involving oxidized and reduced forms of sulfur and iron on
Mechanisms for aqueous photolysis of adsorbed benzoate, oxalate, and succinate on iron oxyhydroxide (goethite) surfaces
Cunningham, K.M.
Photolysis of carboxylate anions adsorbed onto highly crystalline goethite (??-FeOOH) with 300-400-nm light produces Fe2+(aq) and ??OH from surface and solution redox reactions. The production of Fe2+(aq) and ??OH was studied in N2-purged and aerated aqueous suspensions, respectively, of goethite containing equimolar (10-3 M) concentrations of oxalate and benzoate (ob + g), succinate and benzoate (sb + g), benzoate alone (b + g), and goethite alone (g). The hydroxyl radical was measured by fluorescence analysis of salicylate formed in a reaction between benzoate and ??OH. Fe2+(aq) was determined colorimetrically. A proposed reaction mechanism includes the photoexcitation of Fe(III) surface complexes with OH-, HCO3-, and RCOO- ligands to form Fe2+(aq) and corresponding ligand radicals. Additional ??OH is made by the O2 oxidation of Fe2+(aq) (Haber-Weiss mechanism). Comparison of Fe2+(aq) and ??OH yields permitted an estimate of the relative importance of pathways leading to ??OH.
Bioremediation of a mineral soil with high contents of clay and organic matter contaminated with herbicide 2,4-dichlorophenoxyacetic acid using slurry bioreactors: Effect of electron acceptor and supplementation with an organic carbon source
Ireri Robles-Gonzßlez; Elvira RĒos-Leal; Ronald Ferrera-Cerrato; Fernando Esparza-GarcĒa; NoemĒ Rinderkenecht-Seijas; Hķctor M. Poggi-Varaldo
Ad situ remediation techniques appear as an interesting alternative for the treatment of polluted solid matrices that are not amenable to in situ remediation, such as soils characterized by high contents of clay and organic matter coupled to low hydraulic conductivity and permeability. In this work, the removal of 2,4-dichlorophenoxyacetic acid (2,4-D) from an agricultural mineral soil with high contents
Effect of soil-plant-animal mineral interactions in the genesis of puerperal haemoglobinuria in dairy animals
Paris-Sud XI, Universitķ de
extracts were analysed for simultaneous determination of minerals on inductably coupled argon plasma atomic) decline in P (52 %), Ca, Cu (64 %) and Mg associated with significant increase in Mo, Zn, Fe, Na and K but high in Mo, S, Al, Cd, Fe, Pb, Cr, Ni and As contents with a wider Ca : P which resulted in development
Increase in pH stimulates mineralization of ænativeÆ organic carbon and nitrogen in naturally salt-affected sandy soils
Xiao-gang Li; Zed Rengel; Emmanuel Mapfumo; Bhupinderpal-Singh
Large amounts of terrestrial organic C and N reserves lie in salt-affected environments, and their dynamics are not well understood.\\u000a This study was conducted to investigate how the contents and dynamics of ænativeÆ organic C and N in sandy soils under different\\u000a plant species found in a salt-affected ecosystem were related to salinity and pH. Increasing soil pH was associated
Evidence for adaptation of riverine sediment microbial communities to diuron mineralization: incidence of runoff and soil erosion
Stķphane Pesce; Fabrice Martin-Laurent; Nadine Rouard; AgnĶs Robin; Bernard Montuelle
PurposeĀĀSurface runoff and erosion are major drivers of pesticide transport from soils to rivers draining vineyard watersheds. A recent\\u000a study showed that applications of diuron on vineyards and diuron dispersal could lead to microbial adaptation to diuron biodegradation\\u000a from treated soils to the receiving hydrosystem. Given the limited knowledge on microbial adaptation to pesticide degradation\\u000a in aquatic environments, we conducted
Herbivore influence on soil microbial biomass and nitrogen mineralization in a northern grassland ecosystem: Yellowstone National Park
Benjamin F. Tracy; Douglas A. Frank
Microorganisms are largely responsible for soil nutrient cycling and energy flow in terrestrial ecosystems. Although soil\\u000a microorganisms are affected by topography and grazing, little is known about how these two variables may interact to influence\\u000a microbial processes. Even less is known about how these variables influence microorganisms in systems that contain large populations\\u000a of free-roaming ungulates. In this study, we
Nitrogen mineralization as influenced by climate, soil and vegetation in a subtropical humid forest in northeast India
Kusum Maithani; A. Arunachalam; R. S. Tripathi; H. N. Pandey
Nitrogen mineralization was studied in 7-, 13- and 16-year old regrowing forest stands by determining ammonium-N, nitrate-N, ammonification and nitrification rates during different seasons for two annual cycles. Mean concentrations of ammonium and nitrate-N were highest in the 16-year old stand, and lowest in the 7-year old stand. Inorganic-N (ammonium+nitrate) was highest during winter and lowest during rainy season in
Mineral oil content in sediments and soils: comparability, traceability and a certified reference material for quality assurance
Roland Becker; Hans-Gerhard Buge; Wolfram Bremser; Irene Nehls
The performance of twelve laboratories with previously established proficiency in the determination of the mineral oil content\\u000a in a fresh water sediment is described. The summation parameter total petrol hydrocarbon (TPH) is defined according to ISO\\u000a 16703:2004 with regard to the sample preparation to be applied, the flame ionisation detection (FID) and the boiling range\\u000a of C10¢C40 to be integrated.
Effects of Va mycorrhizae on growth and mineral uptake of sorghum grown at varied levels of soil acidity
P. S. Raju; R. B. Clark; J. R. Ellis; J. W. Maranville
The effects of the vesicular?arbuscular mycorrhizal (VAM) fungus Glomus deserticola (Trappe, Bloss, and Menge) on growth and mineral element uptake of sorghum [Sorghum bicolor (L.) Moench] were investigated in greenhouse experiments with acid Cecil sandy clay loam (clayey, kaolinitic, thermic, Typic Hapludults) at five pH values (4.1 to 5.8). Control experiments consisted of sterile VAM inocula. Dry matter yields and
Protocol comparison for quantifying in situ mineralization
Technology Transfer Automated Retrieval System (TEKTRAN)
In situ mineralization methods are intended to quantify mineralization under realistic environmental conditions. This study was conducted to compare soil moisture and temperature in intake soil cores contained in cylinders to that in adjacent bulk soil, compare the effect of two resin bag techniques...
Accumulation and Crop Uptake of Soil Mineral Nitrogen as Influenced by Tillage, Cover Crops, and Nitrogen Fertilization
Upendra M. Sainju; Bharat P. Singh; Wayne F. Whitehead; Shirley Wang
Management practices may influence soil N levels due to crop up- take and leaching. We evaluated the effects of three tillage practices (no-till (NT), strip till (ST), and chisel till (CT)), four cover crops (hairy vetch (Vicia villosa Roth), rye (Secale cereale L.), vetch 1 rye biculture, and winter weeds or no cover crop), and three N fertilization rates (0,
Spatial and temporal fluctuations in bacteria, microfauna and mineral nitrogen in response to a nutrient impulse in soil
V. V. Zelenev
Fluctuations of bacterial populations can be observed when frequent and sufficiently long series of samples are obtained for direct microscopic or plate counts of bacteria. Fluctuations in bacterial numbers are especially noticeable after some disturbance of soil such as substrate addition. However, very seldom were bacterial fluctuations subjected to proper statistical analysis to detect significant periodical components in the data.
Persistence and leaching potential of microorganisms and mineral N in animal manure applied to intact soil columns.
