مجلة الاربعين المحكمة
Twenty-four groundwater samples were collected at different depths within the Dammam aquifer and Quaternary deposits. A detailed hydro-chemical study of water samples was conducted, including physical properties; Hydrogen number (pH), total dissolved solids (TDS), and electrical conductivity (EC), while the chemical analysis included the major anions; SO4-2, Cl-, HCO3-, and major cations; Ca+2, Mg+2, Na+, and K+, in addition to the minor element (NO3-). The results indicate a neutral to slightly alkaline water with pH of 7.17 which characterized by hard water that is neutral- slightly alkaline water. The TDS exceeds the permissible limits for drinking, with an average of 2787 ppm, which represents slightly brackish water. Conductivity EC indicates heavily mineralized water with EC of 4310.8 μs/cm. The predominant cation was Mg+2, and Na+, while the predominant anions were SO4-2, and Cl-. The prevalent cation in the aquifer Na+ of 49%, followed by Ca+2 of 30%, Mg+2 of 17%, and K+ of 4%, while the prevalent anion was SO4-2 of 48%, Cl- of 31%, and HCO3- of 21%. Groundwater is classified as unsuitable for drinking, while it is suitable for irrigation. The water type is Na- SO4 affected by the interaction between aquifer material (Halite, dolomite, and calcite), and the groundwater in contact.