Identification of Natural and Anthropogenic Geochemical Processes Determining the Groundwater Quality in Port del Comte High Mountain Karst Aquifer (SE, Pyrenees)

The Port del Comte Massif (SE, Pyrenees) contains one of the most important vulnerable and strategic karst aquifers for supplying freshwater to city Barcelona (Spain). It is a fragile system, whose possible environmental impact highly conditioned by land use. To improve hydrogeological knowledge between September 2013 October 2015, detailed fieldwork was carried out revision geological model, inventory water points, in situ physico-chemical characterization on major elements isotopes up total 43 springs, as well precipitation water. This paper focuses geochemical processes that allow explanation observed chemical variability groundwater drained pristine aquifer system determine origin salinity. results show main process dissolution calcite dolomite, followed gypsum halite, minor cation exchange-like process. Sulfur oxygen from dissolved sulfate studied springs point geogenic related Triassic Tertiary materials, contribution anthropogenic sources, like fertilizers, lower. Nitrate not an issue, with few localized cases agricultural activities. multidisciplinary approach has allowed development consistent conceptual model functioning which can be replicated other places understand character hydrogeochemistry.