HR: 17:30h
AN: A54C-07    [Abstracts]
TI: Determination of a NMHC Signature for U.S. Cities
AU: * Beyersdorf, A J
EM: abeyersd@uci.edu
AF: Department of Chemistry, University of California Irvine, 570 Rowland Hall, Irvine, CA 92697 United States
AU: Baker, A K
EM: akyoung@uci.edu
AF: Department of Chemistry, University of California Irvine, 570 Rowland Hall, Irvine, CA 92697 United States
AU: Doezema, L A
A54C-07 AF: Department of Chemistry and Biochemistry, Loyola Marymount University, 301 Seaver Hall, Los Angeles, CA 90045 United States
AU: Katzenstein, A S
A54C-07 AF: South Coast Air Quality Management District, 21865 Copley Drive, Diamond Bar, CA 91765 United States
AU: Meinardi, S
A54C-07 AF: Department of Chemistry, University of California Irvine, 570 Rowland Hall, Irvine, CA 92697 United States
AU: Rowland, F S
A54C-07 AF: Department of Chemistry, University of California Irvine, 570 Rowland Hall, Irvine, CA 92697 United States
AU: Blake, D R
EM: drblake@uci.edu
AF: Department of Chemistry, University of California Irvine, 570 Rowland Hall, Irvine, CA 92697 United States
AB: A seven-year study (1999 through 2005) has been conducted in United States cities in order to determine volatile organic compound abundance and sources. In total, 29 cities were studied (one to six cities were sampled each August). Air samples were collected in stainless steel canisters and analyzed using GC and GC-MS. Sampling sites were located in parks and open spaces throughout the urban area. This was done in order to decrease the contribution of any point sources. Measurements of methane, carbon monoxide (CO), and 21 nonmethane hydrocarbons (NMHCs) are used here to provide a U.S. signature for urban sources. Key ratios of certain NMHC to CO and to each other are used to determine source contribution, air mass age, and emission factors. The predominant source of most NMHCs was found to be vehicular exhaust. However, in five of the cities studied an additional regional source of light alkanes was present. Elevated levels of C₂-C₅ alkanes present in Oklahoma City, El Paso, and Baton Rouge have been identified as being from oil production and storage. These cities are characterized by an ethane to CO ratio in excess of 18 pptv/ppbv which is three times that seen in cities without a regional ethane source (6 pptv/ppbv). Charleston and Pittsburgh also exhibited enhanced C₂-C₅ alkanes with ethane to CO ratios above 35 pptv/ppbv. Possible sources of these compounds in this region of the country will be discussed.
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
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005