Different biogeochemical processes in seawater have distinct effects on dissolved inorganic carbon (DIC) and total alkalinity (TA): photosynthesis and respiration primarily change DIC (through carbon uptake or release) with only a minor, largely indirect effect on TA (via nutrient uptake/release); denitrification changes TA (through the consumption of nitrate, which affects the charge balance) without directly altering DIC; but calcium carbonate (CaCO3) precipitation or dissolution directly changes both DIC and TA simultaneously, since each mole of CaCO3 precipitated removes one mole of carbon (DIC) and two equivalents of alkalinity (TA), reflecting the stoichiometry of the carbonate mineral reaction.