Amin, M G Mostofa; Forslund, Anita; Bui, Xuan Thanh; Juhler, Renķ K; Petersen, S°ren O; Lµgdsmand, Mette
Pathogens may reach agricultural soils through application of animal manure and thereby pose a risk of contaminating crops as well as surface and groundwater. Treatment and handling of manure for improved nutrient and odor management may also influence the amount and fate of manure-borne pathogens in the soil. A study was conducted to investigate the leaching potentials of a phage (Salmonella enterica serovar Typhimurium bacteriophage 28B) and two bacteria, Escherichia coli and Enterococcus species, in a liquid fraction of raw pig slurry obtained by solid-liquid separation of this slurry and in this liquid fraction after ozonation, when applied to intact soil columns by subsurface injection. We also compared leaching potentials of surface-applied and subsurface-injected raw slurry. The columns were exposed to irrigation events (3.5-h period at 10 mm h(-1)) after 1, 2, 3, and 4 weeks of incubation with collection of leachate. By the end of incubation, the distribution and survival of microorganisms in the soil of each treatment and in nonirrigated columns with injected raw slurry or liquid fraction were determined. E. coli in the leachates was quantified by both plate counts and quantitative PCR (qPCR) to assess the proportions of culturable and nonculturable (viable and nonviable) cells. Solid-liquid separation of slurry increased the redistribution in soil of contaminants in the liquid fraction compared to raw slurry, and the percent recovery of E. coli and Enterococcus species was higher for the liquid fraction than for raw slurry after the four leaching events. The liquid fraction also resulted in more leaching of all contaminants except Enterococcus species than did raw slurry. Ozonation reduced E. coli leaching only. Injection enhanced the leaching potential of the microorganisms investigated compared to surface application, probably because of a better survival with subsurface injection and a shorter leaching path. PMID:23124240
Effect of measurement network densities and stratification on the uncertainty of implied emission factors for national N2O budgets from agricultural mineral soils
NASA Astrophysics Data System (ADS)
Dechow, Rene; Gebbert, Soeren
Among other GHG sources that are reported under the United Nations Framework Convention on Climate Change (UNFCCC) national budgets of nitrous oxide emissions from agricultural soils are often characterized by the highest estimation uncertainties within the sectors "agriculture" and "land use and land use change". The majority of recent national emission inventories in Europe are based on Tier 1 approaches. Nitrous oxide emissions from mineral soils are highly influenced by anthropogenic and environmental conditions like soil properties and climate. Specification of those controlling factors on a national to regional scale can highly influence the spatial emission pattern and might cause systematic errors when using Tier 1 emission factors. Regionally stratified emission factors reflecting conditions that determine the N2O flux rates from agricultural soils could significantly improve the accuracy of national nitrous oxide emission inventories (Tier 2). If these stratified emission factors are based on measurement networks the density and stratification of measurement networks with respect to spatial variability of soil properties and climate is an important driver of emission factor uncertainty. In the last two decades, intensive effort has been spend on the experimentally determination of nitrous oxide emissions at plot scale and related drivers resulting in numerous published data sets that were collected and analyzed within meta-studies and European and international projects. We give an overview on recently available data on direct nitrous oxide emissions on agricultural land in Europe. Mixed linear models are trained on these data sets. These models estimate N2O emissions in response to management, meteorological data and soil properties. Based on the developed mixed linear models the effect of N2O measurement network density and stratification on bias and uncertainty of national implied emission factors from agricultural soils are quantified by Monte Carlo analyses for 4 European countries. Model results show that croplands and grasslands differ with respect to the effect of environmental conditions and management on N2O emissions, which requires specific measurement network designs for these agro-ecosystems. With regard to croplands the signal of nitrous oxide fluxes on nitrogen fertilization is strongly driven by environmental conditions. Measurement networks to improve N2O emission factors of croplands should focus on representing the spatial variability of key drivers like seasonal temperature, precipitation and soil texture. In terms of N2O emissions from croplands requirements on measurement network densities necessary to derive implied emission factors within an uncertainty of ▒ 20% are in most cases not met by recently available data on national level. Nitrous oxide emissions of grasslands show a relative consistent nonlinear response on nitrogen fertilization. Besides representing environmental conditions, measurement networks to derive regional emission factors for grassland soils should focus on covering the range of possible nitrogen fertilization rates, which are often higher than on croplands, especially in regions with high livestock densities.
Alaska Geochemical Database, Version 2.0 (AGDB2)--including ōbest valueö data compilations for rock, sediment, soil, mineral, and concentrate sample media
Granitto, Matthew; Schmidt, Jeanine; Shew, Nora B.; Gamble, Bruce M.; Labay, Keith A.
The Alaska Geochemical Database Version 2.0 (AGDB2) contains new geochemical data compilations in which each geologic material sample has one ōbest valueö determination for each analyzed species, greatly improving speed and efficiency of use. Like the Alaska Geochemical Database (AGDB, http://pubs.usgs.gov/ds/637/) before it, the AGDB2 was created and designed to compile and integrate geochemical data from Alaska in order to facilitate geologic mapping, petrologic studies, mineral resource assessments, definition of geochemical baseline values and statistics, environmental impact assessments, and studies in medical geology. This relational database, created from the Alaska Geochemical Database (AGDB) that was released in 2011, serves as a data archive in support of present and future Alaskan geologic and geochemical projects, and contains data tables in several different formats describing historical and new quantitative and qualitative geochemical analyses. The analytical results were determined by 85 laboratory and field analytical methods on 264,095 rock, sediment, soil, mineral and heavy-mineral concentrate samples. Most samples were collected by U.S. Geological Survey personnel and analyzed in U.S. Geological Survey laboratories or, under contracts, in commercial analytical laboratories. These data represent analyses of samples collected as part of various U.S. Geological Survey programs and projects from 1962 through 2009. In addition, mineralogical data from 18,138 nonmagnetic heavy-mineral concentrate samples are included in this database. The AGDB2 includes historical geochemical data originally archived in the U.S. Geological Survey Rock Analysis Storage System (RASS) database, used from the mid-1960s through the late 1980s and the U.S. Geological Survey PLUTO database used from the mid-1970s through the mid-1990s. All of these data are currently maintained in the National Geochemical Database (NGDB). Retrievals from the NGDB were used to generate most of the AGDB data set. These data were checked for accuracy regarding sample location, sample media type, and analytical methods used. This arduous process of reviewing, verifying and, where necessary, editing all U.S. Geological Survey geochemical data resulted in a significantly improved Alaska geochemical dataset. USGS data that were not previously in the NGDB because the data predate the earliest U.S. Geological Survey geochemical databases, or were once excluded for programmatic reasons, are included here in the AGDB2 and will be added to the NGDB. The AGDB2 data provided here are the most accurate and complete to date, and should be useful for a wide variety of geochemical studies. The AGDB2 data provided in the linked database may be updated or changed periodically.
Assessment of heavy-metal contamination of floodplain soils due to mining and mineral processing in the Harz Mountains, Germany
H.-E. Gõbler; J. Schneider
2ĀĀ study area was assessed with respect to its heavy-metal load on the basis of the current guideline values. The heavy-metal\\u000a loads of the soils in the study area have ranges of ?1 for Cd, ?1 for Pb, 7¢10,000?mg kg?1 for Cu and 50¢55,000?mg kg?1 for Zn. Mobility of the heavy metals was determined by extraction at different pH values.
