Effects of organic carbon supply rates on mobility of previously bioreduced uranium in a contaminated sediment

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Bioreduction-based strategies for remediating uranium (U)-contaminated sediments face the challenge of maintaining the reduced status of U for long times. Because groundwater influxes continuously bring in oxidizing terminal electron acceptors (O{sub 2}, NO{sub 3}{sup -}), it is necessary to continue supplying organic carbon (OC) to maintain the reducing environment after U bioreduction is achieved. We tested the influence of OC supply rates on mobility of previously microbial reduced uranium U(IV) in contaminated sediments. We found that high degrees of U mobilization occurred when OC supply rates were high, and when the sediment still contained abundant Fe(III). Although 900 days with ... continued below

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Wan, J.; Tokunaga, T.K.; Kim, Y.; Brodie, E.; Daly, R.; Hazen, T.C. et al. May 15, 2008.

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Bioreduction-based strategies for remediating uranium (U)-contaminated sediments face the challenge of maintaining the reduced status of U for long times. Because groundwater influxes continuously bring in oxidizing terminal electron acceptors (O{sub 2}, NO{sub 3}{sup -}), it is necessary to continue supplying organic carbon (OC) to maintain the reducing environment after U bioreduction is achieved. We tested the influence of OC supply rates on mobility of previously microbial reduced uranium U(IV) in contaminated sediments. We found that high degrees of U mobilization occurred when OC supply rates were high, and when the sediment still contained abundant Fe(III). Although 900 days with low levels of OC supply minimized U mobilization, the sediment redox potential increased with time as did extractable U(VI) fractions. Molecular analyses of total microbial activity demonstrated a positive correlation with OC supply and analyses of Geobacteraceae activity (RT-qPCR of 16S rRNA) indicated continued activity even when the effluent Fe(II) became undetectable. These data support our earlier hypothesis on the mechanism responsible for re-oxidation of microbial reduced U(IV) under reducing conditions; that microbial respiration caused increased (bi)carbonate concentrations and formation of stable uranyl carbonate complexes, thereby shifted U(IV)/U(VI) equilibrium to more reducing potentials. The data also suggested that low OC concentrations could not sustain the reducing condition of the sediment for much longer time.

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  • Journal Name: Environmental Science and Technology

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  • Report No.: LBNL-619E
  • Grant Number: DE-AC02-05CH11231
  • DOI: 10.1021/es800951h | External Link
  • Office of Scientific & Technical Information Report Number: 940401
  • Archival Resource Key: ark:/67531/metadc897783

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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  • May 15, 2008

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  • Sept. 27, 2016, 1:39 a.m.

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  • Sept. 29, 2017, 4:22 p.m.

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Wan, J.; Tokunaga, T.K.; Kim, Y.; Brodie, E.; Daly, R.; Hazen, T.C. et al. Effects of organic carbon supply rates on mobility of previously bioreduced uranium in a contaminated sediment, article, May 15, 2008; Berkeley, California. (digital.library.unt.edu/ark:/67531/metadc897783/: accessed October 16, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.