Geochemical and Isotopic Tools to Deciphering the Origin of Mineralization of the Coastal Aquifer of Essaouira Basin, Morocco

The determination of the origin of salinity and mineralization of groundwater from the Plio-Quaternary aquifer of Essaouira Basin was the main goal of this research, investigated by the combined study of chemical (particularly Br and Cl) and isotopic (18O and 2H) compositions. The study of Br / Cl ratio vs Cl showed that mineralized waters of the shallow aquifer in the Essaouira Basin is the result of: (i) the marine influence (precipitation and aerosols directly from the ocean), (ii) dissolution of evaporite minerals (halite), (iii) seawater intrusion and iv) ion exchange mechanisms. The 18O-2H diagram showed that the groundwater recharge is maintained by direct precipitation without evaporation and runoff. The Cl/18O ratio showed the existence of a mixture trend of seawater-groundwater.