title: Impact of size distributions of major chemical components in fine particles on light extinction in urban Guangzhou.
abstract: To evaluate the impact of fine particulate matter (PM2.5) size distribution on aerosol chemical and optical properties, dominant chemical components including water-soluble inorganic ions (WSII), organic carbon (OC) and elemental carbon (EC) in PM1and PM2.5, aerosol scattering coefficient (bsp), and aerosol absorption coefficient (bap) were collected synchronously at an urban site in Guangzhou, south China during a typical summer month in 2009 and a winter month in 2010. PM1(sizes smaller than 1μm) constituted 77% and 63% of PM2.5in summer and winter, respectively. From the reconstructed mass concentrations, the sum of SO42-, NO3-and NH4+(SNA) distributed more in PM1than in PM1-2.5(PM2.5minus PM1) in summer and the opposite was found in winter, while carbonaceous aerosols distributed more in PM1in both summer and winter. With the aggravation of PM2.5pollution, the mass fraction of PM1/PM2.5increased for (NH4)2SO4(AS), NH4NO3(AN) and EC but decreased for organic matter (OM) in summer, and the opposite was found in winter. Bspof PM1and PM1-2.5was estimated from the mass extinction efficiencies (MSEs) of the dominant chemical components, which showed good correlations (R2=0.99) with measured ones and those estimated using the IMPROVE formula. The fractional contributions of dominant chemical components to extinction coefficient (bext) were consistent with their respective mass size distributions, indicating the importance of chemically-resolved aerosol size distributions on aerosol optical properties and haze formation.
authors.affiliation: College of Atmospheric Sciences, Chengdu University of Information Technology, Plateau Atmosphere and Environment Key Laboratory of Sichuan Province, Chengdu, China; CAS Key Laboratory of Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China. Electronic address: xiayunjie@mail.iap.ac.cn.
authors.forename: Yunjie
authors.initials: Y
authors.lastname: Xia
authors.affiliation: South China Institute of Environmental Sciences, Ministry of Environmental Protection, Guangzhou, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Tao
authors.affiliation: Air Quality Research Division, Science Technology Branch, Environment and Climate Change Canada, Toronto, Canada.
authors.forename: Leiming
authors.initials: L
authors.lastname: Zhang
authors.affiliation: CAS Key Laboratory of Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China. Electronic address: zrj@mail.iap.ac.cn.
authors.forename: Renjian
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Nansen-Zhu International Research Centre, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China.
authors.forename: Shuanglin
authors.initials: S
authors.lastname: Li
authors.affiliation: CAS Key Laboratory of Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China.
authors.forename: Yunfei
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Key Laboratory of Aerosol, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China.
authors.forename: Junji
authors.initials: J
authors.lastname: Cao
authors.affiliation: CAS Key Laboratory of Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China.
authors.forename: Xiaojia
authors.initials: X
authors.lastname: Wang
authors.affiliation: CAS Key Laboratory of Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China.
authors.forename: Qingxia
authors.initials: Q
authors.lastname: Ma
authors.affiliation: CAS Key Laboratory of Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Xiong
keywords: Aerosol chemical components; Aerosol optical properties; PM(1); PM(1–2.5)