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| Titel |
Observations of high rates of NO2-HONO conversion in the nocturnal atmospheric boundary layer in Kathmandu, Nepal |
| VerfasserIn |
Y. Yu, B. Galle, A. Panday, E. Hodson, R. Prinn, S. Wang |
| 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 ; 9, no. 17 ; Nr. 9, no. 17 (2009-09-07), S.6401-6415 |
| Datensatznummer |
250007608
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| Publikation (Nr.) |
 copernicus.org/acp-9-6401-2009.pdf |
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| Zusammenfassung |
| Nitrous acid (HONO) plays a significant role in the atmosphere, especially in
the polluted troposphere. Its photolysis after sunrise is an important source
of hydroxyl free radicals (OH). Measurements of nitrous acid and other
pollutants were carried out in the Kathmandu urban atmosphere during
January–February 2003, contributing to the sparse knowledge of nitrous acid
in South Asia. The results showed average nocturnal levels of HONO
(1.7±0.8 ppbv), NO2 (17.9±10.2 ppbv), and PM10 (0.18±0.11 mg m−3) in urban air in Kathmandu. Surprisingly high
ratios of chemically formed secondary [HONO] to [NO2] (up to 30%)
were found, which indicates unexpectedly efficient chemical conversion of
NO2 to HONO in Kathmandu. The ratios of [HONO]/[NO2] at night were
found to be much higher than previously reported values from measurements in
urban air in Europe, North America and Asia. The influences of aerosol
surface, ground reactive surface, and relative humidity on NO2-HONO
chemical conversion were discussed. The high humidity, strong and low
inversion layer at night, and high aerosol pollution burden in Kathmandu may
explain the particularly efficient conversion of NO2 to HONO. |
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