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Biogeochemistry

, Volume 94, Issue 2, pp 191–196 | Cite as

Impact of the Fe(III)-reducing bacteria Geobacter sulfurreducens and Shewanella oneidensis on the speciation of plutonium

  • J. C. Renshaw
  • N. Law
  • A. Geissler
  • F. R. Livens
  • J. R. Lloyd
Article

Abstract

Microbial bioreduction of radionuclides has been the subject of much recent interest, in particular as a method for the in situ bioremediation of uranium contaminated sites. However, there have been very few studies investigating the microbially mediated redox transformations of plutonium. The redox chemistry of Pu is complicated, but the dominant environmental oxidation state is insoluble Pu(IV). However, microbial reduction of Pu(IV) to more soluble Pu(III) may enhance migration of Pu in the environment. In this study we investigated the effect of two model metal-reducing bacteria, Geobacter sulfurreducens and Shewanella oneidensis, on the redox speciation of Pu. Our results show that in all cases, the presence of bacterial cells enhanced removal of Pu from solution. UV/Visible spectra of cells and precipitates formed (dissolved in 1 M HCl), showed that the sorbed and precipitated Pu was mainly Pu(IV), but Pu(III) was also present. The results suggest that the mechanism of interaction between Pu(IV) and the two microorganisms is initial sorption to the cell surface, followed by slow reduction. Although both bacteria could reduce Pu(IV) to Pu(III), there was no increase in the solution concentrations of Pu. This suggests that the potential reduction of sorbed Pu(IV) in sediments that have been stimulated to bioremediate U(VI) may not result in problematic mobilization of Pu(III).

Keywords

Plutonium Microbial reduction Actinides Radioactive contamination 

Notes

Acknowledgments

The financial support of the US DOE NABIR/ERS programmes and UK NERC are acknowledged.

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Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  • J. C. Renshaw
    • 1
  • N. Law
    • 2
  • A. Geissler
    • 2
  • F. R. Livens
    • 2
    • 3
  • J. R. Lloyd
    • 2
  1. 1.School of Geography, Earth & Environmental SciencesUniversity of BirminghamBirminghamUK
  2. 2.School of Earth, Atmospheric & Environmental SciencesUniversity of ManchesterManchesterUK
  3. 3.School of ChemistryUniversity of ManchesterManchesterUK

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