pH Decrease and Effects on the Chemistry of Seawater

Abstract

Variation in seawater pH is just one response to the increased CO2 concentration in the atmosphere due to anthropogenic activities. The decrease in pH has a significant effect on the carbonate chemistry of the ocean and causes a decrease in the calcium carbonate saturation state (Omega). Ten years of experimental pH measurements at the ESTOC station show a progressive reduction on pH in the ocean (-0.0017 +/- 0.0002 year(-1)) and its effects on its carbonate chemistry. The calcium carbonate saturation state decreases by 0.018 +/- 0.006 unit year(-1) for calcite and 0.012 +/- 0.004 unit year(-1) for aragonite. The direct consequences of the pH decrease are a decrease in the buffer capacity (-1.99 +/- 0.25 mu mol kg(-1) year(-1)) and an increase in the Revel le factor (0.02 +/- 0.002 year(-1)) of the surface seawater.