Distribution and Characteristics of Radon Gas in Soil from a High-Background-Radiation City in China

A soil survey using a portable radon monitor employing semiconductor alpha spectroscopy has been performed on a large scale to determine the distribution of radon in soil in Zhuhai City, Guangdong Province. The survey with 469 sample sites covered an area of more than 100 km2. The average soil radon concentrations at a depth of 0.6 m were 55.94±58.54 kBqm-3 in the Zhuhai Urban Area (ZUA) and 7.14±8.75, 37.64±25.92, and 151.25±196.23 kBqm-3, respectively, in the Quaternary sediment, mixtures of sediment and weather grain of granite, and weathered granite in Doumen District. The areas with high radon potential were located within areas of biotitic granites and new developing industrial districts, as indicated by a strong correlation between the radioactivity level and geological lithology. The mean radon concentration in ZUA is about ten times higher than those in Guangzhou City, Quanzhou City, and Jinjiang City. The results show that the Zhuhai area has a higher radon potential, and protective measures against radon should be considered.