Study on the environmental behavior of air pollutants by using airborne radioactivity as a tracer

研究东亚地区大气污染物向西北太平洋的区域扩散及其与核事故有关的大面积扩散是东亚地区一个重要而紧迫的环境问题。氡是大气污染物的良好示踪剂。在中国的北京和青岛、韩国的首尔、东海和济州岛、日本海的大木岛和平仓岛、日本的松江岛、金泽岛、名古屋岛和滨冈岛以及太平洋的初间岛、八城岛和小笠原岛建立了大气氡监测站网络。大气氡浓度从中国到日本和太平洋逐渐降低。2005年7月至2006年10月对首尔、滨冈和八丈岛的氡浓度进行了连续监测。滨冈氡浓度在7 - 10月受海气团影响，在12月底- 2月受大陆气团影响。利用东亚地区观测到的大气氡浓度，建立了远程输运模型并对其进行了评价。将计算的氡浓度与2004年1月和12月在八城岛、初间岛、名古屋和北京的观测值进行了比较。在所有测量地点计算的氡浓度都被低估了。原因可能有：(1)垂直扩散系数估计过高；(2)氡流入超出计算域；(3)垂直风速插值；(4)氡通量评估。在考虑了这些因素后，计算出的浓度有了很大的提高。

The study on the regional diffusion of atmospheric pollutants from East Asia region to Northwest Pacific Ocean and the dispersion over a wide area associated with nuclear accident is an important and urgent environmental problem in East Asia. Radon is a good tracer for atmospheric pollutants. A network of atmospheric radon monitoring stations was constructed at Beijing and Qingdao in China, at Seoul, Donghae and Jeju in Korea, at Oki and Hekura islands on the Sea of Japan at Matsue, Kanazawa, Nagoya and Hamaoka in Japan and at Hateruma, Hachijo and Ogasawara islands on the Pacific Ocean. The atmospheric radon concentration decreases gradually from China to Japan and on the Pacific Ocean. Continuous data of radon concentrations were obtained at Seoul, Hamaoka and Hachijojima island from July 2005 to October 2006. The radon concentrations at Hamaoka were affected by maritime air mass during July to October and continental air mass during the end of December to February.The long-range transport model was developed and evaluated by using atmospheric radon concentrations observed in East Asia region. The calculated radon concentrations were compared with the values observed at Hachijo and Hateruma islands, Nagoya and Beijing during January and December 2004. The calculated radon concentrations were underestimate at all measuring locations. The reasons were expected to be (1) over estimate of vertical diffusion coefficient, (2) inflow of radon out of computational domain, (3) Interpolation of vertical wind speed and (4) evaluation of radon flux. After considering these factors, the calculated concentrations were substantially improved.