NH3 gas treatment of low water content sediments resulted in a significant decrease in aqueous and adsorbed uranium, which is attributed to incorporation into precipitates. Uranium associated with carbonates showed little change. Uranium associated with hydrous silicates such as Na-boltwoodite showed a significant decrease in mobility but no change in Na-boltwoodite concentration (by EXAFS/XANES), so is most likely caused by non-U precipitate coatings. Complex resistivity changes occurred in the sediment during NH3 and subsequent N2 gas injection, indicating ERT/IP could be used at field scale for injection monitoring.
Revised: February 12, 2013 |
Published: October 30, 2012
Citation
Szecsody J.E., M.J. Truex, L. Zhong, T.C. Johnson, N. Qafoku, M.D. Williams, and W.J. Greenwood, et al. 2012.Geochemical and Geophysical Changes during Ammonia Gas Treatment of Vadose Zone Sediments for Uranium Remediation.Vadose Zone Journal 11, no. 4.PNNL-SA-86840.doi:10.2136/vzj2011.0158