福岛核事故后上海气溶胶中^(131)I、^(134)Cs和^(137)Cs的来源途径分析  

Source and Pathway of ^(131)I,^(134)Cs and ^(137)Cs in Aerosols of Shanghai After the Fukushima Nuclear Accident

作　　者：刘丹彤[1] 王锦龙[1] 毕倩倩[1] 杜金洲[1] 

机构地区：[1]华东师范大学河口海岸学国家重点实验室,上海200062

出　　处：《核化学与放射化学》2017年第1期103-112,共10页Journal of Nuclear and Radiochemistry

基　　金：河口海岸学国家重点实验室基本科研业务费资助项目(2011KYYW04)

摘　　要：利用对气溶胶中典型放射性核素(^(131)I和134,^(137)Cs)的分析,可以评估福岛核事故产生的放射性物质对上海及全球的大气放射性本底水平造成的影响。本工作结合核事故释放过程、核素的天然衰变以及气象条件等因素,获得核事故期间上海的气溶胶中^(131)I和134,^(137)Cs活度浓度及其比值的分布特征:^(131)I被检出的时间(2011-03-27)早于^(134)Cs(2011-04-06)和^(137)Cs(2011-04-08),^(131)I的活度浓度(0.01~1.20 mBq/m3)比^(134)Cs(0.01~0.58mBq/m3)和^(137)Cs(0.01~0.65mBq/m3)大2~10倍,而且在不同的时间段出现相应的多峰值现象;^(131)I/^(137)Cs活度浓度比值(1.3~10.6)在2011年4月5日之后呈递减趋势,但是^(134)Cs/^(137)Cs活度浓度比值(0.8~2.9)则一直在1.1左右波动。利用HYSPLIT模型模拟放射性气团运移轨迹的分析方法,表明在核事故期间输入到上海的放射性气溶胶的途径有东北和西北两条主要迁移路径。同时通过结合国内相关城市核事故期间大气放射性监测数据,证实了东北路径在中国境内的控制地位。另外,通过总结和分析北半球大气监测数据中^(131)I/^(137)Cs和^(134)Cs/^(137)Cs活度浓度比值最大值的分布特征,验证了日本核事故产生的放射性气溶胶在北半球的传输过程。The typical radionuclides（^131I and 134,^137Cs）in aerosols could be efficiently used to evaluate the impacts of radioactive materials from the Fukushima nuclear accident on the radioactive background level of the atmosphere in Shanghai and the world.In the present work,combining impact factors,such as the nuclear accident release process,natural radioactive decay and the meteorological conditions,the distribution patterns of 131 I and 134,137 Cs activities and their ratios in Shanghai aerosols were obtained.The date when ^131I（2011-03-27）could be detectable is earlier than ^134Cs（2011-04-06）and ^137Cs（2011-04-08）.The ^131Iactivity（0.01-1.20mBq/m^3）is 2-10 times higher than those of ^134Cs（0.01-0.58mBq/m^3）and ^137Cs（0.01-0.65mBq/m^3）.Moreover,multiple peak values of ^131I are found with time series.The activity ratios of ^131I/^137Cs（1.3-10.6）decrease after the date of April 5th,2011,however,the activity ratios of ^134Cs/137 Cs（0.8-2.9）are constant to be around 1.1.Using the analytical method of HYSPLIT model,the primary air mass migration pathways of radioaerosols in Shanghai during this accident can be qualitatively inferred as the northeast and northwest paths.Meanwhile,the northeast pathway of radio-aerosols in Shanghai is further confirmed to be dominant by analysis of the reported radio-aerosol data in the concerned cities of China during that time period.In addition,the results of maximum values of ^131I/137 Cs and^134Cs/137 Cs activity ratios are summarized and analyzed to reveal the spreading pathways of radio-aerosols in the northern hemisphere.

关 键 词：气溶胶 ^131I/^137Cs活度浓度比值 ^134Cs/^137Cs活度浓度比值 迁移路径 

分 类 号：TL732[核科学技术—辐射防护及环境保护] TL751