Bioaccumulation of Heavy Metals in Indoplnorbis exustus From Godavari River

Book excerpt: Most of the heavy metal are constituents of the aquatic environment some of them are biologically essential. But some metals like Hg, Cd, Zn etc. are highly hazardous to aquatic biota and normally occur in low concentration. A few investigators studied the toxic effects of mercury and other heavy metals to aquatic animals, particularly fishes to assess the pollution hazards due to metals. Amongst pollutants, non-essential metals are major cause of concern for aquatic environment because of their toxicity, persistency, tendency to accumulate in organism and in undergoing food chain amplification (Kneip and Louer, 1973 and Vinikour et al., 1980). Heavy metals such as Hg, Cu, Cd, Zn, Ni etc. generally exist within the earth crust in trace concentrations. In traces these metals are necessary for normal metabolism of the living organisms as these facilitate physiological functioning and also form part of structural components. However, anthropogenic activities such as industrial processing and use of metals, alloys and metallic compounds result in environmental contamination (Dar, 2002). Discharge of such metal containing effluents into the aquatic environment and drainage of residues of mining, there is manifold increase in the contents of these metals in the aquatic media (Kelkar, 2001) such as ponds, lakes, rivers and dams of India. According to a survey report of ATSDR (2001) almost 70% of the Indian available water has been reported to be extensively contaminated by heavy metals and other categories of chemicals. Heavy metal pollution in freshwater bodies assumes considerable significance because these are stable compounds and hence, not readily disposed off by the processes of oxidation, precipitation etc and adversely affect the activity of the animals. Heavy metals have a unique property of accumulation in organisms from very low concentration in water from lakes, rivers and dams (Kulkarni, 2000).