Timing the Onset of Sulfate Reduction over Multiple Subsurface Acetate Amendments by Measurement and Modeling of Sulfur Isotope Fractionation

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• 作者：Jennifer L. Druhan ; Carl I. Steefel ; Sergi Molins ; Kenneth H. Williams ; Mark E. Conrad ; Donald J. DePaolo
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2012
• 出版时间：August 21, 2012
• 年：2012
• 卷：46
• 期：16
• 页码：8895-8902
• 全文大小：375K
• 年卷期：v.46,no.16(August 21, 2012)
• ISSN：1520-5851

文摘

Stable isotope fractionations of sulfur are reported for three consecutive years of acetate-enabled uranium bioremediation at the US Department of Energy鈥檚 Rifle Integrated Field Research Challenge (IFRC) site. The data show a previously undocumented decrease in the time between acetate addition and the onset of sulfate reducing conditions over subsequent amendments, from 20 days in the 2007 experiment to 4 days in the 2009 experiment. Increased sulfide concentrations were observed at the same time as 未³⁴S of sulfate enrichment in the first year, but in subsequent years elevated sulfide was detected up to 15 days after increased 未³⁴S of sulfate. A biogeochemical reactive transport model is developed which explicitly incorporates the stable isotopes of sulfur to simulate fractionation during the 2007 and 2008 amendments. A model based on an initially low, uniformly distributed population of sulfate reducing bacteria that grow and become spatially variable with time reproduces measured trends in solute concentration and 未³⁴S, capturing the change in onset of sulfate reduction in subsequent years. Our results demonstrate a previously unrecognized hysteretic effect in the spatial distribution of biomass growth during stimulated subsurface bioremediation.