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Biogeochemical Barriers: Redox Behavior of Metals and Metalloids
WILKIN, R. T. Biogeochemical Barriers: Redox Behavior of Metals and Metalloids. In Proceedings, The American Geophysical Union 2008, San Francisco, CA, December 15 - 19, 2008. American Geophysical Union, Washington, DC, 53, (2008).
Monitoring oxidation-reduction processes in groundwater systems.
Redox conditions and pH are arguably the most important geochemical parameters that control contaminant transport and fate in groundwater systems. Oxidation-reduction (redox) reactions mediate the chemical behavior of both inorganic and organic chemical constituents by affecting solubility, reactivity, and bioavailability. In recent years, innovative technologies have emerged to meet groundwater cleanup goals that take advantage of the redox behavior of contaminant species. Remedial technologies that strategically manipulate subsurface redox conditions may emphasize reductive processes, as in subsurface permeable reactive barriers, or, oxidative processes, as in permanganate injection. The speciation and mobility of inorganic contaminants can be directly impacted by redox conditions (e.g., arsenic, selenium) or can be indirectly tied to redox conditions in cases where complexation or metal precipitation (e.g., Pb, Cd, Ni) occurs with some other redox-sensitive element (e.g., sulfur). Monitoring oxidation-reduction processes in groundwater systems is frequently challenging and should be viewed as an integrated assessment of hydrogeochemical processes, microbiological diversity, and aquifer characteristics. The presentation will discuss some of the approaches of applying field data with geochemical models. A case study site with over two decades of groundwater monitoring data will also be used to explore the contrasting redox behaviors of metals (Pb, Cd) and selected oxyanion species (As, Se).
Record Details:Record Type: DOCUMENT (PAPER IN NON-EPA PROCEEDINGS)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL RISK MANAGEMENT RESEARCH LABORATORY
GROUND WATER AND ECOSYSTEMS RESTORATION DIVISION