车江铜矿室外氡水平研究

Study on outdoor radon level in Chejiang copper mine

原环保部2014年对湖南衡阳272尾矿库及周边进行了航测,意外发现在尾矿库西南方向、湘江上游附近有一辐射水平异常区域,后经调查该地区为车江铜矿地区。为了调查车江铜矿这一非铀矿山及其周边的氡活度浓度水平与氡的来源,采用了固体核径迹法与活性炭盒法对其氡活度浓度和氡析出率展开测量,并将氡析出率连续测量与活性炭盒法所测氡析出率结果进行对比分析。调查发现,该区域所有取样点位冬季和夏季氡活度浓度测量结果平均值分别为31.0 Bq·m^-3和22.9 Bq·m^-3;从区域分布上来看最高的均为农田区,其次为原采矿区。土壤氡析出率测量结果最高的同样为农田区,但是均远低于铀尾矿的氡析出率限值0.74 Bq·m^-2·s^-1。氡活度浓度日变化趋势与氡析出率的日变化趋势较为一致。上述结果表明车江铜矿地区的室外氡活度浓度较高与其土壤氡的析出有关。

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 31.0 Bq · 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.