Carbonate System
D1. Physical and chemical oceanography and marine meteorologyDefinition
Equilibrium chemistry of CO2, bicarbonate, carbonate, and pH in seawater.
The marine carbonate system is the coupled equilibrium of dissolved CO2, carbonic acid, bicarbonate, and carbonate ions that buffers seawater pH and governs air-sea CO2 exchange. Bicarbonate dominates, holding most of the dissolved inorganic carbon. Knowing any two of the four measurable parameters (DIC, total alkalinity, pH, and pCO2) fixes the rest, which is how the ocean carbon sink and acidification are quantified from ship and float data.