Lusa M, Bomberg M, Aromaa H, Knuutinen J, Lehto J
Laboratory of Radiochemistry, Department of Chemistry, P.O. Box 55, 00014 University of Helsinki, Finland.
VTT Technical Research Centre of Finland, P.O. Box 1000, 02044 VTT, Finland.
J Environ Radioact. 2015 Sep;147:85-96. doi: 10.1016/j.jenvrad.2015.05.014. Epub 2015 Jun 4.
(79)Se is among the most important long lived radionuclides in spent nuclear fuel and selenite, SeO3(2-), is its typical form in intermediate redox potential. The sorption behaviour of selenite and the bacterial impact on the selenite sorption in a 7-m-deep profile of a nutrient-poor boreal bog was studied using batch sorption experiments. The batch distribution coefficient (Kd) values of selenite decreased as a function of sampling depth and highest Kd values, 6600 L/kg dry weight (DW), were observed in the surface moss and the lowest in the bottom clay at 1700 L/kg DW. The overall maximum sorption was observed at pH between 3 and 4 and the Kd values were significantly higher in unsterilized compared to sterilized samples. The removal of selenite from solution by Pseudomonas sp., Burkholderia sp., Rhodococcus sp. and Paenibacillus sp. strains isolated from the bog was affected by incubation temperature and time. In addition, the incubation of sterilized surface moss, subsurface peat and gyttja samples with added bacteria effectively removed selenite from the solution and on average 65% of selenite was removed when Pseudomonas sp. or Burkholderia sp. strains were used. Our results demonstrate the important role of bacteria for the removal of selenite from the solution phase in the bog environment, having a high organic matter content and a low pH.
（79）硒是乏核燃料中最重要的长寿命放射性核素之一，亚硒酸盐（SeO3(2-)）是其在中等氧化还原电位下的典型形态。通过批量吸附实验，研究了亚硒酸盐在一个7米深的贫营养北方沼泽剖面中的吸附行为以及细菌对亚硒酸盐吸附的影响。亚硒酸盐的批量分配系数（Kd）值随采样深度的增加而降低，在表层苔藓中观察到最高的Kd值为6600升/千克干重（DW），而在底部黏土中最低，为1700升/千克DW。在pH值为3至4时观察到总体最大吸附量，并且未灭菌样品中的Kd值显著高于灭菌样品。从沼泽中分离出的假单胞菌属、伯克霍尔德菌属、红球菌属和类芽孢杆菌属菌株对溶液中亚硒酸盐的去除受培养温度和时间的影响。此外，用添加了细菌的灭菌表层苔藓、亚表层泥炭和泥炭土样品进行培养可有效去除溶液中的亚硒酸盐，当使用假单胞菌属或伯克霍尔德菌属菌株时，平均有65%的亚硒酸盐被去除。我们的结果表明，在有机质含量高且pH值低的沼泽环境中，细菌对于从溶液相中去除亚硒酸盐起着重要作用。
