Back to Search
Start Over
Competitive Reduction of Pertechnetate (99TcO4-) by Dissimilatory Metal Reducing Bacteria and Biogenic Fe(II).
- Source :
-
Environmental Science & Technology . 2/1/2011, Vol. 45 Issue 3, p951-957. 7p. - Publication Year :
- 2011
-
Abstract
- The fate of pertechnetate (99Tc(VII)O4-) during bioreduction was investigated in the presence of 2-line ferrihydrite (Fh) and various dissimilatory metal reducing bacteria (DMRB) (Geobacter, Anaeromyxobacter, Shewanella) in comparison with TcO4- bioreduction in the absence of Fh. In the presence of Fh, Tc was present primarily as a fine-grained Tc(IV)/Fe precipitate that was distinct from the Tc(IV)O2∙nH2O solids produced by direct biological Tc(VII) reduction. Aqueous Tc concentrations (<0.2 μm) in the bioreduced Fh suspensions (1.7 to 3.2 × 10-9 mol L-1) were over 1 order of magnitude lower than when TcO4- was biologically reduced in the absence of Fh (4.0 × 10-8 to 1.0 × 10-7 mol L-1). EXAFS analyses of the bioreduced Fh-Tc products were consistent with variable chain length Tc-O octahedra bonded to Fe-O octahedra associated with the surface of the residual or secondary Fe(III) oxide. In contrast, biogenic TcO2∙nH2O had significantly more Tc-Tc second neighbors and a distinct long-range order consistent with small particle polymers of TcO2. In Fe-rich subsurface sediments, the reduction of Tc(VII) by Fe(II) may predominate over direct microbial pathways, potentially leading to lower concentrations of aqueous 99Tc(IV). [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 0013936X
- Volume :
- 45
- Issue :
- 3
- Database :
- Academic Search Index
- Journal :
- Environmental Science & Technology
- Publication Type :
- Academic Journal
- Accession number :
- 59782581
- Full Text :
- https://doi.org/10.1021/es1027647