Insight into the composition of organic compounds (> C6) in PM2.5 in Wintertime in Beijing

Research output: Contribution to journalArticle

Authors

  • Ruihe Lyu
  • Xuefang Wu
  • Christopher Stark
  • Pingqing Fu
  • Yinchang Feng

External organisations

  • College of Resource and Environmental Sciences, Hebei Normal University for Nationalities, Chengde 067000, China
  • King Abdulaziz University
  • Nankai University
  • China University of Geosciences

Abstract

Organic matter is a major component of PM2.5 in megacities. In order to understand the detailed characteristics of organic compounds (≥C6) at a molecular level on non-haze and haze days, we determined more than 300 organic compounds in the PM2.5 from an urban area of Beijing collected in November-December 2016 using two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC-TOFMS). The identified organic compounds have been classified into groups, and quantitative methods were used to calculate their concentrations. Primary emission sources make significant contributions to the atmospheric organic compounds and six groups (including n-alkanes, polycyclic aromatic hydrocarbons (PAHs), levoglucosan, branched-alkanes, n-alkenes and alkyl-benzenes) account for 66% of total identified organic compound mass. In addition, PAHs, and oxygenated PAHs (O-PAHs) were abundant amongst the atmospheric organic compounds on both haze and non-haze days. The most abundant hydrocarbon groups were observed with a carbon atom range of C19-C28. In addition, the total concentration of unidentified compounds present in the chromatogram was estimated in the present study. The total identified compounds account for approximately 47% of total organic compounds (≥C6) in the chromatogram on both the non-haze and haze days. The total mass concentrations of organic compounds (≥C6) in the chromatogram were 4.0 μg m-3 and 7.4 μg m-3 on the non-haze and haze days respectively, accounting for 26.4% and 18.5% of organic matter respectively on those days estimated from the total organic carbon concentration. Ratios of individual compound concentrations between haze and non-haze days do not give a clear indication of the degree of oxidation, but the overall distribution of organic compounds in the chromatogram provides strong evidence that the organic aerosol is less G.C.-volatile and hence more highly oxidised on haze days.

Details

Original languageEnglish
Pages (from-to)10865-10881
JournalAtmospheric Chemistry and Physics
Volume19
Publication statusPublished - 29 Aug 2019

Keywords

  • Organic aerosol, GC × GC-TOFMS, PAHs, Haze, PM2.5, Beijing, China