Science Inventory

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:

https://doi.org/10.1021/acs.est.8b04081   Exit

Record Details:

Record Type: DOCUMENT (JOURNAL/PEER REVIEWED JOURNAL)
Product Published Date: 12/09/2018
Record Last Revised: 01/29/2019
OMB Category: Other
Record ID: 343800

Organization:

U.S. ENVIRONMENTAL PROTECTION AGENCY

OFFICE OF RESEARCH AND DEVELOPMENT

NATIONAL RISK MANAGEMENT RESEARCH LABORATORY

GROUNDWATER, WATERSHEDS, AND ECOSYSTEM RESTORATION DIVISION

SUBSURFACE PROCESSES AND PROTECTION BRANCH