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

研究核事故引起的东亚地区大气污染物向西北太平洋的区域扩散和大范围扩散是东亚地区一个重要而紧迫的环境问题。氡是一种很好的大气污染物示踪剂。在中国的北京和青岛，韩国的首尔、东海和济州，日本的松江、金泽、名古屋和滨冈，以及太平洋的八照间、八丈和小笠原等岛屿，建立了一个大气氡监测站网络。大气氡浓度从中国到日本和太平洋逐渐降低。从2005年7月到2006年10月，在首尔、滨冈和八丈岛获得了氡浓度的连续数据。滨冈氡浓度在7 ~ 10月受海洋气团影响，在12月底~ 2月受大陆气团影响。将计算的氡浓度与2004年1月至12月期间在八丈岛和波照间岛、名古屋和北京观测到的值进行了比较。计算的氡浓度在所有测量点都被低估了。其原因可能是：（1）垂直扩散系数的估计过高;（2）氡的流入超出计算范围;（3）垂直风速的插值;（4）氡通量的估算。在考虑这些因素后，计算的浓度大大提高。

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.