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| Titel |
Measuring the biosphere-atmosphere exchange of total reactive nitrogen by eddy covariance |
| VerfasserIn |
C. Ammann, V. Wolff, O. Marx, C. Brümmer, A. Neftel |
| 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 ; 9, no. 11 ; Nr. 9, no. 11 (2012-11-02), S.4247-4261 |
| Datensatznummer |
250007373
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| Publikation (Nr.) |
 copernicus.org/bg-9-4247-2012.pdf |
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| Zusammenfassung |
The (net) exchange of reactive nitrogen (Nr) with the atmosphere is an
important driver for ecosystem productivity and greenhouse gas exchange. The
exchange of airborne Nr includes various trace compounds that usually
require different specific measurement techniques, and up to now fast
response instruments suitable for eddy covariance measurements are only
available for few of these compounds.
Here we present eddy covariance flux measurements with a recently introduced
converter (TRANC) for the sum of all Nr compounds
(∑Nr). Measurements were performed over a managed grassland
field with phases of net emission and net deposition of ∑Nr
and alternating dominance of oxidized (NOX) and reduced species
(NH3). Spectral analysis of the eddy covariance data exhibited the
existence of covariance function peaks at a reasonable time lag related to
the sampling tube residence time under stationary conditions. Using ogive
analysis, the high-frequency damping was quantified to 19%–26% for
a low measurement height of 1.2 m and to about 10% for 4.8 m
measurement height.
∑Nr concentrations and fluxes were compared to parallel NO and
NO2 measurements by dynamic chambers and NH3 measurements by the
aerodynamic gradient technique. The average concentration results indicate
that the main compounds NO2 and NH3 were converted by the TRANC
system with an efficiency of near 100%. With an optimised sample inlet
also the fluxes of these compounds were recovered reasonably well including
net deposition and net emission phases. The study shows that the TRANC
system is suitable for fast response measurements of oxidized and reduced
nitrogen compounds and can be used for continuous eddy covariance flux
measurements of total reactive nitrogen. |
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