上海市大气总汞季节变化特征及与气象条件的关系

Total Gaseous Mercury in Ambient Air of Shanghai:Its Seasonal Variation in Relation to Meteorological Condition

2008年到2010年对上海市西南部大气中总汞(TGM———Total Gaseous Mercury)的污染水平进行监测,结果表明TGM日均浓度为ND^57.23ng/m(3(7.79±3.29)ng/m)3。TGM呈现出一定的季节性变化特征,浓度最高的是秋季,然后依次是冬季、春季、夏季,平均浓度分别为(9.30±2.48)、(8.32±2.79)、(7.78±2.33)、(2.16±3.29)ng/m3。TGM浓度受东南风向影响最大,其次为西北和东北风向。在置信水平为95%的情况下,TGM浓度与日平均温度呈正相关性,而与日温差、相对湿度、日相对湿度差、风速无显著相关性。但TGM浓度分别与日均O3浓度和NO2浓度均呈显著正相关。利用HYSPLIT_4模型对TGM浓度高值与低值几天的空气气团来源轨迹进行反演,结果发现高低浓度日的气团来源略有差别,总体上看,冬季、春季和秋季受北方气团影响较大,夏季则受我国东部海域影响,具体的局部和长距离输送的贡献需要进一步研究。

This paper presents a set of total gaseous mercury（TGM） concentration data collected during the period from 2008 to 2010 in southeast Shanghai,showing the changes of TGM concentrations due to seasonal climatic factor.According to the observation,the southeastern wind had a larger influence on gaseous TGM,the next was northwestern and northeastern wind,and factors such as daily mean temperature,ozone and NO2 were positively correlative to the TGM concentration in southeast part of Shanghai.Besides,5-day air mass back-trajectories were given by the HYSPLIT-4 Model during the days with high or low TGM concentrations.TGM was mainly affected by the air mass form north China in winter,spring and fall,while in summer was influenced by the ocean to the east of Shanghai.