were restated and popularized by the British scientist and writer, James Lovelock, under the label of the Gaia Hypothesis. Lovelock emphasized a concept that life processes regulate the Earth through feedback mechanisms to keep it habitable. The research of Manfred Schidlowski was concerned with the biochemistry of the Early Earth. Biogeochemical cycles Biogeochemical cycles are the pathways by which chemical substances cycle (are turned over or moved through) the biotic and the abiotic compartments of Earth. The biotic compartment is the biosphere and the abiotic compartments are the atmosphere, hydrosphere and lithosphere. There are biogeochemical cycles for chemical elements, such as for calcium, carbon, hydrogen, mercury, nitrogen, oxygen, phosphorus, selenium, iron and sulfur, as well as molecular cycles, such as for water and silica. There are also macroscopic cycles, such as the rock cycle, and human-induced cycles for synthetic compounds such as polychlorinated biphenyls (PCBs). In some cycles there are reservoirs where a substance can remain or be sequestered for a long period of time. Research Biogeochemistry research groups exist in many universities around the world. Since this is a highly interdisciplinary field, these are situated within a wide range of host disciplines including: atmospheric sciences, biology, ecology, geomicrobiology, environmental chemistry, geology, oceanography and soil science. These are often bracketed into larger disciplines such as earth science and environmental science. Many researchers investigate the biogeochemical cycles of chemical elements such as carbon, oxygen, nitrogen, phosphorus and sulfur, as well as their stable isotopes. The cycles of trace elements such as the trace metals and the radionuclides are also studied. This research has obvious applications in the exploration for ore deposits and oil, and in remediation of environmental pollution. Some important research fields for biogeochemistry include: modelling of natural systems soil and water acidification recovery processes eutrophication of surface waters carbon sequestration environmental remediation global change climate change biogeochemical prospecting for ore deposits soil chemistry chemical oceanography See also Acid rain Atlantic Data Base for Exchange Processes at the Deep Sea Floor Carbon sink Ecosystem model Edaphology Environmental engineering science Geochemistry Geophysiology GEOTRACES Hydrogen isotope biogeochemistry IMBER Marine biogeochemical cycles Pedology Physical impacts of climate change References Representative books and publications Vladimir I. Vernadsky, 2007, Essays on Geochemistry and the Biosphere, tr. Olga Barash, Santa Fe, NM, Synergetic Press, (originally published in Russian in 1924) Schlesinger, W. H. 1997. Biogeochemistry: An Analysis of Global Change, 2nd edition. Academic Press, San Diego,