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| Titel |
Influence of local air pollution on the deposition of peroxyacetyl nitrate to a nutrient-poor natural grassland ecosystem |
| VerfasserIn |
A. Moravek, P. Stella, T. Foken, I. Trebs |
| 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 ; 15, no. 2 ; Nr. 15, no. 2 (2015-01-26), S.899-911 |
| Datensatznummer |
250119346
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| Publikation (Nr.) |
 copernicus.org/acp-15-899-2015.pdf |
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| Zusammenfassung |
| Dry deposition of peroxyacetyl nitrate (PAN) is known to have a phytotoxic
impact on plants under photochemical smog conditions, but it may also lead
to higher productivity and threaten species richness of vulnerable
ecosystems in remote regions. However, underlying mechanisms or controlling
factors for PAN deposition are not well understood and studies on dry
deposition of PAN are limited. In this study, we investigate the impact of
PAN deposition on a nutrient-poor natural grassland ecosystem situated at
the edge of an urban and industrialized region in Germany. PAN mixing ratios
were measured within a 3.5 months summer to early autumn period. In
addition, PAN fluxes were determined with the modified Bowen ratio technique
for a selected period. The evaluation of both stomatal and non-stomatal
deposition pathways was used to model PAN deposition over the entire
summer–autumn period. We found that air masses at the site were influenced
by two contrasting pollution regimes, which led to median diurnal PAN
mixing ratios ranging between 50 and 300 ppt during unpolluted and between
200 and 600 ppt during polluted episodes. The measured PAN fluxes showed a
clear diurnal cycle with maximal deposition fluxes of ~−0.1 nmol m−2 s−1 (corresponding to a deposition velocity of
0.3 cm s−1) during daytime and a significant non-stomatal contribution
was found. The ratio of PAN to ozone deposition velocities was found to be
~0.1, which is much larger than assumed by current deposition
models. The modelled PAN flux over the entire period revealed that PAN
deposition over an entire day was 333 μg m−2 d−1 under
unpolluted and 518 μg m−2 d−1 under polluted episodes.
Additionally, thermochemical decomposition PAN deposition accounted for 32%
under unpolluted episodes and 22% under polluted episodes of the total
atmospheric PAN loss. However, the impact of PAN deposition as a nitrogen
source to the nutrient-poor grassland was estimated to be only minor, under
both unpolluted and polluted episodes. |
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