Abstract
Metal ion toxicity of the River Ravi stretch, from Shahdera to Baloki headworks, was studied. The river water showed considerable variation for. the concentration of heavy metals due to variable discharges of untreated industrial and sewage wastes into the river through different tributaries. The concentration of zinc, lead and nickel in water was found dependent positively and significantly on water temperature. Iron and manganese showed negatively significant regression on dissolved oxygen. Increase in water hardness also significantly increased the iron, manganese and nickel concentration in water. There were significant variations in the concentration of heavy metals in effluent discharging tributaries. Same was true for the river stretch which might be due to changes in the volumes of industrial and domestic sewage waste, being added into the river. Water at Farrukhabad, Munshi hospital, Bakar Mandi nullas and Degh fall was highly polluted. Heavy metals loads in the six effluent discharging tributaries were significantly higher than the standard values set by the EPA (Pakistan) for municipal and liquid industrial effluent discharges. The water throughout the stretch of river was not suitable for aquatic life, freshwater fisheries and drinking purposes considering the criteria of the EPA, USA. Key words: correlation, metal toxicity, physico-chemical variables, regression, River Ravi
