EFFECT OF TEMPERATURE ON THE p H OF SEAWATER 1

The temperature coefficient of the p II of seawater, calculated from existing data on the carbonate system in seawater, is confirmed experimentally as +0.0114 p H units per degree Celsius at 1 atm pressure. Although pH measurements with a given system are reproducible to ±0.005 or ±0.000 p H units, direct p H measurements on seawater are accurate only to about ±0.02 p II units; hence computations of components of the carbonate system are uncertain by 1% in bicarbonate and 5% in carbonate. These uncertainties can be halved if p H values are derived from precise determination of other components of the carbonate system, such as alkalinity and total CO 2 .