福建省环境地表γ辐射剂量率估算与人居环境安全性评价

The environmental terrestrial gamma-radiation dose rate estimation andthe living environment safety evaluation in Fujian Province

福建省位于东南沿海,花岗岩大面积出露,导致土壤中的放射性核素普遍高,从而使环境地表γ辐射剂量率也较高。近年来,人居环境安全越来越受重视,较高的γ辐射剂量率是否存在风险成为人们关心的问题。本项目选择永安罗坊、武平忠地两处重点区开展1∶5万环境地表γ辐射剂量率测量,并在同点采集配套土壤样品。通过研究土壤放射性元素238 U、232 Th、40 K比活度与γ辐射剂量率的关系特征建立多元回归方程,利用福建省1∶25万多目标区域地球化学调查所获得的31303个表层土壤U、Th、K测试成果换算福建省2 km×2 km网格环境地表γ辐射剂量率,编制人居环境适宜性评价图。得出福建省γ辐射安全区(无风险)约12.1万km 2,占研究区总面积的99.64%,风险区(可能存在风险)433 km 2,占0.36%,管制区(存在风险)仅4 km 2,天然放射性人居环境优良。

Fujian Province is located in the southeast coastal area of China,where granite is extensively exposed,which causes the fact that radionuclide is generally high in the soil,so that the environmental terrestrial gamma-radiation dose rate is higher too.In recent years,the living environment safety has aroused more and more attention,and the problem whether higher gamma radiation dose rate there is a risk has become much concern from the people.This study chose Luofang of Yong'an and Zhongdi of Wuping which are two key areas to carry out the 1∶50000 environment terrestrial gamma radiation dose rate measurement,supported by soil samples at the same collection points.Through the study of relationship between specific activity of soil radioactive elements 238 U,232 Th,40 K and gamma radiation dose rate,a multivariate regression equation was established.The U,Th,K test results of 31303 surface soil samples obtained from 1∶250000 multi-purpose regional geochemical survey in Fujian Province were converted into 2 km×2 km grid environmental terrestrial gamma-radiation dose rate in Fujian Province,so that human settlement environment suitability evaluation could be conducted.The authors have reached the conclusion that gamma radiation safety area(with no risk)in Fujian Province possesses about 121000 km 2,accounting for 99.64%,the risk area(probably with some risk)possesses 433 km 2,accounting for 0.36%,and controlarea(with risk)only possesses 4 km 2,suggesting an excellent natural radioactive environment.