The level and distribution of 220Rn concentration in soil-gas in Guangdong province, China.

In order to understand the level and distribution of 220Rn concentrations in soil-gas in the high-radiation-background area, an 220Rn survey was carried out for the first time using a RAD7 portable radon monitor at 67 locations covering a total area of 1800 km2 in the South of China. 220Rn concentrations were significantly different from that in the surface areas covered by the weathered granite of Yanshan Period or Quaternary sediments. The 220Rn concentrations varied between 6.65 and 461 kBq m−3 and the averages were 294.42±81.36 and 23.30±25.84 kBq m−3 for weathered granite products and sediments, respectively. A high positive correlation between 220Rn concentrations and 232Th activity concentrations was found. 220Rn concentrations had no statistically significant variations from depths of 20–140 cm with an interval of 20 cm. It is worth paying attention to the problem of such a high soil 220Rn concentration in Zhuhai City and Zhongshan City. [ABSTRACT FROM AUTHOR]