Experimental data on precipitation chemistry were collected at a semi-arid savanna in Senegal (Dahra) in 2013, 2014 and 2017. The chemical composition of precipitation was analyzed for inorganic and organic ions, using ionic chromatography. The pH values of precipitation range from 4.50 to 8.50 with 89% of the samples having basic pH. The composition of precipitation was controlled by four source contributions: marine, terrigenous, biogenic, and organic acids emissions from vegetation. The terrigenous contribution was the highest accounting for 42% of the total annual Volume Weighted Mean ionic concentrations, due to the proximity of the Saharan desert, followed by the marine source representing 36%, due to the location of Dahra close to the Atlantic Ocean. Nitrogenous (N) contribution represents 16% of the mean annual total ionic charge, from biogenic sources and livestock crossing the site all year round. Finally, the lowest contribution is from organic acidity (5%), due to the low density of vegetation especially during the dry season. Wet deposition fluxes in Dahra for all compounds show larger values than at other Sahelian savanna sites. Dry N deposition in Dahra was also estimated by inferential method using gas concentration measurements and modeled dry deposition velocities. The total N deposition fluxes (wet plus dry) range from 3.80 to 4.81 kgN ha⁻¹ yr⁻¹, comparable to fluxes at other semi-arid savannas in Niger and Mali. Wet deposition contributed with 37–53% of the total N flux, suggesting that wet N deposition is equally important to dry deposition fluxes for direct N loading to savanna ecosystems in the Sahel, with a large contribution of reduced compounds. This study shows that Dahra presents a precipitation chemistry composition with characteristics close to those from other Sahelian sites, with however the specificity of being more influenced by the proximity of the Atlantic ocean and the presence of livestock year round.

于2013年，2014年和2017年在塞内加尔（达拉）的半干旱热带稀树草原上收集了沉淀化学的实验数据。使用离子色谱法分析了沉淀的化学组成，包括无机离子和有机离子。沉淀的pH值为4.50至8.50，其中89％的样品具有碱性pH。降水的组成受到四个来源的贡献的控制：海洋，陆生，生物和有机酸从植被中的排放。由于撒哈拉沙漠的临近，陆源的贡献最大，占年度总体积加权平均离子浓度的42％，其次是海洋源，占36％，这是由于Dahra的位置靠近大西洋。氮（N）贡献占年平均总离子电荷的16％，全年都来自生物源和牲畜。最后，最低的贡献是有机酸度（5％），因为植被密度低，尤其是在干旱季节。Dahra中所有化合物的湿沉降通量显示出比其他Sahelian稀树草原站点更大的值。达拉（Dahra）的干氮沉积也通过推论方法使用气体浓度测量和模拟的干沉积速度来估算。N沉积总通量（湿加干）范围为3.80至4.81 kgN·ha 达拉（Dahra）的干氮沉积也通过推论方法使用气体浓度测量和模拟的干沉积速度来估算。N沉积总通量（湿加干）范围为3.80至4.81 kgN·ha 达拉（Dahra）的干氮沉积也通过推论方法使用气体浓度测量和模拟的干沉积速度来估算。N沉积总通量（湿加干）范围为3.80至4.81 kgN·ha^-1  yr ^-1，与尼日尔和马里其他半干旱热带稀树草原的通量相当。湿沉降占总氮通量的37-53％，这表明湿氮沉降对干沉降通量同样重要，因为干氮通量直接将氮装载到萨赫勒的稀树草原生态系统中，其中还原化合物的贡献很大。这项研究表明，达赫拉的降水化学成分与其他萨赫勒地区的化学成分很接近，但是其特异性受到大西洋的临近和全年牲畜的存在的影响更大。