Characterization of the relationship between microbial degradation processes at a hydrocarbon contaminated site using isotopic methods

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• 作者：Stefan Feisthauer^a ; Martin Seidel^a ; Petra Bombach^a ; ^{petra.bombach@ufz.de} ; Sebastian Traube^a ; Kay Kn&ouml ; ller^b ; Martin Wange^c ; Stefan Fachmann^c ; Hans H. Richnow^a
• 关键词：Isotope fractionation ; Electron transfer ; BTEX ; Methanogenesis ; Sulfate reduction ; Crude oil contaminated aquifer
• 刊名：Journal of Contaminant Hydrology
• 出版年：2012
• 期刊代码：43_01697722
• 类别：env
• 出版时间：15 May, 2012
• 卷：133
• 期：Complete
• 页码：17-29
• 文件大小：1068 K

摘要

Decisions to employ monitored natural attenuation (MNA) as a remediation strategy at contaminated field sites require a comprehensive characterization of the site-specific biodegradation processes. In the present study, compound-specific carbon and hydrogen isotope analysis (CSIA) was used to investigate intrinsic biodegradation of benzene and ethylbenzene in an aquifer with high levels of aromatic and aliphatic hydrocarbon contamination. Hydrochemical data and isotope fractionation analysis of sulfate and methane was used complementarily to elucidate microbial degradation processes over the course of a three year period, consisting of six sampling campaigns, in the industrial area of Wei脽andt-G枚lzau (Saxony-Anhalt, Germany).

Enrichment of ¹³C and ²H isotopes in the residual benzene and ethylbenzene pool downgradient from the pollution sources provided evidence of biodegradation of BTEX compounds at this site, targeting both compounds as the key contaminants of concern. The enrichment of heavy sulfur isotopes accompanied by decreasing sulfate concentrations and the accumulation of isotopically light methane suggested that sulfate-reducing and methanogenic processes are the major contributors to overall biodegradation in this aquifer. Along the contaminant plume, the oxidation of methane with 未¹³C_CH4 values of up to + 17.5鈥?was detected. This demonstrates that methane formed in the contaminant source can be transported along groundwater flow paths and be oxidized in areas with higher redox potentials, thereby competing directly with the pollutants for electron acceptors. Hydrochemical and isotope data was summarized in a conceptual model to assess whether MNA can be used as viable remediation strategy in Wei脽andt-G枚lzau. The presented results demonstrate the benefits of combining different isotopic methods and hydrochemical approaches to evaluate the fate of organic pollutants in contaminated aquifers.