Field evidence for uranium nanocrystallization and its implications for uranium transport
Field evidence for uranium nanocrystallization and its implications for uranium transport
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铀纳米结晶的现场证据及其对铀运输的影响
DOI：
10.1016/j.chemgeo.2005.04.004
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发表时间：
2005
期刊：
影响因子：
3.9
通讯作者：
H. Isobe
中科院分区：
文献类型：
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作者：
T. Murakami;Tsutomu Sato;T. Ohnuki;H. Isobe
高分辨率透射和扫描电子显微镜（HRTEM和SEM）都配备了能量色散X射线光谱仪（EDS），已被用于确定岩石中U（VI）的化学形式，并在澳大利亚Koongarra铀矿存款的下行梯度中研究低U浓度（10−8-10− 7 mol/L）下的U吸收机制。铀富集在以针铁矿和赤铁矿为主的氧化铁结核和脉中。磷酸铀酰的纳米晶体（尺寸为20-100 nm），如偏水铀云母[Cu（UO 2）2（PO 4）2·8H 2 O]分散在针铁矿和赤铁矿的纳米晶体（2-50 nm）之间并牢固地附着在针铁矿和赤铁矿的纳米晶体上。发生纳米化的环境可能是孤立的Koongarra地下水不饱和的磷酸铀酰。EDS化学分析表明，磷酸铀酰纳米晶对铀的吸收贡献大于吸附的铀。铁（氢）氧化物之间的铀酰磷酸盐纳米晶体的存在解释了先前在宏观和微观尺度上在孔加拉研究的U分布。高分辨透射电镜和扫描电镜的观察表明，在针铁矿和赤铁矿从水铁矿中结晶的过程中，吸附在水铁矿上的铀、磷和铜、镁从水铁矿中释放出来，在针铁矿和赤铁矿的表面富集，最终形成纳米级的磷酸铀酰晶体。因此，铀酰磷酸盐纳米微晶化，虽然开始吸附，是一个占主导地位的机制，U吸收和控制长期U运输在低浓度的U。
High-resolution transmission and scanning electron microscopies (HRTEM and SEM) both equipped with energy dispersive X-ray spectrometers (EDS) have been used to determine the chemical form of U(VI) in rocks and to examine U uptake mechanisms at low U concentrations (10−8–10−7mol/L) in the downgradient of the Koongarra U ore deposit in Australia. Uranium was concentrated in Fe-(hydr)oxide nodules and veins that consisted mainly of goethite and hematite. Nanocrystals (20–100 nm in size) of uranyl phosphates such as metatorbernite [Cu(UO2)2(PO4)2·8H2O] were scattered between and firmly attached to nanocrystals (2–50 nm) of goethite and hematite. The environment where the nanocrystallization occurred was probably isolated from the Koongarra groundwaters undersaturated with respect to the uranyl phosphates. Chemical analyses by EDS showed that the uranyl-phosphate nanocrystals contribute more to the U uptake than adsorbed U. The presence of the uranyl-phosphate nanocrystals between Fe-(hydr)oxides explains the U distribution previously studied in the macro- and micro-scale in Koongarra. Our HRTEM and SEM observations suggest that during crystallization of goethite and hematite from ferrihydrite, U, P, and Cu or Mg adsorbed onto ferrihydrite are released from ferrihydrite, accumulated on the surface of forming goethite and hematite, and finally form nanocrystals of uranyl phosphates. Thus, uranyl-phosphate nanocrystallization, though initiated by adsorption, is a dominating mechanism of the U uptake and controls long-term U transport at low U concentrations.
偏赤铁矿族矿物偏赤铁矿、偏钠铁矿和偏红铁矿的脱水过程
DOI：
--
发表时间：
2005
期刊：
影响因子：
--
作者：
Yohey Suzuki;Tsutomu Sato;H. Isobe;T. Kogure;T. Murakami
通讯作者：
T. Murakami
溶解磷灰石浸出层中铀矿物的形成：磷灰石掺入铀的机制
DOI：
--
发表时间：
2004
期刊：
Chemical Geology 211
影响因子：
--
作者：
Ohnuki;T.
通讯作者：
T.