| 青岛沿海地区夏季和冬季新粒子生成特征对比 |
| 摘要点击 2698 全文点击 803 投稿时间：2020-07-24 修订日期：2020-10-12 |
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| 中文关键词 沿海地区 新粒子生成(NPF) 大气颗粒物数浓度 气态前体物 化学组成 |
| 英文关键词 coastal area new particle formation(NPF) atmospheric particle number concentration gaseous precursors chemical composition |
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| 中文摘要 |
| 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，大气颗粒物数浓度可增加1~4倍，新粒子表观生成速率和增长速率（除7月20日特殊事件）分别为（5.2±4.3）cm-3·s-1和（6.5±2.2）nm·h-1，相关分析结果暗示生物源有机物（BVOCs）对新粒子生成有促进作用，人为源有机物（AVOCs）起抑制作用.冬季，NPF事件发生频率为27%，新粒子表观生成速率和增长速率分别为（3.3±3.1）cm-3·s-1和（5.3±3.3）nm·h-1，大气颗粒物总数浓度在NPF天和非NPF天无显著差异.与夏季相反，相关分析结果暗示冬季人为源有机物（AVOCs）对新粒子生成有促进作用，而生物源有机物（BVOCs）与新粒子生成的关系不明显.此外，新粒子增长到CCN粒径范围（>50 nm）的增长特征呈现季节性差异：在夏季，新粒子生成后可在光化学作用下直接增长到CCN粒径范围，而在冬季，新粒子需经历两阶段增长，第二阶段增长中颗粒态硝酸铵的生成方可使新粒子增长至CCN粒径范围. |
| 英文摘要 |
| 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. |
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