Université Côte d'Azur, CNRS, Institut de Chimie de Nice, UMR 7272, 06108 Nice, France.
Université Côte d'Azur, CNRS, Institut de Chimie de Nice, UMR 7272, 06108 Nice, France; Laboratory of Radiochemistry, Department of Chemistry, University of Helsinki, FI, 00014, Finland.
J Environ Radioact. 2017 Nov;178-179:343-348. doi: 10.1016/j.jenvrad.2017.08.008. Epub 2017 Sep 22.
Uranium is naturally present in seawater at trace levels and may in some cases be present at higher concentrations, due to anthropogenic nuclear activities. Understanding uranium speciation in seawater is thus essential for predicting and controlling its behavior in this specific environmental compartment and consequently, its possible impact on living organisms. The carbonato calcic complex CaUO(CO) was previously identified as the main uranium species in natural seawater, together with CaUO(CO). In this work, we further investigate the role of the alkaline earth cation in the structure of the ternary uranyl-carbonate complexes. For this purpose, artificial seawater, free of Mg and Ca, using Sr as a spectroscopic probe was prepared. Combining TRLIF and EXAFS spectroscopy, together with DFT and theoretical thermodynamic calculations, evidence for the presence of Sr alkaline earth counter ion in the complex structure can be asserted. Furthermore, data suggest that when Ca is replaced by Sr, SrUO(CO) is the main complex in solution and it occurs with the presence of at least one monodentate carbonate in the uranyl coordination sphere.
海水中铀以痕量形式自然存在，由于人为核活动，某些情况下其浓度可能会更高。因此，了解海水中铀的形态对于预测和控制其在该特定环境介质中的行为，以及评估其对生物体的可能影响至关重要。此前已鉴定出碳酸钙钙复合物 CaUO(CO)和 CaUO(CO)是天然海水中的主要铀物种。在这项工作中，我们进一步研究了碱土阳离子在三元铀碳酸盐配合物结构中的作用。为此，我们使用 Sr 作为光谱探针，制备了不含 Mg 和 Ca 的人工海水。结合 TRLIF 和 EXAFS 光谱学以及 DFT 和理论热力学计算，可证明 Sr 碱土阳离子存在于配合物结构中。此外，数据表明，当 Ca 被 Sr 取代时，SrUO(CO)是溶液中的主要配合物，并且在铀的配位球中至少存在一个单齿碳酸根。
