| DOI: | 10.2172/1079214
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| 报告号: | DOE/SC0001389-1
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| 报告题名: | DOE/SC0001389 Final technical report: Investigation of uranium attenuation and release at column and pore scales in response to advective geochemical gradients |
| 作者: | Savage, Kaye S. [Wofford College]; Zhu, Wenyi [Wofford College]; Barnett, Mark O. [Auburn University]
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| 出版年: | 2013
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| 发表日期: | 2013-05-13
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| 国家: | 美国
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| 语种: | 英语
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| 英文关键词: | X-ray absorption spectroscopy
; reactive transport
; ground water
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| 中文主题词: | 吸收
; PH
; 磷酸盐
; 吸附作用
; 荧光
; 铁
; X射线
; 地下水
; PH值
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| 主题词: | ABSORPTION
; PH
; PHOSPHATE
; FLUORESCENCE
; IRON
; X-RAY
; GROUND WATER
|
| 英文摘要: | Experimental approach Column experiments were devised to investigate the role of changing fluid composition on mobility of uranium through a sequence of geologic media. Fluids and media were chosen to be relevant to the ground water plume emanating from the former S-3 ponds at the Oak Ridge Integrated Field Research Challenge (ORIFC) site. Synthetic ground waters were pumped upwards at 0.05 mL/minute for 21 days through layers of quartz sand alternating with layers of uncontaminated soil, quartz sand mixed with illite, quartz sand coated with iron oxides, and another soil layer. Increases in pH or concentration of phosphate, bicarbonate, or acetate were imposed on the influent solutions after each 7 pore volumes while uranium (as uranyl) remained constant at 0.1mM. A control column maintained the original synthetic groundwater composition with 0.1mM U. Pore water solutions were extracted to assess U retention and release in relation to the advective ligand or pH gradients. Following the column experiments, subsamples from each layer were characterized using microbeam X-ray absorption spectroscopy (XANES) in conjunction with X-ray fluorescence mapping and compared to sediment core samples from the ORIFC, at SSRL Beam Line 2-3. Results U retention of 55-67mg occurred in phosphate >pH >control >acetate >carbonate columns. The mass of U retained in the first-encountered quartz layer in all columns was highest and increased throughout the experiment. The rate of increase in acetate- and bicarbonate-bearing columns declined after ligand concentrations were raised. U also accumulated in the first soil layer; the pH-varied column retained most, followed by the increasing-bicarbonate column. The mass of U retained in the upper layers was far lower. Speciation of U, interpreted from microbeam XANES spectra and XRF maps, varied within and among the columns. Evidence of minor reduction to U(IV) was observed in the first-encountered quartz layer in the phosphate, bicarbonate, and pH columns while only U(VI) was observed in the control and acetate columns. In the soil layer, the acetate and bicarbonate columns both indicate minor reduction to U(IV), but U(VI) predominated in all columns. In the ORIFC soils, U was consistently present as U(VI); sorption appears to be the main mechanism of association for U present with Fe and/or Mn, while U occurring with P appears in discrete particles consistent with a U mineral phase. U in soil locations with no other elemental associations shown by XRF are likely uranium oxide phases. |
| URL: | http://www.osti.gov/scitech/servlets/purl/1079214
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| 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/41146
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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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| 1079214.pdf（5052KB） | 研究报告 | -- | 开放获取 | | View
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| Recommended Citation: | |
Savage, Kaye S. [Wofford College],Zhu, Wenyi [Wofford College],Barnett, Mark O. [Auburn University]. DOE/SC0001389 Final technical report: Investigation of uranium attenuation and release at column and pore scales in response to advective geochemical gradients. 2013-01-01.
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