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Metal pollution in the river Godavari in India, due to discharges of liquid wastes from a paper mill, has been studied for a period of two years. At the discharge point and 1 km from the point of discharge, iron, manganese, and zinc were recorded in high concentrations, whereas cadmium and chromium were observed in low concentrations. No metal was in detectable concentration in water before the river receives the effluents. A considerable drop in pH values and an appreciable increase in organic matter, hardness, and calcium levels were noticed after entry of wastes. Diatoms were more diversified in fresh water, whereas cyanobacteria were more prevalent both qualitatively and quantitatively at the polluted stations. Mathematical equations involving heavy metals and physicochemical factors were drawn for better understanding of the distribution of algae.

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The impact of liquid wastes from a paper mill on the benthic diatoms in flowing waters has been studied for a period of two years. Water and algal samples were analysed at monthly intervals at three sites along the course of the river, along with raw effluents. The water before the confluence of effluents was well oxygenated with an alkaline pH. Organic matter, NH3 and nutrients were recorded at low concentrations. At the entry of effluents, the water showed considerable decline in dissolved oxygen content, increase in organic matter, hardness, Cl, HCO3 and total dissolved solids. Diatoms constituted 61% by numerical abundance and were reduced to 25% of total algae at the entry of effluents. Multiple regression analysis was employed to discover the relative importance of various physicochemical variables on the abundance and distribution of diatoms at various sampling stations. Mathematical equations were derived involving the physicochemical variables for better prediction of algal number.