Heavy metals level in Oreochromis niloticus collected from Lake Geriyo, Yola, Adamawa State, Nigeria

Kefas M., Micheal K.G., Haziel H. and Adokwe J. B.

Net Journal of Agricultural Science
Published: September 17 2021
Volume 9, Issue 3
Pages 51-58

ABSTRACT

Oreochromis niloticus is an important species of fish that is a major component and source of animal proteins in most diets of the people of Yola in particular, and Nigeria in general. This work assessed concentrations of some heavy metals: Zinc, iron, copper, manganese and lead (Zn, Fe, Cu, Mn and Pb) in O. niloticus organs (muscle, gills and liver ) from Lake Geriyo, using Atomic Absorption Spectrophotometer, after wet digestion for the period of six months. The concentrations of the metals differed significantly in the organs of the fish species at the different sites. Zinc, Iron and Copper (Zn, Fe, and Cu) at sites A, B and C recorded concentrations (1.77, 11.65 and 1.77 mg/kg) within the permissible limits in fish organs. Manganese (Mn) and Lead (Pb) recorded concentrations (2.33 and 0.11 mg/kg) above the permissible limit in fish organs. Gills and liver of O. niloticus contained the highest concentrations of most of the detected heavy metals, while muscles appeared to be the least preferred site for the bioaccumulation of heavy metals. The liver and muscle of O. niloticus showed higher levels of Manganese (Mn) and Lead (Pb) in the study area. This may be due to bioaccumulation over a period of time in the liver and muscles of O. niloticus. Generally, the concentrations of the metals in the different organs of the fish were significantly higher (P < 0.05) compared to the FAO/WHO and WHO permissible limits of these metals in fish. This shows a possible high risk of heavy metal toxicity consequent upon the consumption of this fish from these sources.

Keywords: Pollution, AAS, Oreochromis niloticus, heavy metals, Lake Geriyo.

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