Fractal Dimensions and Mixing Structures of Soot Particles during Atmospheric Processing

Research output: Contribution to journalArticle

Authors

  • Yuanyuan Wang
  • Fengshan Liu
  • Cenlin He
  • Lei Bi
  • Tianhai Cheng
  • Zhili Wang
  • Hua Zhang
  • Xiaoye Zhang
  • Weijun Li

Colleges, School and Institutes

External organisations

  • Shandong University
  • Zhejiang University
  • National Research Council of Canada
  • UNIVERSITY OF CALIFORNIA LOS ANGELES
  • Chinese Academy of Sciences
  • Chinese Academy of Meteorological Sciences
  • Nanjing University of Information Science and Technology
  • China Meteorological Administration

Abstract

Soot particles strongly absorb sunlight and hence act as a short-lived warming agent. Atmospheric aging of soot particles changes their morphology and mixing state and consequently alters their optical properties. Here we collected soot particles at tunnel, urban, mountaintop, and background sites in the North China Plain and analyzed their mixing structures and morphology using transmission electron microscopy. Soot particles were further classified into three types: bare-like, partly coated, and embedded. Bare-like soot particles were dominant at the tunnel site, while most soot particles were of the partly coated or embedded type at other sites. Fractal dimensions (Df) of different types of soot particles ranged from 1.80 to 2.16 and increased in the following order: bare-like < partly coated < embedded. Moreover, their average Df changed from 1.8 to 2.0 from the tunnel to the background site. We conclude that the Df can characterize the shape of soot aggregates reasonably well, and its variation reflects soot aging processes. Compared with the reported Df of soot particles, we found that the Df value of 1.8 used in previous optical models primarily represents freshly emitted soot aggregates, rather than the ambient ones.

Details

Original languageEnglish
Pages (from-to)487-493
Number of pages7
JournalEnvironmental Science and Technology Letters
Volume4
Issue number11
Publication statusPublished - 16 Nov 2017