Particle size distribution, chemical composition and meteorological factor analysis: A case study during wintertime snow cover in Zhengzhou, China
Particle size distribution, chemical composition and meteorological factor analysis: A case study during wintertime snow cover in Zhengzhou, China
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DOI：
10.1016/j.atmosres.2017.11.016
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发表时间：
2018-04
影响因子：
5.5
通讯作者：
Fei Yu;Qun Wang;Qishe Yan;Nan Jiang;Junhua Wei;Zhi-Qin Wei;Shasha Yin
中科院分区：
文献类型：
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作者：
Fei Yu;Qun Wang;Qishe Yan;Nan Jiang;Junhua Wei;Zhi-Qin Wei;Shasha Yin
2015年11月23日至25日，华北地区出现了一次较强的降雪。考虑到大部分裸露地面和道路粉尘被积雪覆盖，可以忽略粉尘和土壤的影响。在2015年11月28日至12月4日的一次雾霾事件中，采集了中国郑州地区的大气颗粒样本。为了更好地了解这次雾霾事件的形成和演变，对其粒径分布、颗粒数量、颗粒组成和气象参数进行了测量和分析。结果表明，气象条件对该事件的发生和消除起着重要作用。逐时细颗粒物（PM2.5）浓度与相对湿度呈正相关（r = 0.84, p < 0.01），与风速呈负相关（r = - 0.62, p < 0.01）。颗粒质量浓度在1.0 ~ 1.6 μm之间达到峰值，但总颗粒数浓度在雾霾日低于晴空日。雾霾日数值浓度的中位数直径约为60 nm，晴空日数值浓度的中位数直径约为26 nm。在晴朗的日子里观察到两个新的颗粒形成过程。二次无机离子（SO42−、NO3−和NH4+）在雾霾日的比例高于晴空日。本例NH4+浓度偏高可能是交通和燃煤排放所致。在雾霾天气中，地壳物质占pm2.5的2.4%，证实了此次雾霾天气中粉尘排放源的贡献可以忽略不计。NO3−/SO42−比值在0.41 ~ 0.67之间，表明了稳态燃烧的相对重要性。OC/EC比值在2.73 ~ 3.42之间变化，表明存在次生有机碳。有效缓解雾霾应加强对一次排放（粉尘）和二次气溶胶气态前体（NH3、no2和SO2）的污染物控制措施。
There was a significant snowfall event in North China from November 23 to 25 in 2015. Considering that most of the bare surface and road dust were covered by snow, the effect of dust and soil could be ignored. Atmospheric particle samples were collected in Zhengzhou, China during a haze event from November 28 to December 4, 2015. To better understand the formation and evolution of this hazy event, the size distribution, particle number, composition of particles and meteorological parameters were measured and analyzed. Results show that the meteorological conditions played an important role in the occurrence and elimination of this event. The hourly fine particle matter (PM2.5) concentration was positively correlated with relative humidity (r = 0.84, p < 0.01) but negatively correlated with wind speed (r = − 0.62, p < 0.01). The particle mass concentrations peaked at the sizes of 1.0 to 1.6 μm on hazy days, however, the total particle number concentrations on hazy days were lower than those on clean days. The median diameter of the number concentration during hazy days was approximately 60 nm, whereas it was 26 nm on clean days. Two new particle formation processes were observed on the clean days both. The proportion of secondary inorganic ions (SO42 −, NO3−and NH4+) on hazy days was higher than that on clean days. The higher NH4+concentration in this case may be contributed by traffic and coal-power emission. Crustal matter accounted for 2.4% in PM2.5on hazy days, and it confirmed that the contribution of dust emission source was negligible during this event. The ratios of NO3−/SO42 −ranging from 0.41 to 0.67 indicated the relative importance of stationary combustion. The ratios of OC/EC varied from 2.73 to 3.42 and indicated the presence of secondary organic carbon. Effective haze mitigation should enforce pollutant control measures for primary emission (dust) and secondary aerosol gaseous precursor (NH3, NO2and SO2).