Carbon and Chlorine Isotope Fractionation During Microbial Degradation of Tetra- and Trichloroethene

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• 作者：Charline Wiegert ; Manolis Mandalakis ; Tim Knowles ; Paraskevi N. Polymenakou ; Christoph Aeppli ; Ji艡ina Mach谩膷kov谩 ; Henry Holmstrand ; Richard P. Evershed ; Richard D. Pancost ; 脰rjan Gustafsson
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2013
• 出版时间：June 18, 2013
• 年：2013
• 卷：47
• 期：12
• 页码：6449-6456
• 全文大小：332K
• 年卷期：v.47,no.12(June 18, 2013)
• ISSN：1520-5851

文摘

Two-dimensional compound-specific isotope analysis (2D-CSIA), combining stable carbon and chlorine isotopes, holds potential for monitoring of natural attenuation of chlorinated ethenes (CEs) in contaminated soil and groundwater. However, interpretation of 2D-CSIA data sets is challenged by a shortage of experimental Cl isotope enrichment factors. Here, isotope enrichments factors for C and Cl (i.e., 蔚_C and 蔚_Cl) were determined for biodegradation of tetrachloroethene (PCE) and trichloroethene (TCE) using microbial enrichment cultures from a heavily CE-contaminated aquifer. The obtained values were 蔚_C = 鈭?.6 卤 0.7鈥?(95% CI) and 蔚_Cl = 鈭?.0 卤 0.5鈥?for PCE degradation and 蔚_C = 鈭?.8 卤 0.2鈥?and 蔚_Cl = 鈭?.5 卤 0.5鈥?for TCE degradation. Combining the values for both 蔚_C and 蔚_Cl yielded mechanism-diagnostic 蔚_Cl/蔚_C ratios of 0.35 卤 0.11 and 0.37 卤 0.11 for the degradation of PCE and TCE, respectively. Application of the obtained 蔚_C and 蔚_Cl values to a previously investigated field site gave similar estimates for the fraction of degraded contaminant as in the previous study, but with a reduced uncertainty in assessment of the natural attenuation. Furthermore, 16S rRNA gene clone library analyses were performed on three samples from the PCE degradation experiments. A species closely related to Desulfitobacterium aromaticivorans UKTL dominated the reductive dechlorination process. This study contributes to the development of 2D-CSIA as a tool for evaluating remediation strategies of CEs at contaminated sites.