Individual particle analysis of aerosols collected under haze and non-haze conditions at a high-elevation mountain site in the North China plain 1Environment Research Institute, Shandong University, Jinan, Shandong 250100, China
24 Nov 2011
2State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Beijing 100083, China
3State Key of Laboratory of Atmospheric Boundary Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
4Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto 862-8502, Japan
Received: 10 July 2011 – Published in Atmos. Chem. Phys. Discuss.: 08 August 2011 Abstract. The North China plain is a region with megacities and huge populations.
Aerosols over the highly polluted area have a significant impact on the
regional and global climate. In order to investigate the physical and
chemical characteristics of aerosol particles in elevated layers there,
observations were carried out at the summit of Mt. Tai (1534 m a.s.l.) from
19 to 28 April, 2010, when the air masses were advected from the east
(phase-I: 19–21 April), from the south (phase-II: 22–25 April), and from the
northwest (phase-III: 26–28 April). Individual aerosol particles were
identified with transmission electron microscopy (TEM), new particle
formation (NPF) and growth events were monitored by a wide-range particle
spectrometer, and ion concentrations in PM2.5 were analyzed. During
phase-I and phase-II, haze layers caused by anthropogenic pollution were
observed, and a high percentage of particles were sulfur-rich (47–49%).
In phase-III, the haze disappeared due to the intrusion of cold air from the
northwest, and mineral dust particles from deserts were dominant (43%).
NPF followed by particle growth during daytime was more pronounced on hazy
than on clear days. Particle growth during daytime resulted in an increase
of particle geometric mean diameter from 10–22 nm in the morning to 56–96 nm
in the evening. TEM analysis suggests that sulfuric acid and secondary
organic compounds should be important factors for particle nucleation and
growth. However, the presence of fine anthropogenic particles (e.g., soot,
metal, and fly ash) embedded within S-rich particles indicates that they
could weaken NPF and enhance particle growth through condensation and
coagulation. Abundant mineral particles in phase-III likely suppressed the
NPF processes because they supplied sufficient area on which acidic gases or
Revised: 08 November 2011 – Accepted: 08 November 2011 – Published: 24 November 2011
Citation: Li, W. J., Zhang, D. Z., Shao, L. Y., Zhou, S. Z., and Wang, W. X.: Individual particle analysis of aerosols collected under haze and non-haze conditions at a high-elevation mountain site in the North China plain, Atmos. Chem. Phys., 11, 11733-11744, doi:10.5194/acp-11-11733-2011, 2011.