HR: 1340h
AN: B53A-0983    [Abstracts]
TI: Self-potential and Geochemical Measurements of Microbially Mediated Bacterial Sulfate Reduction in Saturated Sediments
AU: Park, S
EM: parkste@auburn.edu
AF: Auburn University, Dept Geology 210 Petrie Hall, Auburn, AL 36849 United States
AU: * Wolf, L W
EM: lwolf@auburn.edu
AF: Auburn University, Dept Geology 210 Petrie Hall, Auburn, AL 36849 United States
AU: Lee, M
EM: leeming@auburn.edu
AF: Auburn University, Dept Geology 210 Petrie Hall, Auburn, AL 36849 United States
AU: Saunders, J
EM: saundja@auburn.edu
AF: Auburn University, Dept Geology 210 Petrie Hall, Auburn, AL 36849 United States
AB: In situ bioremediation is a non-invasive groundwater remediation technique that stimulates microorganisms to catalyze desirable redox reactions. Using a series of laboratory experiments, we explored the suitability of self-potential methods for monitoring bioremediation of metals contamination. Each experiment was designed to quantify the relationship between electrical potential and changing redox conditions and to determine factors influencing this relationship. In the first experiment, we introduced sulfate-reducting bacteria (SRB) into a Plexiglas tank containing autoclaved quartz sand saturated with an iron-rich Desulfovibrio (a sulfate-reducing bacteria) media. An array of non-polarizable electrodes positioned on the sediment surface was used to record electrical potentials both prior to and after inoculation for about 40 days. Changes in water chemistry were determined through a series of samples taken before, during and after the experiments. A significant decrease in total iron occurred after 3 days near the injection site; however, a clearly discernable decrease in electrical potential was not perceived until ~ day 10. Contoured SP data indicate that the redox front migrated away from the injection site over time. This change probably reflects the changing water chemistry as well as bacterial migration, as iron close to the injection site was consumed. The second experiment consisted of 4 glass columns, two of which were inoculated with SRB. The first pair contained sediment similar to the tank experiment saturated with an iron-rich media. The second pair contained the same sediment but was saturated with acid-mine drainage (AMD) collected from a contaminated field site. Each column was identically instrumented with a system of four electrodes. In the active columns, an increase in pH, a decrease in sulfate and a significant decrease in total iron in the media column accompany a decrease in electrical potential after about 10 days. Results of the study suggest that the redox reactions catalyzed by SRB are detectable using self-potential geophysical methods and that these methods may offer a low-cost supplement to more costly monitoring programs.
DE: 1831 Groundwater quality
DE: 1099 General or miscellaneous
DE: 0400 Biogeosciences
DE: 0925 Magnetic and electrical methods
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting