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| Titel |
Exchange of reactive nitrogen compounds: concentrations and fluxes of total ammonium and total nitrate above a spruce canopy |
| VerfasserIn |
V. Wolff, I. Trebs, T. Foken, F. X. Meixner |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 7, no. 5 ; Nr. 7, no. 5 (2010-05-25), S.1729-1744 |
| Datensatznummer |
250004780
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| Publikation (Nr.) |
 copernicus.org/bg-7-1729-2010.pdf |
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| Zusammenfassung |
| Total ammonium (tot-NH4+) and total nitrate (tot-NO3−)
provide chemically conservative quantities in the measurement of surface
exchange of reactive nitrogen compounds ammonia (NH3), particulate
ammonium (NH4+), nitric acid (HNO3), and particulate nitrate
(NO3−), using the aerodynamic gradient method. Total fluxes were
derived from concentration differences of total ammonium (NH3 and
NH4+) and total nitrate (HNO3 and NO3−) measured at
two levels. Gaseous species and related particulate compounds were measured
selectively, simultaneously and continuously above a spruce forest canopy in
south-eastern Germany in summer 2007. Measurements were performed using a
wet-chemical two-point gradient instrument, the GRAEGOR. Median
concentrations of NH3, HNO3, NH4+, and NO3−
were 0.57, 0.12, 0.76, and 0.48 μg m−3, respectively. Total
ammonium and total nitrate fluxes showed large variations depending on
meteorological conditions, with concentrations close to zero under humid and
cool conditions and higher concentrations under dry conditions. Mean fluxes
of total ammonium and total nitrate in September 2007 were directed towards
the forest canopy and were −65.77 ng m−2 s−1 and
−41.02 ng m−2 s−1 (in terms of nitrogen), respectively.
Their deposition was controlled by aerodynamic resistances only, with very
little influence of surface resistances. Including measurements of wet
deposition and findings of former studies on occult deposition (fog water
interception) at the study site, the total N deposition in September 2007
was estimated to 5.86 kg ha−1. |
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