Aerobic Biodegradation of Chlorinated Ethenes in a Fractured Bedrock Aquifer: Quantitative Assessment by Compound-Specific Isotope Analysis (CSIA) and Reactive Transport Modeling

A model-based analysis of concentration and isotope data was carried out to assess natural attenuation of chlorinated ethenes in an aerobic fractured bedrock aquifer. Tetrachloroethene (PCE) concentrations decreased downgradient of the source, but constant δ13C signatures indicated the absence of PC...

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Bibliographic Details
Published in:Environmental science & technology 2009-10, Vol.43 (19), p.7458-7464
Main Authors: Pooley, Kathryn E, Blessing, Michaela, Schmidt, Torsten C, Haderlein, Stefan B, MacQuarrie, Kerry T. B, Prommer, Henning
Format: Article
Language:English
Subjects:
Aerobiosis
Applied sciences
Aquifers
Biodegradation
Biodegradation, Environmental
Chemical compounds
Earth Sciences
Environmental Modeling
Ethylene
Ethylenes - chemistry
Exact sciences and technology
Hydrocarbons, Chlorinated - chemistry
Isotopes
Models, Chemical
Pollution
Sciences of the Universe
Water - chemistry
Water Pollutants, Chemical - chemistry
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Summary:A model-based analysis of concentration and isotope data was carried out to assess natural attenuation of chlorinated ethenes in an aerobic fractured bedrock aquifer. Tetrachloroethene (PCE) concentrations decreased downgradient of the source, but constant δ13C signatures indicated the absence of PCE degradation. In contrast, geochemical and isotopic data demonstrated degradation of trichloroethene (TCE) and cis-1,2-dichloroethene (DCE) under the prevailing oxic conditions. Numerical modeling was employed to simulate isotopic enrichment of chlorinated ethenes and to evaluate alternative degradation pathway scenarios. Existing field information on groundwater flow, solute transport, geochemistry, and δ13C signatures of the chlorinated ethenes was integrated via reactive transport simulations. The results provided strong evidence for the occurrence of aerobic TCE and DCE degradation. The chlorinated ethene concentrations together with stable carbon isotope data allowed us to reliably constrain the assessment of the extent of biodegradation at the site and plume simulations quantitatively linked aerobic biodegradation with isotope signatures in the field. Our investigation provides the first quantitative assessment of aerobic biodegradation of chlorinated ethenes in a fractured rock aquifer based on compound specific stable isotope measurements and reactive transport modeling.
ISSN:0013-936X
1520-5851
DOI:10.1021/es900658n