China CDC Key Laboratory of Radiological Protection and Nuclear Emergency, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing, 100088, China.
Chemosphere. 2019 Oct;233:76-80. doi: 10.1016/j.chemosphere.2019.05.158. Epub 2019 May 20.
The natural radioactive elements uranium(U) and thorium(Th) in atmospheric environment should be given attention, and their particle size distribution and concentration are important for estimating their hazardous effects to the human body. The concentrations of U and Th in 360 aerosol samples collected using six-stage aerosol collector from June - December, 2016 in Beijing were determinated using ICP-MS after acid digestion. The mass concentration ranges of U in PM0.39-0.69, PM0.69-1.3, PM1.3-2.1, PM2.1-4.2, PM4.2-10.2, and PM10.2- reached 0.0030-0.079, 0.0020-0.069, 0.0015-0.095, 0.0053-0.054, 0.0039-0.098, and 0.0083-0.10 ng/m3, respectively. The mass concentration range of Th in PM0.39-0.69, PM0.69-1.3, PM1.3-2.1, PM2.1-4.2, PM4.2-10.2, and PM10.2- amounted to 0.011-0.11, 0.0065-0.11, 0.0026-0.18, 0.0078-0.14, 0.015-0.30, and 0.0021-0.19 ng/m3, respectively. The contents of U and Th in all PM increased from June to December, and the contents in PM2.1 increased more sharply compared with those in other PM. A positive correlation was observed between the concentrations of U and Th and air quality index and relative humidity, whereas a negative correlation was identified between temperature and PM2.1, PM10.2, and total suspended particulates (TSP) after the Spearman-rank correlation test. The formation of PM was affected by meteorological conditions, which concurrently influenced the contents of U and Th in PM. The atmospheric contents of U and Th at night were higher than those in daytime. Compared with Th, the dose contribution of U to the public can be negligible. The median effective dose in public owing to inhalation of natural radioactive U and Th in the atmosphere measures 1.206 μSv/a.
大气环境中的天然放射性元素铀（U）和钍（Th）应引起重视，其粒径分布和浓度是估算其对人体危害的重要因素。采用 ICP-MS 对 2016 年 6 月至 12 月使用六级大气采样器采集的 360 个气溶胶样品进行酸消解后测定，结果表明，U 在 PM0.39-0.69、PM0.69-1.3、PM1.3-2.1、PM2.1-4.2、PM4.2-10.2 和 PM10.2-中的质量浓度范围分别为 0.0030-0.079、0.0020-0.069、0.0015-0.095、0.0053-0.054、0.0039-0.098 和 0.0083-0.10ng/m3，Th 在 PM0.39-0.69、PM0.69-1.3、PM1.3-2.1、PM2.1-4.2、PM4.2-10.2 和 PM10.2-中的质量浓度范围分别为 0.011-0.11、0.0065-0.11、0.0026-0.18、0.0078-0.14、0.015-0.30 和 0.0021-0.19ng/m3。6 月至 12 月，各 PM 中 U 和 Th 的含量呈上升趋势，其中 PM2.1 增加更为明显。Spearman 秩相关检验结果表明，U 和 Th 的浓度与空气质量指数和相对湿度呈正相关，而与温度呈负相关，PM2.1、PM10.2 和总悬浮颗粒物（TSP）。PM 的形成受气象条件的影响，同时也影响 PM 中 U 和 Th 的含量。夜间大气中 U 和 Th 的含量高于白天。与 Th 相比，U 对公众的剂量贡献可以忽略不计。公众因吸入大气中的天然放射性 U 和 Th 而导致的有效剂量中值为 1.206μSv/a。
