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| Titel |
Seasonal trends of dry and bulk concentration of nitrogen compounds over a rain forest in Ghana |
| VerfasserIn |
F. Fattore, T. Bertolini, S. Materia, S. Gualdi, A. Thongo M'Bou, G. Nicolini, R. Valentini, A. De Grandcourt, D. Tedesco, S. Castaldi |
| 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 ; 11, no. 11 ; Nr. 11, no. 11 (2014-06-12), S.3069-3081 |
| Datensatznummer |
250117454
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| Publikation (Nr.) |
 copernicus.org/bg-11-3069-2014.pdf |
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| Zusammenfassung |
| African tropical forests of the equatorial belt might receive significant
input of extra nitrogen derived from biomass burning occurring in the north
savanna belt and transported equatorward by northeastern winds. In order to
test this hypothesis an experiment was set up in a tropical rain forest in
the Ankasa Game Reserve and Nini-Suhien National Park (Ghana) aimed at
quantifying magnitude and seasonal variability of concentrations of N
compounds, present as gas and aerosol (dry nitrogen) or in the rainfall (bulk
nitrogen), over the studied forest; and relating their seasonal variability
to trends of local and regional winds and rainfall and to variations of fire
events in the region. Three DELTA systems, implemented for monthly
measurements of NO2, were mounted over a tower at 45 m height, 20 m
above forest canopy to sample gas (NH3, NO2, HNO3, HCl,
SO2) and aerosol (NH4+, NO3−, and several ions),
together with three tanks for bulk rainfall collection (to analyze
NH4+, NO3− and ion concentration). The tower was provided
with a sonic anemometer to estimate local wind data. The experiment started
in October 2011 and data up to October 2012 are presented. To interpret the
observed seasonal trends of measured compounds, local and regional meteo data
and regional satellite fire data were analyzed. The concentration of N
compounds significantly increased from December to April, during the drier
period, peaking from December to February when NE winds (the Harmattan) were
moving dry air masses over the west-central African region, and the
Intertropical Convergence Zone (ITCZ) was at its minimum latitude over the
Equator. This period also coincided with fire peaks in the whole region. On
the contrary, N concentration in gas, aerosol and rain decreased from May to
October when prevalent winds arrived from the sea (southeast), during the
monsoon period. Both ionic compositions of rain and analysis of local wind
direction showed a significant and continuous presence of see breeze at site.
The ionic composition of rainwater resulted much closer to seawater and
poorer in N compounds from May to October. |
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