Shurong Wang1, Kaili Zhou1, Xiaohui Lu1, Hong Chen1, Fan Yang2, Qiang Li3, Xin Yang This email address is being protected from spambots. You need JavaScript enabled to view it.1,4,5, Xiaofei Wang This email address is being protected from spambots. You need JavaScript enabled to view it.1,4

1 Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China
2 Environmental Monitoring Station of Pudong New District, Shanghai 200135, China
3 Cambustion Ltd., Cambridge CB1 8DH, United Kingdom
4 Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
5 School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China


Received: July 3, 2021
Revised: September 4, 2021
Accepted: October 13, 2021

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.


Download Citation: ||https://doi.org/10.4209/aaqr.210162  


Cite this article:

Wang, S., Zhou, K., Lu, X., Chen, H., Yang, F., Li, Q., Yang, X., Wang, X. (2021). Measurement of Density and Shape for Single Black Carbon Aerosols in a Heavily Polluted Urban Area. Aerosol Air Qual. Res. 21, 210162. https://doi.org/10.4209/aaqr.210162


HIGHLIGHTS

  • The density and shape of single black carbon particle was investigated.
  • BC-dominated aerosol was near-spherical, suggesting rapid aging of fresh BC.
  • Condensation of sulfates and nitrates contributed to the aging process of BC.
 

ABSTRACT


Black carbon (BC) aerosol imposes adverse effects on atmospheric visibility, climate, and health. The particle density and morphology are often needed to investigate the mixing state and aging process of BC particles. A method, combining an aerodynamic aerosol classifier (AAC), a differential mobility analyzer (DMA), a single-particle soot photometer (SP2) and a single particle aerosol mass spectrometer (SPAMS), was developed to determine the density and dynamic shape factor (χ) of ambient BC particles with three different aerodynamic diameters (Da, 200 nm, 350 nm, and 500 nm) in Shanghai, China, a typical urban area. The BC particles were either classified as “BC-dominated particle” which is mainly made of black carbon or “BC-mixed particle” which is a mixture of both BC and non-BC substances. The results showed that BC-dominated particles whose BC core mass (~2.2 fg) was almost equal to particle mass (~2.3 fg) were observed in particles with 200 nm Da. The morphology of these BC-dominated particles was near-spherical (χ ≈ 1.02), indicating that they had undergone rapid morphology modification from the initial highly irregular morphology to near-spherical shape. Most BC particles with 350 nm or 500 nm Da were BC-mixed particles. Combining the effective densities (1.62–1.77 g cm–3) and average single particle mass spectra of particle, the ammonium sulfate and ammonium nitrate were found to be the main secondary substances of these BC-mixed particles, indicating that condensation of inorganic species such as nitrates and sulfates could play a significant role in the aging process of fresh BC in Shanghai. Generally, the morphology and density information of single BC particle is crucial to identify the mixing state and aging process of BC aerosols.


Keywords: Black carbon aerosol, Particle mass, BC content mass, Aerodynamic diameter, Electrical mobility diameter, Dynamic shape factor, Density




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