Evaluation of Heavy Metals in Fish, Water and Sediment of the New Calabar River

Abstract

Aim: This study is aimed at determining the levels of some heavy metals in the water, sediment and fishes (Oreochromis niloticus, Periopthalmus koelreuteri, Micropogonias undulatus, Carassius auratus and Liza felcipinis) from new Calabar River located at Rumuolumeni Community in Obio/Akpor, Rivers State, Nigeria.
 Study Design: Fish, water and sediment samples were selected collected and analyzed for Pb, Cd, Fe, Cr, Mn, Cu and Zn.
 Methodology: The heavy metals concentration was determined by AAS. Health risk assessment of the samples was evaluated by Estimated daily intake (EDI), Toxic Hazard Quotient (THQ) and Carcinogenic Risk (CR).
 Results: P. koelreuteri had the highest mean concentration of Pb (3.82±0.11 mg/Kg); C. auratus samples had the highest mean concentration of Cd (3.82±0.06 mg/Kg); P. koelreuteri had the highest mean concentration of Fe and Cr (189.87±0.04 mg/Kg and 4.75±0.02 mg/Kg respectively); M. undulatus had the highest mean concentration of Cu (3.14±0.05 mg/Kg); O. niloticus had the highest mean concentration of Zn and Mn (38.48±0.02 mg/Kg and 17.25±0.02 mg/Kg respectively). Heavy metals concentration was significantly low (P=.05) when compared with the experimental groups. The sediment samples showed the following trends in concentration (mg/Kg): Fe>Mn>Zn>Cr>Cu>Pb>Cd. Water samples had very low levels of Pb, Cd, Cu and Cr (<0.001 mg/Kg) except Fe (8.68±0.01 mg/Kg), Zn (0.10±0.02 mg/Kg) and Mn 0.11±0.00 mg/Kg. Health risk assessment of the metals in the samples analyzed indicates that the EDI of all the metals were within permissible limits, THQ for all the metals analyzed (especially Pb and Cd) indicates a potential deleterious effect on humans who depend of these aquatic organisms for their protein sources while only Cr has CR values above permissible limits.
 Conclusion: Therefore the heavy metal levels of edible aquatic species within this area should be continuously monitored to ensure the safety of consumers of such organisms.