New particle formation (NPF) events are an increasingly interesting topic in air quality and climate science.In this study,the particle number size distributions,and the frequency of NPF events over Hefei were investigated from November 2018 to February 2019.The proportions of the nucleation mode,Aitken mode,and accumulation mode were 24.59％,53.10％,and 22.30％,respectively,which indicates the presence of abundant ultrafine par-ticles in Hefei.Forty-six NPF events occurred during the observation days,accounting for 41.82％ of the entire observation period.Moreover,the favorable meteorological conditions,potential precursor gases,and PM2.5 range of the NPF events were analyzed.Compared to non-NPF days,the NPF events preferentially occurred on days with lower relative humid-ity,higher wind speeds,and higher temperatures.When the PM2.5 was 15-20,70-80,and 105-115 μg/m3,the frequency of the NPF events was higher.Nucleation mode particles were positively related to atmospheric oxidation indicated by ozone when PM2.5 ranged from 15 to 20 μg/m3,and related to gaseous precursors like SO2 and NO2 when PM2.5 was located at 70-80 and 105-115 μg/m3.On pollution days,NPF events did not directly contribute to the increase in the PM2.5 in the daytime,however,NPF events would occur during the night and the growth of particulate matter contributes to the nighttime PM2.5 contents.This could lead to pollution that lasted into the next day.These findings are significant to the improvement of our understanding of the effects of aerosols on air quality.

Jinping Ou;Qihou Hu;Haoran Liu;Shiqi Xu;Z.huang Wang;Xiangguang Ji;Xinqi Wang;Zhouqing Xie;Hui Kang

Institute of Physical Science and Information Technology,Anhui University,Hefei 230601,China;Key Lab of Environmental Optics and Technology,Anhui Institute of Optics and Pine Mechanics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,China;School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,China;School of Environmental Science and Optoelectronic Technology,University of Science and Technology of China,Hefei 230026,China;Center for Excellence in Regional Atmospheric Environment,Institute of Urban Environment,Chinese Academy of Sciences,Xiamen 361021,China;Institute of Polar Environment & Anhui Province Key Laboratory of Polar Environment and Global Change,Department of Environment Science and Technology,University of Science and Technology of China,Hefei 230026,China

环境科学学报（英文版）

[1]Jinping Ou;Qihou Hu;Haoran Liu;Shiqi Xu;Z.huang Wang;Xiangguang Ji;Xinqi Wang;Zhouqing Xie;Hui Kang-.Exploring the impact of new particle formation events on PM2.5 pollution during winter in the Yangtze River Delta,China)[J].环境科学学报（英文版）,2022(01):75-83

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