Uranyl Incorporation into Calcite and Aragonite: XAFS and Luminescence Studies
Uranyl Incorporation into Calcite and Aragonite: XAFS and Luminescence Studies
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DOI：
10.1021/es990981j
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发表时间：
2000-01
影响因子：
11.4
通讯作者：
R. Reeder;M. Nugent;G. Lamble;A. Tait;D. E. Morris
中科院分区：
文献类型：
--
作者：
R. Reeder;M. Nugent;G. Lamble;A. Tait;D. E. Morris
对含 U(VI) 方解石和文石的 X 射线吸收、发光和拉曼光谱研究表明，与文石（CaCO3 的常见多晶型物）相比，U 离子（近地表水中溶解铀的主要和移动形式）在掺入方解石时具有无序且明显不稳定的配位环境。我们的研究结果表明，方解石是土壤和近地表沉积物中广泛分布的自生矿物，也是混凝土安全壳结构的主要风化产物，不太可能成为长期封存 U(VI) 的合适宿主。霰石提供的更稳定的配位表明，在这个阶段应该有利于其长期保留，直到转化为方解石。因此，在污染场地评估中不应排除未来与碳酸钙矿物共沉淀的 U(VI) 的再活化。我们观察到霰石中 U 的类似赤道配位以及主导......
X-ray absorption, luminescence, and Raman spectroscopic studies of U(VI)-containing calcite and aragonite show that the U ion, the dominant and mobile form of dissolved uranium in near-surface waters, has a disordered and apparently less stable coordination environment when incorporated into calcite in comparison to aragonite, both common polymorphs of CaCO3. Our findings suggest that calcite, a widely distributed authigenic mineral in soils and near-surface sediments and a principal weathering product of concrete-based containment structures, is not likely to be a suitable host for the long-term sequestration of U(VI). The more stable coordination provided by aragonite suggests that its long-term retention should be favored in this phase, until it inverts to calcite. Consequently, future remobilization of U(VI) coprecipitated with calcium carbonate minerals should not be ruled out in assessments of contaminated sites. Our observation of a similar equatorial coordination of U in aragonite and the dominant...