EPA Grant Number: R827015-01-0
Title: Continuation of an Investigation into the Anaerobic Intrinsic Bioremediation of Whole Gasoline
Investigators: Joseph Suflita, G. Todd Townsend
Institution: University of Oklahoma
EPA Project Officer: Bala Krishnan
Project Period: March 1, 2001 to February 28, 2002 (N/C Ext. to August 28, 2002)
Project Amount: $111,344
Research Category: Intrinsic bioremediation/natural attenuation
Technical Abstract: The reliance upon intrinsic bioremediation for the removal of spilt gasoline hydrocarbons has gained increased acceptance as our understanding of the underlying microbial processes has evolved. Regulators and site operators are faced with the difficult challenge of determining which sites are amenable to intrinsic bioremediation and which will require a more active and costly remediation effort. Furthermore, despite the demonstration of the anaerobic biodegradation of a wide range of petroleum hydrocarbons, the acceptance of intrinsic bioremediation as a remedy for petroleum contamination is largely limited to BTEX compounds. Finally, intrinsic bioremediation has not been without controversy and its detractors, many of who view intrinsic bioremediation as a "do-nothing" approach that does not aggressively remediate sites and thus protect public health and the environment. All of these issues are influenced by the inherent difficulty in measuring the biodegradation of hydrocarbon mixtures in the environment.
This proposal is a request to continue and extend an ongoing study on the anaerobic biodegradation of whole gasoline. Specifically, it will address i) the anaerobic removal of BTEX hydrocarbons in the presence of other HC co-contaminants, ii) the prospects for the biodegradation of non-BTEX hydrocarbons present in gasoline spills, iii) the influence of alternate electron acceptors on these processes, iv) the identification of the most recalcitrant components of gasoline as possible biomarkers of anaerobic decay, and v) the identification of unique metabolites of anaerobic hydrocarbon biodegradation. The project will use sediments from a site contaminated by gas condensate that has demonstrated robust anaerobic hydrocarbon biodegradative activities. The removal of over fifty individual components of gasoline will be monitored along with the concurrent consumption of electron acceptors and/or production of reduced products. Extended incubation of the ongoing experiments (> two years) will allow us to define the limits of anaerobic gasoline bioremediation and provide an assessment of gasoline decay under realistic conditions. Furthermore, the initial sequence of anaerobic attack on the most labile fraction of gasoline will be determined during a shorter, forty-day incubation. As unequivocal indicators of hydrocarbon decay, unique novel metabolites of anaerobic biodegradation will be identified by GCMS analysis in parallel incubations. The development of more sophisticated tools to assess intrinsic bioremediation is needed to make sound Risk Based Corrective Action assessments. To this end, we aim to identify both the most recalcitrant compounds of gasoline and unique signature metabolites of anaerobic microbial decay.