Investigation of hydrogeochemistry and water quality of Mahabad Reservoir Dam,West Azarbaijan province, Northwest Iran

Mahabad reservoir dam is the main drinking water source for Mahabad town and its downstream villages. To investigation of water quality, the physicochemical parameters including pH, Eh, EC, TDS, total hardness (TH), total alkalinity (TA), temperature, salinity, concentrations of main cations and anions (for 5 samples) and some of the heavy metals (for 11 samples) were measured in water sampling stations. According to the chemical analysis results and compare to the international standards, main cations and anions concentrations and physicochemical parameters values (exception total hardness) of the water samples are located in permissible ranges and suitable for drinking water. Compare to the world health organization (WHO) standards, all of the water samples indicate Cd and Pb pollution, point of view of drinking water. In KDT3 sampling station, the concentration of Cd and Pb are 26 times and 3.5 times of permissible values, respectively. Also, the water of Mahabad reservoir dam and upstream tributaries are polluted regarding to Cd for livestock and poultry requirements. These pollution can be related to geogenic source (mineralization) and anthropogenic source (wastewater derived from upstream villages). But for irrigiation, the water of Mahabad reservoir dam and upstream tributaries have low salinity (C2S1 class) and suitable for agricultural uses. Piper diagram revealed bicarbonate type and calcic facies for water of Mahabad reservoir dam. The surface water of the study area, for the reason of high total hardness, needs to softening prior to use for different industries.