COMPARATIVE ASSESSMENT OF HEAVY METALS IN THE ORGANS AND TISSUES OF FISHES SOURCED FROM RIVER NIGER AND RIVER NULL IN NIGER DELTA AREA OF NIGERIA

ATAMAN, KELVIN OSEREMEN (2016-07-01)

M.Sc THESIS

Thesis

ABSTRACT The study comparatively assessed the level of heavy metals in the tissue of fish sourced from River Niger at Illushi, Esan South East Local Government area of Edo state and River Null at Kiama, Kolokuma/Opokuma Local Government Area of Bayelsa state. Samples of Clarias gariepinus, Momyrops cabalus, Hemisynodontis membranaceous, Momyrops rume, and Parachyna obscura fish were collected from River Niger and Null respectively. Standard biochemical procedures were applied in the determination of heavy metals such as zinc (Zn), copper (Cu), nickel (Ni), lead (Pb) and iron (Fe) present in the tissue, heart, liver, lungs and kidney of the various fish samples. Some selected non-heavy metals, magnesium (Mg), sodium (Na), potassium (K) and calcium (Ca) were also investigated. These heavy metals were assessed with atomic absorption spectrophotometer while sodium and potassium was assessed using flame photometer. Result of this study revealed that three heavy metals (nickel, lead and cadmium) were not detected in the organs of the fishes sourced from both rivers. The level of zinc obtained in all assessed organs of Clarias gariepinus, Momyrops cabalus, and Hemisynodontis membranaceous was higher in fish collected from river Null compared to those obtained from River Niger. However, organs of Clarias gariepinus, Hemisynodontis membranaceous, and Parachyna obscura from both rivers contained lower zinc levels when compared to the WHO recommended permissible limit of 2003. However elevated levels were observed in the heart (0.134mmol/kg), liver (0.107mmol/kg) and kidney (0.134mmol/kg) of Momyrops cabalus as well as in the liver (0.069mmol/kg) and kidney (0.055mmol/kg) of Momyrops rume both from river Null as they possessed significantly (p < 0.05) higher zinc level compared to the recommended limit. Higher copper levels were also observed in fish from River Null compared to those from River Niger, but these observed values were lower than the WHO recommended for copper standard limits studied. Iron was significantly (p < 0.05) higher in the various organs of the fish, especially those sourced from River Niger. Consequently, the presence of the assessed heavy metals (apart from iron) in the investigated organs of the selected fish from river Niger at Illushi were noticed in concentrations within permissible maximum limits, compared to those obtained from River null. Thus, except for the bioaccumulation of iron above the WHO permissible limit, fishes from river Niger could be better for consumption than those from River Null, based on their heavy metal contents

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