title: The characteristics of Beijing aerosol during two distinct episodes: impacts of biomass burning and fireworks.
abstract: The chemical composition of Beijing aerosol was measured during summer and winter. Two distinct episodes were identified. Water-soluble potassium (K(+)) increased significantly during the firework episode in winter with an episode to non-episode ratio of 4.97, whereas the biomass burning (BB) episode in summer was characterized by high episode to non-episode ratios of levoglucosan (6.38) and K(+) (6.90). The BB and firework episodes had only a minor influence on the water-soluble OC (organic carbon) to OC ratio. Based on separate investigations of episode and non-episode periods, it was found that: (i) sulfate correlated strongly with both relative humidity and nitrate during the typical winter period presumably indicating the importance of the aqueous-phase oxidation of sulfur dioxide by nitrogen dioxide, (ii) oxalate and WSOC during both winter and summer in Beijing were mainly due to secondary formation, and (iii) high humidity can significantly enhance the formation potential of WSOC in winter.
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China. Electronic address: ycheng@mail.tsinghua.edu.cn.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Cheng
authors.affiliation: Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Guenter
authors.initials: G
authors.lastname: Engling
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China; State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing, China. Electronic address: hekb@tsinghua.edu.cn.
authors.forename: Ke-bin
authors.initials: KB
authors.lastname: He
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China.
authors.forename: Feng-kui
authors.initials: FK
authors.lastname: Duan
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China.
authors.forename: Zhen-yu
authors.initials: ZY
authors.lastname: Du
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China.
authors.forename: Yong-liang
authors.initials: YL
authors.lastname: Ma
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China.
authors.forename: Lin-lin
authors.initials: LL
authors.lastname: Liang
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China.
authors.forename: Zi-feng
authors.initials: ZF
authors.lastname: Lu
authors.affiliation: School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, United States.
authors.forename: Jiu-meng
authors.initials: JM
authors.lastname: Liu
authors.affiliation: College of Environmental Sciences and Engineering, Peking University, Beijing, China.
authors.forename: Mei
authors.initials: M
authors.lastname: Zheng
authors.affiliation: School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, United States.
authors.forename: Rodney J
authors.initials: RJ
authors.lastname: Weber
mesh_terms: D000336:Aerosols / Q000032:analysis*; D000393:Air Pollutants / Q000032:analysis*; D018533:Biomass; D002681:China; D004784:Environmental Monitoring; D053834:Explosive Agents; D005390:Fires; D009566:Nitrates / Q000032:analysis; D009585:Nitrogen Dioxide / Q000032:analysis; D012621:Seasons; D013431:Sulfates / Q000032:analysis; D013458:Sulfur Dioxide / Q000032:analysis
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D053834:Explosive Agents; D009566:Nitrates; D013431:Sulfates; D013458:Sulfur Dioxide; D009585:Nitrogen Dioxide
keywords: Biomass burning; Firework; Levoglucosan; Secondary aerosol; WSOC