Changes in uranium speciation through a depth sequence of contaminated Hanford sediments
Changes in uranium speciation through a depth sequence of contaminated Hanford sediments
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DOI：
10.1021/es0520969
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发表时间：
2006-04-15
影响因子：
11.4
通讯作者：
Brown, GE
中科院分区：
文献类型：
--
作者：
Catalano, JG;McKinley, JP;Brown, GE
碱性铝酸钠和酸性U（VI）-Cu（II）废物在汉福德场地现已干燥的南北300 A工艺池塘中的处置导致了U（VI）的地下水羽流。为了深入了解废物处置过程中发生的地球化学过程以及影响铀羽流当前和未来命运和迁移的地球化学过程，采用标准化学和矿物学分析、电子和X射线微探针测量、和X射线吸收精细结构光谱。近地表沉积物中含有与方解石共沉淀的铀，方解石是由于用碱（NaOH）过度中和废水池而形成的。在渗流带的中间深度，可能在池塘作业期间沉淀出了变水钠长石[Cu（UO 2 PO 4）（2）中心点8H（2）O]。铀主要发生吸附到层状硅酸盐在较深的包气带和地下水，吸附铀也是一个重要的组成部分，在中间深度。由于含方解石的池塘沉积物已被删除的补救工作，铀的命运和运输将主要由吸附的铀的解吸和溶解的变斑铜矿控制。
The disposal of basic sodium aluminate and acidic U(VI)-Cu(II) wastes in the now-dry North and South 300 A Process Ponds at the Hanford site resulted in a groundwater plume of U(VI). To gain insight into the geochemical processes that occurred during waste disposal and those affecting the current and future fate and transport of this uranium plume, the solid-phase speciation of uranium in a depth sequence of sediments from the base of the North Process Pond through the vadose zone to groundwater was investigated using standard chemical and mineralogical analyses, electron and X-ray microprobe measurements, and X-ray absorption fine structure spectroscopy. Near-surface sediments contained uranium coprecipitated with calcite, which formed due to overneutralization of the waste ponds with base (NaOH). At intermediate depths in the vadose zone, metatorbernite [Cu(UO2PO4)(2)center dot 8H(2)O] precipitated, likely during pond operations. Uranium occurred predominantly sorbed onto phyllosilicates in the deeper vadose zone and groundwater; sorbed uranium was also an important component at intermediate depths. Since the calcite-bearing pond sediments have been removed in remediation efforts, uranium fate and transport will be controlled primarily by desorption of the sorbed uranium and dissolution of metatorbernite.