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| Titel |
Comparison of measurements of peroxyacyl nitrates and primary carbonaceous aerosol concentrations in Mexico City determined in 1997 and 2003 |
| VerfasserIn |
N. A. Marley, J. S. Gaffney, R. Ramos-Villegas, B. Cárdenas González |
| 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 ; 7, no. 9 ; Nr. 7, no. 9 (2007-05-04), S.2277-2285 |
| Datensatznummer |
250004950
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| Publikation (Nr.) |
 copernicus.org/acp-7-2277-2007.pdf |
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| Zusammenfassung |
| The concentrations of peroxyacetyl nitrate (PAN) in ambient air can be a
good indicator of air quality and the effectiveness of control strategies
for reducing ozone levels in urban areas. As PAN is formed by the oxidation
of reactive hydrocarbons in the presence of nitrogen dioxide (NO2), it
is a direct measure of the peroxyacyl radical levels produced from reactive
organic emissions in the urban air shed. Carbon soot, known as black carbon
(BC) or elemental carbon (EC), is a primary atmospheric aerosol species and
is a good indicator of the levels of combustion emissions, particularly from
diesel engines, in major cities. Mexico City is the second largest megacity
in the world and has long suffered from poor air quality. Reported here are
atmospheric measurements of PAN and BC obtained in Mexico City during the
Mexico Megacity 2003 field study. These results are compared with
measurements obtained earlier during the Investigación sobre
Materia Particulada y Deterioro Atmosférico – Aerosol and Visibility
Research (IMADA-AVER) campaign in 1997 to obtain an estimate of the changes
in emissions in Mexico City and the effectiveness of control strategies
adopted during that time. Concentrations of PAN in 1997 reached a maximum of
34 ppb with an average daily maximum of 15 ppb. The PAN levels recorded in
2003 were quite different, with an average daily maximum of 3 ppb. This
dramatic reduction in PAN levels observed in 2003 indicate that reactive
hydrocarbon emissions have been reduced in the city due to controls on
olefins in liquefied petroleum gas (LPG) and also due to the significant
number of newer vehicles with catalytic converters that have replaced older
higher emission vehicles. In contrast, black/elemental carbon levels were
similar in 1997 and 2003 indicating little improvement likely due to the
lack of controls on diesel vehicles in the city. Thus, while air quality and
ozone production have improved, Mexico City and other megacities continue to
be a major source of black carbon aerosols, which can be an important
species in determining regional radiative balance and climate. |
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