into the atmosphere. Nitrification and sulfide oxidation both decrease alkalinity by releasing protons as a byproduct of oxidation reactions. Throughout recent history, there have been many attempts to measure, record, and study oceanic alkalinity, together with many of the other characteristics of seawater, like temperature and salinity. These include: GEOSECS (Geochemical Ocean Sections Study), TTO/NAS (Transient Tracers in the Ocean/North Atlantic Study), JGOFS (Joint Global Ocean Flux Study), WOCE (World Ocean Circulation Experiment), CARINA (Carbon dioxide in the Atlantic Ocean). Global temporal and spatial variability The ocean's alkalinity varies over time, most significantly over geologic timescales (millennia). Changes in the balance between terrestrial weathering and sedimentation of carbonate minerals (for example, as a function of ocean acidification) are the primary long-term drivers of alkalinity in the ocean. Over human timescales, mean ocean alkalinity is relatively stable. Seasonal and annual variability of mean ocean alkalinity is very low. Alkalinity varies by location depending on evaporation/precipitation, advection of water, biological processes, and geochemical processes. Local AT can be affected by two main mixing patterns: current and river. Current dominated mixing occurs close to the shore in areas with strong water flow. In these areas, alkalinity trends follow current and have a segmented relationship with salinity. River dominated mixing also occurs close to the shore; it is strongest close to the mouth of a large river. Here, the rivers can act as either a source or a sink of alkalinity. AT follows the outflow of the river and has a linear relationship with salinity. This mixing pattern is most important in late winter and spring, because snowmelt increases the river's outflow. As the season progresses into summer, river processes are less significant, and current mixing can become the dominant process. Oceanic alkalinity also follows general trends based on latitude and depth. It has been shown that AT is often inversely proportional to sea surface temperature (SST). Therefore, it generally increases with high latitudes and depths. As a result, upwelling areas (where water from the deep ocean is pushed to the surface) also have higher alkalinity values. Interventions to add alkalinity See also Alkali soils Base (chemistry) Biological pump Dealkalization of water Global Ocean Data Analysis Project Ocean acidification References External links Holmes-Farley, Randy. "Chemistry and the Aquarium: What is Alkalinity?," Advanced Aquarist's Online Magazine. Alkalinity as it pertains to salt-water aquariums. DOE (1994) ","Handbook of methods for the analysis of the various parameters