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| Titel |
Evaluation of nitrogen dioxide chemiluminescence monitors in a polluted urban environment |
| VerfasserIn |
E. J. Dunlea, S. C. Herndon, D. D. Nelson, R. M. Volkamer, F. San Martini, P. M. Sheehy, M. S. Zahniser, J. H. Shorter, J. C. Wormhoudt, B. K. Lamb, E. J. Allwine, J. S. Gaffney, N. A. Marley, M. Grutter, C. Márquez, S. Blanco, B. Cárdenas, A. Retama, C. R. Ramos Villegas, C. E. Kolb, 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 ; 7, no. 10 ; Nr. 7, no. 10 (2007-05-23), S.2691-2704 |
| Datensatznummer |
250004996
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| Publikation (Nr.) |
 copernicus.org/acp-7-2691-2007.pdf |
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| Zusammenfassung |
| Data from a recent field campaign in Mexico City are used to evaluate the
performance of the EPA Federal Reference Method for monitoring the ambient
concentrations of NO2. Measurements of NO2 from standard
chemiluminescence monitors equipped with molybdenum oxide converters are
compared with those from Tunable Infrared Laser Differential Absorption
Spectroscopy (TILDAS) and Differential Optical Absorption Spectroscopy
(DOAS) instruments. A significant interference in the chemiluminescence
measurement is shown to account for up to 50% of ambient NO2
concentration during afternoon hours. As expected, this interference
correlates well with non-NOx reactive nitrogen species (NOz) as
well as with ambient O3 concentrations, indicating a photochemical
source for the interfering species. A combination of ambient gas phase
nitric acid and alkyl and multifunctional alkyl nitrates is deduced to be
the primary cause of the interference. Observations at four locations at
varying proximities to emission sources indicate that the percentage
contribution of HNO3 to the interference decreases with time as the air
parcel ages. Alkyl and multifunctional alkyl nitrate concentrations are
calculated to reach concentrations as high as several ppb inside the city,
on par with the highest values previously observed in other urban locations.
Averaged over the MCMA-2003 field campaign, the chemiluminescence monitor
interference resulted in an average measured NO2 concentration up to
22% greater than that from co-located spectroscopic measurements. Thus,
this interference has the potential to initiate regulatory action in areas
that are close to non-attainment and may mislead atmospheric photochemical
models used to assess control strategies for photochemical oxidants. |
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