Hydrogeochemical Modeling and Isotopic Assessment of the Quaternary Aquifer at Ali al-Garbi Area in Misaan Governorate, South of Iraq

Geochemical modeling and environmental isotopes were used to determine the hydrogeochemical evolution and the main factors controlling the groundwater chemistry in Misaan, South of Iraq. All available δ¹⁸O and δ²H data for the study area are plotted along the Global Meteoric Water Line (G-MWL) and Mediterranean Meteoric Water Line (M-MWL), indicating a meteoric origin of all waters. The groundwater samples were exposed to evaporation before entering the aquifer. Tritium values of groundwater are between 0.8 and 1.2 TU. These are estimated as modern and pre-modern (older than about 50 years). The geochemical modeling results show that the dissolution of dolomite, gypsum, halite, siderite, the cation exchange of Ca²⁺/Na⁺, and the precipitation of calcite, sylvite and hematite are the main chemical reactions in the first period (dry period), whereas there are no specific reactions that can be shown in the second period (wet period). The inverse geochemical modeling shows that the main reaction controlling the groundwater quality is the Dedolomitization process (dolomite dissolution driven by anhydrite dissolution and calcite precipitation).