Competitive Reduction of Pertechnetate (99TcO4鈭?/sup>) by Dissimilatory Metal Reducing Bacteria and Biogenic Fe(II)
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- 作者：Andrew E. Plymale ; James K. Fredrickson ; John M. Zachara ; Alice C. Dohnalkova ; Steve M. Heald ; Dean A. Moore ; David W. Kennedy ; Matthew J. Marshall ; Chongmin Wang ; Charles T. Resch ; Ponnusamy Nachimuthu
- 刊名：Environmental Science & Technology
- 出版年：2011
- 出版时间：February 1, 2011
- 年：2011
- 卷：45
- 期：3
- 页码：951-957
- 全文大小：330K
- 年卷期：v.45,no.3(February 1, 2011)
- ISSN：1520-5851
文摘
The fate of pertechnetate (99Tc(VII)O4鈭?/sup>) 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鈭?/sup> 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路nH2O solids produced by direct biological Tc(VII) reduction. Aqueous Tc concentrations (<0.2 渭m) in the bioreduced Fh suspensions (1.7 to 3.2 脳 10鈭? mol L鈭?) were over 1 order of magnitude lower than when TcO4鈭?/sup> was biologically reduced in the absence of Fh (4.0 脳 10鈭? to 1.0 脳 10鈭? mol L鈭?). EXAFS analyses of the bioreduced Fh-Tc products were consistent with variable chain length Tc鈭扥 octahedra bonded to Fe鈭扥 octahedra associated with the surface of the residual or secondary Fe(III) oxide. In contrast, biogenic TcO2路nH2O had significantly more Tc鈭扵c 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).