Abdullahi I Mohammed, Joseph CAkan, Zaynab MChellube and Zakari Mohammed
Keywords: Komadugu, heavy metals, fish, species, risk assessment
Abstract: In this study, Fish samples Clarias anguillaris, Synodontis budgetti, and Heterotis niloticus were collected during the rainy and dry season from Komadugu river basin, Yobe State, Nigeria for the determination of some heavy metals. The concentrations of heavy metals were determined using Perkin-Elmer Analyst 300 Atomic Absorption Spectroscopy (AAS) and X-Ray Fluoresces (XRF). The concentrations of all the heavy metals in the fish samples ranged from 1.18E+03 mg/kg. Heterotis niloticus were observed to show the highest total concentration of the heavy metals studied with a value of 2.19E+03 mg/kg, while Clarias anguillaris shows the lowest concentration with a value of 0.03 mg/kg. The accumulation of tissues of fish samples were observed to be in the order of gills>liver>intestine>flesh in both methods. The concentrations of all heavy metals were significantly higher using XRF method when compared with AAS. Fe shows the highest ADI value of 1.53E+00 mg/kg/day in Clarias anguillaris, while Synodontis budgetti shows the lowest value of ADI value of 8.23E-01 mg/kg/day among all the four species of fish samples studied. From the results obtained, the HQ values of some of the heavy metals in the fish samples during the rainy season were all above one (1), with the exception of HQ values during the dry season which was lower than 1. The lowest HQ value of 9.00E- 08 in all the fish samples study was lower than 1, while the highest HQ of 1.50E+01 As detected in all the fish samples was higher than the HQ values of one (1). Cancer risks were computed as 5.10E-02 for highest and 5.40E-07 for lowest chances for the study fish respectively. These risk values indicate that consumption of fish from the study area would result in an excess of 5 cancer cases per 1,000,000 people
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