EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Kinetics of sulfuric acid-amine nucleation in the urban atmospheric environment

Runlong Cai1,2,3, Chao Yan1,2, Jun Zheng4, Lin Wang5, Markku Kulmala1,2, and Jingkun Jiang3
Runlong Cai et al.
  • 1Beijing University of Chemical Technology, Beijing, China
  • 2University of Helsinki, Helsinki, Finland
  • 3Tsinghua University, Beijing, China
  • 4Nanjing University of Information Science and Technology, Nanjing, China
  • 5Fudan University, Shanghai, China

The formation of new secondary aerosols form gaseous precursors is a frequent phenomenon in various atmospheric environments and it impacts aerosol number concentration, cloud formation, and hence climate. There has been a considerable number of new particle formation (NPF) studies in various atmospheric environments, but current knowledge on NPF in the polluted atmospheric boundary layer (e.g., the urban environment in megacities) is still limited. The clustering of H2SO4 and amines is a possible mechanism driving the fast nucleation and initial growth of new particles in the polluted urban environment. Laboratory studies using typical ambient H2SO4 concentrations and theoretical calculations based on quantum chemistry have provided insights into H2SO4-amine nucleation. However, the molecular-level mechanism and governing factors for H2SO4-amine nucleation have not been quantitatively investigated in the real atmosphere. Some previous studies indicate that differently from clean environments, the coagulation scavenging is a governing factor for NPF in polluted environments. In the presence of a high aerosol concentration in the polluted environment, a considerable fraction of the newly formed particles are scavenged by coagulation within minutes and hence, NPF is significantly suppressed. Similarly, the coagulation scavenging may also impact the steady-state cluster concentrations and the new particle formation rate. Due to the differences in the coagulation scavenging and perhaps some gaseous precursor concentrations between laboratory and atmospheric conditions, the reaction kinetics determined in previous laboratory studies may not directly applicable to the real atmosphere. Herein, based on long-term atmospheric measurements from January 2018 to March 2019 in urban Beijing, we show the different reaction kinetics under laboratory and atmospheric conditions and how to unify them using proper normalization approaches. The influences of governing factors on particle formation rate are then quantitatively elucidated. Based on the synergistic effects of these factors, an indicator for the occurrence of NPF in the urban environment is proposed and verified.

How to cite: Cai, R., Yan, C., Zheng, J., Wang, L., Kulmala, M., and Jiang, J.: Kinetics of sulfuric acid-amine nucleation in the urban atmospheric environment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8262,, 2020