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| Titel |
Impact of external industrial sources on the regional and local SO2 and O3 levels of the Mexico megacity |
| VerfasserIn |
V. H. Almanza, L. T. Molina, G. Li, J. Fast, G. Sosa |
| 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 ; 14, no. 16 ; Nr. 14, no. 16 (2014-08-22), S.8483-8499 |
| Datensatznummer |
250118967
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| Publikation (Nr.) |
 copernicus.org/acp-14-8483-2014.pdf |
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| Zusammenfassung |
The air quality of megacities can be influenced by external emission
sources on both global and regional scales. At the same time their outflow
emissions can exert an impact to the surrounding environment. The present
study evaluates an SO2 peak observed on 24 March 2006 at the suburban
supersite T1 and at ambient air quality monitoring stations located in the
northern region of the Mexico City Metropolitan Area (MCMA) during the
Megacity Initiative: Local and Global Research Observations (MILAGRO) field campaign. We found that this peak could be related to an important
episodic emission event coming from Tizayuca region, northeast of the MCMA.
Back-trajectory analyses suggest that the emission event started in the
early morning at 04:00 LST and lasted for about 9 h. The estimated emission
rate is about 2 kg s−1. To the best of our knowledge, sulfur dioxide
emissions from the Tizayuca region have not been considered in previous studies.
This finding suggests the possibility of "overlooked" emission sources in
this region that could influence the air quality of the MCMA. This further
motivated us to study the cement plants, including those in the state of
Hidalgo and in the State of Mexico. It was found that they can contribute to the SO2 levels in
the northeast (NE) region of the basin (about 42%), at the suburban
supersite T1 (41%) and that at some monitoring stations their
contribution can be even higher than the contribution from the Tula
Industrial Complex (TIC).
The contribution of the Tula Industrial Complex to regional ozone levels is
estimated. The model suggests low contribution to the MCMA (1 to 4 ppb) and
slightly higher contribution at the suburban T1 (6 ppb) and rural T2
(5 ppb) supersites. However, the contribution could be as high as 10 ppb in
the upper northwest region of the basin and in the southwest and
south-southeast regions of the state of Hidalgo. In addition, the results
indicated that the ozone plume could also be transported to northwest
Tlaxcala, eastern Hidalgo, and farther northeast of the State of Mexico, but
with rather low values. A first estimate of the potential contribution from
flaring activities to regional ozone levels is presented. Results suggest
that up to 30% of the total regional ozone from TIC could be related to
flaring activities.
Finally, the influence on SO2 levels from technological changes in the
existing refinery is briefly discussed. These changes are due to the
upcoming construction of a new refinery in Tula. The combination of emission
reductions in the power plant, the refinery and in local sources in the MCMA
could result in higher reductions on the average SO2 concentration.
Reductions in external sources tend to affect more the northern part of the
basin (−16 to −46%), while reductions of urban sources in the
megacity tend to diminish SO2 levels substantially in the central,
southwest, and southeast regions (−31 to −50%). |
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