TY - JOUR
T1 - Sulfur isotopes as indicators of amended bacterial sulfate reduction processes influencing field scale uranium bioremediation
AU - Druhan, Jennifer L.
AU - Conrad, Mark E.
AU - Williams, Kenneth H.
AU - N'Guessan, Lucie
AU - Long, Philip E.
AU - Hubbard, Susan S.
N1 - Funding Information:
ACKNOWLEDGEMENTS The study was funded by the Department of Fisheries and Oceans, Ontario Ministry of Natural Resources, Ontario Power Generation, Parks Canada and Industrial NSERC and Ontario Graduate scholarships. Field sampling was assisted by P. Addison, J. Barnucz, A. Edwards, H. Gignac, and N. Koutrilides. Fin ray sections were prepared by the Ontario Federation of Anglers and Hunters Fisheries Research Unit (Peterborough, Ontario). Comments provided by A. Dextrase and A. Timmerrnan greatly improved earlier versions of the manuscript.
PY - 2008/11/1
Y1 - 2008/11/1
N2 - Aqueous uranium (U(VI)) concentrations in a contaminated aquifer in Rifle Colorado have been successfully lowered through electron donor amended bioreduction. Samples collected during the acetate amendment experiment were analyzed for aqueous concentrations of Fe(II), sulfate, sulfide, acetate, U(VI), and δ34S of sulfate and sulfide to explore the utility of sulfur isotopes as indicators of in situ acetate amended sulfate and uranium bioreduction processes. Enrichment of up to 7% in δ34S of sulfate in down-gradient monitoring wells indicates a transition to elevated bacterial sulfate reduction. A depletion in Fe(II), sulfate, and sulfide concentrations at the height of sulfate reduction, along with an increase in the δ34S of sulfide to levels approaching the δ 34S values of sulfate, indicates sulfate limited conditions concurrent with a rebound in U(VI) concentrations. Upon cessation of acetate amendment, sulfate and sulfide concentrations increased, while δ34S values of sulfide returned to less than -20‰ and sulfate δ34S decreased to near-background values, indicating lower levels of sulfate reduction accompanied by a corresponding drop in U(VI). Results indicate a transition between electron donor and sulfate-limited conditions at the height of sulfate reduction and suggest stability of biogenic FeS precipitates following the end of acetate amendment.
AB - Aqueous uranium (U(VI)) concentrations in a contaminated aquifer in Rifle Colorado have been successfully lowered through electron donor amended bioreduction. Samples collected during the acetate amendment experiment were analyzed for aqueous concentrations of Fe(II), sulfate, sulfide, acetate, U(VI), and δ34S of sulfate and sulfide to explore the utility of sulfur isotopes as indicators of in situ acetate amended sulfate and uranium bioreduction processes. Enrichment of up to 7% in δ34S of sulfate in down-gradient monitoring wells indicates a transition to elevated bacterial sulfate reduction. A depletion in Fe(II), sulfate, and sulfide concentrations at the height of sulfate reduction, along with an increase in the δ34S of sulfide to levels approaching the δ 34S values of sulfate, indicates sulfate limited conditions concurrent with a rebound in U(VI) concentrations. Upon cessation of acetate amendment, sulfate and sulfide concentrations increased, while δ34S values of sulfide returned to less than -20‰ and sulfate δ34S decreased to near-background values, indicating lower levels of sulfate reduction accompanied by a corresponding drop in U(VI). Results indicate a transition between electron donor and sulfate-limited conditions at the height of sulfate reduction and suggest stability of biogenic FeS precipitates following the end of acetate amendment.
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U2 - 10.1021/es800414s
DO - 10.1021/es800414s
M3 - Article
C2 - 19031870
AN - SCOPUS:55349119486
VL - 42
SP - 7842
EP - 7849
JO - Environmental Science & Technology
JF - Environmental Science & Technology
SN - 0013-936X
IS - 21
ER -