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| Titel |
Measurement of atmospheric nitrous acid at Bodgett Forest during BEARPEX2007 |
| VerfasserIn |
X. Ren, H. Gao, X. Zhou, J. D. Crounse, P. O. Wennberg, E. C. Browne, B. W. LaFranchi, R. C. Cohen, M. McKay, A. H. Goldstein, J. Mao |
| 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 ; 10, no. 13 ; Nr. 10, no. 13 (2010-07-12), S.6283-6294 |
| Datensatznummer |
250008617
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| Publikation (Nr.) |
 copernicus.org/acp-10-6283-2010.pdf |
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| Zusammenfassung |
| Nitrous acid (HONO) is an important precursor of the hydroxyl radical (OH)
in the lower troposphere. Understanding HONO chemistry, particularly its
sources and contribution to HOx (=OH+HO2) production, is very
important for understanding atmospheric oxidation processes. A highly
sensitive instrument for detecting atmospheric HONO based on wet chemistry
followed by liquid waveguide long path absorption photometry was deployed in
the Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX) at
Blodgett Forest, California in late summer 2007. The median diurnal
variation shows minimum HONO levels of about 20–30 pptv during the day and
maximum levels of about 60–70 pptv at night, a diurnal pattern quite
different from the results at various other forested sites. Measured
HONO/NO2 ratios for a 24-h period ranged from 0.05 to 0.13 with a
mean ratio of 0.07. Speciation of reactive nitrogen compounds (NOy)
indicates that HONO accounted for only ~3% of total NOy.
However, due to the fast HONO loss through photolysis, a strong HONO source
(1.59 ppbv day−1) existed in this environment in order to sustain the
observed HONO levels, indicating the significant role of HONO in NOy
cycling. The wet chemistry HONO measurements were compared to the HONO
measurements made with a Chemical Ionization Mass Spectrometer (CIMS) over a
three-day period. Good agreement was obtained between the measurements from
the two different techniques. Using the expansive suite of photochemical and
meteorological measurements, the contribution of HONO photolysis to HOx
budget was calculated to be relatively small (6%) compared to results
from other forested sites. The lower HONO mixing ratio and thus its smaller
contribution to HOx production are attributed to the unique
meteorological conditions and low acid precipitation at Blodgett Forest.
Further studies of HONO in this kind of environment are needed to test this
hypothesis and to improve our understanding of atmospheric oxidation and
nitrogen budget. |
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