Relationships between paddy soil radiocesium interception potentials and physicochemical properties in Fukushima, Japan

The radiocesium interception potential (RIP) of bulk soil (RIP_soil) can reliably be used to predict the magnitude of soil-to-plant radiocesium transfer. There has been some controversy about which soil properties control the RIP_soil, although the RIP is theoretically proportional to the amount of frayed edge sites in micaceous clay minerals. The RIP_soil was determined for 97 paddy soils in three regions (Hama-dori, Naka-dori, and Aizu) in Fukushima Prefecture, Japan, and the relationships between selected physicochemical properties and the RIP were analyzed. The mean (± standard deviation) of the RIP_soil for the 97 soils was 1.67 (±0.87) mol kg^-1, and the range was 0.34 to 5.36 mol kg^-1. Pearson correlation analysis revealed that the RIP_soil positively correlated best (P < 0.01) with the clay fraction K content as a mass fraction of the bulk soil (clay-Ksoil) and negatively correlated with the total C content and the phosphate absorption coefficient (P < 0.05). Therefore, clay-Ksoil, an indicator of the amount of micaceous clay minerals in a soil, was confirmed as being useful for estimating the magnitude of the RIP_soil for paddy soils in Fukushima. The RIP_soil was invariably low if either the total C content exceeded 6.0% or the phosphate absorption coefficient exceeded 1500 mg kg^-1, suggesting that these parameters could be useful for screening soils with particularly low RIP_soil values.