Studies on levels of mercury, lead and zinc in some environmental samples from the Ankobra and Tano River basins in Southwestern Ghana

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Metal contamination of aquatic environment may lead to deleterious effects from localised inputs which may be acutely, chemically toxic to aquatic life and humans. This study has been carried out to determine the levels of Mercury(Hg), Lead(Pb) and Zinc(Zn) in water, sediment and fish, and including Mercury(Hg) in human samples (blood, urine, hair and nail) in the Ankobra and Tano River basins where majority of the Ghanaian Gold Mines are located. Mercury was determined using the Cold vapour technique on the Perkin-Elmer 51 OOPC AAS equipped with F1-MHS. Lead (Pb) and Zinc (Zn) were determined using the Flame technique. The average levels of Hg in water from the Ankobra and Tano basins were.O.384p.gIL and 0.227μg/L with the average levels in sediment being 4.312μg/L and 17.37μg/Kg respectively. Pb and Zn in water registered an average of 0.1 50mg/L and 0.224mg/L, and 0.1 l4mg/L and 0.O44mgfL in the Ankobra and Tano basins respectively. The levels of Pb and Zn in sediment from the Ankobra and Tano basins averaged 42.63mg/kg and 48.04mg/kg respectively. The levels of the heavy metals in fish from the Ankobra basin ranged as follows; Hg(0. 03-0.443μg/g), Pb(2. 504-14.04mg/kg) and Zn(4.756-l 5.49mg/kg), with that of the Tano basin being Hg(0.068-0.41 3p.g/g), Pb (2.747-1 2.01mg/Kg) and Zn(4.834-1 5.61mg/Kg). The results of Hg in human samples revealed that subjects of Anwiaso in the Ankobra basin have significantly higher Mercury levels. The subject with the highet blood Hg level registered 21 8.3μg/L. Levels in other media of the same subject, aged l4years, were; urine(66.98μg/L), hair(3.O85μg/g), and nail(6. 182μg/g).
A thesis submitted to the Board of Postgraduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirement for the award of Master of Science in Analytical Chemistry, 2000