LOOKING FOR THE SIGNATURE OF THE
INTRINSIC BIOREMEDIATION OF BTEX IN
SUBSURFACE MICROBIAL ECOLOGY USING BIO-SEP® BIO-TRAPS
Marjorie Boone*
Kerry L. Sublette
Laura Ford
University of Tulsa
600 S College Ave.
Tulsa, OK 74104
Voice: 918-631-3334
Fax: 918-631-3268
E-mail: marjorie-boone@utulsa.edu
Anita Biernacki
Aaron Peacock
University of Tennessee
Knoxville, TN
Greg Davis
Microbial Insights
Rockford, TN
The most important mechanism of natural attenuation leading to destruction of the contaminants in groundwater is intrinsic bioremediation. It has now been clearly established that BTEX hydrocarbons are amenable to microbial degradation even in the absence of oxygen under the right conditions with respect to geochemistry, environmental parameters, and microbial ecology. More recently it has been shown that aliphatic hydrocarbons are also susceptible to anaerobic biodegradation by similar mechanisms. When clear proof of natural attenuation exists and environmental receptors will not be threatened during the life of a hydrocarbon plume, a risk-based management approach can be both cost-effective and protective of human health and ecological receptors. However, gathering the necessary evidence for natural attenuation can itself be a costly undertaking. Conventional indicators of intrinsic bioremediation include the distribution of hydrocarbons, metabolites, and the correlation of temporal trends with the concentrations and distributions of geochemical parameters (electron acceptors, products of reduction of electron acceptors, DO, alkalinity, electrical conductivity, etc.). These data are typically collected over the entire plume and in suitable control areas over a period of time at significant cost. The actual extent of site characterization required to support a risk-based management strategy varies from state to state. However, the goals remain the same: to deduce the prevalent bioprocesses in the subsurface and to determine whether natural attenuation will prevent exposure of environmental receptors to the hydrocarbon plume. With respect to the prevalent bioprocesses the key word here is deduced -- that is, these data amount to circumstantial evidence of intrinsic bioremediation. What is needed is a definitive signature. We propose that this signature lies in the in situ microbial ecology and that this signature can be obtained at a reduced cost compared to more conventional site investigations. In our research we use "bio-traps" based on Bio-Sep® beads to rapidly and efficiently collect biofilms which may be analyzed by biomarker (PLFA, DNA, respiratory quinones) analysis to characterize subsurface microbial communities.