Geochemical processes of groundwater salinization in an arid area, southeastern Tunisia

Salinization is an environmental issue that affects different regions worldwide. Geochemical approaches and statistical tools are combined to investigate the origin and process of groundwater salinization in Menzel Habib shallow aquifer. The inland aquifer from Menzel Habib area is in the northwest of Gabes, southeastern Tunisia. A total of twenty-five water samples were selected and collected in the study area. Physicochemical parameters (electrical conductivity, pH, total dissolved solids) were measured in situ, and major ions (Na, Mg, Ca, K, Cl, SO4, HCO3, F, and Br) were determined. The obtained results show a Na-Cl groundwater dominant facies (60%), Na-SO4 (36%), and mixed water type (4%). Thus, a correlation between total dissolved solids and major ions shows the contribution of SO4, Cl, Na, Ca, and Mg in groundwater salinization. The salinization of groundwater is due to the dissolution of Triassic evaporites, which are related to the tectonic context of the region, and to the cationic exchange. Furthermore, statistical approaches, especially principal component analysis, reveal that the high groundwater mineralization is due to the evaporite dissolution. Multiple linear regression leads to establish a model linking total dissolved solids to the different chemical elements involved in groundwater salinization.