Heavy Metals Concentration in Water, Muscles and Gills of Oreochromis niloticus Collected from the Sewage-Treated Water and the White Nile

Abstract

The concentrations of heavy metals (Cd, Cr, Ni, Pb, Cu, Zn, Fe, and Sr) were detected by ICP-OES in muscle tissues and gills of Nile Tilapia (O. niloticus) collected from the effluent of sewage treatment plant, and the released sewage-treated water into the White; and in water samples collected from four station along the sewage treatment plant. The highest concentration of the heavy metal in tissues and gills of was recorded for Sr, followed by Fe, Zn, Cu and Pb, where Sr and Fe recorded higher concentrations in the muscle compared to fish gills. The same trend was found in the other heavy metals. The range of Fe was (10.6 – 11.6 µg/g) in water from sampling stations, with no significant difference between the four stations, while, the level was (2.2 - 3.2 µg/g) in muscle and fish gills. The level of Sr in water was (6.32 – 7.86 µg/g) with increased concentration in station 4, the discharge point of the treated waste-water into the WN; and (2.1 -3.4 µg/g) in muscle and fish gills. The concentration of lead was (0.11 – 0.2 µg/g) in water with the highest level in station 3, the discharge point of industrial effluents and (0.2 – 0.3 µg/g). The level of Zn was (0.5 - 0.9 µg/g) in muscle and fish gills, and (<0.0001 µg/g), but long-term disposal of wastewater into the Nile resulted in high level of Zn and Cu in the tissues and gills of the fish. In conclusion, the levels heavy metals observed in the fish and water samples can be considered as a serious matter of concern as it may be consumed and be harmful to human health in the study area. More safe and economic methods for the elimination of heavy metals from contaminated waters are needed and continuous assessment of the level of pollution of the Nile waters and fish with heavy metals is also necessary.