AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Direct Measurements of Near-Highway Aerosol Emissions and Volatile Organic Compounds in a High Diesel Environment
H. LANGLEY DEWITT, Stig Hellebust, Brice Temime-Roussel, Sylvain Ravier, Lucie Polo, Jean Luc Jaffrezo, Veronique Jacob, Aurelie Charron, Jean-Luc Besombes, Nicolas Marchand, Aix Marseille Université, Laboratoire Chimie Environnement
Abstract Number: 250 Working Group: Source Apportionment
Abstract In France, the diesel passenger car market has grown rapidly since the 1980s. Recent data show that diesel vehicles now outnumber gasoline vehicles on the road by a factor of 2-3. While diesel-powered engines usually offer an advantage in fuel efficiency over gasoline-powered engines, there is some controversy over the role of each vehicle type's emission in both primary organic aerosol and volatile organic compounds (VOCs) that react in the atmosphere to form secondary organic aerosol (SOA). In this context, the fall 2011 Measuring and mOdelling traffic COngestion and Pollution (MOCOPO) field campaign was designed to measure aerosol directly affected by vehicular emissions in-situ while capturing parallel data on local traffic. From September 11-September 23 2011, an Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and a Proton Transfer Reaction-Time of Flight-Mass Spectrometer (PTR-ToF-MS) continuously measured the aerosol and VOC chemical composition, respectively, beside a heavily trafficked highway on the outskirts of Grenoble (France). Black carbon measurements and 4-hr filter samples for offline chemical analysis were also collected. The Positive Matrix Factorization model was applied to the high resolution aerosol and VOC data (both with and without inorganic ions) to resolve chemically and temporally aerosol and VOC mixtures for source apportionment. Periods heavily influenced by vehicular emissions were compared with periods more influenced by regional SOA. Two factors were found to exhibit diurnal trends related to traffic peaks: a typical Hydrocarbon-like Organic Aerosol (HOA) factor, which correlated well with black carbon, and possibly a nitrogen-containing organic aerosol factor (NOA). While the concentration of diesel- and gasoline-powered vehicles on the highway largely co-varied, estimated emission factors from traffic data and aerosol concentration in this high diesel environment were calculated and smog chamber data from diesel and gasoline vehicular emissions were compared to these ambient measurements.