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.