The effect of COVID-19 restrictions on atmospheric new particle formation in Beijing
- 1Aerosol and Haze Laboratory, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, China
- 2Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Finland
- 3State Key Joint Laboratory of Environment Simulation and Pollution Control, State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, School of Environment, Tsinghua University, Beijing, China
- 4Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
- 5Joint International research Laboratory of Atmospheric and Earth System Research (JirLATEST), School of Atmospheric Sciences, Nanjing University, Nanjing, China
- 6Finnish Meteorological Institute, 00560 Helsinki, Finland
- 7Finnish Meteorological Institute, 70211 Kuopio, Finland
- 8Department of Environmental Science & Engineering, Fudan University, Shanghai, China
- 9State Key Laboratory of Severe Weather & Key Laboratory of Atmospheric Chemistry of China Meteorological Administration (CMA), Chinese Academy of Meteorological Sciences, Beijing 100081, China
- 10Institute of Atmospheric Physics, Chinese Academy of Science, Beijing, China
- 11Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, PA, USA
- 12Aerodyne Research Inc., Billerica, Massachusetts 01821, USA
- These authors contributed equally to this work.
Abstract. During the COVID-19 lockdown, the dramatic reduction of anthropogenic emissions provided a unique opportunity to investigate the effects of reduced anthropogenic activity and primary emissions on atmospheric chemical processes and the consequent formation of secondary pollutants. Here, we utilize comprehensive observations to examine the response of atmospheric new particle formation (NPF) to the changes in the atmospheric chemical cocktail. We find that the main clustering process was unaffected by the drastically reduced traffic emissions, and the formation rate of 1.5 nm particles remained unaltered. However, particle survival probability was enhanced due to an increased particle growth rate (GR) during the lockdown period, explaining the enhanced NPF activity in earlier studies. For GR at 1.5–3 nm, sulfuric acid (SA) was the main contributor at high temperatures, whilst there were unaccounted contributing vapors at low temperatures. For GR at 3–7 nm and 7–15 nm, oxygenated organic molecules (OOMs) played a major role. Surprisingly, OOM composition and volatility were insensitive to the large change of atmospheric NOx concentration; instead the associated high particle growth rates and high OOM concentration during the lockdown period were mostly caused by the enhanced atmospheric oxidative capacity. Overall, our findings suggest a limited role of traffic emissions in NPF.
Chao Yan et al.
Chao Yan et al.
Chao Yan et al.
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