title: Chemical characterization of size-resolved aerosols in four seasons and hazy days in the megacity Beijing of China.
abstract: Size-resolved aerosol samples were collected by MOUDI in four seasons in 2007 in Beijing. The PM10 and PM1.8 mass concentrations were 166.0±120.5 and 91.6±69.7 μg/m3, respectively, throughout the measurement, with seasonal variation: nearly two times higher in autumn than in summer and spring. Serious fine particle pollution occurred in winter with the PM1.8/PM10 ratio of 0.63, which was higher than other seasons. The size distribution of PM showed obvious seasonal and diurnal variation, with a smaller fine mode peak in spring and in the daytime. OM (organic matter=1.6×OC (organic carbon)) and SIA (secondary inorganic aerosol) were major components of fine particles, while OM, SIA and Ca2+ were major components in coarse particles. Moreover, secondary components, mainly SOA (secondary organic aerosol) and SIA, accounted for 46%-96% of each size bin in fine particles, which meant that secondary pollution existed all year. Sulfates and nitrates, primarily in the form of (NH4)2SO4, NH4NO3, CaSO4, Na2SO4 and K2SO4, calculated by the model ISORROPIA II, were major components of the solid phase in fine particles. The PM concentration and size distribution were similar in the four seasons on non-haze days, while large differences occurred on haze days, which indicated seasonal variation of PM concentration and size distribution were dominated by haze days. The SIA concentrations and fractions of nearly all size bins were higher on haze days than on non-haze days, which was attributed to heterogeneous aqueous reactions on haze days in the four seasons.
authors.affiliation: College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China; State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
authors.forename: Kang
authors.initials: K
authors.lastname: Sun
authors.affiliation: State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China. Electronic address: liuxingang@bnu.edu.cn.
authors.forename: Xingang
authors.initials: X
authors.lastname: Liu
authors.affiliation: College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
authors.forename: Jianwei
authors.initials: J
authors.lastname: Gu
authors.affiliation: College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
authors.forename: Yunpeng
authors.initials: Y
authors.lastname: Li
authors.affiliation: State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Qu
authors.affiliation: State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, China.
authors.forename: Junling
authors.initials: J
authors.lastname: An
authors.affiliation: Institute for Urban Meteorology, China Meteorological Administration, Beijing 100081, China.
authors.forename: Jingli
authors.initials: J
authors.lastname: Wang
authors.affiliation: College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China. Electronic address: yhzhang@pku.edu.cn.
authors.forename: Yuanhang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
authors.forename: Min
authors.initials: M
authors.lastname: Hu
authors.affiliation: College of Global Change and Earth System Science, Beijing Normal University, Beijing 100875, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Zhang
mesh_terms: D000336:Aerosols; D000393:Air Pollutants / Q000032:analysis / Q000737:chemistry*; D002681:China; D002947:Cities; D004784:Environmental Monitoring / Q000379:methods*; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis / Q000737:chemistry*; D012621:Seasons; D014887:Weather
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D052638:Particulate Matter
keywords: Beijing; Chemical components; Haze day; Seasonal variation; Size resolved aerosols