Sagebrush carbon allocation patterns and grasshopper nutrition: the influence of CO 2 enrichment and soil mineral limitation
Robert H. Johnson; David E. Lincoln
Artemisia tridentata seedlings were grown under carbon dioxide concentrations of 350 and 650 Ąl l-1 and two levels of soil nutrition. In the high nutrient treatment, increasing CO2 led to a doubling of shoot mass, whereas nutrient limitation completely constrained the response to elevated CO2. Root biomass was unaffected by any treatment. Plant root\\/shoot ratios declined under carbon dioxide enrichment
Mineralization of Monomeric Components of Biodegradable Plastics in Preconditioned and Enriched Sandy Loam Soil Under Laboratory Conditions
Michela Siotto; Maurizio Tosin; Francesco Degli Innocenti; Valeria Mezzanotte
In the last 20Āyears, a new generation of materials was developed: the biodegradable plastics. They reduce the accumulation\\u000a of plastic in the environment and the cost of waste management because they can be fed in composting plants or, if used in\\u000a agriculture (mulch films), they are applied to the soil and left there. Ten monomers were chosen among the most
Weathering of primary minerals and mobility of major elements in soils affected by an accidental spill of pyrite tailing.
MartĒn, Francisco; Diez, MarĒa; GarcĒa, Inķs; Sim¾n, Mariano; Dorronsoro, Carlos; Iriarte, Angel; Aguilar, Josķ
In the present work, soil profiles were sampled 40 days and three years after an accidental pyrite tailing spill from the Aznalc¾llar mine (S Spain) in order to figure out the effects of the acidic solution draining from the tailing. The composition of the acidic solution, the mineralogy, and the total and soluble content of the major elements were analysed at varying depths. The results show a weathering process of carbonates and of primary silicates. Calcium released is leached or reacts with the sulphate ions to form gypsum. Magnesium, aluminium and potassium tend to leach from the uppermost millimetres of the soil, accumulating where the pH>/=5.0; also the iron, probably forming more or less complex hydroxysulphates, precipitate in the upper 5 cm. The strong releasing of soluble salts increases the electrical conductivity, while the soluble potassium tends to decrease in the uppermost part of the soil due to the neoformation of jarosite. Iron is soluble only where the pH=2.3, and aluminium where the pH=5.5. PMID:17307236
Persulfate activation by subsurface minerals
NASA Astrophysics Data System (ADS)
Ahmad, Mushtaque; Teel, Amy L.; Watts, Richard J.
Persulfate dynamics in the presence of subsurface minerals was investigated as a basis for understanding persulfate activation for in situ chemical oxidation (ISCO). The mineral-mediated decomposition of persulfate and generation of oxidants and reductants was investigated with four iron and manganese oxides and two clay minerals at both low pH (< 7) and high pH (> 12). The manganese oxide birnessite was the most effective initiator of persulfate for degrading the oxidant probe nitrobenzene, indicating that oxidants are generated at both low and high pH regimes. The iron oxide goethite was the most effective mineral for degrading the reductant probe hexachloroethane. A natural soil and two soil fractions were used to confirm persulfate activation by synthetic minerals. The soil and soil fractions did not effectively promote the generation of oxidants or reductants. However, soil organic matter was found to promote reductant generation at high pH. The results of this research demonstrate that synthetic iron and manganese oxides can activate persulfate to generate reductants and oxidants; however, iron and manganese oxides in the natural soil studied do not show the same reactivity, most likely due to the lower masses of the metal oxides in the soil relative to the masses studied in isolated mineral systems.
2.20 Properties of Rocks and Minerals -Magnetic Properties of Rocks and Minerals
Dunin-Borkowski, Rafal E.
2.20 Properties of Rocks and Minerals - Magnetic Properties of Rocks and Minerals R. J. Harrison, R 621 622 623 623 579 #12;580 Magnetic Properties of Rocks and Minerals 188.8.131.52 188.8.131.52 2, and are present in all types of rocks, sediments, and soils. These minerals retain a memory of the geomagnetic
NSDL National Science Digital Library
This University of Florida website educates the public about soil texture, which is the distribution of sizes of mineral particles found in soils. After learning the basics about soil separates, students and educators can learn about the USDA textural triangle and the characteristics of the twelve textural classes. Researchers can discover how to determine the correct soil texture in the field. The website addresses the important role soil textures play in the determination of proper land use activities and management practices. Visitors will also find a short discussion about other factors that affect the behavior and qualities of soils.
Effects of Potassium Mineral Fertilization on Potato (Solanum tuberosum L.) Yield on a Chernozem Soil in Hungary
NASA Astrophysics Data System (ADS)
Lßszl¾, Mßrton, ,, Dr.
Nowadays potato (Solanum tuberosum L.) is a more important throughout the world between field crops. As potato is such a potassium demanding crop, it is particularly important that the potassium fertilizers used should be correctly balanced. Applying the adequate quantity of balanced K- fertilizer is the first requirement for achieving optimum yield and doing so will result in potatoes of acceptable quality. Potato potassium nutrition has been studied at the Research Institute for Soil Science and Agricultural Chemistry of the Hungarian Academy of Sciences (RISSAC-HAS)- Experiment Station, Nagyh÷rcs÷k (chernozem soil) in a long term field experiment designed to determine NPK- nutrient requirements. The method of the experiment was 43 mixed factorial design with 64 treatments in 2 repetitions with 128 plots. The residual effects of K- levels brought about by build- up fertilization were studied. Potato were planted in 1978. The experimental dates were estimated by multivariate analysis of variance (MANOVA). On the basis of foliar analysis at early flowering about 4.5 to 5.0% K in dry matter proved to be satisfactory for obtaining maximum yield (32.6 t/ha). The yields increased by 22%, 34%, and 38% at 124-140, 141-168 and 169-208 ppm soil AL- K2O rates, respectively. The tubers concentrated much N 19% and less P 81% than potassium. Results for tuber maximum uptake of potassium reached a maximum about 130 days after planting. The improvement of the K supply of the soil increased yield and induced low concentrations of numerous microelements on leaves considered to be important. Key words: Potato (Solanum tuberosum L.), chernozem soil, potassium, yield Introduction Potato is an important food crop, more particularly in the temperate zone, especially in Europe and Asia. Between 1981 and 1995, in spite of an 18% decrease in cultivated area production increased by 13% because the average yield increased from 11.0 to 15.1 t/ha. Potato is a soil nutrients demanding crop and has a particularly high requirement for potassium. Tubers remove 1.5 times more potassium than nitrogen and 4 or 5 times the amount of phosphate. The quantity of nutrients taken up by a crop is not necessarily an indication of responsiveness to fertilizers but potato, because its root system is relativly poorly developed in relation to yield is extremly responsive to all nutrients (Mßrton 1984). As potato is such a demanding crop, it is particularly important that the potassium fertilizers used should be correctly balanced (Burton 1966). Applying the adequate quantity of balanced K- fertilizer is the first requirement for achieving optimum yield and doing so will result in potatoes of acceptable quality (Mßrton 2000). It is not the objective of present publication to give recommendations K- fertilizers which vary greatly according to local conditions. We intend to discuss various aspects of potassium effects on the basis of our research results. The importance of potatoes In terms of area planted, potato is the twelfth most important crop in all the world (18.48 million hectares) by FAO in 1995. In terms of total production it occupies the 5th position with 280 million t, between maize (515 mio) and sugar beet (266 mio). It is a high yielding crop. The world average being 15.1 t/ha, the third highest yielding crop on the bases of fresh matter following sugar cane (62.6 t/ha) and sugar beet (33.9 t/ha). Area planted, production and yield (1981 and 1995) Between 1981 and 1995 the total world area planted declined by 18%. While the importance of the crop declined more or less markedly in Europe, and in N. and C. America, there has been an increase in S. America (Mßrton 1999). The area planted in Asia has more than doubled and in Africa tripled. Despite of the reduction in area, world production has actually increased by 13% in the same period. This increase in production is due to a general 37% growth in yield from 11 to 15.1 t/ha. The potential yields of varieties, estimated at 85-100 t/ha for potato, 75-85 t/ha for beet and 12-15 t/ha for wheat (Evans 1977
Magnetic Properties, Processes and Minerals in Crustal Rocks of the Terrestrial Planets and Their Satellites
NASA Astrophysics Data System (ADS)
Dunlop, D. J.
