北京市冬季大气细粒子数浓度的粒径分布特征

Size Distribution of Fine Particle Number in Winter in Beijing

考虑到对人体的健康危害,大气颗粒物的数浓度值可能比质量浓度值更重要。通过对北京市交通道路边、生活区和远郊背景点大气细粒子数浓度的监测,对北京市大气细粒子数浓度的主要来源、浓度和粒径分布特征进行研究。文章认为交通源是城市大气细粒子数浓度的主要来源。城市生活区的大气细粒子主要是污染源稀释后扩散而来。远郊区既可能存在气象污染物光化学成核生成的超细颗粒物,也存在外部运移而来的细粒子。与国外其他城市相比,北京市大气细粒子数浓度在道路边处于中等偏下水平,但生活区和背景点处于相当或偏高的水平。

Considering the health effects, the number of PM may be more important than their mass. According to the monitoring result carried out at urban residential site, a roadside site and a remote background site in Beijing, the sources, concentration and size distribution of fine particles were studied. Traffic emission was considered as the main source of the number of atmospheric fine particle. The fine particles at urban residential mainly come from the dilution and transportation of fine particle sources. Two types of fine particle may exist at remote sites ： long range transported fine particles and photochemical nucleation. Compared with that of oversea cities, the number concentration of fine particles was relatively lower at roadside in Beijing, and comparative or higher at residential and remote sites.