HR: 1340h
AN: B33A-0855    [Abstracts]
TI: Evolution of the Microbial Community Structure and Iron Reduction Rate in a Column Biostimulation Experiment During the Transition From Iron to Sulfate Reduction
AU: * Jaffe, P R
EM: jaffe@princeton.edu
AF: Princeton University, Department of Civil and Environmental Engineering, Princeton, NJ 08544, United States
AU: ElBishlawi, H
EM: helbishl@princeton.edu
AF: Princeton University, Department of Civil and Environmental Engineering, Princeton, NJ 08544, United States
AU: Hettich, R L
EM: hettichrl@ornl.gov
AF: Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37830, United States
AU: Kerkhof, L
EM: kerkhof@marine.rutgers.edu
AF: Rutgers University, Institute of Marine and Coastal Sciences, New Brunswick, NJ 08901, United States
AU: Komlos, J
EM: jkomlos@princeton.edu
AF: Princeton University, Department of Civil and Environmental Engineering, Princeton, NJ 08544, United States
AU: Kukkadapu, R P
EM: Ravi.Kukkadapu@pnl.gov
AF: Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 98816, United States
AU: Lipton, M S
EM: mary.lipton@pnl.gov
AF: Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 98816, United States
AU: Long, P E
EM: philip.long@pnl.gov
AF: Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 98816, United States
AU: McGuinness, L
EM: mcguinne@marine.rutgers.edu
AF: Rutgers University, Institute of Marine and Coastal Sciences, New Brunswick, NJ 08901, United States
AU: Moon, H
EM: hmoon@Princeton.EDU
AF: Princeton University, Department of Civil and Environmental Engineering, Princeton, NJ 08544, United States
AU: Peacock, A D
EM: apeacock@haleyaldrich.com
AF: Microbial Insights, Inc., 2340 Stock Creek Blvd., Rockford, TN 37853, United States
AU: VerBerkmoes, N C
EM: verberkmoesn@ornl.gov
AF: Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37830, United States
AU: Williams, K H
EM: KHWilliams@lbl.gov
AF: Lawrence Berkeley National Laboratory, Earth Sciences Division, Berkeley, CA 94720, United States
AB: During the biostimulation of iron reducers for the purpose of concurrent biological reduction of U(VI), it has been postulated that iron reduction proceeds while bioavailable iron is present, after which the system switches to sulfate reduction if sulfate is present. Field experiments from the Rifle Integrated Field Challenge (IFC) site in Colorado showing that the onset of sulfate reduction has been associated with decreased removal of U(VI) from groundwater support this hypothesis. However, column experiments using sediments from the Rifle site and synthetic groundwater with comparable (7 mM) sulfate levels as in the field, showed that the onset of sulfate reduction occurred within a month with no negative effect on U(VI) reduction. Separate column experiments using low (9 uM) sulfate concentrations showed that iron reduction can be maintained for over 200 days with no indication of iron limitations. To address the discrepancy between field and column experiments, an experiment is being conducted to determine the activity of iron reducers before and after the onset of sulfate reduction. Since Fe(II) buildup is difficult to quantify in the presence of sulfate reduction, the sediments were augmented with Fe- 57 goethite. Minute changes in the Fe-57 goethite can be detected via Mössbauer spectroscopy. Ten columns (2.5 cm internal diameter and 15 cm in length), loaded with sediment from the Rifle site, have been set up and are being operated at 17 °C. Groundwater from the Rifle site, amended with 3mM acetate and 20 μM U(VI), is pumped through the columns at a rate of 0.035 ml/min. Column effluent concentrations are being monitored for acetate, Fe(II), U(VI), and sulfate. Columns are sacrificed at 10 day intervals and the sediment samples are analyzed for Fe(II), U(IV), and acid volatile sulfides using standard analytical procedures. Changes in Fe-57 goethite measured using Mössbauer spectroscopy during biostimulation of the native microorganisms at 10-day intervals are showing measurable decreases in the goethite over these time intervals. Initial characterization of the microbial community in the sediment via DGGE of 16S rDNA shows the presence of Geobacter, Rhodoferax, Flexibacter, Flavobacterium, and Desulfuromonaceae. Very similar microbial populations were observed in column effluents using TRFLP analysis. Changes in individual bacterial cell numbers are being quantified via qPCR, while changes in bacterial activity are being quantified via proteomics.
DE: 0418 Bioremediation
DE: 0463 Microbe/mineral interactions
DE: 0465 Microbiology: ecology, physiology and genomics (4840)
DE: 1831 Groundwater quality
SC: Biogeosciences [B]
MN: 2007 Fall Meeting