Articles | Volume 16, issue 24
Atmos. Chem. Phys., 16, 15451–15460, 2016
Atmos. Chem. Phys., 16, 15451–15460, 2016

Research article 15 Dec 2016

Research article | 15 Dec 2016

Investigating the impact of regional transport on PM2.5 formation using vertical observation during APEC 2014 Summit in Beijing

Yang Hua1,2, Shuxiao Wang1,2, Jiandong Wang1,2, Jingkun Jiang1,2, Tianshu Zhang3, Yu Song4, Ling Kang4, Wei Zhou1,2, Runlong Cai1,2, Di Wu1,2, Siwei Fan1,2, Tong Wang1,2, Xiaoqing Tang5, Qiang Wei6, Feng Sun6, and Zhimei Xiao7 Yang Hua et al.
  • 1State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
  • 2State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing 100084, China
  • 3Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
  • 4College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China
  • 5Hebei Environmental Monitoring Center, Hebei 050051, China
  • 6Beijing Environmental Monitoring Center, Beijing 100048, China
  • 7Tianjin Environmental Monitoring Center, Tianjin 300191, China

Abstract. During the APEC (Asia-Pacific Economic Cooperation) Economic Leaders' 2014 Summit in Beijing, strict regional air emission controls were implemented, providing a unique opportunity to investigate the transport and formation mechanism of fine particulate matter (PM2.5). This study explores the use of vertical observation methods to investigate the influence of regional transport on PM2.5 pollution in Beijing before and during the APEC Summit. Vertical profiles of extinction coefficient, wind, temperature and relative humidity were monitored at a rural site on the border of Beijing and Hebei Province. Three PM2.5 pollution episodes were analyzed. In episode 1 (27 October to 1 November), regional transport accompanied by the accumulation of pollutants under unfavorable meteorological conditions led to the pollution. In episode 2 (2–5 November), pollutants left from episode 1 were retained in the boundary layer of the region for 2 days and then settled down to the surface, leading to an explosive increase of PM2.5. The regional transport of aged aerosols played a crucial role in the heavy PM2.5 pollution. In episode 3 (6–11 November), emissions from large point sources had been controlled for several days while primary emissions from diesel vehicles might have led to the pollution. It is found that ground-level observation of meteorological conditions and air quality could not fully explain the pollution process, while vertical parameters (aerosol optical properties, winds, relative humidity and temperature) improved the understanding of regional transport influence on heavy pollution processes. Future studies may consider including vertical observations to aid investigation of pollutant transport, especially during episodic events of rapidly increasing concentrations.

Short summary
The characteristics of three PM2.5 pollution episodes were analyzed during the APEC Summit at a rural site outside of Beijing. It was found that meteorological conditions on the ground could not explain the pollution process, while vertical parameters helped improve the understanding of heavy pollution processes. Our research suggests that regional transport of air pollutants contributes significantly to severe secondary particle pollution, even when local emission is controlled effectively.
Final-revised paper