Biotic and Abiotic Reduction and Solubilization of Pu(IV)O2鈥?i>xH2O(am) as Affected by Anthraquinone-2,6-disulfonate (AQDS) and Ethylenediaminetetraacetate (EDTA)

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• 作者：Andrew E. Plymale ; Vanessa L. Bailey ; James K. Fredrickson ; Steve M. Heald ; Edgar C. Buck ; Liang Shi ; Zheming Wang ; Charles T. Resch ; Dean A. Moore ; Harvey Bolton ; Jr.
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2012
• 出版时间：February 21, 2012
• 年：2012
• 卷：46
• 期：4
• 页码：2132-2140
• 全文大小：453K
• 年卷期：v.46,no.4(February 21, 2012)
• ISSN：1520-5851

文摘

This study measured reductive solubilization of plutonium(IV) hydrous oxide (Pu(IV)O₂路xH₂O_(am)) with hydrogen (H₂) as electron donor, in the presence or absence of dissimilatory metal-reducing bacteria (DMRB), anthraquinone-2,6-disulfonate (AQDS), and ethylenediaminetetraacetate (EDTA). In PIPES buffer at pH 7 with excess H₂, Shewanella oneidensis and Geobacter sulfurreducens both solubilized <0.001% of 0.5 mM Pu(IV)O₂路xH₂O_(am) over 8 days, with or without AQDS. However, Pu_(aq) increased by an order of magnitude in some treatments, and increases in solubility were associated with production of Pu(III)_(aq). The solid phase of these treatments contained Pu(III)(OH)_3(am), with more in the DMRB treatments compared with abiotic controls. In the presence of EDTA and AQDS, PuO₂路xH₂O_(am) was completely solubilized by S. oneidensis and G. sulfurreducens in 24 h. Without AQDS, bioreductive solubilization was slower (22 days) and less extensive (83鈥?4%). In the absence of DMRB, EDTA facilitated reductive solubilization of 89% (without AQDS) to 98% (with AQDS) of the added PuO₂路xH₂O_(am) over 418 days. An in vitro assay demonstrated electron transfer to PuO₂路xH₂O_(am) from the S. oneidensis outer-membrane c-type cytochrome MtrC. Our results (1) suggest that PuO₂路xH₂O_(am) reductive solubilization may be important in reducing environments, especially in the presence of complexing ligands and electron shuttles, (2) highlight the environmental importance of polynuclear, colloidal Pu, (3) provide additional evidence that Pu(III)-EDTA is a more likely mobile form of Pu than Pu(IV)-EDTA, and (4) provide another example of outer-membrane cytochromes and electron-shuttling compounds facilitating bioreduction of insoluble electron acceptors in geologic environments.