Earth is unique in having active plate tectonics which continually renews the crust. Deeply eroded ancient crust survives in Precambrian shields but retains little evidence of impact cratering. Continental plutonic rocks owe most of their magnetic signal to magnetite or hemoilmenite, whose potentially strong TRM and susceptibility give rise to both remanent and induced magnetic anomalies. Mafic gneisses and granulites of the middle and lower crust are also probable magnetic anomaly sources. High temperatures enhance the magnetite viscous induced signal but degrade the TRM through thermoviscous demagnetization. Hematite and iron oxyhydroxides are ubiquitous at Earths surface but their magnetic signals are overwhelmed by those of magnetite, whose spontaneous magnetization Ms is two orders of magnitude larger. The primary magnetic minerals of the oceanic crust are Ti-rich titanomagnetites with Ms values about 1/4 that of magnetite. They become more magnetic with phase-splitting to magnetite + ilmenite but less magnetic when altered by seawater to titanomaghemites. The Curie point isotherm of titanomagnetite is shallow, so that oceanic magnetic anomalies have predominantly near-surface remanent sources. Mars and other terrestrial planets have much smaller fields than Earths: their anomaly sources are entirely remanent. The very large anomalies in parts of the southern highlands crust of Mars suggest a deep Curie point isotherm, a high-Ms mineral, single-domain structure (associated with fine grain size) and perhaps also an unusual abundance of magnetic material. Fe-rich titanomagnetites fit the bill in all respects and form in abundance in synthesized basalts of Martian crustal composition. Large impact craters on both Mars and the Moon have low magnetic expression, probably due to shock demagnetization and/or randomization of remanence vectors. Iron-nickel minerals like kamacite and tetrataenite dominate in lunar rocks and meteorites. In most grain sizes they are unstable remanence carriers and lead to weak sample magnetizations and planetary crustal anomalies. Iron sulphides such as pyrrhotite and troilite are common in lunar samples and meteorites, and may well be significant in the Martian crust also.
Effects of Atmospheric CO2 Enrichment on the Growth and Mineral Nutrition of Quercus alba Seedlings in Nutrient-Poor Soil 1
Norby, Richard J.; O'Neill, Elizabeth G.; Luxmoore, R. J.
One-year-old dormant white oak (Quercus alba L.) seedlings were planted in a nutrient-deficient forest soil and grown for 40 weeks in growth chambers at ambient (362 microliters per liter) or elevated (690 microliters per liter) levels of CO2. Although all of the seedlings became severely N deficient, CO2 enrichment enhanced growth by 85%, with the greatest enhancement in root systems. The growth enhancement did not increase the total water use per plant, so water-use efficiency was significantly greater in elevated CO2. Total uptake of N, S, and B was not affected by CO2, therefore, tissue concentrations of these nutrients were significantly lower in elevated CO2. An increase in nutrient-use efficiency with respect to N was apparent in that a greater proportion of the limited N pool in the CO2-enriched plants was in fine roots and leaves. The uptake of other nutrients increased with CO2 concentration, and P and K uptake increased in proportion to growth. Increased uptake of P by plants in elevated CO2 may have been a result of greater proliferation of fine roots and associated mycorrhizae and rhizosphere bacteria stimulating P mineralization. The results demonstrate that a growth response to CO2 enrichment is possible in nutrient-limited systems, and that the mechanisms of response may include either increased nutrient supply or decreased physiological demand. PMID:16665028
Mineral Composition and Abundance of the Rocks and Soils at Gusev and Meridiani from the Mars Exploration Rover Mini-TES Instruments
NASA Technical Reports Server (NTRS)
Christensen, P. R.; Wyatt, M. B.; Glotch, T. D.; Rogers, A. D.; Anwar, S.; Arvidson, R. E.; Bandfield, J. L.; Blaney, D. L.; Budney, C.; Calvin, W. M.
The Miniature Thermal Emission Spectrometer (Mini-TES) has provided remote measurements of mineralogy, thermophysical properties, and atmospheric temperature profile and composition of the outcrops, rocks, spherules, and soils surrounding the Spirit and Opportunity Rovers. The mineralogy of volcanic rocks provides insights into the composition of the source regions and the nature of martian igneous processes. Carbonates, sulfates, evaporites, and oxides provide information on the role of water in the surface evolution. Oxides, such as crystalline hematite, provide insight into aqueous weathering processes, as would the occurrence of clay minerals and other weathering products. Diurnal temperature measurements can be used to determine particle size and search for the effects of sub-surface layering, which in turn provide clues to the origin of surficial materials through rock disintegration, aeolian transport, atmospheric fallout, or induration. In addition to studying the surface properties, Mini-TES spectra have also been used to determine the temperature profile in the lower boundary layer, providing evidence for convective activity, and have determined the seasonal trends in atmospheric temperature and dust and cloud opacity.
Protozoa enhance foraging efficiency of arbuscular mycorrhizal fungi for mineral nitrogen from organic matter in soil to the benefit of host plants.
Koller, Robert; Rodriguez, Alia; Robin, Christophe; Scheu, Stefan; Bonkowski, Michael
Dead organic matter (OM) is a major source of nitrogen (N) for plants. The majority of plants support N uptake by symbiosis with arbuscular mycorrhizal (AM) fungi. Mineralization of N is regulated by microfauna, in particular, protozoa grazing on bacteria. We hypothesized that AM fungi and protozoa interactively facilitate plant N nutrition from OM. In soil systems consisting of an OM patch and a root compartment, plant N uptake and consequences for plant carbon (C) allocation were investigated using stable isotopes. Protozoa mobilized N by consuming bacteria, and the mobilized N was translocated via AM fungi to the host plant. The presence of protozoa in both the OM and root compartment stimulated photosynthesis and the translocation of C from the host plant via AM fungi into the OM patch. This stimulated microbial activity in the OM patch, plant N uptake from OM and doubled plant growth. The results indicate that protozoa increase plant growth by both mobilization of N from OM and by protozoa-root interactions, resulting in increased C allocation to roots and into the rhizosphere, thereby increasing plant nutrient exploitation. Hence, mycorrhizal plants need to interact with protozoa to fully exploit N resources from OM. PMID:23534902
Soil Science Society of America Journal Soil Sci. Soc. Am. J. 78:14581468
Battles, John
cm of mineral soil to track the fate of the added Ca. We also measured soil pH and exchangeable horizon or the top 10 cm of mineral soil. Soil pH and exchangeable Ca concentrations increasedSoil Science Society of America Journal Soil Sci. Soc. Am. J. 78:1458Ł1468 doi:10.2136/sssaj2014
NSDL National Science Digital Library
According to the Minerals Yearbook Web site, the US Geological Survey Minerals Information Team's mission is to collect, analyze, and disseminate information on the domestic and international supply of and demand for minerals and mineral materials essential to the US economy and national security. The yearbook reviews the mineral and material industries of the United States and foreign countries, contains statistical data on materials and minerals, and includes information on economic and technical trends and development. Volume I contains metals and minerals information, volume II US area reports, and volume III international reports. A lot of data is presented in the various documents; thankfully, the site is organized well and easy to navigate.
