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| Titel |
Measurements of volatile organic compounds at a suburban ground site (T1) in Mexico City during the MILAGRO 2006 campaign: measurement comparison, emission ratios, and source attribution |
| VerfasserIn |
D. M. Bon, I. M. Ulbrich, J. A. Gouw, C. Warneke, W. C. Kuster, M. L. Alexander, A. Baker, A. J. Beyersdorf, D. Blake, R. Fall, J. L. Jimenez, S. C. Herndon, L. G. Huey, W. B. Knighton, J. Ortega, S. Springston, O. Vargas |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 6 ; Nr. 11, no. 6 (2011-03-16), S.2399-2421 |
| Datensatznummer |
250009499
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| Publikation (Nr.) |
 copernicus.org/acp-11-2399-2011.pdf |
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| Zusammenfassung |
| Volatile organic compound (VOC) mixing ratios were measured with two
different instruments at the T1 ground site in Mexico City during the
Megacity Initiative: Local and Global Research Observations (MILAGRO)
campaign in March of 2006. A gas chromatograph with flame ionization
detector (GC-FID) quantified 18 light alkanes, alkenes and acetylene while a
proton-transfer-reaction ion-trap mass spectrometer (PIT-MS) quantified 12
VOC species including oxygenated VOCs (OVOCs) and aromatics. A GC separation
system was used in conjunction with the PIT-MS (GC-PIT-MS) to evaluate
PIT-MS measurements and to aid in the identification of unknown VOCs. The
VOC measurements are also compared to simultaneous canister samples and to
two independent proton-transfer-reaction mass spectrometers (PTR-MS)
deployed on a mobile and an airborne platform during MILAGRO. VOC diurnal
cycles demonstrate the large influence of vehicle traffic and liquid propane
gas (LPG) emissions during the night and photochemical processing during the
afternoon. Emission ratios for VOCs and OVOCs relative to CO are derived
from early-morning measurements. Average emission ratios for non-oxygenated
species relative to CO are on average a factor of ~2 higher than
measured for US cities. Emission ratios for OVOCs are estimated and
compared to literature values the northeastern US and to tunnel studies in
California. Positive matrix factorization analysis (PMF) is used to provide
insight into VOC sources and processing. Three PMF factors were
distinguished by the analysis including the emissions from vehicles, the use
of liquid propane gas and the production of secondary VOCs + long-lived
species. Emission ratios to CO calculated from the results of PMF analysis
are compared to emission ratios calculated directly from measurements. The
total PIT-MS signal is summed to estimate the fraction of identified versus
unidentified VOC species. |
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