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Contaminations Of Heavy Metals In Water And Hemichromis fasciatus Of A Waste Pit Influenced By Petroleum Activities
The concentrations of heavy metals (Zn, Cd, Cu, Pb, Ni, Fe, Mn, Co, Cr, V and Hg) in water and Hemichromis fasciatus (a piscivore) in the burrow pit constructed by Shell Petroleum Development Company were studied. Water and fish samples were collected monthly from January to December 2000. The range values (mg/l) of heavy metals in water were: Zn (0.025 – 2.91), Cd (BD – 0.044), Cu (BD – 0.106), Pb (0.001 – 0.252), Ni (BD – 0.14), Fe (0.143 – 5.204), Mn (0.025 – 0.138), Co (BD – 0.202), Cr (0.002 – 0.018), V (BD – 0.005) and Hg (BD – 0.001) while in Hemichromis fasciatus, values (mg/kg) were Zn (15.28 – 90.93), Cd (BD – 5.04), Cu (0.42 – 5.82), Pb (0.03 – 3.43), Ni (0.36 – 1.71), Fe (43.16 – 145.24), Mn (2.16 – 5.74), Co (BD – 1.63), Cr (BD – 1.61), V (BD – 0.12) and Hg (BD =below detection level).Seasonally, Cd, Cu, Pb, Mn, Co, Cr, V and Hg had higher mean values in water during the dry season while Zn, Ni and Fe were higher during the raining season. All heavy metals except Fe were higher in mean values during the dry season in H. fasciatus than during the rainy season. The mean abundance of heavy metals in H. fasciatus was Fe>Zn>Mn>Cu>Cd>Co>Pb>Ni>Cr>V. The monthly concentrations of heavy metals in H. fasciatus were far higher than those in water. The concentrations of Pb, Fe and Mn were above WHO limits for drinking water for some months while Fe and Mn values in H. fasciatus were above WHO limits for food in twelve months with Zn, Cd, Cu, Pb, Ni, Co and Cr exceeding WHO limits for some months. The findings reveal that the water and the fish (H. fasciatus) are contaminated and not fit for drinking and consumption by humans.
Keywords: Heavy metals, water, fish, seasonality, distribution coefficients, burrow pit, Niger Delta, Nigeria.
Tropical Freshwater Biology Vol. 16 (2) 2007: pp. 45-56