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Geochemical and Isotope Study of Trichloroethene Degradation in a Zero-Valent Iron Permeable Reactive Barrier: A Twenty-Two-Year Performance Evaluation
Citation:
Wilkin, Richard T., Tony R. Lee, M. Sexton, Steven D. Acree, R. Puls, D. Blowes, C. Kalinowski, J. Tilton, AND L. Woods. Geochemical and Isotope Study of Trichloroethene Degradation in a Zero-Valent Iron Permeable Reactive Barrier: A Twenty-Two-Year Performance Evaluation. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 53:296-306, (2019). https://doi.org/10.1021/acs.est.8b04081
Impact/Purpose:
Volatile organic compounds are the most frequently encountered groundwater contaminants at hazardous waste sites. This study examines a twenty-two-year record of performance of a groundwater remediation technology used to treat volatile organic compounds, including trichloroethene, cis-dichloroethene, and vinyl chloride. These long-term performance data will help to improve system designs and guide the selection of remedial measures that best match site-specific hydrogeochemical conditions.
Description:
This study provides a twenty-two-year record of in situ degradation of chlorinated organic compounds by a granular iron permeable reactive barrier (PRB). Groundwater concentrations of trichloroethene (TCE) entering the PRB were as high as 10,670 µg/L. Treatment efficiency ranged from 81 to >99% and TCE concentrations ranged from C4 compounds, and possibly CO2(aq) and methane. Daughter products, cis-DCE and VC, represented <10% of influent TCE on a molar basis indicating low accumulation rates of undesired chlorinated products. The carbon isotope signal of TCE showed 13C-enrichment up to 18.7‰ within treated groundwater and an estimate of the bulk enrichment factor (ε) was -14‰. The δ13C values of methane within and down-gradient of the PRB varied widely from -94‰ to -16‰; these values cover most of the isotopic range encountered in natural methanogenic systems. The carbon isotope signatures of methane and inorganic carbon were consistent with open-system behavior and 22% molar conversion of CO2(aq) to methane.
URLs/Downloads:
DOI: Geochemical and Isotope Study of Trichloroethene Degradation in a Zero-Valent Iron Permeable Reactive Barrier: A Twenty-Two-Year Performance Evaluation
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