Effects of biotite on diffusion and sorption of cations in crystalline rocks by through-diffusion and laser-ablation ICP-MS experiments

透過拡散試験とレーザーアブレーションICP-MS分析に基づく結晶質岩中の陽イオンの拡散と収着に及ぼす黒雲母の効果

深津 勇太  ; Hu, Q.*; 舘 幸男  

Fukatsu, Yuta; Hu, Q.*; Tachi, Yukio

Matrix diffusion and sorption are key processes to predict the transport of radionuclides in crystalline rocks for geological repository. Based on the previous studies, cationic sorption onto biotite would play an important role to evaluate the sorption and diffusivity of radionuclides in crystalline rock. In order to investigate the impact of sorption of cations in biotite on the diffusivity, in this study, we conducted through-diffusion tests of Cs, Co and Sr for several types of crystalline rocks, and compared the results in different concentrations of K that is one of the major cations of groundwater and also strong competitor for Cs sorption onto biotite. Moreover, the elemental maps of multiple tracers sorbed onto biotite of these rocks were directly obtained by using a laser ablation (LA)-ICP-MS, which provides microscale distribution of tracer elements within the rocks.