The hydrogeochemical investigation of groundwaters in Erbil basin (North of Iraq)

This study aims to investigate the chemical and trace element hydrogeochemistry of groundwaters in the Erbil Basin. The analyses of groundwaters were carried out in the rainy and dry seasons. Samples were collected for isotopic analyzes during the dry season. The pH, temperature, and EC measurements of the groundwaters were made in the field. The temperature, pH, and EC of the groundwaters in the rainy season were between 21.9 ºC and 27.2 ºC; 7.8 and 9.1, 60 μS/cm and 3310 μS/cm, respectively. In the dry season, ranged from 20 °C to 25 °C; 7.4 to 7.8, and, from 380 μS/cm to 5178 μS/cm, respectively. The chemical analysis results were evaluated with the help of Piper, Scholler, and Gibbs diagrams. The dominant cations in the groundwaters were Mg2+, and Ca2+, whereas the dominant anions were HCO3- and Cl-. Related to the Gibbs diagrams groundwater-rock interaction is the major source of chemical compositions of groundwaters. The δ18O and δ2H contents of groundwaters were ranged from -4.65‰ to -7.02‰, and from -25.98‰ to -42.68‰, respectively. The 3H contents of the groundwaters were analysed between 0.27TU and 2.77 TU. According to the results of isotope analysis, the investigated groundwaters are of meteoric origin. The concentrations of Mg2+, HCO3-, NO3-, B, and Pb are high and exceed the permissible limits of WHO and Iraqi drinking water standards. The reasons are urbanization, septics, sewage, waste disposal leaking, fertilizers, and pesticides. For sustainability of groundwater quality, it should be avoided to use excessive fertilizers in agriculture, implementations such as septic tanks and domestic waste must be discharged into an appropriate sewage system.