Inhibition of sulphate reduction in anoxic marine sediment by Group VI anions

Abstract

The addition of various concentrations (1, 10 and 20 mM) of Group VI anions to sediment slurry resulted in inhibition of the rate of sulphate reduction at the two higher concentrations, the degree of inhibition being in the order of molyb-date (MoO4=)>selenate(SeO4=)>tungstate(WO4=). The addition of 20 mM concentrations of these inhibitors almost entirely eliminated sulphate reduction. Doubling the sulphate concentration while using the highest concentration of inhibitors (20 mM) led to the re-establishment of some sulphate reduction in the SeO4= and WO4= treated slurries whereas no such reversal was noticed with MoO4=. These observations suggested that SeO4= and WO4= are competitive inhibitors of sulphate reduction, while MoO4= is a non-competitive inhibitor.