A toxicity experiment was performed in order to determine the level of gasoline which can safely be amended to Ft. Lupton microcosms without greatly inhibiting endogenous microbial activity.
EPA Grant Number: R827015-01-0
Title: Anaerobic Intrinsic Bioremediation of Whole Gasoline
Investigators: Joseph Suflita
Institution: University of Oklahoma
EPA Project Officer: Bala Krishnan
Project Period: February 1, 1999 to January 31, 2000 (N/C Ext. to
February 28, 2001)
Project Amount: $130,036
Research Category: Intrinsic bioremediation/natural attenuation
Dr. G. Todd Townsend was hired as the Research Associate to implement experiments examining the prospect for whole gasoline degradation under anaerobic conditions. Dr. Townsend received a Ph.D. in environmental microbiology and most recently studied the intrinsic bioremediation of hydrocarbons as a postdoctoral researcher. He has a strong background in both the anaerobic microbiology and analytical chemistry skills that will be required for this research.
Dr. Greg Thoma, IPEC QA officer, made a laboratory visit on June 6 and performed a quality assurance audit. All facets of the Quality Assurance Project Plan were discussed, and the laboratory and data gathering practices in place were reviewed and found to be satisfactory.
On April 22, a field sampling trip to the Ft. Lupton, CO site was made to gather aquifer solids and sitewater. Contaminated, sulfidogenic aquifer solids were removed from a fresh borehole approximately 15 m downgradient of the source of contamination; groundwater was removed from an adjacent monitoring well. During this trip, a series of groundwater chemistry parameters in an array of existing monitoring wells was also measured as part of an ongoing monitoring program intended to assess intrinsic bioremediation at this site.
The aquifer solids and ground water were used to construct over 200 replicate microcosms to be used in a variety of experiments. High rates of endogenous methanogenesis and sulfate reduction were measured in these microcosms, indicating a large active microbial population and a large amount of endogenous electron donors. However, these results suggests there may difficulties observing increased activity (i.e. sulfate reduction and methanogenesis) above unamended controls due to gasoline amendments.
A toxicity experiment was performed in order to determine the level of gasoline which can safely be amended to Ft. Lupton microcosms without greatly inhibiting endogenous microbial activity.
Gasoline amendments resulted in little inhibition of sulfate reduction; however, methanogenesis appears to be more sensitive. Because of detection limits of the GC method which will be used to analyze the individual components of gasoline, it was decided that 10 µl of whole gasoline per microcosm will be used for the primary biodegradation study. This experiment has been started. Additionally, experiments examining the degradation of BTEX compounds as a mixture and a series of alkanes as individual compounds were also initiated to further display the biodegradative capacity of the Ft. Lupton sediment microbiota.