Impact of microbial mn oxidation on the remobilization of bioreduced U(IV)

Kelly L. Plathe, Sung Woo Lee, Bradley M. Tebo, John R. Bargar, Rizlan Bernier-Latmani

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

Effects of Mn redox cycling on the stability of bioreduced U(IV) are evaluated here. U(VI) can be biologically reduced to less soluble U(IV) species and the stimulation of biological activity to that end is a salient remediation strategy; however, the stability of these materials in the subsurface environments where they form remains unproven. Manganese oxides are capable of rapidly oxidizing U(IV) to U(VI) in mixed batch systems where the two solid phases are in direct contact. However, it is unknown whether the same oxidation would take place in a porous medium. To probe that question, U(IV) immobilized in agarose gels was exposed to conditions allowing biological Mn(II) oxidation (HEPES buffer, Mn(II), 5% O2 and Bacillus sp. SG-1 spores). Results show the oxidation of U(IV) to U(VI) is due primarily to O2 rather than to MnO2. U(VI) produced is retained within the gel to a greater extent when Mn oxides are present, suggesting the formation of strong surface complexes. The implication for the long-term stability of U in a bioremediated site is that, in the absence of competing ligands, biological Mn(II) oxidation may promote the immobilization of U(VI) produced by the oxidation of U(IV).

Original languageEnglish (US)
Pages (from-to)3606-3613
Number of pages8
JournalEnvironmental Science and Technology
Volume47
Issue number8
DOIs
StatePublished - Apr 16 2013

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

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