title: Linking Load, Fuel, and Emission Controls to Photochemical Production of Secondary Organic Aerosol from a Diesel Engine.
abstract: Diesel engines are important sources of fine particle pollution in urban environments, but their contribution to the atmospheric formation of secondary organic aerosol (SOA) is not well constrained. We investigated direct emissions of primary organic aerosol (POA) and photochemical production of SOA from a diesel engine using an oxidation flow reactor (OFR). In less than a day of simulated atmospheric aging, SOA production exceeded POA emissions by an order of magnitude or more. Efficient combustion at higher engine loads coupled to the removal of SOA precursors and particle emissions by aftertreatment systems reduced POA emission factors by an order of magnitude and SOA production factors by factors of 2-10. The only exception was that the retrofitted aftertreatment did not reduce SOA production at idle loads where exhaust temperatures were low enough to limit removal of SOA precursors in the oxidation catalyst. Use of biodiesel resulted in nearly identical POA and SOA compared to diesel. The effective SOA yield of diesel exhaust was similar to that of unburned diesel fuel. While OFRs can help study the multiday evolution, at low particle concentrations OFRs may not allow for complete gas/particle partitioning and bias the potential of precursors to form SOA.
authors.affiliation: Department of Mechanical Engineering, Colorado State University , Fort Collins, Colorado 80525, United States.
authors.forename: Shantanu H
authors.identifier: 0000-0003-4106-2358
authors.initials: SH
authors.lastname: Jathar
authors.affiliation: Department of Chemistry, Colorado State University , Fort Collins, Colorado 80523, United States.
authors.forename: Beth
authors.initials: B
authors.lastname: Friedman
authors.affiliation: Department of Mechanical Engineering, Colorado State University , Fort Collins, Colorado 80525, United States.
authors.forename: Abril A
authors.initials: AA
authors.lastname: Galang
authors.affiliation: Department of Chemistry, Colorado State University , Fort Collins, Colorado 80523, United States.
authors.forename: Michael F
authors.identifier: 0000-0002-1841-2455
authors.initials: MF
authors.lastname: Link
authors.affiliation: Department of Chemistry, Colorado State University , Fort Collins, Colorado 80523, United States.
authors.forename: Patrick
authors.initials: P
authors.lastname: Brophy
authors.affiliation: Department of Mechanical Engineering, Colorado State University , Fort Collins, Colorado 80525, United States.
authors.forename: John
authors.initials: J
authors.lastname: Volckens
authors.affiliation: Department of Mechanical Engineering, Colorado State University , Fort Collins, Colorado 80525, United States.
authors.forename: Sailaja
authors.initials: S
authors.lastname: Eluri
authors.affiliation: Department of Chemistry, Colorado State University , Fort Collins, Colorado 80523, United States.
authors.forename: Delphine K
authors.identifier: 0000-0002-6470-9970
authors.initials: DK
authors.lastname: Farmer
mesh_terms: D000336:Aerosols; D056804:Biofuels; D005742:Gasoline; D010084:Oxidation-Reduction; D001335:Vehicle Emissions
chemical_list: D000336:Aerosols; D056804:Biofuels; D005742:Gasoline; D001335:Vehicle Emissions