title: Inter-annual variability of wintertime PM2.5 chemical composition in Xi'an, China: Evidences of changing source emissions.
abstract: Chemical characteristics of PM2.5 in Xi'an in wintertime of 2006, 2008, and 2010 were investigated. Markers of OC2, EC1, and NO3(-)/SO4(2-) ratio were calculated to investigate the changes in PM2.5 emission sources over the 5-year period. Positive matrix factorization (PMF) model was used to identify and quantify the main sources of PM2.5 and their contributions. The results showed that coal combustion, motor vehicular emissions, fugitive dust, and secondary inorganic aerosol accounted for more than 80% of PM2.5 mass. The importance of these major sources to the PM2.5 mass varied yearly: coal combustion was the largest contributor (31.2% ± 5.2%), followed by secondary inorganic aerosol (20.9% ± 5.2%) and motor vehicular emissions (19.3% ± 4.8%) in 2006; the order was still coal combustion emissions (27.6% ± 3.4%), secondary inorganic aerosol (23.2% ± 6.9%), and motor vehicular emissions (20.9% ± 4.6%) in 2008; while coal combustion emission further decreased (24.1% ± 3.1%) with fugitive dust (19.4% ± 5.5%) increasing in 2010. The changes in PM2.5 chemical compositions and source contributions can be attributed to the social and economic developments in Xi'an, China, including energy structure adjustment, energy consumption, the expansion of civil vehicles, and the increase of urban construction activities.
authors.affiliation: Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an, China; Key Lab of Aerosol Chemistry & Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China. Electronic address: xuhongmei@mail.xjtu.edu.cn.
authors.forename: Hongmei
authors.initials: H
authors.lastname: Xu
authors.affiliation: Key Lab of Aerosol Chemistry & Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China; Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an, China. Electronic address: cao@loess.llqg.ac.cn.
authors.forename: Junji
authors.initials: J
authors.lastname: Cao
authors.affiliation: Key Lab of Aerosol Chemistry & Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China; Desert Research Institute, Reno, USA.
authors.forename: Judith C
authors.initials: JC
authors.lastname: Chow
authors.affiliation: Laboratory of Atmospheric Chemistry, Paul Scherrer Institute (PSI), Switzerland.
authors.forename: R-J
authors.initials: RJ
authors.lastname: Huang
authors.affiliation: Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an, China.
authors.forename: Zhenxing
authors.initials: Z
authors.lastname: Shen
authors.affiliation: Desert Research Institute, Reno, USA.
authors.forename: L W Antony
authors.initials: LW
authors.lastname: Chen
authors.affiliation: School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Kin Fai
authors.initials: KF
authors.lastname: Ho
authors.affiliation: Key Lab of Aerosol Chemistry & Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China; Desert Research Institute, Reno, USA.
authors.forename: John G
authors.initials: JG
authors.lastname: Watson
keywords: China aerosols; Emission changes; Fugitive dust; PM(2.5); Source apportionment