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

E. Kathryne Pooley (1, 2) , Michaela Blessing (1, 3) , Torsten C Schmidt (1) , Stefan B. Haderlein (1) , Kerry T. B. Macquarrie (4) , Henning Prommer (5, 6)

1 ZAG - Center for Applied Geoscience
2 Infrastructure and Environment
3 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)
4 UNB Civil Engineering - Department of Civil Engineering
5 CSIRO Land and Water
6 School of Earth and Environment

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 aerobicTCEandDCEdegradation. 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.

Domaines: Planète et Univers [physics]; Sciences de la Terre

E. Kathryne Pooley, Michaela Blessing, Torsten C Schmidt, Stefan B. Haderlein, Kerry T. B. Macquarrie, et al.. Aerobic Biodegradation of Chlorinated Ethenes in a Fractured Bedrock Aquifer: Quantitative Assessment by Compound-Specific Isotope Analysis (CSIA) and Reactive Transport Modeling. Environmental Science and Technology, 2009, 43 (19), p. 7458-7464. ⟨10.1021/es900658n⟩. ⟨hal-00516258⟩