Journal article
Abiotic reduction of uranium by Fe(II) in soil
Applied geochemistry, Vol.27(8), pp.1512-1524
08/2012
DOI: 10.1016/j.apgeochem.2012.03.003
Abstract
► Abiotic reduction and immobilization of U(VI) occurs in a reduced Iowa soil. ► The U is immobilized as U(IV) and non-uranyl U(V) or U(VI) phases. ► Soil characterization indicates the presence of structural Fe(II) in clay minerals or a green-rust like phase. ► U(VI) reduction is coupled with Fe(II) oxidation in the soil. ► Abiotic reduction of U(VI) may be an important process in reduced, Fe-rich environments.
Structural Fe(II) has been shown to reduce several oxidized environmental contaminants, including NO3, chlorinated solvents, Cr(VI), and U(VI). Studies investigating reduction of U(VI) by soils and sediments, however, suggest that abiotic reduction of U(VI) by Fe(II) is not significant, and that direct enzymatic reduction of U(VI) by metal-reducing bacteria is required for U(VI) immobilization as U(IV). Here evidence is presented for abiotic reduction and immobilization of U(VI) by structural Fe(II) in a redoximorphic soil collected from a hillside spring in Iowa. Oxidation of Fe(II) in the soil after reaction with U(VI) was demonstrated by Mössbauer spectroscopy and reduction of U(VI) by the pasteurized soil using U LIII-edge X-ray absorption spectroscopy (XAS). XAS indicates that both reduced U(IV) and oxidized U(VI) or U(V) are present after U(VI) interaction with the Fe(II) containing soil. The EXAFS data show the presence of a non-uraninite U(IV) phase and evidence of the oxidized U(V) or U(VI) fraction being present as a non-uranyl species. Little U(VI) reduction is observed by soil that has been exposed to air and oxidation of Fe(II) to goethite has occurred. Soil characterization based on chemical extractions, Mössbauer spectroscopy, and Fe K-edge XAS indicate that the majority of Fe(II) in the soil is structural in nature, existing in clay minerals and possibly a green rust-like phase. These data provide compelling evidence for abiotic reduction of U(VI) by structural Fe(II) from soil near Fe-rich oxic–anoxic boundaries in natural environments. The work highlights the potential for abiotic reduction of U(VI) by Fe(II) in reduced, Fe-rich environments.
Details
- Title: Subtitle
- Abiotic reduction of uranium by Fe(II) in soil
- Creators
- Drew E Latta - Department of Civil and Environmental Engineering, The University of Iowa, 4105 Seamans Center, Iowa City, IA 52242, USAMaxim I Boyanov - Biosciences Division, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, IL 60439, USAKenneth M Kemner - Biosciences Division, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, IL 60439, USAEdward J O’Loughlin - Biosciences Division, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, IL 60439, USAMichelle M Scherer - Department of Civil and Environmental Engineering, The University of Iowa, 4105 Seamans Center, Iowa City, IA 52242, USASubsurface Biogeochemical Research (SBR)
- Resource Type
- Journal article
- Publication Details
- Applied geochemistry, Vol.27(8), pp.1512-1524
- Publisher
- Elsevier Ltd
- DOI
- 10.1016/j.apgeochem.2012.03.003
- ISSN
- 0883-2927
- eISSN
- 1872-9134
- Language
- English
- Date published
- 08/2012
- Academic Unit
- Civil and Environmental Engineering; IIHR--Hydroscience and Engineering
- Record Identifier
- 9983991956502771
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