Assessment of heavy metal concentrations in water, plankton, and fish of lake Manzala, Egypt

摘要

The levels of some heavy metals (Cu, Zn, Cd, and Pb) were determined in water, plankton, and fish (Liza aurata) collected from 5 sites in Lake Manzala. Metals in the water and fish exhibited a significant seasonal and regional variation, in which all metals attained their maximum value during summer, while the lowest levels were found during winter. The concentration of different metals in water, plankton, and fish tissues followed the same order: Zn > Cu > Pb > Cd. The mean concentrations of metals in the water were as follow: Cu, 0.055; Zn, 0.311; Cd, 0.020; and Pb, 0.022 mg/L. The Cd level in the water was found to be higher than the permissible limit recommended for drinking water.Metals in plankton were much higher than those of water and fish. Gills of the examined fish contained the highest concentration of all of the measured metals, while muscles retained the lowest. In spite of the contamination of Lake Manzala by heavy metals, the level of the metals in fish muscle (the edible part) did not exceed the recommended permissible limit and the fish is considered safe for human consumption.