Elucidating the Role of Carbon Sources on Abiotic and Biotic Release of Arsenic into Cambodian Aquifers.

Arsenic (As) is a naturally occurring contaminant in Cambodia that has been contaminating well-water sources and poisoning millions of people. Typical studies look into the biotic factors that cause the arsenic to be released from aquifer sediments to groundwater. However, abiotic release of As from sediments, though little studied, could also play a key role in As contamination of well water. The goal of this research is to quantitatively compare organic-carbon mediated abiotic and biotic release of arsenic from sediments to groundwater. Batch anaerobic incubation experiments under abiotic and biotic conditions are being conducted using Cambodian aquifer sediments, four different organic carbon sources,Êand six different carbon concentrations. Dissolved arsenic concentrations in the treatments are being measured over time Êthrough 112 days of incubations. Carbon mass balance is being assessed by measuring the sediment carbon and total and inorganic carbon for the solution. Collectively, these results are expected to show how different carbon sources, different carbon concentrations, and how abiotic and biotic factors impact the release of arsenic from Cambodian sediments into aquifers.