title: Using an improved Source Directional Apportionment method to quantify the PM(2.5) source contributions from various directions in a megacity in China.
abstract: The transport of particulate matter (PM) and chemical species is an essential mechanism for determining the fate of PM pollutants and their effects. To determine source transport quantitatively, an ambient PM2.5 dataset from a megacity in China was analysed using a novel method called "Source Directional Apportionment" (SDA). The SDA method is developed in this work to quantify contributions of each source category from various directions. The three steps of SDA are (1) to estimate source categories and time series of source contributions to PM with a factor analysis model, (2) to identify directions by trajectory cluster analysis and (3) to quantify source directional contributions for each source category by combining the time series of source contributions to the back trajectories in each direction. For PM2.5 in Chengdu, crustal dust, vehicular exhaust, coal combustion and secondary sulphate are all important contributors to PM; secondary nitrate and cement dust are relatively less influential. Four potential source directions were identified in Chengdu during the sampling period from 2009 to 2011. The percentages of source directional contributions from Directions 1-4 (northeast, southwest to south, southwest and west) were estimated as follows: crustal dust (7.9%, 9.1%, 6.4% and 6.2%, respectively), cement dust (1.0%, 1.2%, 1.3% and 1.1%, respectively), vehicular exhaust (6.4%, 6.0%, 5.6% and 7.0%, respectively), secondary sulphate (5.1%, 5.2%, 5.6% and 8.6%, respectively) and secondary nitrate (2.0%, 2.4%, 2.5% and 2.3%, respectively). Finally, the source directional contributions to important chemical species were quantified to determine their transport from sources to receptor.
authors.affiliation: State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China.
authors.forename: Ying-Ze
authors.initials: YZ
authors.lastname: Tian
authors.affiliation: State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China. Electronic address: nksgl@hotmail.com.
authors.forename: Guo-Liang
authors.initials: GL
authors.lastname: Shi
authors.affiliation: College of Software, Nankai University, Tianjin 300071, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Han
authors.affiliation: State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China.
authors.forename: Jian-Hui
authors.initials: JH
authors.lastname: Wu
authors.affiliation: State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China.
authors.forename: Xiao-Yu
authors.initials: XY
authors.lastname: Zhou
authors.affiliation: Chengdu Research Academy of Environmental Sciences, Chengdu 610042, China.
authors.forename: Lai-Dong
authors.initials: LD
authors.lastname: Zhou
authors.affiliation: Chengdu Research Academy of Environmental Sciences, Chengdu 610042, China.
authors.forename: Pu
authors.initials: P
authors.lastname: Zhang
authors.affiliation: State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China.
authors.forename: Yin-Chang
authors.initials: YC
authors.lastname: Feng
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D002681:China; D002947:Cities; D004391:Dust / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods*; D005163:Factor Analysis, Statistical; D008962:Models, Theoretical; D009566:Nitrates / Q000032:analysis; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D013431:Sulfates / Q000032:analysis; D001335:Vehicle Emissions / Q000032:analysis
chemical_list: D000393:Air Pollutants; D004391:Dust; D009566:Nitrates; D052638:Particulate Matter; D013431:Sulfates; D001335:Vehicle Emissions
keywords: Chemical species; PM; PMF; SDA; Source apportionment; Trajectories cluster analysis