青岛沿海地区夏季和冬季新粒子生成特征对比

利用宽范围粒径谱仪(WPS)和电迁移率粒径分析仪(SMPS)对青岛沿海地区夏、冬两季大气颗粒物数浓度和粒径谱分布进行了实时测量,同时结合无机和有机气态前体物、大气颗粒物化学组分、气象参数以及后向气流轨迹,对新粒子生成(NPF)特征进行了分析对比.结果表明,在夏季,NPF事件发生频率较低,为18％.夏季NPF事件发生时,...

New Particle Formation Events in Summer and Winter in the Coastal Atmosphere in Qingdao, China

Atmospheric particle number size distributions were measured by a wide-range particle size spectrometer and a scanning mobility particle size spectrometer in the summertime and wintertime in the coastal area of Qingdao (China). The inorganic and organic gaseous precursors and particulate chemical composition were measured to characterize new particle formation (NPF) events by combining meteorological parameters and backward trajectories. In summer, the occurrence frequency of NPF events was 18% lower. However, the atmospheric particle number concentration increased by approximately 1-4 times during the NPF events compared with those without NPF. The apparent formation rates and growth rates were (5.2±4.3) cm^-3·s^-1 and (6.5±2.2) nm·h^-1, respectively, except for a special NPF event on July 20. The correlation analysis results implied that biogenic volatile organic compounds (BVOCs) seemingly favor NPF, and the reverse is true for anthropogenic volatile organic compounds (AVOCs). The occurrence frequency of NPF events of 27% in winter was clearly higher than that in summer. The apparent formation rates and growth rates, i.e., (3.3±3.1) cm^-3·s^-1 and (5.3±3.3) nm·h^-1, decreased, although the decreases were not significant (P>0.05). The correlation analyses implied that AVOCs favored NPF. However, BVOCs had no correlation with NPF. For the cases in which new particles could grow to CCN sizes (>50 nm), the particle growth characteristics showed significant seasonal differences, i.e., in summer, new particles could grow to CCN sizes via photochemical reactions, whereas in winter, second-stage growth driven by the formation of nitrate aerosols was needed to grow new particles to CCN sizes.