GEOC 49 |
| James E. Saiers1, John J. Lenhart2, and Bin Gao1. (1) School of Forestry, Yale University, 205 Prospect Street, New Haven, CT 06511, (2) Department of Civil Engineering, Ohio State University, 2070 Neil Avenue, Columbus, OH 43210 |
| Mineral colloids exhibit a high capacity for adsorbing toxic metals; therefore, predictions of the movement of these contaminants through near-surface soils and sediments rely on knowledge of the processes that govern colloid transport within the vadose zone. We examined the transport and mass transfer of inorganic colloids (silica, illite clay, and kaolinite clay) in laboratory column experiments conducted under unsaturated conditions. Results of the experiments reveal that colloid-mobilization kinetics were linked closely to temporal changes in moisture content and porewater ionic strength during porous-medium imbibition and that moving air-water interfaces scoured colloids from mineral-grain surfaces during porous-medium drainage. Mobilized colloids were susceptible to removal from the porewater due to mass-transfer reactions at air-water and solid-water interfaces. The rates of these deposition reactions varied significantly between colloid types and were sensitive to changes in porewater chemistry, volumetric moisture content, and wetting history of the porous medium. |
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Colloid-Facilitated Transport of Contaminants in the Subsurface: The Life and Death of a Colloid
1:00 PM-5:20 PM, Monday, March 29, 2004 Marriott -- Marquis NW, Oral
Division of Geochemistry |