ABSTRACT

Reaction between sodium sulfate and acetic acid under hydrothermal conditions has been investigated in order to demonstrate the thermochemical reduction of seawater sulfate by organic matter at moderate temperatures during diagenesis. Although no reduction of sodium sulfate occurred directly, the sulfate was reduced by acetic acid to hydrogen sulfide in the presence of native sulfur over the temperature range of 200–270°C. The sulfur isotopic behavior of sulfur compounds suggests that the isotope fractionations are not controlled by kinetic isotope effects but rather by the isotope exchange reaction between the sulfate and sulfide.