ABSTRACT

Abiogenic reduction of sulfate by acetic acid has been conducted at temperatures ranging from 241 to 340°C. The sulfides produced and the remaining sulfates have been chemically and isotopically quantified. The reaction of the aqueous sulfate reduction obey first-order kinetics. The rate constants are strongly dependent on temperature. The temperature dependence of the reaction rate (min^-1) is given by the following rate law: log k=-10.3×10³/T+15.1. The activation energy for the reaction of sulfate reduction is 208 kJ mol^-1. The remaining sulfates display distinct sulfur isotopic variations under a closed system due to the kinetic isotope effect. The kinetic isotope fractionation factor can be expressed as: 10³(α-1)=3.32×10⁶/T²-4.19. The kinetic isotope effects during abiogenic reduction of the sulfate may depend on the atomic hydrogen produced, independent of the reducing agents.