Colloid-Facilitated Transport of Cations in an Unsaturated Fractured Soil Under Transient Conditions

doi:10.2172/1168955

GSTDTAP > 地球科学

DOI	10.2172/1168955
报告编号	DOE-UCB-64189-1
来源ID	OSTI ID: 1168955
	Colloid-Facilitated Transport of Cations in an Unsaturated Fractured Soil Under Transient Conditions
	Ryan, Joseph
	2015-01-31
出版年	2015
语种	英语
国家	美国
领域	地球科学
英文摘要	Rainfall experiments were conducted using intact soil cores and an instrumented soil pedon to examine the effect of physical heterogeneity and rainfall characteristics on the mobilization of colloids, organic matter, cesium, and strontium in a fractured soil. To measure the spatial variability of infiltration of colloids and contaminants, samples were collected through a 19-port grid placed below the soil core in laboratory study and in 27 samplers at multiple depths in the soil pedon in the field study. Cesium and strontium were applied to the soil cores and the soil pedon prior to mobilization experiments. Rainwater solutions of multiple ionic strengths and organic matter concentrations were applied to the soil cores and soil pedon to mobilize in situ colloids, cesium, and strontium. The mobilization of colloids and metal cations occurred through preferential flow paths in the soil cores. Compared to steady rainfall, greater amounts of colloids were mobilized during rainfall interrupted by pauses, which indicates that the supply of colloids to be mobilized was replenished during the pauses. A maximum in the amount of mobilized colloids were mobilized during a rainfall following a pause of 2.5 d. Pauses of shorter or longer duration resulted in less colloid mobilization. Freeze-thaw cycles, a transient condition in winter, enhanced colloid mobilization and colloid-facilitated transport of cesium and strontium in the soil cores. The exchange of solutes between the soil matrix and macropores caused a hysteretic mobilization of colloids, cesium, and strontium during changes in ionic strength. Colloid-facilitated mobilization of cesium and strontium was important at low ionic strength in fractures where slow flow allowed greater exchange of flow between the fractures and the surrounding matrix. The release of cesium and strontium by cation exchange occurred at high ionic strength in fractures where there is a little exchange of pore water with the surrounding matrix. The results of the field experiment suggested that ion exchange, and not organic matter- or colloid-facilitated transport, was the dominant mechanism for mobilization of cesium and strontium through the macropores of the fractured soil.
英文关键词	colloid soil contaminant transport
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来源平台	US Department of Energy (DOE)
引用统计
文献类型	科技报告
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/6838
专题	地球科学
推荐引用方式 GB/T 7714	Ryan, Joseph. Colloid-Facilitated Transport of Cations in an Unsaturated Fractured Soil Under Transient Conditions,2015.