title: Chemically-speciated on-road PM(2.5) motor vehicle emission factors in Hong Kong.
abstract: PM(2.5) (particle with an aerodynamic diameter less than 2.5microm) was measured in different microenvironments of Hong Kong (including one urban tunnel, one Hong Kong/Mainland boundary roadside site, two urban roadside sites, and one urban ambient site) in 2003. The concentrations of organic carbon (OC), elemental carbon (EC), water-soluble ions, and up to 40 elements (Na to U) were determined. The average PM(2.5) mass concentrations were 229+/-90, 129+/-95, 69+/-12, 49+/-18microg m(-3) in the urban tunnel, cross boundary roadside, urban roadside, and urban ambient environments, respectively. Carbonaceous particles (sum of organic material [OM] and EC) were the dominant constituents, on average, accounting for approximately 82% of PM(2.5) emissions in the tunnel, approximately 70% at the three roadside sites, and approximately 48% at the ambient site, respectively. The OC/EC ratios were 0.6+/-0.2 and 0.8+/-0.1 at the tunnel and roadside sites, respectively, suggesting carbonaceous aerosols were mainly from vehicle exhausts. Higher OC/EC ratio (1.9+/-0.7) occurred at the ambient site, indicating contributions from secondary organic aerosols. The PM(2.5) emission factor for on-road diesel-fueled vehicles in the urban area of Hong Kong was 257+/-31mg veh(-1) km(-1), with a composition of approximately 51% EC, approximately 26% OC, and approximately 9% SO(4)(=). The other inorganic ions and elements made up approximately 11% of the total PM(2.5) emissions. OC composed the largest fraction (approximately 51%) in gasoline and liquid petroleum gas (LPG) emissions, followed by EC (approximately 19%). Diesel engines showed higher emission rates than did gasoline and LPG engines for most pollutants, except for V, Br, Sb, and Ba.
authors.affiliation: Department of Environmental Science and Technology, School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Shaanxi, China. chengyan6@gmail.com
authors.forename: Y
authors.initials: Y
authors.lastname: Cheng
authors.forename: S C
authors.initials: SC
authors.lastname: Lee
authors.forename: K F
authors.initials: KF
authors.lastname: Ho
authors.forename: J C
authors.initials: JC
authors.lastname: Chow
authors.forename: J G
authors.initials: JG
authors.lastname: Watson
authors.forename: P K K
authors.initials: PK
authors.lastname: Louie
authors.forename: J J
authors.initials: JJ
authors.lastname: Cao
authors.forename: X
authors.initials: X
authors.lastname: Hai
mesh_terms: D000336:Aerosols; D006723:Hong Kong; D010316:Particle Size; D001335:Vehicle Emissions
chemical_list: D000336:Aerosols; D001335:Vehicle Emissions