Effects of photochemical oxidation on the mixing state and light absorption of black carbon in the urban atmosphere of China

Qiyuan Wang, Rujin Huang, Zhuzi Zhao, Junji Cao, Haiyan Ni, Xuexi Tie, Chongshu Zhu, Zhenxing Shen, Meng Wang, Wenting Dai, Yongming Han, Ningning Zhang, André S.H. Prévôt

Research output: Journal article publicationJournal articleAcademic researchpeer-review

35 Citations (Scopus)

Abstract

The relationship between the refractory black carbon (rBC) aerosol mixing state and the atmospheric oxidation capacity was investigated to assess the possible influence of oxidants on the particles' light absorption effects at two large cities in China. The number fraction of thickly-coated rBC particles (F rBC) was positively correlated with a measure of the oxidant concentrations (OX = O3 + NO2), indicating an enhancement of coated rBC particles under more oxidizing conditions. The slope of a linear regression of F rBC versus OX was 0.58% ppb-1 for Beijing and 0.84% ppb-1 for Xi'an, and these relationships provide some insights into the evolution of rBC mixing state in relation to atmospheric oxidation processes. The mass absorption cross-section of rBC (MACrBC) increased with OX during the daytime at Xi'an, at a rate of 0.26 m2 g-1 ppb-1, suggesting that more oxidizing conditions lead to internal mixing that enhances the light-absorbing capacity of rBC particles. Understanding the dependence of the increasing rates of F rBC and MACrBC as a function of OX may lead to improvements of climate models that deal with the warming effects, but more studies in different cities and seasons are needed to gauge the broader implications of these findings.

Original languageEnglish
Article number044012
JournalEnvironmental Research Letters
Volume12
Issue number4
DOIs
Publication statusPublished - 3 Apr 2017
Externally publishedYes

Keywords

  • black carbon
  • light absorption
  • mass absorption cross-section
  • mixing state
  • photochemical oxidation

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • General Environmental Science
  • Public Health, Environmental and Occupational Health

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