The influence of microbial redox cycling on radionuclide mobility in the subsurface at a low‐level radioactive waste storage site
The influence of microbial redox cycling on radionuclide mobility in the subsurface at a low‐level radioactive waste storage site
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微生物氧化还原循环对低放射性废物储存场地下放射性核素迁移率的影响
DOI：
10.1111/j.1472-4669.2007.00101.x
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发表时间：
2007
期刊：
影响因子：
3.7
通讯作者：
J. Lloyd
中科院分区：
文献类型：
--
作者：
M. Wilkins;F. Livens;D. Vaughan;I. Beadle;J. Lloyd
由于厌氧微生物代谢可能对地下放射性核素的形态和流动性产生重大影响，因此在从Drigg低放射性废物储存场（英国）附近的沉积物制备的微宇宙中测定了铀，锝和镭的溶解度。铀（U（VI）;）和Tc（Tc（VII）;）从地下水中去除的同时，微生物Fe（III）的还原，大概是通过还原到不溶性U（IV）和Tc（IV），分别，而Ra（Ra 2+），已迅速吸附到矿物表面上没有释放后Fe（III）还原。还原Drigg沉积物中的生物成因Fe（II）矿物不能非生物地还原U（VI），但可以还原Tc（VII）。在向还原的沉积物中加入氧化剂硝酸盐之后，铀被再活化并释放到溶液中，而锝仍然与不溶性相结合。一个近亲的假单胞菌stutzeri占主导地位的微生物群落在反硝化条件下，还原硝酸盐亚硝酸盐的缩影，这是能够再氧化Fe（II）和U（IV），与后者释放到溶液中的U（VI）。这些数据表明，Drigg远场的微生物Fe（III）还原有可能减少地下一些放射性核素的迁移，并且硝酸盐（核废物流中的常见污染物）的再氧化和再活化潜力是放射性核素特异性的。
As anaerobic microbial metabolism can have a major impact on radionuclide speciation and mobility in the subsurface, the solubility of uranium, technetium and radium was determined in microcosms prepared from sediments adjacent to the Drigg low‐level radioactive waste storage site (UK). Both uranium (as U(VI); ) and Tc (as Tc(VII); ) were removed from groundwater concurrently with microbial Fe(III) reduction, presumably through reduction to insoluble U(IV) and Tc(IV), respectively, while Ra (Ra2+) that had rapidly sorbed onto mineral surfaces was not released following Fe(III) reduction. Biogenic Fe(II) minerals in reduced Drigg sediments were unable to reduce U(VI) abiotically but could reduce Tc(VII). Following addition of the oxidant nitrate to the reduced sediments, uranium was remobilized and released into solution, whereas technetium remained associated with an insoluble phase. A close relative of Pseudomonas stutzeri dominated the microbial communities under denitrifying conditions, reducing nitrate to nitrite in the microcosms, which was able to reoxidize Fe(II) and U(IV), with release of the latter into solution as U(VI). These data suggest that microbial Fe(III) reduction in the far‐field at Drigg has the potential to decrease the migration of some radionuclides in the subsurface, and the potential for reoxidation and remobilization by nitrate, a common contaminant in nuclear waste streams, is radionuclide‐specific.