Two sites have TCA plumes; low levels of 1,4-dioxane are present in down gradient wells in one plume. In the other, dioxane was not observed in any down gradient wells but only detected later at high concentrations in a detailed investigation of a highly anaerobic source area. No dioxane in a distal plume did not agree with the current belief that dioxane does not biodegrade under anaerobic conditions. Calculations generated from field data using other compounds as conservative tracers gave half-life estimates for dioxane of 0.5 to 1.5 years.
I did oversight on a lab study looking at dioxane degradation in site samples. Custom synthesized 14C-labeled dioxane was obtained for the study being done by Dr. David Freedman and a grad student (Francisco Barajas) at Clemson. Up to 29% 14C-labeled soluble products were observed at 137 days under an anaerobic condition (Barajas et al. 2011, 2012). CSIA was attempted to confirm biodegradation. UPDATE: Although the site was clearly anaerobic and dioxane was degraded in the field, a culture that degrades dioxane under anaerobic conditions could not be isolated. I have a theory why degradation is occurring but it is not worth pursuing given current site status, and, that if correct, is not relevant to most other dioxane sites.
