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United States Department of Agriculture

Agricultural Research Service

Title: Cesium Desorption from Illite As Affected by Exudates from Rhizosphere Bacteria

Authors
item Wendling, Laura
item Harsh, James - WASHINGTON STATE UNIVER
item Ward, Thomas - INEEL
item Palmer, Carl - INEEL
item Hamilton, Melinda - INEEL

Submitted to: Journal of Environmental Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 2005
Publication Date: June 30, 2005
Repository URL: http://www.ars.usda.gov/sp2UserFiles/Place/53482500/BrentonSharratt/CesiumDesorptionfromIllitepdf.pdf
Citation: Wendling, L.A., J.B. Harsh, T.E. Ward, M.A. Hamilton, C.D. Palmer, J.S. Boyle, and M. Flury. 2005. Cesium desorption from illite as influenced by bacterial exudates. Environmental Science and Technology 39:1205-1212.

Interpretive Summary: Biogeochemical processes in the rhizosphere can significantly alter interactions between contaminants and soil minerals. In this study, several strains of bacteria that exude aluminum (Al)-chelating compounds were isolated from the rhizosphere of crested wheatgrass (Agropyron desertorum) collected from the Idaho National Engineering and Environmental Laboratory (INEEL). We examined the effects of exudates from bacteria in the genera Bacillus, Ralstonia, and Enterobacter on cesium (Cs) desorption from illite. Exudates from all strains of rhizosphere bacteria significantly enhanced Cs desorption from illite. In addition, Cs desorption increased at greater Bacillus exudate concentrations. Cesium desorption from illite as a function of both exudate type and concentration was positively correlated with Al solubilization, suggesting that the Al-complexing ability of the exudates played an important role in enhancing Cs desorption. The density of frayed edge sites (FES) on illite increased as a result of treatment with bacterial exudates, while the Cs/K selectivity of FES decreased. Results suggest that exudates from rhizosphere bacteria can enhance Cs desorption from frayed edges of illite and, therefore, can alter Cs availability in micaceous soils.

Technical Abstract: Biogeochemical processes in the rhizosphere can significantly alter interactions between contaminants and soil minerals. In this study, several strains of bacteria that exude aluminum (Al)-chelating compounds were isolated from the rhizosphere of crested wheatgrass (Agropyron desertorum) collected from the Idaho National Engineering and Environmental Laboratory (INEEL). We examined the effects of exudates from bacteria in the genera Bacillus, Ralstonia, and Enterobacter on cesium (Cs) desorption from illite. Exudates from all strains of rhizosphere bacteria significantly enhanced Cs desorption from illite. In addition, Cs desorption increased at greater Bacillus exudate concentrations. Cesium desorption from illite as a function of both exudate type and concentration was positively correlated with Al solubilization, suggesting that the Al-complexing ability of the exudates played an important role in enhancing Cs desorption. The density of frayed edge sites (FES) on illite increased as a result of treatment with bacterial exudates, while the Cs/K selectivity of FES decreased. Results suggest that exudates from rhizosphere bacteria can enhance Cs desorption from frayed edges of illite and, therefore, can alter Cs availability in micaceous soils.

Last Modified: 4/21/2014
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