Effects of Nanjing fog process on the spectral distribution and chemical composition of atmospheric aerosols

In order to explore the effects of fog process on the chemical composition and size distribution of aerosol particles in Nanjing. Three-stage fog samples and particle-size aerosol samples were collected at the same time in the fog observation in winter 2017. The microphysical quantity and aerosol spectral distribution of fog, the chemical composition of three-stage fog samples and particle-size aerosol samples before, in and after fog were compared and analyzed. The results showed that: in the winter of 2017, the fog droplet liquid water content of the first fog process in Nanjing was in the shape of asymmetric V with the particle size distribution, and the lowest value was located at 7µm. The fog droplet liquid water content in the second fog process was a 3peak shape with the particle size distribution, and the peaks were located at 5, 15and 21.5µm. The mass concentration of small particle size aerosol decreased while that of large particle size aerosol increased in the stage of fog formation and development. The mass concentration of aerosol particles reached the lowest in the whole particle size in the stage of fog maturity, and the mass concentration of larger particle size aerosol decreased significantly. Compared with that before fog, the peak value of aerosol mass concentration after fog moved to the direction of large particle size. Before fog, the water-soluble ion components in aerosol were enriched in small particles with particle size 3-, SO42- and NH4+ concentrations after fog. The neutralization rate of aerosol with smaller size was higher, and the new droplets in the early stage of fog formation were more acidic. With the gradual neutralization of fog process, the pH value of fog water increased. © 2022 Chinese Society for Environmental Sciences. All rights reserved.