Deblonde Gauthier J-P, Morrison Keith, Mattocks Joseph A, Cotruvo Joseph A, Zavarin Mavrik, Kersting Annie B
Physical and Life Sciences Directorate, Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, California 94550, United States.
Glenn T. Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, California 94550, United States.
Environ Sci Technol. 2023 Dec 12;57(49):20830-20843. doi: 10.1021/acs.est.3c06033. Epub 2023 Oct 28.
Minor actinides are major contributors to the long-term radiotoxicity of nuclear fuels and other radioactive wastes. In this context, understanding their interactions with natural chelators and minerals is key to evaluating their transport behavior in the environment. The lanmodulin family of metalloproteins is produced by ubiquitous bacteria and lanmodulin (LanM) was recently identified as one of nature's most selective chelators for trivalent f-elements. Herein, we investigated the behavior of neptunium, americium, and curium in the presence of LanM, carbonate ions, and common minerals (calcite, montmorillonite, quartz, and kaolinite). We show that LanM's aqueous complexes with Am(III) and Cm(III) remain stable in carbonate-bicarbonate solutions. Furthermore, the sorption of Am(III) to these minerals is strongly impacted by LanM, while Np(V) sorption is not. With calcite, even a submicromolar concentration of LanM leads to a significant reduction in the Am(III) distribution coefficient (, from >10 to ∼10 mL/g at pH 8.5), rendering it even more mobile than Np(V). Thus, LanM-type chelators can potentially increase the mobility of trivalent actinides and lanthanide fission products under environmentally relevant conditions. Monitoring biological chelators, including metalloproteins, and their biogenerators should therefore be considered during the evaluation of radioactive waste repository sites and the risk assessment of contaminated sites.
次要锕系元素是核燃料和其他放射性废物长期放射性毒性的主要贡献者。在这种情况下，了解它们与天然螯合剂和矿物质的相互作用是评估其在环境中迁移行为的关键。金属蛋白的镧调蛋白家族由普遍存在的细菌产生，最近镧调蛋白（LanM）被确定为自然界中对三价f元素最具选择性的螯合剂之一。在此，我们研究了镎、镅和锔在LanM、碳酸根离子和常见矿物质（方解石、蒙脱石、石英和高岭土）存在下的行为。我们发现，LanM与Am(III)和Cm(III)的水相络合物在碳酸盐 - 碳酸氢盐溶液中保持稳定。此外，LanM对这些矿物质上Am(III)的吸附有强烈影响，而对Np(V)的吸附没有影响。对于方解石，即使是亚微摩尔浓度的LanM也会导致Am(III)分配系数显著降低（在pH 8.5时，从>10降至约10 mL/g），使其比Np(V)更具迁移性。因此，在环境相关条件下，LanM型螯合剂可能会增加三价锕系元素和镧系裂变产物的迁移性。因此，在评估放射性废物处置场和污染场地的风险评估时，应考虑监测包括金属蛋白在内的生物螯合剂及其生物产生者。
