Pollution par les nitrates des nappes phréatiques sous environnement semi-urbain non assaini: example de la nappe de Yeumbeul, Sénégal

High nitrate concentrations, above the WHO guideline of 50 mg l⁻¹, were observed in samples of shallow wells reaching the Yeumbeul suburb (Senegal) area groundwater. This groundwater is exploited by 7000 houses and therefore there are health implications. Correlations between parameters such as nitrate content (NO₃⁻) in the groundwater and soil water, the distance between shallow wells and family latrines, and soil water chloride (Cl⁻) and colon bacillus content led to two possible sources of groundwater pollution: first, contamination by non impervious and shallow latrines; and second, the leaching of soil NO₃⁻ from waste organic matter carried in groundwater.