Assessment of Groundwater Quality and its Suitability for Drinking and Agricultural Uses in the Oshnavieh Area, Northwest of Iran

Abstract

The Oshnavieh plain is part of the West Azarbaijan province, which is located; 100 km south of Urmia City, northwestern of Iran, and its groundwater resources are developed for water supply and irrigation purposes. In order to evaluate the quality of groundwater in study area, 31 groundwater samples were collected and analyzed for various parameters. Physical and chemical parameters of groundwater such as electrical conductivity, pH, total dissolved solids, Na, K, Ca, Mg, Cl, HCO 3 , CO 3 , SO 4 , NO 3 , NH 3 , PO 4 , Fe, F were determined. Chemical index like percentage of sodium, sodium ad-sorption ratio, and residual sodium carbonated, permeability index (PI) and chloroalkaline indices were calculated. Based on the analytical results, groundwater in the area is generally fresh and hard to very hard. The abundance of the major ions is as follows: HCO 3 > SO 4 > Cl and Ca > Mg > Na > K. The dominant hydrochemical facieses of groundwater is Ca-HCO 3 and Ca-Mg-HCO 3 type. According to Gibbs diagrams samples fall in the rock dominance field and the chemical quality of groundwater is related to the lithology of the area. The results of calculation saturation index by computer pro-gram PHREEQC shows that the nearly all of the water samples were saturated to undersaturated with respect to carbon-ate minerals and undersaturated with respect to sulfate minerals. Assessment of water samples from various methods in-dicated that groundwater in study area is chemically suitable for drinking and agricultural uses. Fluoride and nitrate are within the permissible limits for human consumption and crops as per the international standards.