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Volume 16, issue 13
Atmos. Chem. Phys., 16, 8309–8329, 2016
https://doi.org/10.5194/acp-16-8309-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue: Pan-Eurasian Experiment (PEEX)

Atmos. Chem. Phys., 16, 8309–8329, 2016
https://doi.org/10.5194/acp-16-8309-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 11 Jul 2016

Research article | 11 Jul 2016

Primary and secondary aerosols in Beijing in winter: sources, variations and processes

Yele Sun1,2, Wei Du1,3, Pingqing Fu1, Qingqing Wang1, Jie Li1, Xinlei Ge4, Qi Zhang5, Chunmao Zhu6,7, Lujie Ren1, Weiqi Xu1,3, Jian Zhao1,3, Tingting Han1,3, Douglas R. Worsnop8, and Zifa Wang1 Yele Sun et al.
  • 1State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
  • 2Center for Excellence in Urban Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
  • 3College of Earth Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
  • 4School of Environmental Science and Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China
  • 5Department of Environmental Toxicology, University of California, 1 Shields Ave., Davis, CA 95616, USA
  • 6Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan
  • 7CMA Key Laboratory of Aerosol-Cloud-Precipitation, Nanjing University of Information Science and Technology, Nanjing 210044, China
  • 8Aerodyne Research, Inc., Billerica, MA 01821, USA

Abstract. Winter has the worst air pollution of the year in the megacity of Beijing. Despite extensive winter studies in recent years, our knowledge of the sources, formation mechanisms and evolution of aerosol particles is not complete. Here we have a comprehensive characterization of the sources, variations and processes of submicron aerosols that were measured by an Aerodyne high-resolution aerosol mass spectrometer from 17 December 2013 to 17 January 2014 along with offline filter analysis by gas chromatography/mass spectrometry. Our results suggest that submicron aerosols composition was generally similar across the winter of different years and was mainly composed of organics (60 %), sulfate (15 %) and nitrate (11 %). Positive matrix factorization of high- and unit-mass resolution spectra identified four primary organic aerosol (POA) factors from traffic, cooking, biomass burning (BBOA) and coal combustion (CCOA) emissions as well as two secondary OA (SOA) factors. POA dominated OA, on average accounting for 56 %, with CCOA being the largest contributor (20 %). Both CCOA and BBOA showed distinct polycyclic aromatic hydrocarbons (PAHs) spectral signatures, indicating that PAHs in winter were mainly from coal combustion (66 %) and biomass burning emissions (18 %). BBOA was highly correlated with levoglucosan, a tracer compound for biomass burning (r2 = 0.93), and made a considerable contribution to OA in winter (9 %). An aqueous-phase-processed SOA (aq-OOA) that was strongly correlated with particle liquid water content, sulfate and S-containing ions (e.g. CH2SO2+) was identified. On average aq-OOA contributed 12 % to the total OA and played a dominant role in increasing oxidation degrees of OA at high RH levels (> 50 %). Our results illustrate that aqueous-phase processing can enhance SOA production and oxidation states of OA as well in winter. Further episode analyses highlighted the significant impacts of meteorological parameters on aerosol composition, size distributions, oxidation states of OA and evolutionary processes of secondary aerosols.

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We have a comprehensive characterization of the sources, variations and processes of submicron aerosols in Beijing in winter using HR-AMS and GC/MS measurements. The primary sources including traffic, cooking, biomass burning and coal combustion emissions, and secondary components were separated and quantified with PMF. Our results elucidated the important roles of primary emissions, particularly coal combustion, and aqueous-phase processing in the formation of severe air pollution in winter.
We have a comprehensive characterization of the sources, variations and processes of submicron...
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