To support the environmental monitoring of nuclear sites, reactive transport models used to predict the migration of contaminants such as strontium-90 (⁹⁰Sr) in soils, sediments and aquifers are developed, continuously tested and improved. This study aims at assessing the adequacy of the multi-site ion exchanger model (MSIE) based on a component “additivity approach” and coupled to the advection-dispersion equation (ADE) to simulate Sr transport in a clayey sandstone and a Bt soil horizon. We have also compared the performance of the modelling approach with simulation results obtained by considering a K_d approach (constant K_d). Transport experiments were performed in centimetre- and decimetre-scale columns in order to test the model sensitivities to the mineral abundance and the specificities of their reactive parameters. Non-reactive transport experiments with conservative tracers allowed us to determine the transport parameters, such as porosity and dispersivity. In this paper, we have compared the Sr transport simulation results with Sr experimental breakthrough curves acquired at various flow velocities. The simulations results show that the K_d approach can reproduce experimental data in the case of the clayey sandstone when a certain amount of uncertainty is accepted, whereas the additivity approach better fits the Sr reactive transport in both columns (especially the maximum value) without it being necessary to adjust the parameters. These results advocate for more complex retention models than K_d to better understand and improve the robustness of Sr transport predictions. The clay content, the relative abundance of illite and smectite, and the clay mineral specificity, are all sensitive parameters when it comes to defining the reactive system involved in Sr transport simulation. The results highlight the influence of illite in the spreading of the Sr breakthrough curve, especially through its low-capacity and high-selectivity site. This implies having access to a robust and extensive set of retention parameters acquired on reference minerals. In this study, the results obtained for the clayey sandstone confirm the robustness of our selected parameters when clay minerals have similar reactivity levels as the reference minerals. This set of parameters appears more limited in the case of the Bt soil containing weathered or evolved minerals. The choice of modelling approach is therefore crucial for accurately modelling and predicting Sr transport behaviour in porous media, as is the representativeness of the minerals in the database.

为支持核场址的环境监测，用于预测土壤、沉积物和含水层中锶 90 ( ⁹⁰ Sr)等污染物迁移的反应迁移模型得到了开发、持续测试和改进。本研究旨在评估多位点离子交换器模型 (MSIE) 的充分性，该模型基于组件“可加性方法”并与对流-弥散方程 (ADE) 耦合以模拟粘土砂岩和 Bt 土壤层中的Sr 传输. 我们还将建模方法的性能与通过考虑 K _d方法（常数 K _d）。传输实验在厘米和分米尺度的列中进行，以测试模型对矿物丰度的敏感性及其反应参数的特异性。使用保守示踪剂的非反应性输运实验使我们能够确定输运参数，例如孔隙率和分散性。在本文中，我们将 Sr 输运模拟结果与在各种流速下获得的 Sr 实验突破曲线进行了比较。模拟结果表明，K _d当接受一定量的不确定性时，方法可以重现粘土砂岩情况下的实验数据，而加法方法更好地拟合两列中的 Sr 反应输运（尤其是最大值），而无需调整参数。这些结果提倡使用比 K _d更复杂的保留模型，以更好地理解和提高 Sr 输运预测的稳健性。粘土含量，伊利石的相对丰度在定义 Sr 传输模拟中涉及的反应系统时，蒙脱石和粘土矿物的特异性都是敏感参数。结果突出了伊利石对 Sr 突破曲线扩展的影响，特别是通过其低容量和高选择性位点。这意味着可以访问在参考矿物上获得的一组强大而广泛的保留参数。在这项研究中，当粘土矿物与参考矿物具有相似的反应性水平时，粘土砂岩的结果证实了我们选择的参数的稳健性。在含有风化或演化矿物的 Bt 土壤的情况下，这组参数显得更为有限。因此，建模方法的选择对于准确建模和预测 Sr 输运行为至关重要。多孔介质，以及数据库中矿物的代表性。