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| Titel |
Vehicle fleet emissions of black carbon, polycyclic aromatic hydrocarbons, and other pollutants measured by a mobile laboratory in Mexico City |
| VerfasserIn |
M. Jiang, L. C. Marr, E. J. Dunlea, S. C. Herndon, J. T. Jayne, C. E. Kolb, W. B. Knighton, T. M. Rogers, M. Zavala, L. T. Molina, M. J. Molina |
| 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 ; 5, no. 12 ; Nr. 5, no. 12 (2005-12-16), S.3377-3387 |
| Datensatznummer |
250003199
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| Publikation (Nr.) |
 copernicus.org/acp-5-3377-2005.pdf |
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| Zusammenfassung |
| Black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs) are of concern
due to their effects on climate and health. The main goal of this research
is to provide the first estimate of emissions of BC and particle-phase PAHs
(PPAHs) from motor vehicles in Mexico City. The emissions of other
pollutants including carbon monoxide (CO), oxides of nitrogen (NOx),
volatile organic compounds (VOCs), and particulate matter of diameter 2.5 μm
and less (PM2.5) are also estimated. As a part of the Mexico
City Metropolitan Area field campaign in April 2003 (MCMA-2003), a mobile
laboratory was driven throughout the city. The laboratory was equipped with
a comprehensive suite of gas and particle analyzers, including an
aethalometer that measured BC and a photoionization aerosol sensor that
measured PPAHs. While driving through traffic, the mobile lab continuously
sampled exhaust plumes from the vehicles around it. We have developed a
method of automatically identifying exhaust plumes, which are then used as
the basis for calculation of fleet-average emissions. In the approximately
75 h of on-road sampling during the field campaign, we have identified
~30 000 exhaust measurement points that represent a variety of vehicle types
and driving conditions. The large sample provides a basis for estimating
fleet-average emission factors and thus the emission inventory. Motor
vehicles in the Mexico City area are estimated to emit 1700±200 metric
tons BC, 57±6 tons PPAHs, 1 190 000±40 000 tons CO,
120 000±3000 tons NOx, 240 000±50 000 tons VOCs, and 4400±400 tons
PM2.5 per year, not including cold start emissions. The estimates for
CO, NOx, and PPAHs may be low by up to 10% due to the slower
response time of analyzers used to measure these species. Compared to the
government's official motor vehicle emission inventory for the year 2002,
the estimates for CO, NOx, VOCs, and PM2.5 are 38% lower,
23% lower, 27% higher, and 25% higher, respectively. The
distributions of emission factors of BC, PPAHs, and PM2.5 are highly
skewed, i.e. asymmetric, while those for benzene, measured as a surrogate
for total VOCs, and NOx are less skewed. As a result, the total
emissions of BC, PPAHs, and PM2.5 could be reduced by approximately
50% if the highest 20% of data points were removed, but "super
polluters" are less influential on overall NOx and VOC emissions. |
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