title: Particle number concentration, size distribution and chemical composition during haze and photochemical smog episodes in Shanghai.
abstract: The aerosol number concentration and size distribution as well as size-resolved particle chemical composition were measured during haze and photochemical smog episodes in Shanghai in 2009. The number of haze days accounted for 43%, of which 30% was severe (visibility<2km) and moderate (2km≤visibility<3km) haze, mainly distributed in winter and spring. The mean particle number concentration was about 17,000/cm(3) in haze, more than 2 times that in clean days. The greatest increase of particle number concentration was in 0.5-1μm and 1-10μm size fractions during haze events, about 17.78 times and 8.78 times those of clean days. The largest increase of particle number concentration was within 50-100nm and 100-200nm fractions during photochemical smog episodes, about 5.89 times and 4.29 times those of clean days. The particle volume concentration and surface concentration in haze, photochemical smog and clean days were 102, 49, 15μm(3)/cm(3) and 949, 649, 206μm(2)/cm(3), respectively. As haze events got more severe, the number concentration of particles smaller than 50nm decreased, but the particles of 50-200nm and 0.5-1μm increased. The diurnal variation of particle number concentration showed a bimodal pattern in haze days. All soluble ions were increased during haze events, of which NH4(+), SO4(2-) and NO3(-) increased greatly, followed by Na(+), K(+), Ca(2+) and Cl(-). These ions were very different in size-resolved particles during haze and photochemical smog episodes.
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Fudan Tyndall Centre, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, China. Electronic address: xuemeiwang@fudan.edu.cn.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Wang
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Fudan Tyndall Centre, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, China. Electronic address: jmchen@fudan.edu.cn.
authors.forename: Jianmin
authors.initials: J
authors.lastname: Chen
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Fudan Tyndall Centre, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, China.
authors.forename: Tiantao
authors.initials: T
authors.lastname: Cheng
authors.affiliation: Center for Atmospheric Chemistry and Environment, Department of Atmospheric Science, Texas A&M University, TX 77843, USA. Electronic address: renyi-zhang@neo.tamu.edu.
authors.forename: Renyi
authors.initials: R
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
authors.forename: Xinming
authors.initials: X
authors.lastname: Wang
mesh_terms: D000336:Aerosols / Q000032:analysis; D002681:China; D002947:Cities; D010126:Ozone / Q000032:analysis; D010316:Particle Size; D012905:Smog / Q000032:analysis*
chemical_list: D000336:Aerosols; D012905:Smog; D010126:Ozone
keywords: Chemical composition; Haze; Particle number concentration; Photochemical smog; Shanghai; Size distribution