Effects of season and location on heavy metal contents of fish species and corresponding water samples from Borno State of Nigeria

Amin O. Igwegbe*, Charles A. Negbenebor, Elizabeth C. Chibuzo and Mamudu H. Badau

Department of Food Science and Technology, Faculty of Engineering, University of Maiduguri, P.M.B. 1069 Maiduguri,

Nigeria

*Corresponding Author E-mail: amanjide1964@yahoo.com

Accepted 02 April, 2014

Abstract

This study was designed to investigate the level of toxic heavy metals: lead, cadmium, mercury and arsenic in edible muscles of four fish species namely Tilapia nilotica (Tilapia), Synodontis guntheri (Kurungu), Heterotis niloticus (Bargi), and Clarias anguillaris (Catfish), harvested from three locations ¾ Alua Dam, Doron Baga and Daban Masara within the Lake Chad Basin of Borno State, Nigeria. The main objective was to investigate the possible effects of the locations and season, as well as species of fish, on the concentration of the metals in the fish following wet digestion. The toxic heavy metals, expressed in parts per million (ppm), were detected in all the fish species from the three (3) inland waters investigated. The overall mean concentrations of the heavy metals were significantly higher (P£0.05) in fresh fish samples harvested during the rainy season than the dry season. Significantly different variations were also observed within fish types and between locations in the concentrations of the four heavy metals. Cadmium and arsenic were the lowest recorded metals in fresh fish during the two seasons and in all the locations. The sequence of the heavy metals concentrations in all the fish samples was Pb>Hg>Cd>As. The concentrations of the metals in both the fresh fish and the corresponding water samples from all the locations during the two seasons were however lower than the internationally recommended threshold levels. Follow up studies were recommended while it was concluded that fish from inland waters within the Lake Chad basin are still safe for human consumption in terms of their heavy metal contents.

Key words: heavy metals, fish, season, smoking, AAS, ICP-OES.