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1.1: What is biogeochemistry?
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1.2: Chemistry and Energetics of the Life Process
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About a third of the chemical elements cycle through living organisms, which are responsible for massive deposits of silicon, iron, manganese, sulfur, and carbon. Large quantities of methane and nitrous oxide are introduced into the atmosphere by bacterial action, and plants alone inject about 400,000 tons of volatile substances (including some metals) into the atmosphere annually.
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1.3: Systems, Cycles, Reservoirs, and Fluxes
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Thinking about the Earth as a system has become, in recent years, much in vogue.
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1.4: Gaia - Bioregulation of the Environment
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The physical conditions under which life as we know it can exist encompass a relatively narrow range of temperature, pH, osmotic pressure, and ultraviolet radiation intensity. It seems remarkable enough that life was able to get started at all; it is even more remarkable that it has continued to thrive in the face of all the perils that have, or could have occurred, during the past 3 billion years or so.