title: Organic molecular compositions and size distributions of chinese summer and autumn aerosols from nanjing: characteristic haze event caused by wheat straw burning.
abstract: Size-segregated aerosol samples were collected in urban Nanjing, China during summer and autumn of 2007 including a period of hazy days during June 1-5. Organic aerosols in the haze event were characterized by elevated concentrations of levoglucosan, high molecular weight (HMW) n-alkanes, and HMW fatty acids due to the emissions from field burning of wheat straw. In contrast, organic aerosols on nonhazy days were characterized by a predominance of fossil fuel combustion products. Levoglucosan (4030 n g m(-3)), n-alkanes (1520 ng m(-3)), fatty acids (2629 ng m(-3)), and PAHs (57 ng m(-3)) in the haze samples were 3-40 times more abundant than those in nonevent samples. Approximately 30-90% ofthe organics during the haze period can be attributed to wheat straw burning. Concentrations of particulate material (PM) mass, n-alkanes, and low molecular weight (LMW) PAHs showed a unimodal size distribution, peaking at 0.7-1.1 microm during the hazy days, and a bimodal distribution, peaking at 0.7-1.1 microm and 4.7-5.8 microm during nonhazy days. The geometric mean diameters (GMDs) of organic aerosols are larger in the fine mode (<2.1 microm) during the hazy days, suggesting aerosols emitted from the wheat straw burning are larger than those from fossil fuel combustion, and fine particle coagulation and organic compound repartitioning were enhanced.
authors.affiliation: State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xian 710075, China. wanggh@ieecas.cn
authors.forename: Gehui
authors.initials: G
authors.lastname: Wang
authors.forename: Kimitaka
authors.initials: K
authors.lastname: Kawamura
authors.forename: Mingjie
authors.initials: M
authors.lastname: Xie
authors.forename: Shuyuan
authors.initials: S
authors.lastname: Hu
authors.forename: Junji
authors.initials: J
authors.lastname: Cao
authors.forename: Zhisheng
authors.initials: Z
authors.lastname: An
authors.forename: John G
authors.initials: JG
authors.lastname: Waston
authors.forename: Judith C
authors.initials: JC
authors.lastname: Chow
mesh_terms: D000336:Aerosols; D000393:Air Pollutants / Q000737:chemistry*; D000473:Alkanes / Q000737:chemistry*; D002681:China; D004784:Environmental Monitoring; D008401:Gas Chromatography-Mass Spectrometry; D008968:Molecular Conformation; D008970:Molecular Weight; D010316:Particle Size; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry*; D012621:Seasons; D012906:Smoke / Q000032:analysis*; D014908:Triticum / Q000254:growth & development; D014504:Urban Health
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D000473:Alkanes; D011084:Polycyclic Aromatic Hydrocarbons; D012906:Smoke