Studies on Metals Eco-toxicity of the River Ravi

Abstract

By integrating the chemical, toxicological and ecological data, the impact of heavy metals pollution on the river Ravi stretch from Shandera bridge to Sidhnai barrage was assessed. The role of both plankton and fish as indicators of freshwater contamination by metals has been studied. The present investigation reveals that metals eco-toxicity of river Ravi has crossed the safe limits for sustainable conservation of aquatic habitats as described by the Environmental Protection Agency (EPA), USA. The heavy metals toxicity of water, plankton and sediments at Farrukhabad, Bakar Mandi, Munshi Hospital, Hudiara, Taj Company nullas, Degh nulla I and II, Sammundri and Sukhrawa main drains were extremely high and there has been an increasing tendency towards accumulation of metals in water, fish, plankton and sediments in riverine ecosystem. Considerable deterioration in the quality of river water was recorded at discharge points of Farrukhabad, Bakar Mandi, Munshi Hospital, Hudiara, Taj Company and Degh nullas. The quality of river water improved gradually onwards, after Bakar Mandl nulla, except at Khurd Pur (the point where Hudiara nulla enters river Ravi) where this river receives large quantities of wastes deteriorating its water quality. The gradual improvement in the quality of river water at Baloki headworks was due to merging of less polluted tributary i.e., Q. B. Link Canal, into the river. The river stretch from Baloki headworks to Sidhnai barrage receives bulk discharges of contaminated water from Degh nulla II, Sammundri and Sukhrawa main drains and ultimately deteriorating the quality of water at Sidhnai barrage. All the three freshwater fish species, viz. Catla catla, Labeo rohita and Cirrhina mrigala (major carps) are on the verge of extinction in the river Ravi due to heavy loads of metals in water, plankton, sediments. Three fish species showed significant variations for the accumulation of metals in their bodies. Catla catla showed significantly higher tendency to accumulate metals in its body than Laheo rohita and Cirrhina mrigala. The fish at Sidhnai barrage showed significantly higher metal contamination than that at Baloki headworks. Fish liver appeared to be an organ which had significantly higher tendency for the accumulation of iron. zinc and lead while nickel and manganese accumulations were the maximum in fish skin and gills respectively.All the metal ions, except lead, in sediments and plankton have shown direct relationships with the intensity of water pollution. Thus, both these components of aquatic ecosystem could act as indicators of metal pollution in freshwaters. Regarding the stretch of river from Shandera to Baloki headworks, the phytoplankton, viz. Aphanocapsa, Bacillaria, Closterium, Cyclotella, Cocconeis, Cosmarium, Denticulla, Dinobryon, Euglena, Pinnularia, Spirulina and Spirogyra showed considerable tolerance against heavy metals toxicity both in tributaries and river. Among the zooplankton, Keratella, Cyclops, Monnstyla and Filinia were the sensitive forms and showed their existence according to the severity of pollution at different sites. The river stretch, from Baloki headworks to Sidhnai barrage showed Myxophyceae, Bacillariopgyceae and Chlorophyceae as the important groups distributed with variable densities. Among phytoplankton, Aphanocapsa, Bumilleria, Bacillaria, Cladophora, Cocconeis, Eudorina, Microcystis, Pandorina, Scendesmus, Volvox and Zygnema indicated direct relationships with the intensity of pollution. Among zooplankton, the genus, viz. Bosmina, Keratella and Monnstyla showed considerable tolerance against metallic ion pollution. Daphnia appeared to be a sensitive form against metal pollution in water. The bulk discharges of industrial effluents and domestic sewage into the river Ravi have badly affected the quality of water. However, if we consider rivers as the renal systems of the land spaces then, this kidney system is close to the renal failure at river Ravi. Hence, it is imperative that appropriate steps should be taken by both the Governmental and public agencies to restore river Ravi from effluent tributary to a natural riverine condition.