Abstract
This study was carried out to assess the concentrations of various heavy metals and their distribution in a hyper-eutrophic urban Tumkur tank system, which is being polluted from industrial, domestic and sewage effluents. Samples of water, fish and soil sediment were analyzed for the concentration of seven heavy metals (iron, zinc, copper, nickel, chromium, lead and cadmium) using atomic absorption spectrophotometry. The water-soluble (bioavailable) fractions of heavy metals correlated positively with their total concentration, exhibiting the following sequence of bioavailability: Zn > Cd > Ni > Pb > Cu > Cr > Fe. Cyprinus carpio exhibited a maximum bioaccumulation factor for copper (5500). The mean values of all types of collected samples were correlated with the corresponding mean values in a control tank (Teetha tank). The sequence of the order of the concentration of the metals in water, fish and sediment samples exhibiting higher values than those observed in the control tank was as follows: Cr > Pb > Cu ≈ Ni > Fe > Cd > Zn, Cr > Cd > Cu ≈ Zn > Pb > Fe ≈ Ni and Fe > Pb > Cr > Cu > Ni > Zn > Cd, respectively. The geoaccumulation indices of the heavy metals revealed that the tank is moderately to strongly contaminated. As Cyprinus carpio is extensively used for human consumption, there is a growing health risk that these metals could find their way into the human food chain.