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FIELD EVALUATION OF ARSENIC TRANSPORT: SPECIATION IN SEDIMENT MATERIAL
Citation:
SCHECKEL, K. G., R. G. FORD, A. G. WILLIAMS, T. LUXTON, AND P. Clark. FIELD EVALUATION OF ARSENIC TRANSPORT: SPECIATION IN SEDIMENT MATERIAL. Presented at Advanced Photon Source Science Special Interest Group, Chicago, IL, July 22, 2008.
Impact/Purpose:
To demonstrate the field application of synchrotron research in regulatory approaches at Superfund sites.
Description:
Fort Devens was established in 1917 as Camp Devens, a temporary training camp for soldiers from the New England area for WWI. Throughout its history, Fort Devens served as a training and induction center for military personnel, and as a unit mobilization and demobilization site. Fort Devens is a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) National Priorities List (NPL) (December 21, 1989) site located approximately 35 miles northwest of Boston, Massachusetts. The USEPA began efforts to assess arsenic distribution in ground water, surface water, and sediments at the Fort Devens Superfund Site within the Red Cove Study Area of Plow Shop Pond adjacent to Shepley's Hill Landfill. The sediment-water interface of Red Cove is characterized by a sharp redox boundary observed as a red-orange precipitate of iron (Fe) oxides on the shallow sections of the cove's bottom. The formation of Fe oxides at the sediment-water interface indicates an interaction between ferrous Fe originating from groundwater discharge in the cove and the oxygenated water above. Sediments within the reducing environment have the potential to act as both a source and a sink for arsenic, the contaminant of concern in the cove. In reducing environments, arsenic associated with Fe oxides has the potential to be mobilized as the oxides are reduced. In contrast, reducing environments also have the capacity to sequester arsenic through adsorption/precipitation with iron-sulfides and arsenic-sulfides if sufficient levels of sulfur are present. Due to the complex nature of arsenic attenuation in reducing environments, information regarding the elemental composition of the sediment and the speciation of arsenic in the sediment is necessary to understand its fate and transport for remediation and risk assessment. The application of synchrotron techniques aid in our understanding of arsenic at the site and the results are leading to active steps to resolve the contamination issue. This presentation will demonstrate the field application of synchrotron research in regulatory approaches at Superfund sites.