Linking AS, SE, V, and MN Behavior to Natural Biostimulated Uranium Cycling

Keimowitz, Alison¹  Ranville, James²  Mailloux, Brian³  Figueroa, Linda² 

[1] Vassar College, Poughkeepsie, NY (United States);Colorado School of Mines, Golden, CO (United States);Barnard College, New York, NY (United States)

关键词: Arsenic;    thioarsenic;    uranium;    IFRC Rifle;    remediation;   

DOI  :  10.2172/1241908
RP-ID  :  DOE-BARN--1111-1
PID  :  OSTI ID: 1241908

美国|英语

来源: SciTech Connect

【 摘 要 】

The project ???Linking As, Se, V, and Mn behavior to Natural and Biostimulated Uranium Cycling??? successfully investigated Arsenic cycling the Rifle Colorado IFRC. This project trained undergraduate and graduate students at the Colorado School of Mines, Vassar College, and Barnard College. This resulted in both undergraduate theses and a PhD thesis and multiple publications. The science was highly successful and we were able to test the main hypotheses. We have shown that (H1) under reducing conditions that promote uranium immobilization arsenic is readily mobilized, that (H2) thioarsenic species are abundant during this mobilization, and (H3) we have examined arsenic mobilization for site sediment. At the Rifle IFRC Acetate was added during experiments to immobilize Uranium. These experiments successfully immobilized uranium but unfortunately would mobilize arsenic. We developed robust sampling and analysis methods for thioarsenic species. We showed that the mobilization occurred under sulfate reducing conditions and the majority of the arsenic was in the form of thioarsenic species. Previous studies had predicted the presence of thioarsenic species but this study used robust field and laboratory methods to quantitatively determine the presence of thioarsenic species. During stimulation in wells with high arsenic the primary species were trithioarsenate and dithioarsenate. In wells with low levels of arsenic release thioarsenates were absent or minor components. Fortunately after the injection of acetate ended the aquifer would become less reducing and the arsenic concentrations would decrease to pre-injection levels. In aquifers where organic carbon is being added as a remedial method or as a contaminant the transient mobility of arsenic during sulfidogenesis should be considered especially in sulfate rich aquifers as this could impact downgradient water quality.