Heavy metal pollution of river Ganga in Mirzapur, India

A study on the heavy metal pollution of River Ganga in the Mirzapur region, India has revealed that the river is polluted. The samples were collected from both the confluence of sewers and the river and from midstream points. The river is the dumping ground for domestic, municipal and industrial effluents. All the samples were analysed for certain physiochemical parameters i.e. temperature, pH, chloride content, alkalinity, dissolved oxygen and chemical oxygen demand. On analysis, the concentrations of most of the heavy metal ions were found to be above the prescribed limits for potable waters in the samples collected from confluence points. Cadmium and cobalt were in the range 13.37-32.73 μg/L and 10.50-26.77 μg/L respectively. Copper, iron and manganese were found in the range of 38.0-157.80 μg/L, 19.75-72.77 /ug/L and 34.25-105.55 yug/L respectively. Nickel was recorded to be in the range 67.25-176.13 mg/L while lead and zinc were in the range of 34.25-185.75 μg/L and 94.25-423.75 μg/L. Concentrations of all these ionic species were within the prescribed limits in the samples collected from midstream points, revealing the river to be almost free from pollution at these points. The data obtained have been examined statistically to explain metal-metal association by using the Pearson correlation coefficient. Cobalt, manganese, nickel, lead and zinc reflected positive correlations with most of the species. However cadmium, copper and iron show very weak or negative association with metal ions. Impact of the various parameters and ionic species on environment is critically discussed.