NSDL National Science Digital Library
Dexter Perkins
This three part lab introduces sulfides and other ore minerals. Part one - Ore Minerals: Students fill in a table giving the metal, formula, and mineral group of several ore minerals. Part two - Box of Rocks: Students examine trays of ore minerals and record their physical properties, composition, habit, occurence, economic value, and use and answer questions about color, luster, density, transparency, and availability. Part three - Famous Digs: Students answer a series of questions related to famous ore deposits.
Monday, November 5, 2007 -11:15 AM Microbe-Mineral Interactions and their Influence on ArsenicTransformations in the Soil Environment.
Sparks, Donald L.
. of Plant and Soil Sciences, Newark, DE 19716. Arsenic (As) contamination of soil and water is of concern on ArsenicTransformations in the Soil Environment. Brandon Lafferty, University of Delaware, 152 Townsend Hall, Center for Critical Zone Research, Dept. of Plant and Soil Sciences, Newark, DE 19716 and Donald
NSDL National Science Digital Library
This problem set challenges students to determine the chemical classification of minerals based on their chemical formula (provided). For oxygen-bearing minerals, students must also provide the valences of the various cations.
... Dynamic Stretching A Guy's Guide to Body Image Mineral Chart KidsHealth > Teens > Miscellaneous > Mineral Chart Print A A A Text Size Type ... sources of calcium. You'll also find this mineral in broccoli and dark green, leafy vegetables. Soy ...
NSDL National Science Digital Library
Mineralogy 4 Kids
This site from the Mineralogical Society of America describes the physical properties of minerals in terms that kids will understand. The site also includes the definition of a mineral, an identification chart, and links to descriptions of the physical properties used to identify minerals.
Long-term organic phosphorus mineralization in Spodosols under forests and its relation to carbon and nitrogen mineralization
David L. Achat; Mark R. Bakker; Bernd Zeller; Sylvain Pellerin; Sķverine Bienaimķ; Christian Morel
In forest soils where a large fraction of total phosphorus (P) is in organic forms, soil micro-organisms play a major role in the P cycle and plant availability since they mediate organic P transformations. However, the correct assessment of organic P mineralization is usually a challenging task because mineralized P is rapidly sorbed and most mineralization fluxes are very weak.
Clay mineral status of paddy soils from the Tai Lake Region of China in relation to high paddy-rice productivity
Kazuhiko Egashira; Soichi Iwashita; Shin-ichi Yamasaki
Soil samples which were collected in the Tai Lake region of China during the tour organized after the 14th International Congress of Soil Science in 1990 were analyzed for the determination of the concentration of rare earth elements, particle-size distribution, and clay mineralogical composition. Paddy soils distributed in the plain and polder areas were derived from Xiashu loess. The concentration
Associating rice root morphology and physiological traits with grain mineral concentrations of 24 varieties with extreme mineral compositions
Technology Transfer Automated Retrieval System (TEKTRAN)
The first step towards mineral accumulation in plant seeds is the absorption/uptake of minerals from the soil by roots. Root physiological activities, such as root respiration and metabolism, modify physical (soil temperature), chemical (soil pH, redox potential, root exudates, allelochemicals, and ...
Mineral-Based Amendments for Remediation
OÆDay, Peggy A.; Vlassopoulos, Dimitri
Amending soils with mineral-based materials to immobilize contaminants is both old and new. Although mineral amendments have been used for decades in agriculture, new applications with a variety of natural and reprocessed materials are emerging. By sequestering contaminants in or on solid phases and reducing their ability to partition into water or air, amendments can reduce the risk of exposure to humans or biota. A variety of mineral types are commonly used to amend contaminated soils, with different modes of molecular-scale sequestration. Regulatory, social, and economic factors also influence decisions to employ mineral amendments as a treatment technology. PMID:22203887
NSDL National Science Digital Library
John Pratte
This lesson discusses the question 'What is a mineral?' in the context of the guessing game 'Animal, Vegetable, or Mineral?'. It introduces a definition of the term, discusses the criteria used in the definition, and presents the common physical properties used in mineral identification. The lesson includes an activity in which students observe and record the physical properties of ten specimens and attempt to identify them using an online reference for practice.
Root physiological and morphological characteristics of 24 rice varieties selected for diverse grain mineral
Technology Transfer Automated Retrieval System (TEKTRAN)
To accumulate a mineral in the grain, a plant must first absorb that mineral from the soil. Root physiological characteristics, such as exudation of organic acids or oxygen, impact the availability, solubility and mobility of minerals in the soil, ultimately impacting the amount of minerals absorbe...
Comparing mineral magnetic properties of sediments in two reservoirs in ōstronglyö and ōmildlyö eroded regions on the Guizhou Plateau, southwest China: A tool for inferring differences in sediment sources and soil erosion
NASA Astrophysics Data System (ADS)
Wang, Hongya; Xu, Lin; Sun, Xubo; Lu, Minghui; Du, Xiaoya; Huo, Yuying; Snowball, Ian
Shibanqiao Reservoir (0.24 km2) and Xiaohe Reservoir (0.28 km2) have catchments of 6.00 km2 and 22.69 km2, respectively. They essentially represent ōstrongly erodedö (Shibanqiao) and ōmildly erodedö (Xiaohe) regions in Guizhou Plateau, southwestern China. Sediment cores were retrieved from the two reservoirs and soils were also sampled from their catchments. Mineral magnetic measurements were performed on the sediments and soils, and the particle-size analysis of selected sediment cores and soil profiles were also made. SIRM versus ?lf was used to compare sediment and soil samples. In addition, correlations between percentages of different particle-size fractions and magnetic parameters/ratios of sediment samples were also checked. These results revealed differences in sediment sources and soil erosion in these two representative catchments. The sediments in Shibanqiao Reservoir are derived from both the topsoil and subsoil. When erosion is relatively weak, it is limited to the topsoil and preferentially transports the relatively finer magnetic grains into the reservoir, which may imply rain splash and/or sheet erosion. In this relatively steep catchment, stronger erosional forces are capable of not only moving relatively coarser ferrimagnetic grains from the topsoil, but also incising the subsoil and moving anti-ferromagnetic minerals into the reservoir, which seems to hint at not only sheet-wash but also rill and gully erosion. As there are no stable streams nor channel networks developed in this mountainous catchment, contributions from river-bank erosion to sediment yield are almost negligible. The sediments in Xiaohe Reservoir, which has a lower relief, are predominately derived from topsoil erosion. Here, erosion is concentrated to the topsoil and preferentially transports the relatively fine magnetic grains into the reservoir when erosional forces are weak. However, even when erosional forces increase in this relatively flat catchment, erosion is still restricted to the topsoil. Thus, relatively coarser ferrimagnetic grains from the topsoil are transported to the reservoir, but the subsoil remains undisturbed and there are no significant changes in the proportion of anti-ferromagnetic minerals in the sediments. Consequently, only sheet-washing occurs even when erosion is intensifying in this hilly plain catchment. In general, the more effective erosion in the Shibanqiao Catchment is probably due to its steeper topography than Xiaohe Catchment, although higher and more seasonal rainfalls and lower percentages of woodlands may also contribute to the differences in susceptibility to erosional forces.
