-

Zayandehrud river is the major blood vein of Isfahan plain and its water quality is of prime importance to municipal, agricultural and industerial development in the area. Spatial and temporal changes of water quality in this river were monitored by analysis of seasonal samples taken from 14 stations along the river path, during a 3 year period. Electrical conductivity, pH and concentration of P, SO4 , Cl, HCO3, Ca, Mg, Na, K, Fe, Zn, Cu, Mn, Co, Cd, Ni, Pb, Ag and Cr were determined in water samples. Results incicated a gradual incrase in electrical conductivity and concentration of Ca, Mg, Na, K, Cl, SO4 and HCO3 from station no. 1 (Morgan) to station no. 10 (Ziar) and then a much sharper increase from station no. 10 to station no. 13 (Varzaneh) and then a slight decrease to station no. 14 (Gavkhoni). Water pH was alkaline with a minimum of 7.6 in station no. 10 and a maximum of 8.0 in station no. 13. Concentration ot P was negligible up to station no. 8 then increased sharply to a maximum of 3.2 mg/L in station no.9 or 10, then decreased drastically to station no. 13. Concentration of heavy metals were generaly low and did not exceed 0.2 mg/L in water samples. Concentration of Ni, Co, and Pb were very low upto station no. 12 (Ajieh), then increased sharply upto station no. 13 and decreased slightly to station no.14. Concentration of other heavy metals including Fe, Zn, and Cr, changed irregularly along the river path.