Formation and Geological Sequestration of Uranium Nanoparticles in Deep Granitic Aquifer.
Formation and Geological Sequestration of Uranium Nanoparticles in Deep Granitic Aquifer.
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深花岗岩含水层中铀纳米颗粒的形成和地质隔离。
DOI：
10.1038/srep22701
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发表时间：
2016-03-07
影响因子：
4.6
通讯作者：
Mizuno T
中科院分区：
文献类型：
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作者：
Suzuki Y;Mukai H;Ishimura T;Yokoyama TD;Sakata S;Hirata T;Iwatsuki T;Mizuno T
刺激细菌活动，将六价铀（六）转化为四价铀（四），似乎是可行的，具有成本效益的补救受污染的含水层。然而，U（VI）还原通常导致直径小于5纳米的U（IV）颗粒沉淀，除了富含铁的环境条件。由于这些微小颗粒是移动的，并且在营养物注入终止后容易氧化溶解，原位生物修复仍然是不切实际的。在这里，我们表明，铀云母（U（SiO 4）1-x（OH）4x）的U（IV）纳米颗粒形成于花岗岩含水层的裂缝填充碳酸钙中。原位U-Pb同位素测年表明，U（IV）纳米粒子已经在碳酸钙中被隔离了至少100万年。由于微生物引起的碳酸钙沉淀在世界各地的含水层系统中是非常常见的，我们预计同时刺激碳酸钙和U（IV）纳米粒子的沉淀反应的微生物活动，这将导致铀和其他放射性核素在受污染的含水层和深层地质储存库中的长期封存。
The stimulation of bacterial activities that convert hexavalent uranium, U(VI), to tetravalent uranium, U(IV), appears to be feasible for cost-effective remediation of contaminated aquifers. However, U(VI) reduction typically results in the precipitation of U(IV) particles less than 5 nanometers in diameter, except for environmental conditions enriched with iron. Because these tiny particles are mobile and susceptible to oxidative dissolution after the termination of nutrient injection, in situ bioremediation remains to be impractical. Here we show that U(IV) nanoparticles of coffinite (U(SiO4)1−x(OH)4x) formed in fracture-filling calcium carbonate in a granitic aquifer. In situ U-Pb isotope dating demonstrates that U(IV) nanoparticles have been sequestered in the calcium carbonate for at least 1 million years. As the microbiologically induced precipitation of calcium carbonate in aquifer systems worldwide is extremely common, we anticipate simultaneous stimulation of microbial activities for precipitation reactions of calcium carbonate and U(IV) nanoparticles, which leads to long-term sequestration of uranium and other radionuclides in contaminated aquifers and deep geological repositories.