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从东亚地区向西北太平洋的区域扩散以及与核事故相关的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。在北京和青岛的中国，在韩国的首尔、东海和济州，在日本海的冲绳和黑仓群岛，在日本的松江、金泽、名古屋和滨冈，以及在太平洋的哈特鲁马、八条和小川群岛，建立了大气氡监测站网络。从中国到日本和太平洋，大气氡浓度逐渐降低。从2005年7月至2006年10月，在首尔、滨冈和八岛获得了连续的氡浓度数据。在7-10月期间，滨冈地区的氡浓度受海洋气团的影响，而在12月底-2月期间，则受大陆气团的影响。利用东亚地区的大气氡浓度，建立了一个远距离输送模式。将计算的氡浓度与2004年1月至12月在八条岛和哈特鲁马群岛、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。其原因可能是(1)对垂直扩散系数估计过高，(2)计算区域外的氡流入，(3)垂直风速的内插，(4)氡通量的估算。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.