2008 Joint Annual Meeting (5-9 Oct. 2008): Attenuation of Hexavalent Chromium in the Vadose Zone and Regional Aquifer, Los Almaos, New Mexico
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239-8 Attenuation of Hexavalent Chromium in the Vadose Zone and Regional Aquifer, Los Almaos, New Mexico



Tuesday, 7 October 2008: 9:45 AM
George R. Brown Convention Center, 352DEF
Mei Ding1, Patrick A. Longmire2, Dave Vaniman3, David Broxton3, Danny Katzman4, Michael Rearick5, Brian N. Spall6, John R. Bargar7 and Samuel M. Webb8, (1)EES-6 Group, Earth and Environmental Science Division, Los Alamos National Lab, Los Alamos, NM 87545
(2)Hydrology, Geochemistry, and Geology Group, Los Alamos National Laboratory, Mail Stop D469, Los Alamos, NM 87545
(3)Hydrology, Geochemistry, and Geology Group, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545
(4)Water Stewardship Program, Los Alamos National Laboratory, MS M992, Los Alamos, NM 87545
(5)Earth and Environmental Sciences Division, Los Alamos National Laboratory, MS D469, Los Alamos, NM 87545
(6)Hydrology, Geochemistry, and Geology Group, Los Alamos National Laboratory, Mail Stop T003, Los Alamos, NM 87545
(7)Stanford Synchrotron Radiation Laboratory, 2575 Sand Hill Rd, Menlo Park, CA 94025
(8)Stanford Synchrotron Radiation Laboratory, Stanford Linear Accelerator Ctr, Building 137, MS 69, 2575 Sand Hill Road, Menlo Park, CA 94025
Adsorption coefficients of Cr(VI) in vadose zone and aquifer materials were measured as part of ongoing environmental investigations that address fate and transport of chromium(VI) originating in Sandia Canyon, Los Alamos, NM. Here, we present our initial findings of the characterization of vadose zone and regional aquifer materials with regard to their Cr(VI) retention capacity. We also present an assessment of the role of naturally occurring adsorbents present in the subsurface media such as clay minerals, ferric (oxy)hydroxide, and calcium carbonate on the adsorption of Cr(VI) under relevant field conditions. The results of our studies (1) directly assess the relation between mineralogical and geochemical characterization and transport behavior of Cr(VI) in the hydrogeological setting of interest, (2) provide site-specific adsorption and precipitation parameters obtained through experiments to refine the fate and transport modeling of chromium in the vadose zone and regional aquifer, and (3) reveal the mechanisms of chromate retention processes within the geomedia of interest.
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