Abstract
There is a general consensus that the retention of RCs is controlled by the micaceous clays in soil such as illite, and selectively associates with the frayed-edge-site (FES). Radiocesium interception potential (RIP) is one of intrinsic parameters of soil in terms of their selective adsorption to RCs. In this study, eight soil and five clay mineral samples were selected to characterize their RIP, cation exchange capacity(CEC), total organic carbon content (TOC), and adsorption species by extended X-ray absorption fine structure (EXAFS) spectroscopy. Cs adsorption followed two different linear relationships between RIP, CEC, and total adsorption concentration (QT) of Cs in soil: (1) at trace concentration of Cs, [FES]/QT vs. RIP where [FES] is the capacity of FES; (2) at high concentration of Cs, [FES]/QT vs. RIP/CEC. It means that the contribution to Cs adsorption from FES have a positive linear correlation with RIP whenever it is trace or high Cs concentration.A linear correlation of RIP/CEC was observed with the ratio of coordination number (CN) of IS and OS complexes, i.e., CNis/(CNis+CNos) suggesting that CNis/(CNis+CNos) was very sensitive to the adsorption species of Cs in soil with various RIP and CEC (Fig. 1). Based on our findings, EXAFS approach can be directly employed to evaluate RCs mobility or transportation in environment combining RIP and CEC even high Cs concentration used in EXAFS sample preparation.