Mineral and organic components of the buried paleosols of the Nevado de Toluca, Central Mexico as indicators of paleoenvironments and soil evolution
Sergey Sedov; Elizabeth Solleiro-Rebolledo; Pedro Morales-Puente; Ernestina Vallejo-G"mez; Carolina Jasso-Casta±eda
Results of earlier studies of Quaternary tephra¢paleosol sequences in Central Mexico revealed contradictions between paleopedological and lacustrine records. To settle the contradictions, selected quantitative characteristics of mineral and organic components of the paleosols PT1¢PT7 from the Nevado de Toluca sequence were studied as independent paleoclimate proxies. Mineralogical composition of sand and clay fractions allows assessment of weathering and secondary mineral
Arsenic affects mineral nutrients in grains of various Indian rice ( Oryza sativa L.) genotypes grown on arsenic-contaminated soils of West Bengal
Sanjay Dwivedi; R. D. Tripathi; Sudhakar Srivastava; Ragini Singh; Amit Kumar; Preeti Tripathi; Richa Dave; U. N. Rai; Debasis Chakrabarty; P. K. Trivedi; R. Tuli; B. Adhikari; M. K. Bag
The exposure of paddy fields to arsenic (As) through groundwater irrigation is a serious concern that may not only lead to\\u000a As accumulation to unacceptable levels but also interfere with mineral nutrients in rice grains. In the present field study,\\u000a profiling of the mineral nutrients (iron (Fe), phosphorous, zinc, and selenium (Se)) was done in various rice genotypes with\\u000a respect
Determination of thorium isotopes in mineral and environmental water and soil samples by ?-spectrometry and the fate of thorium in water
Guogang Jia; G. Torri; R. Ocone; A. Di Lullo; A. De Angelis; R. Boschetto
A method has been developed for determination of thorium isotopes in water and soil samples by ?-spectrometry. After fusion with Na2CO3 and Na2O2 at 600░C, soil samples were leached with HNO3 and HCl. Thorium in water sample or in soil leaching solution was coprecipitated together with iron (III) as hydroxides and\\/or carbonates at pH 9 with ammonia solution, separated from
NSDL National Science Digital Library
Students are given cubic cell edge dimensions and asked to calculate mineral densities and vice versa. The final question of this homework assignment provides students with a mineral density and unit cell edge length in order to determine the number of formula units per cell.
NSDL National Science Digital Library
Michael Passow
In this activity, students use written and online materials to answer a set of questions on the general properties and identification of minerals. They will learn about physical properties such as color, hardness, and cleavage; special properties such as fluorescence and effervescence; and complete a chart listing properties for a selection of minerals. Links to the necessary information are provided.
ERIC Educational Resources Information Center
Brady, Lawrence L.
Discusses trends in and factors related to the production of industrial minerals during 1982, indicating that, as 1981 marked a downturn in production of industrial minerals, 1982 continued the trend with temporary and permanent cutbacks in mine and plant production. Includes highlights of several conferences/conference papers in this field.ģ
NSDL National Science Digital Library
In this activity, learners search for various kinds of items made from minerals around their home or school, including toothpaste, wall paint, kitty litter, and bricks. The PDF contains a check off list as well as recommended sites for more information on minerals.
Edaphic Soil Levels of Mineral Nutrients, pH, Organic Matter, and Cationic Exchange Capacity in the Geocaulosphere Associated with Potato Common Scab.
Lazarovits, George; Hill, Jacquelyn; Patterson, Greg; Conn, Kenneth L; Crump, Nigel S
ABSTRACT In order to determine possible relationships between geocaulosphere soil properties and severity of common scab of potato caused by Streptomyces scabies, soils were collected from representative commercial potato fields in Canada: in Simcoe and Dufferin Counties, Ontario and across Prince Edward Island (PEI) in August 2004. Soils immediately adjacent to tubers were sampled and analyzed for select edaphic factors and for pathogen presence using polymerase chain reaction (PCR) tests with primers that amplify a region of the TxtA gene involved in regulating the biosynthesis of the thaxtomin toxin family. Individual tubers were assessed visually for scab severity. The relationships between soil chemical factors and disease severity were investigated for each region to detect the strongest relationships. Principal component analysis revealed a distinctive clustering of samples with respect to disease severity in PEI but not in Ontario soils. Total and percent saturation of K (%K) were the only factors found associated with high disease severity in soils from both provinces. In PEI soils, pH, Mg, Ca, Cu, and %K, %Mg, %Ca, and %Na were associated with high disease severity, whereas cation exchange capacity (CEC) and Al were correlated with low disease severity soils. In Ontario, high Mn content was strongly correlated with low disease severity soils, whereas %K and organic matter content were correlated with disease severity. Partitioning samples into presence or absence of the TxtA PCR product with corresponding high or low severity showed further significant relationships in the data. There was an excellent correlation between Streptomyces spp. presence as detected by PCR and disease severity in PEI soils; however, the relationship was not as clear in Ontario soils, where many PCR-positive soils had low disease incidence. Principal component and partial least square analysis indicated that disease severity was predicted by soil factors such as organic matter, CEC, pH, Al, %Ca, %Mg, and %K for PEI but not for Ontario soils. The data reveal that the relationship between scab severity and soil chemical components is complex and potentially soil specific. PMID:18944172
NSDL National Science Digital Library
Susan Morgan
In this activity, students will discover that minerals have specific characteristics that help to identify them. They will learn that minerals are formed by inorganic processes, are crystalline solids with an internal orderly arrangement of atoms, have specific chemical compositions, and have specific physical and chemical characteristics. They will also learn that minerals are commonly identified by the physical properties they possess, such as hardness, color, crystal shape, specific gravity, and streak. In addition, they will discover some other useful properties such as reaction with hydrochloric acid or a characteristic taste. They should also understand that color is not always a useful property for identifying minerals because it can vary. The students will also develop listening and observational skills and learn the uses of a few common minerals.
CCA Training : Soil and Water Management
Balser, Teri C.
clay sand Clay Sand Silt #12;Textural properties of mineral soils Soil class Properties of moist soil Physical Properties: Texture Ę Relative proportion of sand, silt, and clay that lends a distinct feel to the soil ŁRelative size difference ŁClay particles have greatest effect on soil management ŁHeavy soil
Grant Heiken
The paper summarizes the physical and petrographic characteristics of the finer-grained fractions (less than 1 cm) of lunar regolith soil in Apollo and Luna samples. Lunar soils are poorly sorted and consist mostly of lithic and mineral debris derived by impact comminution of the underlying bedrock and glass particles formed by impact melting. Agglutinates constitute an important soil component and
Impacts of altitude and position on the rates of soil nitrogen mineralization and nitrification in alpine meadows on the eastern Qinghai-Tibetan Plateau, China
Technology Transfer Automated Retrieval System (TEKTRAN)
Alpine and tundra grasslands constitute 7% world terrestrial land but 13% of the total global soil carbon (C) and 10% of the global soil nitrogen (N). Under the current climate change scenario of global warming, these grasslands will contribute significantly to the changing global C and N cycles. It...
Effects of municipal solid waste compost and mineral fertilizer amendments on soil properties and heavy metals distribution in maize plants ( Zea mays L.)
Gregoria Carbonell; Rosario Miralles de Imperial; Manuel Torrijos; Mar Delgado; Josķ Antonio Rodriguez
Soil amendments based on crop nutrient requirements are considered a beneficial management practice. A greenhouse experiment with maize seeds (Zea mays L.) was conducted to assess the inputs of metals to agricultural land from soil amendments. Maize seeds were exposed to a municipal solid waste (MSW) compost (50Mgha?1) and NPK fertilizer (33g plant?1) amendments considering N plant requirement until the
Assessment of mineral nitrogen dynamic and its concentration in the soil profile with the updated NLEAP V.2 model: A case study in South Central Bulgaria
Technology Transfer Automated Retrieval System (TEKTRAN)
Nitrogen fertilization management is important to maximize use efficiencies and reduce losses, especially under irrigated cropping systems grown on sandy soils. The simulation modeling approach provides a fast and efficient means of integrating management effects with soil and climate information to...
