Hydrochemical characteristics and the impact of anthropogenic activity on groundwater quality in suburban area of Urmia city, Iran

摘要

The aim of this research was to determine the main hydrochemical processes, quality change and groundwater pollution resulted from various human activities in the suburban area of Urmia city, located in the northwest of Iran. For this purposes, 62 groundwater samples were collected from urban, suburban and rural areas in September 2015. Furthermore, for determining the effect of anthropogenic activities on urban and suburban groundwater quality, a comparison was made between rural, suburban and urban groundwater. The results indicate that the main type of groundwater is Ca-HCO3, and the important processes controlling groundwater chemistry are mineral weathering, ion exchange and anthropogenic activity. The effect of anthropogenic activity such as increase in urbanization and change in land use caused the increase in the concentration of Ca, HCO3, Cl, Na, Mg, NO3 and pollution of groundwater in the suburban area. In suburban zone and especially in areas with low-depth groundwater, runoff infiltration, domestic effluent sewages and application of fertilizers caused an increase in nitrate in groundwater. In urban areas with impermeable surfaces, due to less infiltration, the amount of nitrate in groundwater is low, and groundwater is not contaminated. The results obtained from groundwater sustainability indicators (index of damages, index of pollution and groundwater quality index) show that the suburban area has low-hazard pollutant problem. Also, quality of 41% groundwater samples in the suburban zone and 13% in the rural zone is poor. In this paper, to determine the water quality for irrigation uses, sodium percent (Na%), sodium absorption ratio, residual sodium carbonate and permeability index were all calculated. The calculation of the irrigation water quality indices indicated that the quality of water for irrigation purposes can be classified as excellent to permissible categories.