Atmos. Chem. Phys. Discuss., 13, 5165-5197, 2013
www.atmos-chem-phys-discuss.net/13/5165/2013/
doi:10.5194/acpd-13-5165-2013
© Author(s) 2013. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Long-term measurements of particle number size distributions and the relationships with air mass history and source apportionment in the summer of Beijing
Z. B. Wang1,2, M. Hu1, Z. J. Wu1,2, D. L. Yue1, L. Y. He3, X. F. Huang3, X. G. Liu1, and A. Wiedensohler2
1State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
2Leibniz Institute for Tropospheric Research, Permoserstr. 15, 04318 Leipzig, Germany
3Key Laboratory for Urban Habitat Environmental Science and Technology, School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen 518055, China

Abstract. A series of long-term and temporary measurements were conducted to study the improvement of air quality in Beijing during Olympic Games period (8–24 August 2008). To evaluate actions taken to improve the air quality, comparisons of particle number and volume size distributions of August 2008 and 2004–2007 were performed. The total particle number and volume concentrations were 14 000 cm−3 and 37 μm3 cm−3 in August of 2008, respectively. These were reductions of 41% and 35% compared with the mean values of August 2004–2007. A cluster analysis on air mass history and source apportionment were performed, exploring reasons of the reduction of particle concentrations. Back trajectories were classified into five major clusters. Air mass from south direction are always associated with pollution events during the summertime of Beijing. In August 2008, the frequency of air mass arriving from south has been twice higher compared to the average of the previous years, these southerly air masses did however not result in elevated particle volume concentrations in Beijing. This result implied that the air mass history was not the key factor, explaining reduced particle number and volume concentrations during the Beijing 2008 Olympic Games. Four factors were found influencing particle concentrations using a Positive matrix factorization (PMF) model. They were identified to local and remote traffic emissions, combustion sources as well as secondary transformation. The reductions of the four sources were calculated to 47%, 44%, 43% and 30%, respectively. The significant reductions of particle number and volume concentrations may attribute to actions taken, focusing on primary emissions, especially related to the traffic and combustion sources.

Citation: Wang, Z. B., Hu, M., Wu, Z. J., Yue, D. L., He, L. Y., Huang, X. F., Liu, X. G., and Wiedensohler, A.: Long-term measurements of particle number size distributions and the relationships with air mass history and source apportionment in the summer of Beijing, Atmos. Chem. Phys. Discuss., 13, 5165-5197, doi:10.5194/acpd-13-5165-2013, 2013.
 
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