Radiocesium interception potential of agricultural soils in northeast Japan

The health risks associated with the long-term intake of radiocesium from food have been of great concern since the Fukushima Daiichi Nuclear Power Station accident in 2011. Therefore, evaluating the phytoavailability and mobility of radiocesium in soil and determining the ability of soil to fix radiocesium are important research topics. The capacity and selectivity for ¹³⁷Cs sorption in soil is evaluated on the basis of the radiocesium interception potential (RIP). Here, we measured the RIP of 925 farmland soil samples collected from Fukushima Prefecture and surrounding regions and plotted the values on a soil classification map and a surface geological map. The RIP values ranged from 73 to 12700 mmol kg⁻¹, and a wide range was also observed among samples with identical soil types and geological features; however, the RIP values were significantly low for Andosols (P ≤ 0.05). In addition, soils that did not contain vermiculite, illite and smectite had low RIP values. All measured RIP values were negatively correlated with the total C content and phosphate absorption capacity and positively correlated with the clay, silt, and exchangeable K and Ca content (P ≤ 0.01). However, the relationship between the RIP and the measured soil properties, except for the exchangeable K content, is strongly dependent on the soil classification and clay mineral composition. Therefore, the soil properties that most significantly influence the RIP values are probably differences in the soil parent materials, which influence the soil classification and clay mineral composition.