Assessment of TCE Oxidation by KMnO4 using Stable Carbon and Chlorine Isotopes at a Fractured Bedrock Site

The oxidation of chlorinated ethenes by potassium permanganate (KMnO4) is increasingly being used to remediate contaminated ground water. Typically the remediation of these sites is assessed by tracking changes in the concentrations of the chlorinated compounds and the chloride produced by the reaction. However, this method can be problematic in a fractured bedrock environment, due to the inherent complexity of the fracture network and the injection process that can displace contaminant mass and result in erroneous determinations. In this study, carbon and chlorine isotopes were tested to monitor the oxidation of trichloroethene (TCE) by potassium permanganate at a fractured limestone site. Laboratory experiments were performed to evaluate isotope enrichment factors, and the isotopic composition of a TCE plume was monitored under pre-injection and post-injection conditions.