Biotic and Abiotic Controls on Arsenic Concentration and Speciation in Groundwater

Peters, Stephen C, Ann Arbor MI

Investigators

Abstract

0000530 Peters The main goal of this study is to characterize the degree to which biotic and abiotic mechanisms control the concentration and speciation of arsenic in groundwater. One explanation for observed variations is that sulfide minerals are inorganically dissolving under varying redox conditions. Another possible cause may be spatially variable catalysis of dissolution processes by microbial communities. Either of these two mechanisms or some combination may explain the observed heterogeneity of arsenic concentration and speciation measurements in groundwater wells. This work will provide information that will aid in making more informed decisions with respect to the management and remediation of arsenic-affected regions. For example, if bacterial activity can be shown to catalyze the reaction of a more harmful species of arsenic into a less harmful one, then one effective remediation plan might involve encouraging such activity. Similarly, if it is discovered that the inorganic process of pyrite dissolution limited by oxygen diffusion primarily controls arsenic concentration, then corrective action might involve drilling deeper wells to obtain unoxygenated water.