Effects of geological formationon groundwater quality in Lordegan Region, Chahar-mahal- va- Bakhtiyari, Iran

ABSTRACT:To study the contamination of groundwater, 32 water samples were collected in an area of 60 km2 and analyzed for major cations and anions. Most of the locations are contaminated by higher concentration of EC, TDS, K and NO3. Major hydro chemical facies were identified using Piper trilinear diagram and Stiff diagram.Na+, Ca2+, HCO3-, Cl- and SO42-dominate the chemical compositions of the groundwater, which have been derived largely from natural chemical weathering of carbonate, gypsum, and anthropogenic activities of fertilizer’s source. In most of water samples, magnesium and bicarbonate were dominant cations and anions, respectively. The water was classified as magnesium-chloride. Considering that the ratio of Mg / (Ca + Mg) was often less than 0.5 in water samples. Therefore, the source of magnesium is dolomite weathering. The major anthropogenic components in the groundwater including Na+, Cl-, SO42- and NO3-, and NO3- being the maincontributors to groundwater pollution in Lordegan area.