EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Size-resolved effective density of submicron aerosol particles in the North China Plain

Yaqing Zhou1,2, Nan Ma1,2, Zhibin Wang3, Jiangchuan Tao1,2, Juan Hong1,2, Long Peng1,2, Linhong Xie1,2, Shaowen Zhu1,2, Chunrong Chen4, Qiang Zhang4, Hang Su5, and Yafang Cheng5
Yaqing Zhou et al.
  • 1Institute for Environmental and Climate Research, Jinan University, 511443, Guangzhou, China
  • 2Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, 511443, Guangzhou, China
  • 3Research Center for Air Pollution and Health, College of Environmental and Resource Sciences, Zhejiang University, 310058, Hangzhou, China
  • 4Department of Earth System Science, Tsinghua University, 100084, Beijing, China
  • 5Multiphase Chemistry Department, Max Planck Institute for Chemistry, 55128, Mainz, Germany

Effective density is one of the most important physical properties of atmospheric aerosol particles, and is linked to particle formation and aging process. Combined characterization of aerosol density, chemical composition, emission and aging processes may provide crucial information for better understanding their interactions and effects on environment and climate. In autumn of 2019, the effective density of sub-micrometer aerosol particles was measured in-situ at a heavily polluted rural site in the North China Plain (NCP). A tandem technique coupling a Centrifugal Particle Mass Analyzer (CPMA) with a differential mobility analyzer (DMA) and a Condensation Particle Counter (CPC) were used to determine the effective density of ambient aerosol particles with diameters of 50, 100, 150, 220 and 300 nm. The probability distribution of effective density exhibits double peak modes in majority cases, with a higher density mode (main-density) and a lower density mode (sub-density). The existence of sub-density particles normally ascribed to freshly emitted or partial aged black carbon (BC) with non-spherical morphology. The number fraction of sub-density mode varies from 4% to 67%, with mean of 22-27% at five particle sizes. Due to the higher aging degree of larger particles, the main-density exhibits an evident ascending trend with particle size. However, the sub-density decreases as mobility size increases, from 0.89 g/cm3 at 50 nm to 0.62 g/cm3 at 300 nm, since larger fresh soot particles usually present a more agglomerated morphology than small particles. A comparison was carried out between the mean effective density at 300 nm and ACSM-derived density using different approximations of BC density. The best agreement is achieved when assuming a BC density of 0.6 g/cm3, indicating that BC typically exists as non-spherical particles with fractal-like or porous morphology in the NCP in cold season.

How to cite: Zhou, Y., Ma, N., Wang, Z., Tao, J., Hong, J., Peng, L., Xie, L., Zhu, S., Chen, C., Zhang, Q., Su, H., and Cheng, Y.: Size-resolved effective density of submicron aerosol particles in the North China Plain, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16424,, 2021.

Corresponding presentation materials formerly uploaded have been withdrawn.