Hydrochemical characteristics and quality assessment of urban groundwater in Urmia City, NW Iran

The aim of this study was to evaluate the quality and hydrochemical characteristics of urban groundwater in Urmia City, northwest of Iran. In order, 59 groundwater samples were collected and analyzed for various anions and cations. Result shows that, mineral weathering, ion exchange and anthropogenic activity are the main hydrochemical processes controlling urban groundwater chemistry. The evaluation of groundwater geochemistry in the flow path beneath the urban area shows that, due to land use changes, the hydrochemical change occurs predominantly in electrical conductivity (EC), Cl- and NO3. The EC is increased in the direction of groundwater flow and in the last decade in industrial areas. According to the groundwater quality index values, most of the samples fit into the good quality class and samples with poor quality are located in the old residential, parks and agricultural areas of the city. The calculation of the irrigation water quality indices (Na%, sodium adsorption ratio, permeability index, residual sodium carbonate), and industrial water quality indices (Ryznar stability index, Langelier saturation index, Larson- Skold, Puckorius scaling index) indicated that the quality of water for irrigation purposes could be classified in the excellent to permissible categories. However, as for the industrial uses, the results also revealed that most of the samples could be classified in the aggressive and very aggressive categories.