Equilibrium states of groundwater chemistry in coastal region of Kuwait

Groundwater samples were collected along the coastal region of Kuwait to determine the geochemical nature of the ions and their thermodynamic states. The state of thermodynamic equilibrium predicts the nature of the reaction in the aquifer. The geochemical nature was determined by stan-dard plots and ion ratios. The geochemical results of the groundwater samples were then studied with stability plots for silicate and carbonate equilibrium and later they were compared with the saturation states with the aid of geochemical model (PHREEQC). The samples reflect higher elec-trical conductivity values with greater values of Na and Cl ranging from brackish to hypersaline nature. The silicate stability plots with respect to major cations reflect that the samples were stable with respect to K-feldspar and kaolinite composition. The carbonate stability plots reflect the stability of the composition predominantly with respect to calcite and dolomite fields. Subsequently, the saturation states of silicates and the carbonate minerals were determined by using PHREEQC. The saturation index values indicate these samples were consistent with the observations made by plotting in the stability plots with minor variations. Though lithology plays a critical role the minor variations were mainly due to the consideration of temperature and the impact of the associated ionic species in the model. The variations were more significant in the carbonate mineral saturation as carbonates react and attain saturation faster than the silicate minerals. The study also infers that the “Common Ion Effect” governs the saturation of these carbonate minerals. Hence, the study reveals the fact that the carbonate minerals are more saturated than the silicate minerals in the groundwater and it is mainly governed by the lithology of the associated ions.