Assessment of Heavy Metals Concentration in Shell and Fin Fish from Iko River Estuary, Southeastern Nigeria

Heavy metals (HM) concentration in croaker (Pseudotolithus typus) and periwinkle (Tympanotonus fuscatus) from Iko River estuary, Southeastern Nigeria were carried out between June and December, 2015 using UNICAM 939 Atomic Absorption Spectrophotometer (AAS). The results in (mg/kg) showed different levels of Cd (cadmium), Cr (chromium), Cu (copper), Fe (iron), Pb (lead), Ni (nickel) and Zn (zinc) in croaker and periwinkle. The order of heavy metals accumulated by P. typus and T. fuscatus were Cu > Zn > Fe > Cd > Pb > Cr >Ni and Fe > Cu > Zn > Pb > Cd > Cr > Ni, respectively. The results showed that Cu and Fe recorded highest concentration in Croaker and periwinkle respectively while Ni concentration was least in both organisms. Both organisms bio-concentrated considerable levels of heavy metals, however, the bio-concentration of periwinkle was significantly higher than croaker. The concentration of Cd, Cu and Fe in both organisms were higher than the WHO/FEPA (World Health Organisation/ Federal Environmental Protection Agency) recommended MPL (maximum permissible limits), while the levels of Cr, Pb, and Ni were below the standards and Zn concentration was within MPL. The results suggest that Iko River estuary has high pollution loads of these metals in fishes and could pose a health hazards to man. Consequently, close monitoring of heavy metal loads in this water body is recommended with a view to minimizing the risks to health of the population that depend on the river for their water and fish supply.