Landa E R, Miller C L, Updegraff D M
Health Phys. 1986 Oct;51(4):509-18. doi: 10.1097/00004032-198610000-00010.
Relatively insoluble sulfate precipitates appear to be a major host for Ra in sulfuric acid-treated, U mill tailings. The dissolution of such precipitates by natural processes, such as metabolism by sulfate-reducing bacteria (SRB), creates the potential for release of Ra to contacting waters. Significant leaching of Ra by SRB was achieved in the laboratory during the anaerobic incubation (1 to 119 days) of U mill tailings with pure cultures of Desulfovibrio desulfuricans and mixed cultures containing SRB isolated from the tailings, all grown on a lactate medium at room temperature. While the maximum 226Ra concentration reached in a sterile media control was 0.44 Bq/L (12 pCi/L), that in the SRB systems was 61 Bq/L (1640 pCi/L) or about 20% of the total Ra inventory in the original tailings sample. The leaching of Ra in SRB systems was accompanied by a decrease in soluble sulfate concentration, an increase in total sulfide concentration, and an increase in the number of SRB. The observed leaching effect does not appear to be due to the action of microbial chelates or to binding to cell walls. Potential implications of these findings to the management of U mill tailings and other radioactive wastes are discussed.
相对难溶的硫酸沉淀物似乎是硫酸处理过的铀矿尾矿中镭的主要宿主。通过自然过程，如硫酸盐还原菌（SRB）的代谢作用，使这些沉淀物溶解，从而有可能将镭释放到与之接触的水体中。在实验室中，利用脱硫弧菌纯培养物以及从尾矿中分离出的含有SRB的混合培养物，在室温下以乳酸盐培养基对铀矿尾矿进行厌氧培养（1至119天），实现了SRB对镭的显著浸出。在无菌培养基对照中达到的最大226Ra浓度为0.44 Bq/L（12 pCi/L），而在SRB系统中则为61 Bq/L（1640 pCi/L），约占原始尾矿样品中总镭存量的20%。SRB系统中镭的浸出伴随着可溶性硫酸盐浓度的降低、总硫化物浓度的增加以及SRB数量的增加。观察到的浸出效应似乎并非由于微生物螯合物的作用或与细胞壁的结合。讨论了这些发现对铀矿尾矿和其他放射性废物管理的潜在影响。
