title: Identification of chemical compositions and sources of atmospheric aerosols in Xi'an, inland China during two types of haze events.
abstract: High time resolution (1h) of TSP filter samples was collected in Xi'an in inland China from December 5 to 13, 2012, during which a 9-day long of haze episode occurred. The hazy days were classified as two types, i.e., Light-haze period with moderate degradation in visibility (5-10km) and relatively dry conditions (RH: 53±19%) and Severe-haze period with a daily visibility less than 5km and humid conditions (RH: 73±14%). TSP in the two periods (415±205 and 530±180μgm(-3) in Light-haze and Severe-haze periods, respectively) was comparable, but crustal Fe and Ca elements presented higher concentrations and strong correlation (R(2)=0.72) with TSP in Light-haze period. SO4(2-), NO3(-) and NH4(+) in Light-haze period were 16±5.9, 12±6.7 and 4.1±2.8μgm(-3), respectively, and increased dramatically to 51±15, 44±9.7 and 23±5.6μgm(-3) in Severe-haze period. Contributions of Fe and Ca to TSP decreased from 9.2% in Light-haze period to 5.3% in Severe-haze period, but those of SO4(2-), NO3(-) and NH4(+) increased from 3.8%, 2.9% and 1.0% in Light-haze period to 9.6%, 8.3% and 4.4% in Severe-haze period, respectively. These results suggest that dust-derived particles were more significant in Light-haze period while secondary aerosols were more important in Severe-haze period. Hopanes (33±24 and 38±29ngm(-3) in Light-haze and Severe-haze periods, respectively) during the two types of haze periods are comparable, indicating that differences in contribution of primary organic aerosols from fossil fuel combustions to TSP were insignificant. In contrast, the ratio of secondary organic aerosols (e.g., o-phthalic acid) to EC was much higher in Severe-haze period (5.8±2.7ngμg(-1)) than in Light-haze period (3.4±2.1ngμg(-1)), probably indicating that the humid conditions in Severe-haze period are favorable for secondary organic aerosol formation.
authors.affiliation: Key Laboratory of Aerosol Chemistry and Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China.
authors.forename: Jianjun
authors.initials: J
authors.lastname: Li
authors.affiliation: Key Laboratory of Aerosol Chemistry and Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an 710079, China; Center for Excellence in Urban Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China. Electronic address: wanggh@ieecas.cn.
authors.forename: Gehui
authors.initials: G
authors.lastname: Wang
authors.affiliation: Key Laboratory of Aerosol Chemistry and Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Yanqin
authors.initials: Y
authors.lastname: Ren
authors.affiliation: Key Laboratory of Aerosol Chemistry and Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Jiayuan
authors.initials: J
authors.lastname: Wang
authors.affiliation: Key Laboratory of Aerosol Chemistry and Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Can
authors.initials: C
authors.lastname: Wu
authors.affiliation: Key Laboratory of Aerosol Chemistry and Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Yanni
authors.initials: Y
authors.lastname: Han
authors.affiliation: Key Laboratory of Aerosol Chemistry and Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Aerosol Chemistry and Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Chunlei
authors.initials: C
authors.lastname: Cheng
authors.affiliation: Key Laboratory of Aerosol Chemistry and Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Meng
keywords: Primary and secondary organic aerosols; Relative humidity; Sulfate, nitrate and dust; TSP and haze