Monday, August 18, 2008


In this section we describe about carbon cycle. There is a diagram for easyness to study.Diagram of the carbon cycle. The black numbers indicate how much carbon is stored in various reservoirs, in billions of tons . The purple numbers indicate how much carbon moves between reservoirs each year. The sediments, as defined in this diagram, do not include the ~70 million GtC of carbonate rock and kerogen.
The carbon cycle is the biogeochemical cycle by which carbon is exchanged between the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth.
The cycle is usually thought of as four major reservoirs of carbon interconnected by pathways of exchange. These reservoirs are:
The atmosphere.
The terrestrial biosphere, which is usually defined to include fresh water systems and non-living organic material, such as soil carbon.
The oceans, including dissolved inorganic carbon and living and non-living marine biota,
The sediments including fossil fuels.
The annual movements of carbon, the carbon exchanges between reservoirs, occur because of various chemical, physical, geological, and biological processes. The ocean contains the largest active pool of carbon near the surface of the Earth, but the deep ocean part of this pool does not rapidly exchange with the atmosphere.
The global carbon budget is the balance of the exchanges (incomes and losses) of carbon between the carbon reservoirs or between one specific loop (e.g., atmosphere ↔ biosphere) of the carbon cycle. An examination of the carbon budget of a pool or reservoir can provide information about whether the pool or reservoir is functioning as a source or sink for carbon dioxide.