Microscopic evidence for phase separation of organic species and inorganic salts in fine ambient aerosol particles

Weijun Li*, Lei Liu, Jian Zhang, Liang Xu, Yuanyuan Wang, Yele Sun, Zongbo Shi

*Corresponding author for this work

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Phase separation is an important microscopic phenomenon in aerosol particles and reflects the surface properties of particles and the aging degree of organic components. However, few data are available to directly reveal phase separation in ambient aerosol particles, although there are abundant data from laboratory experiments. In this study, different state-of-the-art microscopic technologies were used to study the phase separation of organic matter (OM) and inorganic salts in individual particles collected from different atmospheric environments, with one type of surrogate particles prepared in the laboratory. We found that most of the collected particles with an equivalent sphere diameter of >100 nm have a secondary inorganic aerosol core with OM coating in the continental atmosphere. In addition, secondary inorganic aerosol and OM phase separation are more frequent in rural particles than suburban particles, suggesting that particle aging enhances the phase separation. Our results show that the phase separation is a frequent phenomenon that forms organic coatings on inorganic particles of individual particles (>100 nm), and their number abundances depend on the particle size and OM aging degree. The resulting morphology shows that OM is an important particle surface in the atmosphere, which influences gas partitioning, optical and hygroscopic properties, and cloud condensation nuclei formation activities.

Original languageEnglish
Pages (from-to)2234-2242
Number of pages9
JournalEnvironmental Science and Technology
Issue number4
Early online date26 Jan 2021
Publication statusPublished - 16 Feb 2021

Bibliographical note

Funding Information:
Cryo-EM characterization was conducted at the Center of Cryo-Electron Microscopy, Zhejiang University, with the assistance of L. Wu. We gratefully acknowledge Lan Yao for providing the NO /NO data. This work was funded by the National Natural Science Foundation of China (42075096 and 91844301) and Zhejiang Provincial Natural Science Foundation of China (LZ19D050001). Z.S. was funded by the Natural Environmental Research Council (NE/N007190/1 and NE/R005281/1). All the data are presented in the paper.

Publisher Copyright:
© 2021 American Chemical Society.


  • Aerosols
  • Atmosphere
  • Particle Size
  • Salts
  • Wettability

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry


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