Influence of Sulfate Reduction on Arsenic Migration and Transformation in Groundwater Environment

Abstract

The sulfate-reducing bacteria-mediated reduction process is considered to be an important mechanism affecting arsenic migration and transformation in anaerobic environments. To investigate the effect of sulfate-reducing bacteria in a high-arsenic aquifer on arsenic migration and transformation, the typical sulfate-reducing bacteria Desulfovibrio vulgaris was selected for micro-cosmic experiments to simulate a groundwater environment with or without sulfate amendment. The reduction of Fe(III) and As(V) by Desulfovibrio vulgaris was identified, and Fe(III) and As(V) were reduced in both sulfate-free and sulfate-containing systems. However, the addition of 1 mM sulfate significantly enhanced Fe(III) and As(V) reduction. Compared with no sulfate addition, 1 mM sulfate increased the reduction rates of Fe(III) and As(V) by 111.9% and 402.2%, respectively. The sulfate process mediated by Desulfovibrio vulgaris also remarkably promoted arsenic release in sediments. These results indicated that sulfate concentration should be considered when sulfate reduction is used as a remediation method for arsenic pollution in groundwater.