| DOI: | 10.2172/1245538
|
| 报告号: | DOE-Stanford--SC0006772
|
| 报告题名: | Subsurface Conditions Controlling Uranium Incorporation in Iron Oxides: A Redox Stable Sink |
| 作者: | Fendorf, Scott
|
| 出版年: | 2016
|
| 发表日期: | 2016-04-05
|
| 总页数: | 12
|
| 国家: | 美国
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| 语种: | 英语
|
| 英文关键词: | stabilization
; subsurface
; transport
|
| 中文主题词: | 土壤
; 铅
; 放射性核素
; 硅酸盐
; 铁
; 金属
; 矿物
|
| 主题词: | SOILS
; LEAD
; RADIONUCLIDES
; SILICATE
; IRON
; METALS
; MINERALS
|
| 英文摘要: | Toxic metals and radionuclides throughout the U.S. Department of Energy Complex pose a serious threat to ecosystems and to human health. Of particular concern is the redox-sensitive radionuclide uranium, which is classified as a priority pollutant in soils and groundwaters at most DOE sites owing to its large inventory, its health risks, and its mobility with respect to primary waste sources. The goal of this research was to contribute to the long-term mission of the Subsurface Biogeochemistry Program by determining reactions of uranium with iron (hydr)oxides that lead to long-term stabilization of this pervasive contaminant. The research objectives of this project were thus to (1) identify the (bio)geochemical conditions, including those of the solid-phase, promoting uranium incorporation in Fe (hydr)oxides, (2) determine the magnitude of uranium incorporation under a variety of relevant subsurface conditions in order to quantify the importance of this pathway when in competition with reduction or adsorption; (3) identify the mechanism(s) of U(VI/V) incorporation in Fe (hydr)oxides; and (4) determine the stability of these phases under different biogeochemical (inclusive of redox) conditions. Our research demonstrates that redox transformations are capable of achieving U incorporation into goethite at ambient temperatures, and that this transformation occurs within days at U and Fe(II) concentrations that are common in subsurface geochemical environments with natural ferrihydritesâinclusive of those with natural impurities. Increasing Fe(II) or U concentration, or initial pH, made U(VI) reduction to U(IV) a more competitive sequestration pathway in this system, presumably by increasing the relative rate of U reduction. Uranium concentrations commonly found in contaminated subsurface environments are often on the order of 1-10 ÎźM, and groundwater Fe(II) concentrations can reach exceed 1 mM in reduced zones of the subsurface. The redox-driven U(V) incorporation mechanism may help to explain U retention in some geologic materials, improving our understanding of U-based geochronology and the redox status of ancient geochemical environments. Additionally, U(VI) may be incorporated within silicate minerals though encapsulation of U-bearing iron oxides, leading to a redox stable solid. Our research detailing previously unrecognized mechanism of U incorporation within sediment minerals may even lead to new approaches for in situ contamination remediation techniques, and will help refine models of U fate and transport in reduced subsurface zones. |
| URL: | http://www.osti.gov/scitech/servlets/purl/1245538
|
| Citation statistics: |
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| 资源类型: | 研究报告
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/42164
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| Appears in Collections: | 过去全球变化的重建
影响、适应和脆弱性
科学计划与规划
气候变化与战略
全球变化的国际研究计划
气候减缓与适应
气候变化事实与影响
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Content Type |
Version |
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| 1245538.pdf（468KB） | 研究报告 | -- | 开放获取 | | View
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| Recommended Citation: | |
Fendorf, Scott. Subsurface Conditions Controlling Uranium Incorporation in Iron Oxides: A Redox Stable Sink. 2016-01-01.
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