 |
| Titel |
Nitrogen compounds emission and deposition in West African ecosystems: comparison between wet and dry savanna |
| VerfasserIn |
C. Delon, C. Galy-Lacaux, M. Adon, C. Liousse, D. Serça, B. Diop, A. Akpo |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 9, no. 1 ; Nr. 9, no. 1 (2012-01-18), S.385-402 |
| Datensatznummer |
250006672
|
| Publikation (Nr.) |
 copernicus.org/bg-9-385-2012.pdf |
|
|
|
|
|
| Zusammenfassung |
| Surface emission and deposition fluxes of reactive nitrogen compounds have
been studied in five sites of West Africa during the period 2002 to 2007.
Measurements of N deposition fluxes have been performed in IDAF sites
representative of main west and central African ecosystems, i.e., 3
stations in dry savanna ecosystems (from 15° N to 12° N), and 2
stations in wet savanna ecosystems (from 9° N to 6° N). Dry
deposition fluxes are calculated from surface measurements of NO2,
HNO3 and NH3 concentrations and simulated deposition
velocities, and wet deposition fluxes are calculated from NH4+ and
NO3− concentration in samples of rain. Emission fluxes are
evaluated including simulated NO biogenic emission from soils,
emissions of NOx and NH3 from biomass burning and domestic
fires, and volatilization of NH3 from animal excreta. This paper is a
tentative to understand the eventual impact of the monsoon variability from
year to year, with the natural variability of local sources, on the emission
and deposition N fluxes, and to compare these evolutions between dry and wet
savanna ecosystems. In dry savanna ecosystems where the rain season lasts
mainly from June to September, the occurence of rain correlates with the
beginning of emission and deposition fluxes. This link is less obvious in wet
savanna ecosystems (wet season mainly from May to October), where the surface
is less submitted to drastic changes in terms of water content. Whatever the
location, the natural variability of rain from year to year does not exceed
15 %, and the variability of emission and deposition magnitude ranges
between 15 % and 28 %. While quasi providing the same total N budget, and
due to the presence of different types of soils and vegetation, wet and dry
savanna do not present the same distribution in emission and deposition
fluxes contributions: in dry savanna, the emission is dominated by ammonia
volatilization, and the deposition is dominated by the dry contribution. In
wet savanna, emission is equally distributed between ammonia volatilization,
emissions from biomass burning and natural NO emissions from soils, and wet
and dry deposition are equivalent. Due to the scarcity of available data on
the African continent, and despite the numerous uncertainties resulting from
the different calculations and assumptions, this work is a combination of
data from different origins (surface measurements, satellite and modelling)
to document the atmospheric Nitrogen cycle in tropical regions. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|