Abstract
Abstract. New particle formation (NPF) is one of the major sources of atmospheric ultrafine particles. Due to the high aerosol and trace gas concentrations, the mechanism and governing factors for NPF in the polluted atmospheric boundary layer may be quite different from those in clean environments, which is however less understood. Herein, based on long-term atmospheric measurements from January 2018 to March 2019 in Beijing, the nucleation mechanism and the influences of H2SO4 concentration, amine concentrations, and aerosol concentration on NPF are quantified. The collision of H2SO4–amine clusters is found to be the dominating mechanism to initialize NPF in urban Beijing. The coagulation scavenging due to the high aerosol concentration is a governing factor as it limits the concentration of H2SO4–amine clusters and new particle formation rates. The formation of H2SO4–amine clusters in Beijing is sometimes limited by low amine concentrations. Summarizing the synergistic effects of H2SO4 concentration, amine concentrations, and aerosol concentration, we elucidate the governing factors for H2SO4–amine nucleation for various conditions.
Highlights
New particle formation (NPF) is a major source of ambient particles in terms of particle number concentration
The systematic difference that the measured H2SO4 trimer and tetramer concentrations are lower than the simulated concentrations is presumably caused by measurement uncertainties, e.g., cluster fragmentation (Zapadinsky et al, 2019)
The CLOUD study reported that particle formation rate for H2SO4–DMA nucleation was obtained at a high DMA concentration (5– 32 ppt), with a low cluster loss rate (Kürten et al, 2014, 2018)
Summary
New particle formation (NPF) is a major source of ambient particles in terms of particle number concentration. R. Cai et al.: Sulfuric acid–amine nucleation in urban Beijing of NPF with a high aerosol concentration, moderate gaseous precursor (e.g., H2SO4) concentrations, and a high particle formation rate indicate a fast nucleation mechanism in these environments. Due to the high aerosol concentration in the polluted atmospheric boundary layer, the loss rates of new particles during NPF in urban Beijing and Shanghai are usually ∼ 10 times higher than the total loss rate in laboratory chambers. As pointed out in previous studies (Kürten et al, 2014; Yao et al, 2018), the characteristics and limiting factors of nucleation in the polluted atmosphere may be different from those in laboratory experiments, due to differences in the particle loss rate and precursor gas concentrations. The roles of coagulation scavenging and amine concentrations in H2SO4– amine nucleation are revealed and quantified
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
