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| Titel |
HO2NO2 and HNO3 in the coastal Antarctic winter night: a "lab-in-the-field" experiment |
| VerfasserIn |
A. E. Jones, N. Brough, P. S. Anderson, E. W. Wolff |
| 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 ; 14, no. 21 ; Nr. 14, no. 21 (2014-11-12), S.11843-11851 |
| Datensatznummer |
250119151
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| Publikation (Nr.) |
 copernicus.org/acp-14-11843-2014.pdf |
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| Zusammenfassung |
| Observations of peroxynitric acid (HO2NO2) and nitric acid
(HNO3) were made during a 4 month period of Antarctic winter darkness
at the coastal Antarctic research station, Halley. Mixing ratios of
HNO3 ranged from instrumental detection limits to ~8
parts per trillion by volume (pptv), and of HO2NO2 from detection
limits to ~5 pptv; the average ratio of
HNO3 : HO2NO2 was 2.0(± 0.6) : 1, with HNO3 always
present at greater mixing ratios than HO2NO2 during the winter
darkness. An extremely strong association existed for the entire measurement
period between mixing ratios of the respective trace gases and temperature:
for HO2NO2, R2 = 0.72, and for HNO3, R2 = 0.70.
We focus on three cases with considerable variation in temperature, where
wind speeds were low and constant, such that, with the lack of
photochemistry, changes in mixing ratio were likely to be driven by physical
mechanisms alone. We derived enthalpies of adsorption (ΔHads)
for these three cases. The average ΔHads for HNO3 was
−42 ± 2 kJ mol−1 and for HO2NO2 was −56 ± 1 kJ mol−1;
these values are extremely close to those derived in
laboratory studies. This exercise demonstrates (i) that adsorption
to/desorption from the snow pack should be taken into account when
addressing budgets of boundary layer HO2NO2 and HNO3 at any
snow-covered site, and (ii) that Antarctic winter can be used as a natural
"laboratory in the field" for testing data on physical exchange
mechanisms. |
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