Articles | Volume 16, issue 16
Atmos. Chem. Phys., 16, 10671–10687, 2016
Atmos. Chem. Phys., 16, 10671–10687, 2016

Research article 29 Aug 2016

Research article | 29 Aug 2016

Chemical characteristics and causes of airborne particulate pollution in warm seasons in Wuhan, central China

Xiaopu Lyu1, Nan Chen2, Hai Guo1, Lewei Zeng1, Weihao Zhang3, Fan Shen2, Jihong Quan2, and Nan Wang4 Xiaopu Lyu et al.
  • 1Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, Hong Kong
  • 2Hubei Provincial Environment Monitoring Center, Wuhan, China
  • 3Department of Environmental Sciences, School of Resource and Environmental Sciences, Wuhan University, Wuhan, China
  • 4Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction, Institute of Tropical and Marine Meteorology, Guangzhou, China

Abstract. Continuous measurements of airborne particles and their chemical compositions were conducted in May, June, October, and November 2014 at an urban site in Wuhan, central China. The results indicate that particle concentrations remained at a relatively high level in Wuhan, with averages of 135.1 ± 4.4 (mean ± 95 % confidence interval) and 118.9 ± 3.7 µg m−3 for PM10 and 81.2 ± 2.6 and 85.3 ± 2.6 µg m−3 for PM2.5 in summer and autumn, respectively. Moreover, PM2.5 levels frequently exceeded the National Standard Level II (i.e., daily average of 75 µg m−3), and six PM2.5 episodes (i.e., daily PM2.5 averages above 75 µg m−3 for 3 or more consecutive days) were captured during the sampling campaign. Potassium was the most abundant element in PM2.5, with an average concentration of 2060.7 ± 82.3 ng m−3; this finding indicates intensive biomass burning in and around Wuhan during the study period, because almost no correlation was found between potassium and mineral elements (iron and calcium). The source apportionment results confirm that biomass burning was the main cause of episodes 1, 3, and 4, with contributions to PM2.5 of 46.6 % ± 3.0 %, 50.8 % ± 1.2 %, and 44.8 % ± 2.6%, respectively, whereas fugitive dust was the leading factor in episode 2. Episodes 5 and 6 resulted mainly from increases in vehicular emissions and secondary inorganic aerosols, and the mass and proportion of NO3 both peaked during episode 6. The high levels of NOx and NH3 and the low temperature during episode 6 were responsible for the increase of NO3. Moreover, the formation of secondary organic carbon was found to be dominated by aromatics and isoprene in autumn, and the contribution of aromatics to secondary organic carbon increased during the episodes.

Final-revised paper