Extent of natural attenuation of chlorinated ethenes at a contaminated site in Denmark

Abstract

Chlorinated solvents contaminated soils and aquifers are a widespread problem in industrialized countries and many require clean-up due to the risk of contaminant flow into groundwater systems. Clean-up is costly and often invasive, thus there is high interest in stimulating natural attenuation processes. For this, first an assessment of the type and extent of natural attenuation present at the site is required. Here, we present chemical, isotopic and microbial analyses of waters collected at a chlorinated ethene contaminated site in Denmark to give insights into natural attenuation processes. The data gives indication of complete reductive dechlorination by microbial communities but their extent varies greatly across short distances and between the different geological layers. The data further indicates that overall, chlorinated ethene degradation through natural attenuation is small at this site but near surface degradation due to aerobic co-metabolism or abiotic geochemical reduction could potentially play a role.