DISTRlBUTION OF HEAVY METALS IN THE DAMIETTA NILE ESTUARY ECOSYSTEM.

Abstract

Cu, Zn, Cd and Pb concentrations have been determined in water. bottom sediment and fishes (Oreochromi. aureus and Liza ramada ) in Damietta Nile Estuary The results show that, heavy metals concentration in water was foundin the following descending order : Zn > Pb > Cu > Cd , with average concentrations between 0.03 and 0.35 for Cu 0 13 and 0.79 for Zn 0.001 and 0.005 for Cd , 0.02 and 0.51 mg/Ifor Pb. The maximum concentrations of Cu , Zn and Cd in water was found in Damietta city, while Pb concentration was the highest, in El-Borg city coast, where ship building is common. Moreover. Pb concenttdtion in most studied sites was found to exceed the international permissible limit.Heavy metals concentration in sediment was many times higher than those of overlying water, and followed the order : Zn > Cu > Pb > Cd. Zn and Cu concentrations in sediment of most studied sites that far exceeded the international standard concentrations. Heavy metals concentration in the muscles of O.aureus and L.ramada followed theorder: Zn> Cu> Pb> Cd. The muscles and liver of L.ramada accumulated higher levels of heavy metals than those of O. aureus. However, higher concentrations were reported in the liver, while the edible muscles still have lower levels of heavy metals than the international permissible levels.