Presentation on theme: "Biogeochemistry and Biogeochemical Cycles"— Presentation transcript:
1Biogeochemistry and Biogeochemical Cycles Definitions:“…the more or less circular transfer of chemical elements from the (abiotic) environment to the organisms and from organisms back to the (abiotic) environment.” Odum, 1971.“the study of the controls on the concentrations and cycling of elements in and above the earth’s crust by the synthesis, death and decomposition of organisms.” Gorham, 1991.Examples:carbon, nitrogen, sulfur, Fe, Mn, etc.
2Big PictureOver the ‘long term’, biogeochemical cycling has played a fundamental role in planetary evolution on Earth (especially the atmosphere and hydrosphere). Example: rise of O2 in Earth’s atmosphere.At present, many biogeochemical cycles are effectively treated as dynamic equilibria among cycled materials.Anthropogenic effects are measurable.
15Residence Time (steady state) Response Time (non steady-state) Definition: Average time the substance spends in the reservoir. It is the time required to double the concentration in a reservoir (if output ceased).Ri = amti in reservoir/fluxi Example residence times: water in atmosphere: 11 days water in ocean: 3550 yrMaterials can be imported and exported from ecosystems and long-term storage pools.
21Major, Minor, and Trace Elements in Biogeochemical Cycles Major elemental components of living organisms (C, H, O, N, P, S)Carbohydrates, proteins, lipids, nucleic acidsMinor elements: Ca, K, Mg, Na, SiTrace elements: B, Co, Cr, Cu, Fe, Mn, Mo, Ni, Se, Sn, V, Zn, REEsCa and Si are only minor components of protoplasm, but are major components of exo and endoskeletons of microorgs and macroorgsFe, Mn, N, S are also cycled rapidly via redox processes which may not be directly coupled to the production and decay of organic matter