Cesium desorption from illite as affected by exudates from rhizosphere bacteria.
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 Laboratory (INL). We examined the effects of exudates from bacteria in the genera Bacillus, Ralstonia, and Enterobacter on cesium (Cs) desorption from illite. Exudates from these strains of bacteria significantly enhanced Cs desorption from illite. In addition, Cs desorption increased with increasing Bacillus exudate concentrations. Cesium desorption from illite as a function of both exudate type and concentration was positively correlated with Al dissolution, 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. These results suggestthat exudates from bacteria isolated from the rhizosphere can enhance Cs desorption from frayed edges of illite and, therefore, can alter Cs availability in micaceous soils.
Wendling
Laura A
LA
Department of Crop and Soil Sciences and Center for Multiphase Environmental Research, PO Box 646420, Washington State University, Pullman, Washington 99164-6420, USA. lawendling@wsu.edu
Harsh
James B
JB
Ward
Thomas E
TE
Palmer
Carl D
CD
Hamilton
Melinda A
MA
Boyle
Jeffrey S
JS
Flury
Markus
M
D031702:Agropyron; D000535:Aluminum / Q000378:metabolism*; D000704:Analysis of Variance; D001419:Bacteria / Q000378:metabolism*; D002586:Cesium / Q000378:metabolism*; D002614:Chelating Agents / Q000378:metabolism*; D007061:Idaho; D008903:Minerals / Q000378:metabolism*; D012988:Soil Microbiology; D013055:Spectrophotometry, Infrared
D002614:Chelating Agents; D008903:Minerals; C099089:illite; D002586:Cesium; D000535:Aluminum