New Paper on 1,4-Dioxane Published in Environmental Science & Technology

"Evidence of 1,4-Dioxane Attenuation at Groundwater Sites Contaminated with Chlorinated Solvents and 1,4-Dioxane"

This paper highlights results from a DoD-sponsored research project on developing appropriate management strategies for the emerging groundwater contaminant 1,4-dioxane. The study was designed to test the general hypothesis that dioxane attenuation in groundwater is limited, particularly relative to co-occurring chlorinated solvents. Using data mining, we evaluated the extent to which actual conditions at a large number of sites with dioxane-impacted groundwater reflect these assumptions. The findings of this study provide evidence that dioxane is subject to attenuation, and importantly, that this attenuation occurs at a small but significant number of field sites. At sites and wells where significant attenuation was established, the equivalent half-lives for dioxane were on the order of 2 to 5 years. For the purposes of managing these sites, these findings are positive because they indicate that dioxane plumes are behaving relatively similarly to those for certain chlorinated solvents (with the exception of TCA). Positive correlations could be established with factors that promoted biodegradation (dissolved oxygen concentration) while negative correlations could be established with factors that inhibited biodegradation (metals and CVOC concentrations). This is the first wide-ranging set of field data that confirm lab-based studies on attenuation and the conditions that favor attenuation. These results highlight that there may be a role for monitored natural attenuation as a long-term management strategy for 1,4-dioxane at some sites, although it is clear that a site-specific evaluation to identify potentially relevant destructive attenuation mechanisms would be necessary to support its selection and regulatory approval. A companion paper on 1,4-dioxane prevalence and plume lengths can be found in Adamson et al., ES&T Letters, 2014, 1(5), 254−258.

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