Levels of some heavy metals in six species of fish obtained from Challawa River, Kano

Abstract

Concentrations of Co, Cr, Mn, Ni and Pb were determined in muscle, bone, skin and head of six species of fish obtained from Challawa River along Yan danko village in Kano State. The heavy metals content were determined using Atomic Absorption Spectroscopy (AAS) and expressed in μgg^-1 after acid digestion of the samples. The mean concentrations range obtained for the metals analysed in the fish species are as follows; Co (3.93±1.58 - 7.09±1.56) μgg^-1, Cr (0.95±1.09 - 1.89±1.55) μgg^-1, Mn (3.63±1.40 - 6.07±4.21) μgg^-1, Ni (1.83±1.40 - 3.30±1.40) μgg^-1, Pb (0.53±0.61 - 1.06±0.86) μgg^-1. The trend of heavy metal concentration in the fish samples can be represented as: Co > Mn > Ni > Cr > Pb. The concentrations of Ni, Cr and Pb were below the permissible limits specified by most food regulatory bodies (FAO, WHO, FEPA and USFDA), while Co and Mn levels in the fish species was higher than the maximum permissible limits. Thus, fish species from Challawa River, harvested at Yan danko village are not fit for human consumption.

Keywords: AAS, acid digestion, Challawa River, fish species, heavy metals