HR: 1340h
AN: H53A-1200    [Abstracts]
TI: Geochemical Factors Affecting Release of U(VI) from Soils
AU: * Zheng, Z
EM: zzuoping@lbl.gov
AF: Lawrence Berkeley National Laboratory, One Cycltron Road, Berkeley, CA 94720 United States
AU: wan, j
EM: jwan@lbl.gov
AF: Lawrence Berkeley National Laboratory, One Cycltron Road, Berkeley, CA 94720 United States
AB: Abstract: The retention, mobility, and bio-availability of U(VI) in contaminated soils depend strongly on release of U(VI). In this study, laboratory batch experiments were performed to evaluate the factors controlling the release of U(VI) from contaminated soil at the U.S. Department of Energy' Oak Ridge site. We found that the ionic strength of the extraction solution strongly affects release of U(VI). Increase in ionic strength shows a strong effect on U(VI) release as indicated by the increase in release rates and associated release mass of U(VI). We also found that the ratio of solution volume to solid mass (V/M) has a significant impact on the release of U(VI). Increase in the V/M ratio shows a negligible effect on the U(VI) release in a short period (4-day period). However, in the longer time (from 30 to 120 days), larger V/M ratios yield greater U(VI) release. The maximum U(VI) concentrations observed in the release experiments are in the range of schoepite solubility estimated under conditions relevant to the experiments, suggesting that schoepite solubility primarily controls the U(VI) release, but that solubilization and desorption effects cannot be distinguished using macroscopic methods.
DE: 1030 Geochemical cycles (0330)
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting