title: Cesium desorption from illite as affected by exudates from rhizosphere bacteria.
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 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.
authors.affiliation: 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
authors.forename: Laura A
authors.initials: LA
authors.lastname: Wendling
authors.forename: James B
authors.initials: JB
authors.lastname: Harsh
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Ward
authors.forename: Carl D
authors.initials: CD
authors.lastname: Palmer
authors.forename: Melinda A
authors.initials: MA
authors.lastname: Hamilton
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Boyle
authors.forename: Markus
authors.initials: M
authors.lastname: Flury
mesh_terms: 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
chemical_list: D002614:Chelating Agents; D008903:Minerals; C099089:illite; D002586:Cesium; D000535:Aluminum