지역별 토양 성분과 방사능 분석의 상관관계에 관한 연구

Abstract

The concerns of many people regarding radioactive materials present in the surrounding environment have heightened because of the nuclear power plant accident in Japan and the radioactive asphalt incidents in the Seoul area. This study investigated, by area and soil component, the specific radioactivity consequent to the soil composition of the surrounding spaces of daily life, such as schoolyards, parks, and green areas. For this purpose, the whole country was divided into six areas and, from the soil of each area, comparative analyses were done based on the specific radiation concentrations of 40K, 137Cs, and 226Ra, and 13 basic soil components. Samples were extracted from 86 sites with high transient populations in the six areas. From 28 of these sites, to determine the correlation of natural decay series radon, the specific radiation concentration of the soil sample porous layer and the radiation concentration of 226Ra were compared with the soil components analysis, based on specific radiation analyses of 222Rn, 222Rn fast, and 220Rn T nuclides. The soil components by area were graphed on a map using the kriging technique. In order to distinguish the differences in radiation amount depending on soil components, sites containing similar soil components were clustered together, and distinct characteristics of clusters by area were determined through a hierarchical cluster analysis, based on the 13 soil components, by differentiating them into 13 clusters on the basis of average group distance using Euclidian distance. As a region with a high specific radiation value for its soil, the Seoul metropolitan area has the distinct characteristics of Cluster 4 among the 13 clusters. The Jeju area, with a low specific radiation value, was determined to have the characteristics of Clusters 12 and 13. From these results, the Jeju area was found to have lower SiO2, K2O, and Cr2O3 levels, among the 13 soil components, compared to the Seoul metropolitan area. In this study, therefore, it is found that there is a close relationship between the radiation concentration of the surrounding environment and the soil components and that the effect of environmental radiation can be reduced by utilizing as much as possible soil comprised of components with low emission of specific radiation for facilities that are used by large numbers of people. It is thought that the soil component and specific radiation concentration data can be hereby used as basic material for considering radiation impact when creating the environment of a mass-use facility. It is also possible to use it, by quantifying the specific radiation contained by each component, as basic material for establishing the evaluation standards of internal radiation exposure effects and radiation environment effects, as well as for epidemiological surveys of radiation ecology.