What are global biogeochemical cycles?
Environmental scientists recognize that the chemical elements that compose the Earth are not held in static compartments. Clearly, large quantities of the atmosphere and oceans are transported by the fluid movements of these bodies, which determine our daily weather patterns and the major ocean currents such as the Gulf Stream. However, even the solid materials of the Earthits crust and mantlecirculate by the processes that cause mountains to rise from the seafloor and rock materials to break down, delivering dissolved constituents to the sea. For every chemical element of the periodic table, we can outline a global cycle of its movement between the land, the atmosphere, and the oceans. We can compile measurements from studies around the world to estimate the annual transport of materials between these compartments, usually in units of tons/year. There are two broad categories of global cycles: sedimentary cycles and biological cycles. Geologic processes determine the movement of eleme
