2011年春季日本福岛核泄漏污染输送：贵阳^(131)I和^(137)Cs观测示踪分析

Transport of the radioactivity leakage from the Japan Fukushima Nuclear Power Plant in 2011 spring:^(131)I and ^(137)Cs as the tracers observed in Guiyang,China

2011年3月11日,日本本州9.0级地震引发了福岛核电站核泄漏,以及由此引起的131I和137Cs在全球大气环流传输已引起了重视.理论上也对这种输送路径进行了研究.本文报道2011年3月17日—4月28日在贵阳观风山对气溶胶中天然核素(210Pb、7Be)和人为核素(131I、137Cs)近地面空气浓度逐周采样的系统对比观测,并结合该时段贵阳离地面500m高度逐周315h的气团后向轨迹分析.结果表明:福岛核泄漏污染物通过两条显著的途径输送到贵阳地区.第一条是首波核污染通过全球大气环流传输,由西向东,几乎环绕地球一周,历经约10d至两周,最终在3月24日—31日从我国的西北地区入侵抵至贵阳;第二条途径则是福岛地区上空的核污染气团受东北天气系统的挤压南移并在低纬度地区再次先后受到东北和东南气流的影响,于4月7日—14日抵达贵阳.核污染的第一条输送路径是全球尺度,第二条是东亚区域尺度.

The 9.0 Ritcher scale earthquake happened on March 11th,2011 in the Honshu Island,Japan had caused the radioactivity leakage from the Fukushima Nuclear Power Plant.The leaked artificial nuclides,131I and 137Cs,and their transport processes in the global atmosphere had drawn great public attention.In this paper,the concentrations of radioactive isotopes 7Be,210Pb,131I and 137Cs at the surface level in weekly aerosol samples obtained at the Guanfenshan Moutain,Guiyang,China from March 17th to April 28th,2011 were reported.The variations of the nuclide concentrations associated with their transport paths were analyzed with 315 h-backward trajectories initialized at 500m from the surface level at Guiyang.The results revealed that there were two evident transport paths for 131I and 137Cs from Fukushima to Guiyang.The first path,along with which radioactive pollution tracers reached Guiyang faster,was from the north-western China.These tracers transported eastward and took 10 days to two weeks to arrive the north-western China before they were detected on March 24th—31st in Guiyang.The second path extended south-eastward by the north-east Asian synoptic system at the beginning,then transported south-westward and north-westward before their arrivals on April 7th-14th in Guiyang.The first transport path of radioactive pollution tracer from the Fukushima Nuclear Power Plant to Guiyang was in the global scale while the second was in the East Asian regional scale.