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ASSESSING THE MOBILITY OF ARSENIC IN CONTAMINATED SEDIMENTS
Ford*, R G. AND R T. Wilkin*. ASSESSING THE MOBILITY OF ARSENIC IN CONTAMINATED SEDIMENTS. Presented at American Chemical Society Southwest Regional Meeting, Oklahoma City, OK, October 26 - 28, 2003.
To inform the public.
The mobility of arsenic is controlled, in part, by partitioning to mineral surfaces in soils and sediments. Determination of the risk posed to human or ecosystem health by arsenic and identification of remediation technologies that could be employed to eliminate or reduce risk is dependent on determining the processes that control arsenic mobility. This has been the focus of a field study designed to identify the physicochemical processes that control arsenic partitioning to sediments in a wetland system receiving contaminated ground water. Results from field monitoring and laboratory studies indicate that arsenic partitioning is controlled by the precipitation-dissolution cycle of Fe-bearing minerals during transfer between oxic and anoxic zones at the ground water-surface water interaction zone. In-situ water column data indicate that arsenic partitioned to Fe-bearing minerals is labile as a result of mineral instability in anoxic waters. Laboratory leaching studies with reduced sediments indicate that a portion of partitioned arsenic is released upon exposure to oxic water. These results indicate that wetland sediments do not provide a permanent sink for arsenic sequestration.