7/1/2006 - 6/30/2008
- William Hickey, UW-Madison
Chlorinated aliphatic hydrocarbons (CAH) are pervasive groundwater contaminants for which enhanced reductive dechlorination (ERD) is a major bioremediation technology. A major goal of ERD is to establish conditions conducive to the late stage dechlorination processes (reduction of cisdichloroethylene (DCE) and vinyl chloride (VC) to ethene) that are essential for effective remediation. However, the microbes and microbial communities mediating these key processes in ERD are ill-defined. We will investigate these organisms and their activities in field and laboratory microcosm studies. The field site will be a CAH-contaminated aquifer located in southeastern Wisconsin, which is scheduled to begin ERD treatment (carbon source amendment) in April of 2006. Aquifer sediment and water samples will be collected prior to initiation of ERD treatment, and used to establish baseline microbiological and biogeochemical parameters. Microcosms will be established with aquifer sediments, and amended for ERD treatment as applied to the field site. Periodically, field and microcosm samples will be analyzed for CAH, CAH degradation products, biochemical markers and microbial community composition. The latter will include automated ribosomal intergenic space analysis and polymerase chain reaction analysis of reductive dehalogenase genetic markers. Integrating data from controlled microcosm tests and field tests may allow us to triangulate on particular organisms that carry out key functions in situ. We will use numerical methods to determine how dynamics in microbial community composition, biochemical markers (e.g., fermentation products) and genetic markers correlate with changes in dechlorination activity and, in doing so, potentially identify microbial and/or biochemical indicators that are useful as diagnostic tools for process assessment in the field.