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IDENTIFYING THE SIGNATURE OF THE NATURAL ATTENUATION IN THE MICROBIAL ECOLOGY OF HYDROCARBON CONTAMINATED GROUNDWATER USING MOLECULAR METHODS AND “BUG TRAPS”
Impact/Purpose:
Specifically we proposed to search for the signature of MTBE intrinsic bioremediation in the microbial ecology of the contaminated groundwater. BP, in collaboration with EPA, recently conducted an extensive survey of 74 BP retail sites with gasoline spills. Some of these sites indicated MTBE attenuation and others did not. Working with BP we will investigate and compare the in situ microbial ecologies of a subset of these sites using "bug traps" which concentrate organisms for analysis and provide a time-integrated picture of the subsurface microbial community. Further we will supplement this field work with an analysis of the microbial ecology of microcosms currently operated in the laboratory of Dr. Joe Suflita (University of Oklahoma). Microcosms positive for MTBE biodegradation will be sampled using the same bug traps used in the field sampling.
It is hypothesized that the in situ microbiota contain a signature of past and present MTBE exposure and utilization. A comprehensive measure of the in situ microbial ecology of a site will yield the identity of this signature. We maintain that a definition of MTBE natural attenuation in terms of a site's microbial ecology is direct and definitive, whereas a definition in terms of contaminant chemistry and/or geochemistry or hydrology is indirect and inferential. It is well established that indigenous microbes generate various compounds within their cellular structure (biomarkers) that reflect in situ conditions. Therefore, the microbial community contains a record of the sum microbial response to the environment that is written from changes in the biochemistry of individual organisms. We propose that these responses, in association with knowledge of available electron acceptors and donors of a site, will define the signature of a successful MTBE natural attenuation process.
Description:
These related projects have combined biological molecular methods and a novel passive sampling system (bio-trap) to produce a technology that will allow the active component of any contaminated groundwater microbial community to be investigated. Conventional sampling methods cannot effectively distinguish between microbes that are actively growing and those that are dormant. These methods lead to a better understanding of the progress and process of intrinsic bioremediation of hydrocarbons and MTBE and significantly contribute to effective site management. These bio-traps are now a commercially available product.