The control of organic matter on microbially mediated iron reduction and arsenic release in shallow alluvial aquifers, Cambodia

ABSTRACT Microbes may play a key role in the mobilization of arsenic present in elevated concentrations within the aquifers extensively exploited for irrigation and drinking water in West Bengal, Bangladesh, and in other regions of South‐East Asia. Microcosm experiments using Cambodian sediments (which are also representative of other similar reducing aquifers containing arsenic‐rich waters) show that arsenic release and iron reduction are microbially mediated and demonstrate that the type of organic matter present, not necessarily the total abundance of organic matter, is important in controlling the rate and magnitude of microbially mediated arsenic release from these aquifer sediments. The possible role of naturally occurring petroleum in stimulating this process is also demonstrated. In addition to acting as an electron donor,…