| DOI: | 10.2172/1060990
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| 报告号: | INL/EXT-12-27568
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| 报告题名: | LONG-TERM COLLOID MOBILIZATION AND COLLOID-FACILITATED TRANSPORT OF RADIONUCLIDES IN A SEMI-ARID VADOSE ZONE |
| 作者: | Markus Flury; James B. Harsh; Fred Zhang; Glendon W. Gee; Earl D. Mattson; Peter C. L
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| 出版年: | 2012
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| 发表日期: | 2012-08-01
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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: | colloids
; vadose zone
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| 中文主题词: | 沉积物
; 放射性核素
; 下渗
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| 主题词: | SEDIMENTS
; RADIONUCLIDES
; INFILTRATION
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| 英文摘要: | The main purpose of this project was to improve the fundamental mechanistic understanding and quantification of long-term colloid mobilization and colloid-facilitated transport of radionuclides in the vadose zone, with special emphasis on the semi-arid Hanford site. While we focused some of the experiments on hydrogeological and geochemical conditions of the Hanford site, many of our results apply to colloid and colloid-facilitated transport in general. Specific objectives were (1) to determine the mechanisms of colloid mobilization and colloid-facilitated radionuclide transport in undisturbed Hanford sediments under unsaturated flow, (2) to quantify in situ colloid mobilization and colloid-facilitated radionuclidetransport from Hanford sediments under field conditions, and (3) to develop a field-scale conceptual and numerical model for colloid mobilization and transport at the Hanford vadose zone, and use that model to predict long-term colloid and colloid- facilitated radionuclide transport. To achieve these goals and objectives, we have used a combination of experimental, theoretical, and numerical methods at different spatial scales, ranging from microscopic investigationsof single particle attachment and detachment to larger-scale field experiments using outdoor lysimeters at the Hanford site. Microscopic and single particle investigations provided fundamental insight into mechanisms of colloid interactions with the air-water interface. We could show that a moving air water interface (such as a moving water front during infiltration and drainage) is very effective in removing and mobilizing particles from a stationary surface. We further demonstrated that it is particularly the advancing air-water interface which is mainly responsible for colloid mobilization. Forces acting on the colloids calculated from theory corroborated our experimental results, and confirm that the detachment forces (surface tension forces) during the advancing air-water interface movement were stronger than during the receding movement. Theory indicates that, for hydrophilic colloids, the advancing interface movement generally exerts a stronger detachment force than the receding, except when the hysteresis of the colloid-air-water contact angle is small. These results of our study are particularly relevant for colloid mobilization and transport related to three process in the vadose zone at Hanford: (1) water infiltration into sediments during rainfall or snowmelt events, (2) groundwater fluctuations as caused by river stage fluctuations, and (3) steady-state, low-flow recharge in deep vadose zone sediments. Transient water flow, like during infiltration or groundwater level fluctuations, are most conducive for colloid mobilization, but even during steady-state, low-flow recharge, colloids can be mobile, although to a much lesser extent. The results of this project have led to a comprehensive and fundamental understanding of colloid transport and mobilization under unsaturated flow conditions at the Hanford site. |
| URL: | http://www.osti.gov/scitech/servlets/purl/1060990
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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/40823
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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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| 1060990.pdf（3574KB） | 研究报告 | -- | 开放获取 | | View
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| Recommended Citation: | |
Markus Flury,James B. Harsh,Fred Zhang,et al. LONG-TERM COLLOID MOBILIZATION AND COLLOID-FACILITATED TRANSPORT OF RADIONUCLIDES IN A SEMI-ARID VADOSE ZONE. 2012-01-01.
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