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| Titel |
Application of positive matrix factorization to on-road measurements for source apportionment of diesel- and gasoline-powered vehicle emissions in Mexico City |
| VerfasserIn |
D. A. Thornhill, A. E. Williams, T. B. Onasch, E. Wood, S. C. Herndon, C. E. Kolb, W. B. Knighton, M. Zavala, L. T. Molina, L. C. Marr |
| 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 ; 10, no. 8 ; Nr. 10, no. 8 (2010-04-20), S.3629-3644 |
| Datensatznummer |
250008362
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| Publikation (Nr.) |
 copernicus.org/acp-10-3629-2010.pdf |
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| Zusammenfassung |
| The goal of this research is to quantify diesel- and gasoline-powered motor vehicle
emissions within the Mexico City Metropolitan Area (MCMA) using on-road measurements
captured by a mobile laboratory combined with positive matrix factorization (PMF) receptor
modeling. During the MCMA-2006 ground-based component of the MILAGRO field campaign, the
Aerodyne Mobile Laboratory (AML) measured many gaseous and particulate pollutants, including
carbon dioxide, carbon monoxide (CO), nitrogen oxides (NOx), benzene, toluene,
alkylated aromatics, formaldehyde, acetaldehyde, acetone, ammonia, particle number, fine
particulate mass (PM2.5), and black carbon (BC). These serve as inputs to the
receptor model, which is able to resolve three factors corresponding to gasoline engine
exhaust, diesel engine exhaust, and the urban background. Using the source profiles, we
calculate fuel-based emission factors for each type of exhaust. The MCMA's gasoline-powered
vehicles are considerably dirtier, on average, than those in the US with respect to CO and
aldehydes. Its diesel-powered vehicles have similar emission factors of NOx and
higher emission factors of aldehydes, particle number, and BC. In the fleet sampled during
AML driving, gasoline-powered vehicles are found to be responsible for 97% of total vehicular emissions
of CO, 22% of NOx, 95–97% of each aromatic species, 72–85% of each carbonyl
species, 74% of
ammonia, negligible amounts of particle number, 26% of PM2.5, and 2% of BC;
diesel-powered vehicles account for the balance. Because the mobile lab spent 17% of its
time waiting at stoplights, the results may overemphasize idling conditions, possibly
resulting in an underestimate of NOx and overestimate of CO emissions. On the
other hand, estimates of the inventory that do not correctly account for emissions during
idling are likely to produce bias in the opposite direction.The resulting fuel-based estimates of
emissions are lower than in the official inventory for CO and NOx and higher for
VOCs. For NOx, the
fuel-based estimates are lower for gasoline-powered vehicles but higher for diesel-powered
ones compared to the official inventory. While conclusions regarding the inventory should be
interpreted with care because of the small sample size, 3.5 h of driving, the discrepancies
with the official inventory agree with those reported in other studies. |
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