Geochemical modelling of cation-exchange reaction and whole-rock compositional change in Neogene marine sediments

Abe, Takeyasu  ; Iida, Yoshihisa ; Sasamoto, Hiroshi   ; Ishii, Eiichi   

In order to validate safety&performance assessment methodology of radioactive waste disposal, JAEA has been studying geochemical data of boring cores and groundwater in Horonobe. In this study, cation-exchange reactions of meteoric water infiltration zone of Neogene marine sediments in Horonobe were simulated by geochemical model. Calculation results of static cation-exchange in a batch system suggested that NaO/AlO decrease and CaO/AlO increase should be observed in the infiltration zone. Expected geochemical features cannot be fully confirmed in measured geochemical data, and this result implies that other geochemical effects by additional chemical reactions and/or coupled reactive transport should be considered.