Mineralization of 2,4-dichlorophenoxyacetic acid (2,4-D) in soil inoculated with Pseudomonas cepacia DBO1(pRO101), Alcaligenes eutrophus AEO106(pRO101) and Alcaligenes eutrophus JMP134(pJP4): effects of inoculation level and substrate concentration
Carsten Suhr Jacobsen; Jens Chr. Pedersen
Mineralization of 2,4-dichlorophenoxyacetic acid (2,4-D) by two Alcaligenes eutrophus strains and one Pseudomonas cepacia strain containing the 2,4-D degrading plasmids pJP4 or pRO101 (=pJP4::Tn1721) was tested in 50 g (wet wt) samples of non-sterile soil. Mineralization was measured as 14C-CO2evolved during degradation of uniformly-ring-labelled 14C-2,4-D. When the strains were inoculated to a level of approximately 108 CFU\\/g soil, between 20
Influence of Citrate on the Kinetics of Fe(II) Oxidation and the Formation of Iron Oxyhydroxides1
G. S. R. Krishnamurti; P. M. HUANG
The rate of Fe(II) oxidation at a constant rate of oxygen supply in the presence of citrate was measured at pH 6.0 at various citrate\\/Fe(II) molar ratios at 23.5~ in 0.01 M ferrous perch\\/orate system. The kinetics followed a first-order reaction with respect to Fe(II) concentration at constant pH (6.0) and aeration (5 ml\\/min). The rate constant decreased exponentially from
NSSC Soil Survey Laboratory: Soil Characterization Database
NSDL National Science Digital Library
The National Soil Survey Center (NSSC), as part of the Natural Resource Conservation Service, maintains the Soil Survey Laboratory Soil Characterization Database. The application allows users to generate, print and download reports containing soil characterization data held by the NSSC Soil Survey Laboratory. Users are able to choose the location and particular pedon for each query and report generation. The reports are titled Primary Characterization Data and contain the site location, pedon number, sample layer depth, percentage of various sized soil particles, bulk density, water content, mineral content, and much more. Scientists and other professionals will appreciate the easy access to valuable information the site provides.
Influence of glutamic acid enantiomers on C-mineralization.
Formßnek, Pavel; Vranovß, Valerie; Lojkovß, Lea
Seasonal dynamics in the mineralization of glutamic acid enantiomers in soils from selected ecosystems was determined and subjected to a range of treatments: ambient x elevated CO2 level and meadow x dense x thinned forest environment. Mineralization of glutamic acid was determined by incubation of the soil with 2?mg?L- or D-glutamic acid g(-1) of dry soil to induce the maximum respiration rate. Mineralization of glutamic acid enantiomers in soils fluctuates over the course of a vegetation season, following a similar trend across a range of ecosystems. Mineralization is affected by environmental changes and management practices, including elevated CO2 level and thinning intensity. L-glutamic acid metabolism is more dependent on soil type as compared to metabolism of its D-enantiomer. The results support the hypothesis that the slower rate of D- compared to L- amino acid mineralization is due to different roles in anabolism and catabolism of the soil microbial community. PMID:25377997
Short-term CO 2 mineralization after additions of biochar and switchgrass to a Typic Kandiudult
J. M. Novak; W. J. Busscher; D. W. Watts; D. A. Laird; M. A. Ahmedna; M. A. S. Niandou
Biochar additions to soil can increase soil organic carbon (SOC) concentrations; however, minimal information is available on relationships with soil nitrogen (N) cycle. We hypothesized that biochar additions to sandy soils should be resistant to microbial mineralization in short-term studies but may prime organic carbon (OC) mineralization of fresh residue that promotes N immobilization. A laboratory pot incubation study was
Mineralized iron oxidizing bacteria from hydrothermal vents: targeting biosignatures on Mars
NASA Astrophysics Data System (ADS)
Leveille, R. J.
Putative hydrothermal systems have been identified on Mars based on orbital imagery and rover-based analyses. Based on Earth analogs, hydrothermal systems on Mars would be highly attractive for their potential for preserving organic and inorganic biosignatures. For example, iron oxidizing bacteria are ubiquitous in marine and terrestrial hydrothermal systems, where they often display distinctive cell morphologies and are commonly encrusted by minerals, especially bacteriogenic iron oxides and silica. Microfossils of iron oxidizing bacteria have been found in ancient Si-Fe deposits and iron oxidation may be an ancient and widespread metabolic pathway. In order to investigate mineralized iron oxidizing bacteria as a biosignature, we have examined samples collected from extinct hydrothermal vents along Explorer Ridge, NE Pacific Ocean. In addition, microaerophilic iron oxidizing bacteria, isolated from active Pacific hydrothermal vents, were grown in a Fe-enriched seawater medium at constant pH (6.5) and O2 concentration (5%) in a controlled bioreactor system. Samples and experimental products were examined with a combination of variable-pressure and field-emission scanning electron microscopy (SEM), in some cases by preparing samples with a focused ion beam (FIB) milling system. Light-toned seafloor samples display abundant filamentous forms resembling, in both size and shape (1-5 microns in diameter and up to several microns in length), the twisted stalks of Gallionella and the elongated filaments of Leptothrix. Some samples consist entirely of low-density masses of silica (>90% Si) encrusted filamentous forms. The presence of unmineralized filamentous matter rich in C and Fe suggests that these are the remains of iron oxidizing bacteria. Mineralized filaments sectioned by FIB show variable internal material within semi-hollow, tubular-like features. Silica encrustations also show pseudo-concentric growth bands. In the bioreactor runs, abundant microbial growth and formation of an iron oxyhydroxide precipitate, either in direct association with the cells or within the growth medium, were observed. Preliminary analyses suggest that these precipitates are different from abiotic precipitates. Continuing work includes high-resolution TEM observations of cultured organisms and biogenic iron minerals, Raman and reflectance spectroscopy of precipitates, examination of seafloor incubation experiments, and bioreactor silicification experiments in order to better understand the Fe-Si fossilization process. Microaerophilic iron oxidation could have existed on the early Earth in environments containing small amounts of oxygen produced either by locally-concentrated photosynthetic microorganisms (e.g., cyanobacteria) or by chemical reactions. By analogy, similar subsurface or near-surface microaerophilic environments could have existed on Mars in the past, including in low-temperature hydrothermal systems. The distinctive morphologies and Fe-Si mineralization patterns of iron oxidizing bacteria could be a useful biosignature to search for on Mars. Deposits and features similar to those described here could be identified on Mars with existing technologies, and thus hydrothermal systems represent an attractive target for future surface and sample return missions.
A b s t r a c t. The paper presents a comparison of particle size distributions of 23 mineral soils from SE Poland obtained by the
Ahmad, Sajjad
- rements (ISO 11277, 1998). The Mastersizer 2000 apparatus with Hydro MU attach- ment from the Malvern procedure realized Int. Agrophysics, 2010, 24, 177-181 Determination of particle size distrubution of soil
Soil nitrous oxide emissions from a typical semiarid temperate steppe in inner Mongolia: effects of mineral nitrogen fertilizer levels and forms
Qin Peng; Yuchun Qi; Yunshe Dong; Shengsheng Xiao; Yating He
Nitrous oxide (N2O) emissions can be significantly affected by the amounts and forms of nitrogen (N) available in soils, but the effect is\\u000a highly dependent on local climate and soil conditions in specific ecosystem. To improve our understanding of the response\\u000a of N2O emissions to different N sources of fertilizer in a typical semiarid temperate steppe in Inner Mongolia, a
Soil ingestion by dairy cattle
Darwin, R.
