Total Alkalinity (TA)
D1. Physical and chemical oceanography and marine meteorologyDefinition
Excess of proton acceptors over proton donors in seawater.
Total alkalinity is the excess of proton acceptors over proton donors in seawater, dominated by bicarbonate and carbonate ions, measured by acid titration and expressed in microequivalents per kilogram (near 2,300 in the surface ocean). It quantifies the buffering capacity that resists pH change. Combined with DIC, pH, or pCO2 it closes the carbonate system, making TA a core variable for the ocean carbon sink and acidification.