This article presents an analysis of dry reactive nitrogen (Nr) deposits measured between 1998 and 2013 at five sites in INDAAF network, in West and Central Africa, representative of different African ecosystems: dry savannas, wet savannas and equatorial forest. Monthly, seasonal, and annual concentrations of nitrogen gases (NH₃, NO₂, HNO₃) are determined, and the variation in dry reactive nitrogen (Nr) deposits is studied. The results show that dry gaseous-Nr deposits largely dominate total-Nr deposition (approximately 97 to 99%), with maximum ratio in equatorial forest (Zoétélé) and minimum ratio in dry savanna (Banizoumbou). Conversely, the contribution of particulate-Nr deposits remains low (1 to 3%) and varies little between sites. Dry gaseous-Nr deposits increase gradually along the ecosystem transect: dry savanna – wet savanna – equatorial forest during the dry season. In the wet season, they increase in dry savanna but decrease in wet savanna and forest. Particulate-Nr deposits is generally higher during the dry season. These results highlight the major influence of climatic conditions of each ecosystem on the variability of dry reactive nitrogen deposition.
