Department of Radioecology, Institute for Environmental Sciences, 1-7 Ienomae, Obuchi, Rokkasho, Kamikita, Aomori 039-3212, Japan.
Department of Radioecology, Institute for Environmental Sciences, 1-7 Ienomae, Obuchi, Rokkasho, Kamikita, Aomori 039-3212, Japan.
J Environ Radioact. 2017 Apr;169-170:131-136. doi: 10.1016/j.jenvrad.2017.01.016. Epub 2017 Jan 20.
We investigated the vertical distribution of the soil-soil-solution distribution coefficients (K) of I, Cs, and Sr in organic-rich surface soil and organic-poor subsurface soil of a pasture and an urban forest near a spent-nuclear-fuel reprocessing plant in Rokkasho, Japan. K of Cs was highly correlated with water-extractable K. K of Sr was highly correlated with water-extractable Ca and SOC. K of I was low in organic-rich surface soil, high slightly below the surface, and lowest in the deepest soil. This kinked distribution pattern differed from the gradual decrease of the other radionuclides. The thickness of the high-IK middle layer (i.e., with high radioiodide retention ability) differed between sites. K of I was significantly correlated with K of soil organic carbon. Our results also showed that the layer thickness is controlled by the ratio of K-OC between surface and subsurface soils. This finding suggests that the addition of SOC might prevent further radioiodide migration down the soil profile. As far as we know, this is the first report to show a strong correlation of a soil characteristic with K of I. Further study is needed to clarify how radioiodide is retained and migrates in soil.
我们研究了日本六所村再处理厂附近牧场和城市森林的富含有机质表层土和贫有机质亚表层土中碘、铯和锶的土壤-土壤-溶液分配系数（K）的垂直分布情况。Cs 的 K 与水可提取 K 高度相关。Sr 的 K 与水可提取 Ca 和 SOC 高度相关。富含有机质的表层土中 I 的 K 值较低，略微低于表层的 K 值较高，而最深层的 K 值最低。这种曲折的分布模式与其他放射性核素的逐渐减少不同。高 IK 中层（即具有高放射性碘保留能力）的厚度在不同地点有所不同。I 的 K 值与土壤有机碳的 K 值显著相关。我们的研究结果还表明，层厚度受表层和亚表层土壤之间的 K-OC 比值控制。这一发现表明，添加 SOC 可能会阻止放射性碘进一步向下迁移土壤剖面。据我们所知，这是首次报道土壤特性与 I 的 K 值之间存在强相关性。需要进一步研究以阐明放射性碘在土壤中的保留和迁移方式。
