Altitude et géochimie des eaux de source, Nord-Ouest du Massif central, France

In the northwestern Massif Central (France), groundwater chloride concentrations are inversely correlated with elevation, when nitrate-poor. This can be explained by an evolution of the ratio evapotranspiration/rainfall, or of the rainwater composition. Such a relationship may be used for the detection of denitrification phenomena in groundwaters, or nitrate assimilation in surface waters, or for the computation of evapotranspiration, using the chloride mass balance method. However, the main objective will be the selection of groundwaters free of any chloride-bearing contamination, in order to define the natural groundwater quality background. To cite this article: J. Barbier, C. R. Geoscience 337 (2005).