Materials Used by Organisms Are Recycled The Earth is essentially a closed chemical system through which the elements necessary for life are reused and move from abiotic reservoirs to the biota and back in global biogeochemical cycles. Some elements are held as gases in the atmosphere, others are components of the lithosphere (rocks and soil of the Earth's crust), many move through the hydrosphere (marine and freshwaters) before or after their sojourn in the biosphere (the living components). The cycles through the lithosphere are said to be sedimentary cycles (from the sedimentary rocks in which the elements reside) and are of such long duration that the elements are essentially removed from further cycling until tectonic (mountain building) or volcanic eruptions expose the rock layers to new weathering. Elements have shorter residence times in the air in the
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This note was uploaded on 11/14/2011 for the course BIO 1421 taught by Professor Farr during the Fall '08 term at Texas State.