title: Volatility of primary organic aerosol emitted from light duty gasoline vehicles.
abstract: Primary organic aerosol (POA) emitted from light duty gasoline vehicles (LDGVs) exhibits a semivolatile behavior in which heating the aerosol and/or diluting the aerosol leads to partial evaporation of the POA. A single volatility distribution can explain the median evaporation behavior of POA emitted from LDGVs but this approach is unable to capture the full range of measured POA volatility during thermodenuder (TD) experiments conducted at atmospherically relevant concentrations (2-5 μg m(-3)). Reanalysis of published TD data combined with analysis of new measurements suggest that POA emitted from gasoline vehicles is composed of two types of POA that have distinctly different volatility distributions: one low-volatility distribution and one medium-volatility distribution. These correspond to fuel combustion-derived POA and motor oil POA, respectively. Models that simultaneously incorporate both of these distributions are able to reproduce experimental results much better (R(2) = 0.94) than models that use a single average or median distribution (R(2) = 0.52). These results indicate that some fraction of POA emitted from LDGVs is essentially nonvolatile under typical atmospheric dilution levels. Roughly 50% of the vehicles tested in the current study had POA emissions dominated by fuel combustion products (essentially nonvolatile). Further testing is required to determine appropriate fleet-average emissions rates of the two POA types from LDGVs.
authors.affiliation: Department of Civil and Environmental Engineering, University of California at Davis , One Shields Avenue, Davis, California 95616, United States.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Kuwayama
authors.forename: Sonya
authors.initials: S
authors.lastname: Collier
authors.forename: Sara
authors.initials: S
authors.lastname: Forestieri
authors.forename: James M
authors.initials: JM
authors.lastname: Brady
authors.forename: Timothy H
authors.initials: TH
authors.lastname: Bertram
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Cappa
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhang
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Kleeman
mesh_terms: D000336:Aerosols / Q000032:analysis / Q000737:chemistry*; D001336:Automobiles; D005742:Gasoline / Q000032:analysis; D008962:Models, Theoretical; D001335:Vehicle Emissions / Q000032:analysis*; D014835:Volatilization
chemical_list: D000336:Aerosols; D005742:Gasoline; D001335:Vehicle Emissions