AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Effect of Temperature, Humidity, and Background Aerosol Concentrations on Organic Aerosol Emissions from Gasoline and Diesel Fueled Motor Vehicles
Toshihiro Kuwayama, Isabel Faria, Peter Green, MICHAEL KLEEMAN, UC Davis
Abstract Number: 580 Working Group: Aerosol Chemistry
Abstract Experiments were conducted using a dilution air sampler combined with a dynamometer system to explore the effects of temperature, humidity, and background aerosol concentrations on primary organic aerosol (POA) emissions from both gasoline and diesel fueled motor vehicles at realistic ambient concentrations. Successive tests were conducted on the same fleet of 6 on-road vehicles under different control conditions. Temperature was adjusted from ambient to 100 degrees Celsius, RH was adjusted between ambient to 85%, and background EC concentrations were adjusted between 0 to 20 micro gram per m$^(-3) above ambient. All majority of tests diluted exhaust by a factor of ~100 with a residence time of ~60 sec while a subset of tests varied both dilution factor and residence time to determine the effect of these conditions on the evolution of POA.
Aerosol samples were collected with a denuder-filter-PUF sampling train designed to separately capture gaseous and particulate compounds. Primary PM samples were analyzed for elemental carbon (EC) and organic carbon (OC) to characterize the PM mass emissions. All samples were further analyzed for detailed molecular composition using derivatization by PFBHA followed by analysis using GC-MS.
Predictions from absorption and adsorption models for POA partitioning will be compared to measured partitioning results. The volatility of primary organic aerosol at atmospherically relevant concentrations will be evaluated. Previous observations of significant concentrations of small oxygenated compounds in the condensed phase will be analyzed in this context. Significant gaps in the ability of state-of-the-science models for partitioning of POA will be highlighted.