Assessment of Metal Concentration and Bioaccumulation Factor in Surface Water and Fishes Sampled From Four Creeks in the Bonny River Estuary, Niger Delta Region of Nigeria

Abstract

The indiscriminate disposal of industrial and urban waste has added to the concerns of global water pollution. Anthropogenic activities and activities of oil companies (oil spills) have also contributed to the pollution of the aquatic ecosystem in the Niger Delta region of Nigeria. This study was therefore designed to evaluate the concentration of Iron, Nickel, Lead, Cadmium and Chromium in our surface waters and our marine life. Samples of surface water were collected into 50 cl sterile plastic bottles and labelled accordingly. Twenty medium-sized tilapia fishes from about a one-kilometre radius of each site were caught and also labelled accordingly. Water and fishes from each site were then kept in a cooler, iced and immediately transported to the laboratories for analysis for heavy metals after these fishes were homogenised using a blender. Atomic absorption spectrophotometer was used for the metal analysis. Standards were prepared using tracecert of each of the above-mentioned metals. The results of these study sites (Akpajo, Okujagu, Woji and Elelenwo) had high concentrations of metals. Fishes from all these sites also had high concentration of these metals. The trend of metal concentration in the surface water as follows: Okujagu–Pb>Cr> Cd>Fe = Ni, Akpajo–Cd>Fe>Pb>Cr>Ni, Elelenwo–Pb>Cr>Fe>Cd>Ni, Woji–Cr>Cd>Pb>Fe>Ni. Results obtained also revealed the trend of metal concentration in fish muscles as follows: Okujagu–Pb>Cr> Cd>Fe = Ni, Akpajo– Cd>Fe>Pb>Cr>Ni, Elelenwo–Pb>Cr>Fe>Cd>Ni and Woji–Cr>Cd>Pb>Fe>Ni. Fishes and surface water sampled from these four creeks in the Bonny estuary in the Niger Delta region of Nigeria had high concentrations of iron, nickel, cadmium, chromium and lead in relation to their concentration in surface water. The results of this study revealed that metal concentration in surface water had some relative effect on their concentration in the fishes. This, therefore, means consumption of these fishes may lead to the accumulation of these metals in man to a toxic concentration. This may be one of the reasons for the increase in some heavy metal-related health issues (diabetes, renal diseases) in this region.