This research aims to analyze the impact of the nuclear leakage of Japan in March of 2011 on two typical areas in north China, Beijing and Qingdao. TSP and PM10 samples were collected with glass fibre filters. The pollution levels of radioactive nuclides in particulates were analyzed with an HpGeγ spectrometer. Both Models-3/CMAQ model and HYSPLIT-4 dispersion model were applied to analyze the transmission of radioactive nuclides and their impacts on the two areas of China. Results showed that: no detectable levels of 131I, 134Cs, 137Cs, 7Be were observed before March 28th in Beijing. The four isotopes were firstly detected on March 29th, and then rapidly increased until to the peak value on April 1st to 3rd ( concentration of 131I, l34Cs, 137Cs, 7Be in PM10 were 1.87 ×10-3, 4.60× 10-4 , 6.52×10-4, 8. 52×10-3Bq/m3, respectively). Afterthat, 131I reduced gradually until to undetectable level after April 7th due to its 8 d halflife, while 134Cs and 137Cs kept a relatively lower level ( <5 ×10-5 Bq/m3) during the sampling periods. However, 7Be remained a relatively high concentration 4. 23 ×10-3-9. 42 ×10-3 Bq/m3 for all sampling periods, which may be due to its high background level both in Beijing and in Qingdao. The concentrations of four radioactive nuclides kept at a lower level, which should not much influence on people according to the monitoring data. Results from both trajectory analysis and model simulations indicated that air masses from Fukushima all moved to northeast or southeast after the leakage events. Thus the radionuclides from the leakage in Japan should arrive in China through the diffusion at high altitudes.%为研究2011年3月日本核泄漏对我国北方典型区域的影响,通过采集北京、青岛两地的TSP和PM1o样品,对大气颗粒物中的放射性核素进行监测,分析其污染水平；并结合气象条件等因素,运用Models-3/CMAQ模式数值模拟和HYSPLIT-4轨迹,分析了日本放射性核素的传输方向及其可能对我国的影响.结果表明:①北京监测点于3月29日开始监测到微量的131I、134Cs、137 Cs、7Be,随后几天各核素浓度迅速增加,于4月1-3日达到峰值(在PM10中的浓度分别为1.87×10-3、4.60×10-4、6.52×10-4、8.52×10-3 Bq/m3)后,131I逐渐减小直至检测不到,134Cs、137 CS的浓度则保持在较低浓度水平(＜5×10-5 Bq/m3)且稳定,7Be则保持较高的浓度水平(4.23×10-3～9.42×10-3 Bq/m3),并随时间的波动出现峰值.青岛监测点的各放射性核素浓度特征与北京监测点类似.②4种放射性核素均保持在较低的浓度水平,从监测数据看对人体健康应该不会造成太大影响.③Models-3/CMAQ模式数值模拟和HYSPLIT-4轨迹分析均显示,日本核泄漏期间,福岛的气团均是向其东南、东北方迁移,因此检测到的放射性核素应该主要是通过高空扩散由西向东绕地球一圈后传输到我国的.
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