HR: 1340h
AN: A23C-1469    [Abstracts]
TI: PIT-MS Measurements of VOCs at a Suburban Ground Site (T1) in Mexico City During the MILAGRO 2006 Campaign: Emission Ratios and Source Apportionment
AU: * Welsh-Bon, D
EM: daniel.welshbon@noaa.gov
AF: NOAA Earth System Research Laboratory, DSRC, Bldg 33 325 Broadway, Boulder, CO 80305-3328, United States
AU: * Welsh-Bon, D
EM: daniel.welshbon@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado 216 UCB, Boulder, CO 80309-0216, United States
AU: Warneke, C
EM: carsten.warneke@noaa.gov
AF: NOAA Earth System Research Laboratory, DSRC, Bldg 33 325 Broadway, Boulder, CO 80305-3328, United States
AU: Warneke, C
EM: carsten.warneke@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado 216 UCB, Boulder, CO 80309-0216, United States
AU: de Gouw, J A
EM: Joost.DeGouw@noaa.gov
AF: NOAA Earth System Research Laboratory, DSRC, Bldg 33 325 Broadway, Boulder, CO 80305-3328, United States
AU: de Gouw, J A
EM: Joost.DeGouw@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado 216 UCB, Boulder, CO 80309-0216, United States
AU: Kuster, W
EM: William.C.Kuster@noaa.gov
AF: NOAA Earth System Research Laboratory, DSRC, Bldg 33 325 Broadway, Boulder, CO 80305-3328, United States
AU: Vargas, O
EM: olvargas@gatech.edu
AF: Georgia Institute of Technology, Georgia Institute of Technology, Atlanta, GA 30332, United States
AU: Huey, G
EM: greg.huey@eas.gatech.edu
AF: Georgia Institute of Technology, Georgia Institute of Technology, Atlanta, GA 30332, United States
AU: Jimenez, J L
EM: jose.jimenez@colorado.edu
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado 216 UCB, Boulder, CO 80309-0216, United States
AU: Ulbrich, I M
EM: Ingrid.Ulbrich@colorado.edu
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado 216 UCB, Boulder, CO 80309-0216, United States
AB: Volatile organic compounds (VOCs) were measured by several different methods at a suburban ground site (T1) in Mexico City located approximately 30 km north east of the city center during the MILAGRO campaign in March, 2006. Small alkanes and alkenes were measured using an on-line gas chromatography instrument with flame- ionization detection (GC-FID) and by canister collection and subsequent GC analysis. Aromatic hydrocarbons and oxygenated VOCs were quantified by proton-transfer ion-trap mass spectrometry (PIT-MS). For most measured species, a strong diurnal variation was observed with very high mixing ratios at night when VOC emissions accumulated in a shallow boundary layer, and lower mixing ratios during the day when VOCs were mixed in a deeper boundary layer and were removed by photochemistry. However, diurnal patterns in VOC measurements were substantially different for oxygenated VOCs. Emission ratios with CO for the primary VOC emissions are determined for Mexico City and compared to typical values observed for cities in the United States. It was found that the VOC emission ratios are generally higher in Mexico City. Positive Matrix Factorization (PMF) analysis can be used to evaluate differences in diurnal cycles between primary and secondary chemical species. PMF clearly distinguishes compounds with only primary emissions (e.g. alkanes, alkenes, and aromatics) from oxygenated species (e.g. acetaldehyde, acetone), which have both direct emission sources and a large proportion of secondary formation. It also groups both primary and secondary species by their reactivities/lifetimes. Finally, PMF can be used to provide chemical information about unknown ions (for m/z's contributing to PIT-MS signal but not typically monitored by PTR-MS) into these categories, facilitating their chemical identification.
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting