Incorporation of ²²⁶Ra within gypsum (CaSO₄·2H₂O_(s)) and celestite (SrSO_4(s)) was assessed through dedicated batch experiments monitored over hundreds of days. Dissolution/recrystallization and coprecipitation experiments were carried out to investigate a range of chemical conditions, close to or far from equilibrium conditions. These data were used to establish the ability of gypsum and celestite to incorporate ²²⁶Ra. Celestite shows a high ²²⁶Ra incorporation, with a partition coefficient around 105. On the contrary, ²²⁶Ra is not significantly incorporated into pure gypsum. A very low value of (8.8 ± 1.5) × 10^–4 has been estimated, which is much lower than the values reported in the literature. This may explain why ²²⁶Ra incorporation in gypsum is enhanced when Sr impurities are present (above 0.1 molar %). Under such conditions, the radium distribution coefficient is around 0.15 ± 0.09. This behavior can be explained by an ion-exchange mechanism between ²²⁶Ra and Sr, consistently with the existence of a solid solution between celestite and radium sulfate, similarly to the barite (BaSO_4(s)) and radium sulfate solid solution. These results highlight the key role of trace compounds in the incorporation of ²²⁶Ra in sulfate bearing minerals and bring new insights in our understanding of the ²²⁶Ra behavior in the environment. This is illustrated by the radium content observed and modeled within the pore waters of uranium mining tailings.

中文翻译：

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微量元素在硫酸盐矿物质（石膏和天青石）中226-放射性结合中的作用

通过在数百天内监控的专用批处理实验评估了²²⁶ Ra在石膏（CaSO ₄ ·2H ₂ O _（s））和天青石（SrSO _4（s））中的掺入。进行了溶解/重结晶和共沉淀实验，以研究接近或远离平衡条件的一系列化学条件。这些数据用于确定石膏和天青石掺入²²⁶ Ra的能力。天青石显示出较高的²²⁶ Ra掺入，分配系数约为105。相反，²²⁶ Ra没有明显掺入纯石膏中。（8.8±1.5）×10 ^–4的极低值据估计，它远低于文献报道的值。这可以解释为什么当存在Sr杂质（大于0.1摩尔％）时，增强²²⁶ Ra掺入石膏的原因。在这种条件下，镭的分布系数约为0.15±0.09。这种行为可以通过²²⁶ Ra和Sr之间的离子交换机理来解释，这与天青石和硫酸镭之间存在固溶体相一致，类似于重晶石（BaSO _4（s））和硫酸镭固溶体。这些结果突出了微量化合物在含硫酸盐矿物中掺入²²⁶ Ra的关键作用，并为我们对^226的理解提供了新的见解。Ra在环境中的行为。铀开采尾矿孔隙水中观察到的和模拟出的镭含量可以说明这一点。