Impact of in-cloud aqueous processes on the chemical compositions and morphology of individual atmospheric aerosols

• Published in: Atmospheric chemistry and physics Vol. 20; no. 22; pp. 14063 - 14075
• Main Authors: Fu, Yuzhen, Lin, Qinhao, Zhang, Guohua, Yang, Yuxiang, Yang, Yiping, Lian, Xiufeng, Peng, Long, Jiang, Feng, Bi, Xinhui, Li, Lei, Wang, Yuanyuan, Chen, Duohong, Ou, Jie, Wang, Xinming, Peng, Ping'an, Zhu, Jianxi, Sheng, Guoying
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 20-11-2020; Copernicus Publications
• Subjects: Aerosols; Animal morphology; Atmospheric aerosols; Atmospheric particulates; Atmospheric physics; Chemical composition; Chemical reactions; Clouds; Dimensions; Dust storms; Fly ash; Fractal geometry; Humidity; Hygroscopicity; Metals; Morphology; Organic coatings; Organic matter; Physical properties; Protective coatings; Shells; Soot; Soot particles; Sulfates; China
• ISSN: 1680-7324; 1680-7316; 1680-7324
• DOI: 10.5194/acp-20-14063-2020

The composition, morphology, and mixing structure of
individual cloud residues (RES) and interstitial particles (INT) at a
mountaintop site were investigated. Eight types of particles were
identified, including sulfate-rich (S-rich), S-organic matter (OM), aged
soot, aged mineral dust, aged fly ash, aged metal, refractory, and aged
refractory mixture. A shift of dominant particle types from S-rich (29 %)
and aged soot (27 %) in the INT to aged refractory
mixture (23 %) and S-OM (22 %) in the RES is observed. In particular, particles with
organic shells are enriched in the RES (27 %) relative to the INT
(12 %). Our results highlight that the formation of more oxidized organic
matter in the cloud contributes to the existence of organic shells after
cloud processing. The fractal dimension (Df), a morphologic parameter to
represent the branching degree of particles, for soot particles in the RES
(1.82 ± 0.12) is lower than that in the INT (2.11 ± 0.09), which
indicates that in-cloud processes may result in less compact soot. This
research emphasizes the role of in-cloud processes in the chemistry and
microphysical properties of individual particles. Given that organic
coatings may determine the particle hygroscopicity, activation ability, and
heterogeneous chemical reactivity, the increase of OM-shelled particles upon
in-cloud processes should have considerable implications.