中国高本底城市的土壤氡水平及分布

在广东珠海地区采用便携式半导体测氡仪进行了大比例尺土壤氡浓度调查,测点数469个,面积大于100km2。珠海地区地下0.6 m处的平均土壤氡浓度为55.94±58.54 kBq/m3,其中在珠海斗门的第四纪沉积物地区、沉积物和风化花岗岩混合地区,以及风化花岗岩地区的土壤氡浓度分别是7.14±8.75,37.64±25.92和151.25±196.23 kBq/m3。高氡潜势区主要分布在黑云母花岗岩、风化花岗岩地区和新的工业开发区,且表现出与当地岩性密切相关。城市化和工业化改变了原有的天然辐射背景。珠海市区的平均土壤氡浓度分别为广州、泉州和晋江市平均值的8.3倍和15倍。研究结果表明：珠海是一个氡潜势较高的区域,需要进一步开展辐射防护目的的氡测量。

THE DISTRIBUTION AND LEVEL OF RADON GAS IN SOIL IN A HIGH RADIATION BACKGROUND CITY OF CHINA

A soil gas radon survey was performed on a large scale to determine the distribution of radon in soil of Zhuhai City in Guangdong Province by means of a portable radon monitor of a semiconductor alpha spectroscopy.The survey sampled 469 sites covering an area of more than 100 km2.The average of soil radon concentration in the soil depth of 0.6 m is 55.94 ± 58.54 kBq/m3 in Zhuhai urban area,whereas the concentration is 7.14 ± 8.75,37.64 ± 25.92,and 151.25 ± 196.23 kBq/m3 in the Quaternary sediments,the mixtures of sediments and weathered grain of granite,and the weathered granite in Doumen District,respectively.The high radon potential areas are located within biotitic granites and new industrial districts,as indicated by the strong correlation between the radioactivity level and geological lithology.The mean value of soil gas radon concentration in Zhuhai urban area(ZUA) is about ten times as high as that in Guangzhou,Quanzhou and Jinjing City.The results show that Zhuhai area has higher radon potential,and hence protective measures against radon should be taken into account.