Hydrochemical and isotopic characteristics of groundwater in the Continental Intercalaire aquifer system: Insights from Mzab Ridge and surrounding regions, North of the Algerian Sahara

North of Sahara, Algeria. The effects water/rock interactions and hydrodynamic conditions on the characteristics groundwater in Continental Intercalaire aquifer (CI) are demonstrated using hydrochemical isotopic data from Mzab Ridge. results confirm that CI oriental basin is highly mineralized (1010 > EC 3500 ?S/cm) SO4-Cl-Na type. However, it poorly (340 960) occidental predominantly belongs to HCO3-Ca important contribution evaporite minerals has been deduced saturation indices minor element ratios Sr/Ca Br/Cl. This explained by lithological heterogeneities within corroborates observations regional piezometric features which suggest a divide located between 31.55° 31.57 °N latitude. ?18O-NO3 ?15N-NO3 analyses show NO3 natural origin, soil nitrification even for high concentrations exceeding 50 mg/L. groundwaters depleted both ?18O ?2H compared modern rainfall signatures. most ones those situated Great Oriental Erg sub-basin. Isotopic values as low ?18O=?6‰ can be taken limit typically old. In El Golea region, enrichment seems indicate mixing old evaporation-affected infiltrating through dunes Occidental Erg.