Wendling Laura A, Harsh James B, Ward Thomas E, Palmer Carl D, Hamilton Melinda A, Boyle Jeffrey S, Flury Markus
Department of Crop and Soil Sciences and Center for Multiphase Environmental Research, PO Box 646420, Washington State University, Pullman, Washington 99164-6420, USA.
Environ Sci Technol. 2005 Jun 15;39(12):4505-12. doi: 10.1021/es048809p.
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.
根际的生物地球化学过程能够显著改变污染物与土壤矿物质之间的相互作用。在本研究中，从爱达荷国家实验室（INL）采集的冰草（Agropyron desertorum）根际分离出了几株能分泌铝（Al）螯合化合物的细菌。我们研究了芽孢杆菌属、罗尔斯通氏菌属和肠杆菌属细菌的分泌物对伊利石中铯（Cs）解吸的影响。这些菌株的分泌物显著增强了伊利石中Cs的解吸。此外，Cs解吸量随芽孢杆菌分泌物浓度的增加而增加。伊利石中Cs的解吸量与分泌物类型和浓度均呈正相关，且与Al的溶解相关，这表明分泌物的Al络合能力在增强Cs解吸方面发挥了重要作用。经细菌分泌物处理后，伊利石上磨损边缘位点（FES）的密度增加，而FES的Cs/K选择性降低。这些结果表明，从根际分离出的细菌分泌物能够增强伊利石磨损边缘的Cs解吸，因此可以改变云母质土壤中Cs的有效性。
