Dissolved inorganic carbon organic pools

The CO2 in both reactions initially entered the dissolved inorganic carbon (DIG) pool of seawater and was subsequently released to the atmosphere at an annual rate of about 0.2 x lO t of carbon as CO2 gas. It should be recognized that this is a small number compared with the 200xl0 t of carbon that exchanges between the ocean and atmosphere each year because of primary production of organic matter and its subsequent respiration. 

Figure 3. Idealized carbon isotope cycle in a small stratified lake. The isotopic composition of organic matter buried in sediments is determined by the proportions of different terrestrial and lacustrine organic mailer. Ihccartron isotopic composition of dissolved inorganic carbon (DlC), and the rates of primary production and respiration within the water column. Isotope enrichment factors (e), listed here as the difference between the product and the substrate, vary with the form of DlC that lake algae assimilate (e.g., C02(aq) or HCOy ). Inorganic carbonate (CaC03> typically forms in isotopic equilibrium with the dissolved inorganic carbon pool and. as such, is indirectly affected by organic matter sources and primary production and respiration rales.

Dissolved organic carbon (DOC) is the second largest pool (685 Gt C) of carbon in the ocean, the same size as the inorganic carbon in the atmosphere. The pool of particulate organic carbon (POC), although small, is active in exchanging with other phases of oceanic carbon. 

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