Abstract

Contamination of the river by oil spill had put the health of the people who consume fish at risk. Five fish samples each of Liza falicipinis (Mullet), Sarotherodon melanotheron (Tilapia) and Sardinella maderensis (Sardine) (n=15) were collected monthly from the Bonny Estuary from February to July 2018. The samples were oven dried at 100°C and analyzed using Atomic Absorption Spectrophotometer (Model pm ver 2.02 Avanta) to determine the concentration of Zinc (Zn), Lead (Pb), Copper (Cu), Cadmium (Cd), Nickel (Ni), Chromium (Cr), Vanadium (V) and Mercury (Hg). The result show that there is significant difference (F7, 130 = 65.6, P < 0.0001) in heavy metal concentration in the three fish species. Zinc had the highest concentration followed by Lead, Copper, Nickel and Cadmium. There was no seasonal difference (F1, 136 = 1.58, P > 0.05), although dry season had higher concentration.  Sardine had the highest concentration of heavy metal followed by tilapia and mullet. Result of EDI indicates higher intake during the dry season (that is February). Highest EDI was recorded in tilapia (5673.1 ± 5632.5 mg/kg). Similarly, highest Cd, Cu, Cr, Ni and Zn were recorded in sardine whereas Pb was highest in tilapia.  Mullet had highest daily intake for February and March. Sardine had the highest THQ for Cd, Cu, Cr, Ni and Zn, whereas tilapia had high values in Cd and Ni while mullet had high values in Pb.  The implication of this result is that dry season is not the best time to consume these three fish species. 

Key words: Heavy metals, bioaccumulation, Niger Delta, Bonny Estuary, fishes, food chain.