Ingested soil may be a source of minerals to grazing cattle; it may also be a source of radionuclides, heavy metals, and organic toxins. The importance of soil ingestion in the milk pathway depends on the amount of soil ingested, the ratio of the mineral concentration in soil to that in herbage, and the ability of the cattle to solubilize and absorb the soil-derived minerals. The amount of soil ingested by cattle on pasture, in turn, depends upon the stocking level, the quantity of forage available, and the soil ingesting propensity of individual cows. The objective of this note is to summarize some of the information about soil ingestion by dairy cattle and to suggest methods for incorporating soil ingestion into the Hanford Environmental Dose Reconstruction (HEDR) Phase I milk model. 5 refs., 4 tabs.
Clay Minerals are controlled by the environment - Clay Minerals control the environment
NASA Astrophysics Data System (ADS)
Stahr, K.; Zarei, M.
Where clay minerals are analyzed in soils, often there is some confusion, because in the widespread loess-affected and moraine landscapes of Europe quite a variety of clay minerals is found. The sources of these minerals are inherited from the local solid rock, transported through different processes, transformed through mineral changes and inherited from paleo-environments. Very often a miserable assemblage in the clay fraction is found with mica clay, smectite, kaolinite, chlorite and also some quartz. In order to understand the current dynamic of clay mineral formation, very detailed and quantitative analysis in comparison of horizons and landscape are necessary. It is much easier to through light on the development, if conditions are looked for where a single specific mineral can be formed like short range order minerals from volcanic ashes or smectites from basaltic parent material. Old leaching land surfaces will form kaolinitic and in tropical areas gibbsitic clay fractions. In arid environments of deserts and desert fringes, palygorskite and sepiolite can dominate. In general, clay minerals buffer the environment. This is mainly due to the extraordinary large interfaces between mineral surface and pore systems. In the last years mainly the processes of buffering through charging soil solution and of buffering through mineral organic compounds have been analyzed. Development of new microscopic and spectromethods have brought great progress in understanding the role of clays in soil environments.
Dissolution of resistate minerals containing uranium and thorium: Environmental implications
L. K. Selvig; I. M. J. Outola; H. Kurosaki; K. A. Lee
SummaryĀĀMinerals in the soil range from those that easily weather to those that are very resistant to the weathering processes. The minerals used in this study are referred to as ōresistatesö because of their resistance to natural weathering processes.1 It is also known that there are some resistate minerals that have a tendency to contain uranium and thorium within their
Assessment of Hg-contamination in soils and stream sediments in the mineral district of Nambija, Ecuadorian Amazon (example of an impacted area affected by artisanal gold mining)
M. E. Ram??rez Requelme; J. F. F. Ramos; R. S. Angķlica; E. S. Brabo
The Nambija Mineral District (NMD) is located in the southeastern part of Ecuador, east of Zamora (Zamora Chinch??pe's country), Ecuadorian Amazon. In this district, Au occurrences have been know since colonial and pre-colonial times, but only after the early 1980s has intensive artisanal Au mining activity been developed. Currently, the different NMD Au occurrences continue to be exploited by artisanal
Plot-scale spatial patterns of soil water content, pH, substrate-induced respiration and N mineralization in a temperate coniferous forest
A Bruckner; E Kandeler; C Kampichler
Samples of two perpendicular transects from an even-aged Norway spruce (Picea abies) forest were used for geostatistical analysis of forest floor water content (WC), pH, substrate-induced respiration (SIR, a measure of microbial biomass), and N mineralization (Nmin). Nmin data did not fulfil the stationarity assumptions of geostatistics and had to be detrended prior to analysis. All variables exhibited spatial structure.
Role of nitrogen mineralization in fertilizer recommendations
K. D. Frank; J. S. Schepers
Efficient use of nitrogen (N) fertilizer is important to achieve optimum crop yields while avoiding potential contamination of surface and ground water. A major obstacle in achieving optimum N fertilization is the difficulty of predicting soil organic N mineralization under field conditions. Since soils differ in their N?supplying capacity, there is need for a testing procedure that will enable producers
Carbon and nitrogen mineralization are decoupled in organo-mineral fractions
NASA Astrophysics Data System (ADS)
Bim³ller, Carolin; Mueller, Carsten W.; von L³tzow, Margit; Kreyling, Olivia; K÷lbl, Angelika; Haug, Stephan; Schloter, Michael; K÷gel-Knabner, Ingrid
To improve our comprehension how carbon and nitrogen mineralization are linked in soils, we used a controlled laboratory mineralization approach and compared carbon and nitrogen dynamics in the bulk soil and in soil fractions. Topsoil of a Rendzic Leptosol from a beech forest site near Tuttlingen, Germany, was fractionated into three particle size classes: sand (2000 to 20 Ąm), silt (20 to 2 Ąm), and clay (< 2 Ąm). Bulk soil and particle size fractions were incubated for 40 weeks allowing periodic destructive sampling. We monitored carbon and nitrogen mineralization dynamics, and assessed carbon respiration as well as nitrogen mineralization and microbial biomass carbon and nitrogen contents. Soil organic matter in the incubated fractions was considered by a subsequent density fractionation. The chemical composition of selected samples was qualitatively evaluated by 13C-NMR spectroscopy. When summing up the mineralization rates of the single fractions, the values for respired carbon equaled the bulk soil, whereas the mathematical recombination of mineral nitrogen in all fractions was significantly less than in bulk soil. Hence, carbon mineralization was not affected by the damage of the aggregated soil structure via fractionation, whereas nitrogen mineralization was reduced. Fractionation increased the surface area providing accessory mineral surfaces, which allowed new binding of especially nitrogen-rich compounds, besides ammonium fixation via cation exchange. Density fractionation revealed that organic matter in the sand fraction contained mainly particulate organic matter present as light material comprising partly decomposed plant remnants. The organic matter in the clay fraction was mostly adsorbed on mineral surfaces. Organic matter in the sand and in the clay fraction was dominated by O/N-alkyl C indicating low recalcitrance, but the C/N ratio of organic matter narrowed with decreasing particle size. These results also imply that the C/N ratio as well as the alkyl C to O/N-alkyl C ratio are not suitable to draw conclusions regarding biological decomposability of plant residues when characterizing soil fractions where organic matter is mainly stabilized by spatial inaccessibility and by organo-mineral interactions. The specific interactions of both carbon and nitrogen containing components with the mineral matrix strongly modulate the mineralization dynamics, leading to a decoupling of these processes.
Changes in mineral N, microbial biomass and enzyme activities in different soil depths after surface applications of dairy shed effluent and chemical fertilizer
M. Zaman; K. C. Cameron; H. J. Di; K. Inubushi
A field experiment was conducted to determine the effects of surface applications of dairy shed effluent (DSE) (effluent collected from a dairy milking shed and consists of dung, urine and water) or chemical fertilizer (NH4Cl) on N dynamics, microbial biomass C and N and extracellular enzyme activities (protease, deaminase and urease) in different soil depths. The DSE and NH4Cl were
Nitrogen mineralization in a mature boreal forest, Isle Royale, Michigan
Stottlemyer, R.; Toczydlowski, D.
The 115-ha boreal Wallace Lake watershed, located on Isle Royale in the Lake Superior Basin, receives moderate anthropogenic atmospheric N inputs (3 kg ha-1 yr-1). Ecosystem response to atmospheric N inputs is, in part, determined by internal production and consumption of this limiting nutrient. The objectives of this 2-yr study on plots dominated by birch, spruce, or alder were to quantify forest floor and surface soil net and gross N mineralization rates, and examine potential effects of changes in temperature and moisture on these processes. Gross N mineralization rates were 23 times net mineralization rates, and increased with forest floor/soil temperature and moisture. Substrate quality was a likely factor in higher gross mineralization