HR: 0800h
AN: A51E-0125    [Abstracts]
TI: Evidence of Light Alkane Transport From the Southwestern United States During INTEX-NA
AU: * Baker, A
EM: akyoung@uci.edu
AF: Department of Chemistry, University of California, Irvine, 570 Rowland Hall, Irvine, CA 92697 United States
AU: Blake, N
A51E-0125 AF: Department of Chemistry, University of California, Irvine, 570 Rowland Hall, Irvine, CA 92697 United States
AU: Beyersdorf, A
A51E-0125 AF: Department of Chemistry, University of California, Irvine, 570 Rowland Hall, Irvine, CA 92697 United States
AU: Katzenstein, A
A51E-0125 AF: South Coast Air Quality Management District, 21865 Copley Drive, Diamond Bar, CA 91765 United States
AU: Doezema, L
A51E-0125 AF: Deparment of Chemistry and Biochemistry, Loyola Marymount University, 301 Seaver Hall, Los Angeles, CA 90045 United States
AU: Meinardi, S
A51E-0125 AF: Department of Chemistry, University of California, Irvine, 570 Rowland Hall, Irvine, CA 92697 United States
AU: Fuelberg, H
A51E-0125 AF: Department of Meteorology, Florida State University, 362 Love Building, Tallahassee, FL 32306 United States
AU: Blake, D
EM: drblake@uci.edu
AF: Department of Chemistry, University of California, Irvine, 570 Rowland Hall, Irvine, CA 92697 United States
AU: Rowland, F
A51E-0125 AF: Department of Chemistry, University of California, Irvine, 570 Rowland Hall, Irvine, CA 92697 United States
AB: We examine the transport and photochemical processing of light (C₂-C₅) alkane pollution originating from oil producing regions of the Southwestern United States using selected data from 2900 whole air samples collected during the airborne Intercontinental Chemical Transport Experiment (INTEX-NA) field campaign (July - August 2004). These data are compared to ground samples collected in Oklahoma, Texas and Kansas during May 2002. INTEX-NA airmasses with backward trajectories from the Southwest exhibited enhancements in ethane, propane, n-butane, i-butane, n-pentane and i-pentane, and were observed on flights as far east as the Atlantic Coast and as far north as the U.S. - Canadian border. For those airborne samples containing fresh (<1 day) emissions from the Southwest, the ratios of ethane to the other light alkanes were in good agreement with our ground-based data. The ratio of ethane/propane was a particularly robust marker for "Southwest" air pollution. Ratios for freshly influenced airborne samples (average ethane/propane 1.6 ± 0.4 pptv/pptv) were very similar to those for the ground samples (1.6 ± 0.5 pptv/pptv), but significantly lower than those of INTEX-NA samples without Southwest influence (ethane/propane ratios typically in excess of 8 pptv/pptv). We also propose employing ethane/propane ratios as a tool for investigating the photochemical processing of these airmasses. As Southwest airmasses age the ethane/propane ratio increases for 8 -10 days, until reaching a value indistinguishable from other INTEX-NA samples. We also investigated the production rates of alkyl nitrate from their parent alkanes to further elucidate airmass processing. Methane mixing ratios were somewhat enhanced in the Southwest samples, though the relationship between methane and the C₂-C₅ alkanes was variable. We attribute this variability to the small enhancements in methane relative to other natural sources and to high background levels.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0322 Constituent sources and sinks
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0365 Troposphere: composition and chemistry
DE: 0368 Troposphere: constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005