Investigation of Chemical Quality of Groundwater in the Vicinity of Municipal Landfills of Gorgan

Landfill sites could be associated with the environmental impacts of surface and groundwater pollution due to landfill leachate percolation to the hydrological system. Such issues occur due to the unsuitable selection of geological areas as the waste disposal site, characterized without any effective capping and bottom liners. The goal of this research is the investigation of hydro-chemical quality of the groundwater in the vicinity of Gorgan MSW landfill. The result of geochemical study of the groundwater samples in the landfill area indicates that prominent cations and anions concentrations are more than Drinking Water Standards. Although in the south of Gorgan disposal site, the average total concentration of Na+,K+, Mg2+, Cl-, SO42-, PO43-, NO3-, and NH3- are measured 27.80, 2.80, 38.82, 90.20, 141.20, 0.18, 20.37, and 0.02 mg/l respectively in the groundwater wells. But in the nearby Gorgan MSW groundwater wells, the average total concentration of these contaminants are reported 218.8, 7.20, 71.42, 183.30, 200.30, 0.50, 61.90 and 0.17 mg/l respectively. Range of turbidity, E. C., and T.D.S. amounts, along with concentration of Na+, Cl-, SO42- and NO-3 contaminants in the groundwater wells of adjacent of Gorgan MSW is more than groundwater wells in the south of Gorgan disposal site. According to strongly and positive correlation of EC with Na+, K+, Cl-, SO2-4 and TDS of the groundwater, S- SW to N-NE flowing of groundwater, and unsanitary disposal of Gorgan MSW without any effective liner, which lies on the loess deposits (76% slits and 23.5% clays as kaeolinite, illite, and semectite) it could be concluded that the infiltration of landfill leachates have caused the contamination of the ground water.Geohydrochemical facies of groundwater types are determined as Ca2+Na+HCO-3Cl- and Na+HCO-3. Usage of the groundwater resources in the vicinity of landfills area by the residential municipal and rural people, which has a potential impact on public health, requires controlling of the leachate seepage and designing lining systems for preventing contamination of groundwater.