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DOI | 10.1073/pnas.2021844118 |
Diagenetic formation of uranium-silica polymers in lake sediments over 3,300 years | |
Pierre Lefebvre; Alkiviadis Gourgiotis; Arnaud Mangeret; Pierre Sabatier; Pierre Le Pape; Olivier Diez; Pascale Louvat; Nicolas Menguy; Pauline Merrot; Camille Baya; Mathilde Zebracki; Pascale Blanchart; Emmanuel Malet; Didier Jézéquel; Jean-Louis Reyss; John R. Bargar; Jérôme Gaillardet; Charlotte Cazala; Guillaume Morin | |
2021-01-26 | |
发表期刊 | Proceedings of the National Academy of Science |
出版年 | 2021 |
英文摘要 | The long-term fate of uranium-contaminated sediments, especially downstream former mining areas, is a widespread environmental challenge. Essential for their management is the proper understanding of uranium (U) immobilization mechanisms in reducing environments. In particular, the long-term behavior of noncrystalline U(IV) species and their possible evolution to more stable phases in subsurface conditions is poorly documented, which limits our ability to predict U long-term geochemical reactivity. Here, we report direct evidence for the evolution of U speciation over 3,300 y in naturally highly U-enriched sediments (350–760 µg ⋅ g−1 U) from Lake Nègre (Mercantour Massif, Mediterranean Alps, France) by combining U isotopic data (δ238U and (234U/238U)) with U L3-edge X-ray absorption fine structure spectroscopy. Constant isotopic ratios over the entire sediment core indicate stable U sources and accumulation modes, allowing for determination of the impact of aging on U speciation. We demonstrate that, after sediment deposition, mononuclear U(IV) species associated with organic matter transformed into authigenic polymeric U(IV)–silica species that might have partially converted to a nanocrystalline coffinite (UIVSiO4·nH2O)-like phase. This diagenetic transformation occurred in less than 700 y and is consistent with the high silica availability of sediments in which diatoms are abundant. It also yields consistency with laboratory studies that proposed the formation of colloidal polynuclear U(IV)–silica species, as precursors for coffinite formation. However, the incomplete transformation observed here only slightly reduces the potential lability of U, which could have important implications to evaluate the long-term management of U-contaminated sediments and, by extension, of U-bearing wastes in silica-rich subsurface environments. |
领域 | 地球科学 |
URL | 查看原文 |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/312302 |
专题 | 地球科学 |
推荐引用方式 GB/T 7714 | Pierre Lefebvre,Alkiviadis Gourgiotis,Arnaud Mangeret,et al. Diagenetic formation of uranium-silica polymers in lake sediments over 3,300 years[J]. Proceedings of the National Academy of Science,2021. |
APA | Pierre Lefebvre.,Alkiviadis Gourgiotis.,Arnaud Mangeret.,Pierre Sabatier.,Pierre Le Pape.,...&Guillaume Morin.(2021).Diagenetic formation of uranium-silica polymers in lake sediments over 3,300 years.Proceedings of the National Academy of Science. |
MLA | Pierre Lefebvre,et al."Diagenetic formation of uranium-silica polymers in lake sediments over 3,300 years".Proceedings of the National Academy of Science (2021). |
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