Heavy metal concentration in blood and selected tissues of cat fish from Kwalkwalawa River, Sokoto

Abstract

Fish is a cheap source of omega- 3 polyunsaturated fatty acids for humans. However, the presence of toxic heavy metals in water can be detrimental to both fish and humans. The aim of this study was to investigate the levels of heavy metals in the liver, kidney and gills of cat fish obtained from Kwalkwalawa River, Sokoto. Water, sediments, blood and tissue samples of (10) cat fish (Clarias gariepinus) species caught from Kwalkwalawa river were analysed quantitatively for the presence of zinc, copper, lead, chromium and cadmium using atomic absorption spectrophotometer. Bioaccumulation of these heavy metals was estimated in these organs. Results showed that lead concentrations in the water was significantly higher (p < 0.05) compared to the sediment sample. Also, copper and lead accumulated most in the liver and kidney when compared with that observed for the gills. In conclusion, lead and cadmium levels in the samples were above WHO certified limits hence the concentration of metals in this water should be monitored periodically.