EFFECT OF INDIVIDUAL AND CO-EXPOSURE OF COPPER AND CADMIUM ON PHOSPHATASE ACTIVITY IN FRESHWATER FISH, Cyprinus carpio

The discharge of potentially toxic trace metals into the environment has become a global problem. As a result of industrial activities and technological development, the amount of heavy metal ions discharged into streams and rivers by industrial and municipal waste-water have been increasing. In addition to natural sources of heavy metals (i.e. geologic weathering, volcanic activity, and animal excretion), there are several anthropogenic sources like mining and metallurgical industry, agriculture (use of fertilizers and pesticides), waste leaching, and battery production, fossil fuel burning, paint and chlor-alkali industries (Forstner and Whitman, 1979). The toxic metals are held to be the most dangerous, since continuous exposure of aquatic organisms to their low concentration may result in bioaccumulation and transfer to man through food web (Karadede et al., 2004). Heavy metal constitutes serious types of pollution in freshwater and being stable compounds; they are not readily removed by oxidation and affect the animal. Heavy metals have a unique property of accumulation over a period of time, along a food chain and a very high level can be accumulated in an organism from very low level concentration in water and sediments (Bose et al., 1994). Copper is a trace element which is essential to the function of specific proteins enzymes. However, at high concentrations, it may be toxic to organisms. The increasing industrial activities and the use of CuSO4 as a fungicide in agricultural practices as well as in the control of algae and pathogens in fish culture ponds have increased the copper concentrations in aquatic systems. Cadmium is one of the most toxic heavy metals and its environmental concentration is increasing due to industrial and agro-chemical usages and anthropogenic activities. This is very dangerous pollutant which affects animals, arriving through the food chain (ATSDR, 2001).