Geochemical carbon cycle, major

Major Biological Processes within the Geochemical Carbon Cycle. 

Figure 1.5 extends this notion to the geochemical level which shows an estimate of the influence of the global biosphere carbon and oxygen cycles on the fluxes of major elements through the terrestrial reservoirs, and includes the effects of both primary and secondary biogeochemical processes. 

Humic substances are clearly the major constituent of organic matter in lake sediments and therefore should play the central role in the geochemical cycle of carbon compounds in lakes, lake sediments, and sedimentary rocks. The characteristics and geochemistry of humic substances in lake sediments is described in this work by citing research done by the author and his coworkers, some of which is unpublished. 

Of the major volatile elements described above, water, a variety of carbon compounds, nitrogen and sulfur are the volatile compounds which dominate in the modern Earth. In this section we review the modern-Earth geochemical cycles for water, carbon, nitrogen, and sulfur and look in some detail at volatile mass balances between the Earth s surface reservoirs and the deep Earth. Then, having established how the modern Earth works we seek to determine how these geochemical cycles might have operated in the early Earth. 

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