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| Titel |
Dry and wet deposition of inorganic nitrogen compounds to a tropical pasture site (Rondônia, Brazil) |
| VerfasserIn |
I. Trebs, L. L. Lara, L. M. M. Zeri, L. V. Gatti, P. Artaxo, R. Dlugi, J. Slanina, M. O. Andreae, F. X. Meixner |
| 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 ; 6, no. 2 ; Nr. 6, no. 2 (2006-02-08), S.447-469 |
| Datensatznummer |
250003418
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| Publikation (Nr.) |
 copernicus.org/acp-6-447-2006.pdf |
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| Zusammenfassung |
| The input of nitrogen (N) to ecosystems has increased dramatically over the
past decades. While total (wet + dry) N deposition has been extensively
determined in temperate regions, only very few data sets of N wet deposition
exist for tropical ecosystems, and moreover, reliable experimental
information about N dry deposition in tropical environments is lacking. In
this study we estimate dry and wet deposition of inorganic N for a remote
pasture site in the Amazon Basin based on in-situ measurements. The
measurements covered the late dry (biomass burning) season, a transition
period and the onset of the wet season (clean conditions) (12 September to 14
November 2002) and were a part of the LBA-SMOCC (Large-Scale
Biosphere-Atmosphere Experiment in Amazonia – Smoke, Aerosols, Clouds,
Rainfall, and Climate) 2002 campaign. Ammonia (NH3), nitric acid
(HNO3), nitrous acid (HONO), nitrogen dioxide (NO2), nitric oxide
(NO), ozone (O3), aerosol ammonium (NH4+) and aerosol nitrate
(NO3-) were measured in real-time, accompanied by simultaneous
meteorological measurements. Dry deposition fluxes of NO2 and HNO3
are inferred using the ''big leaf multiple resistance approach'' and
particle deposition fluxes are derived using an established empirical
parameterization. Bi-directional surface-atmosphere exchange fluxes of
NH3 and HONO are estimated by applying a ''canopy compensation point
model''. N dry and wet deposition is dominated by NH3 and
NH4+, which is largely the consequence of biomass burning during
the dry season. The grass surface appeared to have a strong potential for
daytime NH3 emission, owing to high canopy compensation points, which
are related to high surface temperatures and to direct NH3 emissions
from cattle excreta. NO2 also significantly accounted for N dry
deposition, whereas HNO3, HONO and N-containing aerosol species were
only minor contributors. Ignoring NH3 emission from the vegetation
surface, the annual net N deposition rate is estimated to be about −11 kgN
ha-1 yr-1. If on the other hand, surface-atmosphere exchange of
NH3 is considered to be bi-directional, the annual net N budget at the
pasture site is estimated to range from −2.15 to −4.25 kgN ha-1 yr-1. |
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