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| Titel |
On the volatility and production mechanisms of newly formed nitrate and water soluble organic aerosol in Mexico City |
| VerfasserIn |
C. J. Hennigan, A. P. Sullivan, C. I. Fountoukis, A. Nenes, A. Hecobian, O. Vargas, R. E. Peltier, A. T. Case Hanks, L. G. Huey, B. L. Lefer, A. G. Russell, R. J. Weber |
| 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 ; 8, no. 14 ; Nr. 8, no. 14 (2008-07-16), S.3761-3768 |
| Datensatznummer |
250006283
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| Publikation (Nr.) |
 copernicus.org/acp-8-3761-2008.pdf |
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| Zusammenfassung |
| Measurements of atmospheric gases and fine particle chemistry were made in
the Mexico City Metropolitan Area (MCMA) at a site ~30 km down wind
of the city center. Ammonium nitrate (NH4NO3) dominated the
inorganic aerosol fraction and showed a distinct diurnal signature
characterized by rapid morning production and a rapid mid-day concentration
decrease. Between the hours of 08:00–12:45, particulate water-soluble
organic carbon (WSOC) concentrations increased and decreased in a manner
consistent with that of NO3−, and the two were highly correlated
(R2=0.88) during this time. A box model was used to analyze these
behaviors and showed that, for both NO3− and WSOC, the
concentration increase was caused primarily (~75–85%) by secondary
formation, with a smaller contribution (~15–25%) from the
entrainment of air from the free troposphere. For NO3−, a majority
(~60%) of the midday concentration decrease was caused by dilution
from boundary layer expansion, though a significant fraction (~40%)
of the NO3− loss was due to particle evaporation. The WSOC
concentration decrease was due largely to dilution (~75%), but
volatilization did have a meaningful impact (~25%) on the decrease,
as well. The results provide an estimate of ambient SOA evaporation losses
and suggest that a significant fraction (~35%) of the fresh MCMA
secondary organic aerosol (SOA) measured at the surface volatilized. |
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