Hydrochemical evaluation of sodium chloride and sodium sulphate groundwater in the Kaboudar Ahang, Hamedan, western Iran.

Hydrogeochemical investigation of groundwater in the Kaboudar Ahang, Hamedan, western Iran was carried out to assess chemical composition of groundwater having complex contamination sources. The chemical compositions of the groundwater are dominated by Na⁺, Cl_- and SO^2- ₄ . The predominant water type of groundwater samples are the NaCl (59%) and NaSO4 (38%) facies. Both Na⁺ and Cl^- +SO^2- ₄ account for 56 and 61% of the total cations and anions. Contamination of groundwater appeared to be affected by the solubility of mineral phases and discharge of sewage effluent, and agricultural activities. Anthropogenic inputs into the groundwater mainly include Na⁺, Cl^- and SO^2- ₄ according to chemical compositions of sewage effluent. Continuous disposal of sewage effluent from power plant (which contains appreciable amounts of Na⁺ ions) through irrigation in closed systems poses a serious threat of soil and groundwater sodification. [ABSTRACT FROM AUTHOR]