In Situ Long-term Reductive Bioimmobilization Of Cr(Ⅵ) In Groundwater Using Hydrogen Release Compound

摘要

The results of a field experiment designed to test the effectiveness of a novel approach for long-term,in situ bioimmobilization of toxic and soluble Cr(VI) in groundwater using a hydrogen release compound (HRC)-a slow release glycerol polylactate-are described.The field experiment was conducted atthe Hanford Site (Washington),a U.S.Department of Energy nuclear production facility,using a combination of hydrogeological,geophysical,geochemical,and microbiological measurements and analyses of water samples and sediments.The results of this experiment show that a single HRC injection into groundwater stimulates an increase in biomass,a depletion of terminal electron acceptors O_2,NO_3~-,and SO_4~(2-),and an increase in Fe~(2+),resulting in a significant decrease in soluble Cr(Ⅵ).The Cr(Ⅵ) concentration has remained below the background concentration in the downgradient pumping/ monitoring well,and below the detection limit in the injection well for more than 3 years after the HRC injection.The degree of sustainability of Cr(Ⅵ) reductive bioimmobilization under different redox conditions at this and other contaminated sites is currently under study.