Assessment of heavy metal levels in fish tissues, water and sediment from Epe Lagoon, Lagos, Nigeria

Abstract

Pollution of heavy metal in water bodies is a threat to public water supplies and also to consumer of fishery sources. This study aimed at investigating the distribution of heavy metals in some fish species, water column and sediment of Epe Lagoon. Water samples, sediments and ten fish species (Synodontis schall, Chrysichthys nigrodigitatus, Megalaspis cordyla, Ulua mentalis, Caranx hippos, Tilapia guineensis, Marcusenius cyprinoides, Xenomystus nigri, Oreochromic niloticus, Clarias gariepinus) were sampled in 2019. Heavy metals (Zinc, Copper, Manganese, Iron, Lead and Cadmium) were detected in three matrices including fish tissues, water and sediment using Atomic Absorption Spectrophotometer (AAS). The heavy metal level ranges of the metals detected were: Zn: 1.128 to 4.875 mg/kg; Cu: ND to 0.488 mg/kg; Mn: 0.5 to 7.480 mg/kg; Fe: 0.125 to 9.125 mg/kg; Pb: ND to 0.875 mg/kg; and Cd: 1.750 to 2.750 mg/kg. The highest mean concentration of the heavy metal in all fish species is Zn, followed by Mn, Cd, Fe, Cu and Pb. The mean concentration of metals determined in the water samples ranged from 0.020 – 0.635 mg/L and for sediments the range was 0.669 – 17.453 mg/kg. The results obtained show high levels of Mn, Fe and Cd in some fish species which can pose danger to consumers of foods and water from this Lagoon. There is therefore the need for continual assessment of the level of pollution of this Lagoon with a view to reducing this level via sensitization and education.