Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6338637 | Atmospheric Environment | 2015 | 9 Pages |
Abstract
Severe PM2.5 pollution was observed frequently on the North China Plain, and nitrate contributed a large fraction of the elevated PM2.5 concentrations. To obtain a comprehensive understanding of the formation pathways of these fine particulate nitrate and the key factors that affect these pathways, field measurements of fine particulate nitrate and related air pollutants were made at a rural site on the North China Plain in the summer of 2013. Extremely high concentrations of fine particulate nitrate were frequently observed at night and in the early morning. The maximum hourly concentration of fine particulate nitrate reached 87.2 μg mâ3. This concentration accounted for 29.9% of the PM2.5. The very high NH3 concentration in the early morning significantly accelerated the formation of fine particulate nitrate, as indicated by the concurrent appearance of NH3 and NO3â concentration peaks and a rising neutralization ratio (the equivalent ratio of NH4+ to the sum of SO42â and NO3â). On a number of other episode days, strong photochemical activity during daytime led to high concentrations of O3 at night. The fast secondary formation of fine particulate nitrate was mainly attributed to the hydrolysis of N2O5, which was produced from O3 and NO2. Considering the important roles of NH3 and O3 in fine particulate nitrate formation, we suggest the control of NH3 emissions and photochemical pollution to address the high levels of fine particulate nitrate and the severe PM2.5 pollution on the North China Plain.
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Physical Sciences and Engineering
Earth and Planetary Sciences
Atmospheric Science
Authors
Liang Wen, Jianmin Chen, Lingxiao Yang, Xinfeng Wang, Caihong Xu Caihong Xu, Xiao Sui, Lan Yao, Yanhong Zhu, Junmei Zhang, Tong Zhu, Wenxing Wang,