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| Titel |
Chemically-resolved aerosol eddy covariance flux measurements in urban Mexico City during MILAGRO 2006 |
| VerfasserIn |
R. Zalakeviciute, M. L. Alexander, E. Allwine, J. L. Jimenez, B. T. Jobson, L. T. Molina, E. Nemitz, S. N. Pressley, T. M. VanReken, I. M. Ulbrich, E. Velasco, B. K. Lamb |
| 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 ; 12, no. 16 ; Nr. 12, no. 16 (2012-08-31), S.7809-7823 |
| Datensatznummer |
250011419
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| Publikation (Nr.) |
 copernicus.org/acp-12-7809-2012.pdf |
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| Zusammenfassung |
| As part of the MILAGRO 2006 field campaign, the exchange of atmospheric
aerosols with the urban landscape was measured from a tall tower erected in
a heavily populated neighborhood of Mexico City. Urban submicron aerosol
fluxes were measured using an eddy covariance method with a quadrupole
aerosol mass spectrometer during a two week period in March, 2006. Nitrate
and ammonium aerosol concentrations were elevated at this location near the
city center compared to measurements at other urban sites. Significant
downward fluxes of nitrate aerosol, averaging −0.2 μg m−2 s−1,
were measured during daytime. The urban surface was not a
significant source of sulfate aerosols. The measurements also showed that
primary organic aerosol fluxes, approximated by hydrocarbon-like organic
aerosols (HOA), displayed diurnal patterns similar to CO2 fluxes and
anthropogenic urban activities. Overall, 47% of submicron organic aerosol
emissions were HOA, 35% were oxygenated (OOA) and 18% were associated
with biomass burning (BBOA). Organic aerosol fluxes were bi-directional, but
on average HOA fluxes were 0.1 μg m−2 s−1, OOA fluxes were
−0.03 μg m−2 s−1, and BBOA fluxes were −0.03 μg m−2 s−1.
After accounting for size differences (PM1 vs PM2.5)
and using an estimate of the black carbon component, comparison of the flux
measurements with the 2006 gridded emissions inventory of Mexico City,
showed that the daily-averaged total PM emission rates were essentially
identical for the emission inventory and the flux measurements. However, the
emission inventory included dust and metal particulate contributions, which
were not included in the flux measurements. As a result, it appears that the
inventory underestimates overall PM emissions for this location. |
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