Abstract: An aerial survey of Hengyang 272 tailing ponds and its surrounding areas were carried out by—Ministry of Environment Protection in 2014 and it showed that there was an abnormal radiation level in a region to the southwest of the tailing ponds and near the upper reaches of Xiangjiang river, an area used to be identified as Chejiang copper mine. In order to investigate the radon concentration level and radon sources in Chejiang copper mine surroundings, soild nuclear track detectors and activated carbon boxes were used to measure the radon concentration and radon exhalation rate. Radon exhalation rate was continuously measured by the activated carbon box and was calibrated. Our study found that the average radon concentration measured at all sampling points in winter and summer were 31.0Bq·m^-3 and 22.9 Bq·m^-3, respectively. From the perspective of regional distribution, the farmland area had the highest radon concentration, followed by the original mining area. The farmland area also showed the highest radon exhalation rate from soil though which is far lower than the limit of 0.74 Bq·m^-2·s^-1 for radon exhalation rate in uranium tailings. In addition, the daily variation of radon concentration was in parallel with that of radon exhalation rate. Therefore, the high outdoor radon concentration in Chejiang copper mine area is related to radon exhalation from its soil.

Key words: Chejiang copper mine, radon concentration, radon exhalation