ACCUMULATION OF COPPER, ZINC AND CADMIUM IN LIVER, GILL AND MUSCLE TISSUES OF OREOCHROMIS NILOTICUS EXPOSED TO THESE METALS SEPARATELY AND IN MIXTURE

摘要

Accumulation of copper, zinc and cadmium in gill, liver and muscle tissues of Oreochromis niloticus was determined after exposing the animals to (ppm) 5.0 Cu, 5.0 Zn, 1.0 Cd, and their mixtures over 24, 48 and 96 h. AAS method was used in determining the tissue metal levels. Accumulation increased with increasing exposure periods when exposed to metals separately or in mixture. Highest zinc and cadmium accumulation was in the order gill ＞ liver ＞ muscle while the order of copper accumulation was liver ＞ gill ＞ muscle when exposed to metals separately. Maximum accumulation of Cu was in liver while those of Zn and Cd were in gill tissues when exposed to metal mixture. Muscle accumulation was lowest in metal mixture-exposed fish. Effects of the metals applied singly increased Cu levels in liver and that of Zn in gill and muscle tissues at the tested concentrations.