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Image : Ocean carbon chemistry and pH

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Schematic of the carbonate system species in seawater and some of the equilibrium reactions that occur among them. Seawater total alkalinity (TA) is commonly defined as “the excess base” in seawater, or the sum of excess proton acceptors, and its component ions are illustrated in light blue.  (right) Accounting of the concentrations of carbonate system species in seawater for a preindustrial atmospheric CO2 of 280 ppm (green) and twice that value (brown). The sum of carbonic acid, bicarbonate, and carbonate concentrations gives total CO2 (TCO2). pH values and saturation states of aragonite (Ω-aragonite) for this situation are also listed. These values were calculated using the “Mehrbach refit” carbonate system constants (Dickson and Millero, 1987, Deep-Sea Research), KSO4 dissociation constant from Dickson (1990, Journal of Chemical Thermodynamics), and the total pH scale. (Adapted from Joanie Kleypas, NCAR)

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Last updated: September 17, 2012