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The oceans contain around 36,000 gigatons of carbon, mostly in the form of bicarbonate ion (over 90%, with most of the remainder being carbonate). * At the surface of the oceans towards the poles, seawater becomes cooler and more carbonic acid is formed as CO2 becomes more soluble. This is coupled to the ocean's thermohaline circulation which transports dense surface water into the ocean's interior (see the entry on the solubility pump). * Although the deep ocean contains much more dissolved inorganic carbon than the surface ocean, the concentration is only 15% higher in the deep ocean as compared to the surface ocean due to the higher volume of the deep ocean. * In upper ocean areas of high biological productivity, organisms convert reduced carbon to tissues, or carbonates to hard body parts such as shells and tests. These are, respectively, oxidized (soft-tissue pump) and redissolved (carbonate pump) at lower average levels of the ocean than those at which they formed, resulting in a downward flow of carbon (see entry on the biological pump). *The flux or absorption of carbon dioxide into the world's oceans is influenced by the presence of widespread viruses within ocean water, that infect many species of bacteria. The resulting bacterial deaths spawn a sequence of events that lead to greatly enlarged respiration of carbon dioxide, enhancing the role of the oceans as a carbon sink.〔C.Michael Hogan. 2010. (Encyclopedia of Earth. National Council for Science and the Environment ). eds. S.Draggan and C.Cleveland〕 * The balance of dissolved inorganic carbon (DIC) : dissolved organic carbon (DOC) : particle organic carbon is about 2000:38:1. * The CaCO3 counter pump increases the partial pressure of CO2 in the ocean, thus leading to higher outgasing of carbon dioxide. * The solution of CO2 in the ocean decreases the ocean's pH, leading to changes in the ecosystem and mineral weathering balance. It is expected to lower GPP, especially in corals and plankton. * Higher ocean temperatures lead to stronger layering, thus less mixing and less capacity for thermohaline circulation to bring carbon into lower ocean layers. * The weathering of silicate rock (see carbonate-silicate cycle). Carbonic acid reacts with weathered rock to produce bicarbonate ions. The bicarbonate ions produced are carried to the ocean, where they are used to make marine carbonates. Unlike dissolved CO2 in equilibrium or tissues which decay weathering does not move the carbon into a reservoir from which it can readily return to the atmosphere. * Much remains to be learned about the cycling of carbon in the deep ocean. For example, a recent discovery is that larvacean mucus houses (commonly known as "sinkers") are created in such large numbers that they can deliver as much carbon to the deep ocean as has been previously detected by sediment traps. Because of their size and composition, these houses are rarely collected in such traps, so most biogeochemical analyses have erroneously ignored them. * The amount of dissolved inorganic carbon in the ocean is significantly higher in the deep layer (below 300 m depth).〔 This is caused by the solubility pump and the biological pump. ==Movement of carbon in the ocean== CO2 is absorbed from the atmosphere at the ocean's surface and converted into dissolved inorganic carbon (DIC). It is then converted in gross primary production (GPP) by phytoplankton into organic carbon. About half of the GPP is autotrophically respirated and converted back into DIC. The rest stays in the form of net primary production (NPP). Some of the organic carbon sinks into the lower ocean levels as detritus or calcium carbonate in shells. Some soft tissue is converted into particulate organic carbon or dissolved organic carbon and, from these forms, into dissolved inorganic carbon. The rest sinks to the ocean floor. Shells out of calcium carbonate are also deposited on the ocean floor as sediment, whereas the carbon can dissolve and reach the lower ocean levels again. Thermohaline circulation can bring carbon in the deep ocean levels to the upper levels, where it can again be exchanged with the atmosphere. Units are in gigatons.〔 In the oceans, dissolved carbonate can combine with dissolved calcium to precipitate solid calcium carbonate, CaCO3, mostly as the shells of microscopic organisms. When these organisms die, their shells sink and accumulate on the ocean floor. Over time these carbonate sediments form limestone which is the largest reservoir of carbon in the carbon cycle. The dissolved calcium in the oceans comes from the chemical weathering of calcium-silicate rocks, during which carbonic and other acids in groundwater react with calcium-bearing minerals liberating calcium ions to solution and leaving behind a residue of newly formed aluminium-rich clay minerals and insoluble minerals such as quartz. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Oceanic carbon cycle」の詳細全文を読む スポンサード リンク
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