Selenium (Se) sorption behaviors have been widely studied for evaluating radionuclide reactive transport in fractured granite. However, with disparate mineral compositions, the impact of fracture filling materials (FFMs) is often ignored in characterizing radionuclide sorption and migration. This study aims to investigate the contribution of FFMs to the sorption of radionuclide by conducting flow-through experiments with granite, FFMs, and their mixtures (GFMs) separately. The relative contribution of major minerals in these materials is further identified by column experiments with pure minerals. Taking the granite core samples collected from a potential repository site as an example, the Se(IV) sorption and migration is mainly influenced by biotite and albite in granite samples, and is controlled by smectite and illite in FFMs. The sorption distribution coefficient (K_d) estimated from the individual mineral experiments decreased in the following order: smectite > illite > biotite > K-feldspar > albite > quartz > calcite. When all minerals were mixed, the sorption ability increased with the mass fraction of FFMs. The component additivity model (CAM) was further tested by predicting K_d in different mineral mixtures. The calculated ${\text{K}}_{\text{d}}$ values were lower than those obtained from experimental fitting results. The largest discrepancy occurred when the mass fractions of the granite and FFMs were equal. This implies that CAM has certain limitations in upscaling ${\text{K}}_{\text{d}}$ directly from individual minerals to mineral mixtures, especially when the mass fraction of FFMs is larger than 0.2. The results from this study provide valuable insights for understanding the sorption behaviors of radionuclides in fractured granite.

硒 (Se) 吸附行为已被广泛研究用于评估裂隙花岗岩中的放射性核素反应输运。然而，由于矿物成分不同，在表征放射性核素吸附和迁移时，裂缝填充材料 (FFM) 的影响常常被忽略。本研究旨在通过分别对花岗岩、FFM 及其混合物 (GFM) 进行流通实验，研究 FFM 对放射性核素吸附的贡献。这些材料中主要矿物的相对贡献通过纯矿物的柱实验进一步确定。采集从潜在 储存库收集的花岗岩岩心样本 以现场为例，Se(IV)的吸附迁移主要受花岗岩样品中黑云母和钠长石的影响，FFMs中受绿土和伊利石控制。从单个矿物实验估计的吸附分布系数（K _d）按以下顺序降低：绿土>伊利石>黑云母>钾长石>钠长石>石英>方解石。当所有矿物混合时，吸附能力随着FFM的质量分数而增加。通过预测不同矿物混合物中的K _{d进一步测试了成分可加性模型 (CAM)。}计算出来的${\text{ķ}}_{\text{d}}$值低于从实验拟合结果中获得的值。当花岗岩和 FFM 的质量分数相等时，差异最大。这意味着 CAM 在升级方面有一定的局限性${\text{ķ}}_{\text{d}}$直接从单个矿物到矿物混合物，尤其是当 FFM 的质量分数大于 0.2 时。这项研究的结果为理解裂隙花岗岩中放射性核素的吸附行为提供了有价值的见解。