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Title: Accumulation of Certain Heavy Metals in Nile Tilapia (oreochromis niloticus) Fish Species Relative to Heavy Metal Concentrations in the Water of Lake Hawassa
Authors: Zenebe, Yirgu
Advisors: Mekibib Dawit(Dr.)
Keywords: Bioaccumulation
Heavy metals
Nile Tilapia
Copyright: May-2011
Date Added: 17-Jul-2012
Publisher: Addis Ababa University
Abstract: The Tiliapia fish samples and water samples were collected from Lake Hawassa at three selected sampling sites namely Tikur Wuha, Dorie basana and Referral H. sites. The concentrations of certain heavy metals ( copper (Cu), lead (Pb), nickel (Ni) and zinc (Zn)) in water and their accumulation in the edible tissue of Nile Tilapia fish (Oreochromis niloticus) were determined in samples collected from Lake Hawassa in the dry season of the area by flame and graphite furnace Atomic Absorption Spectroscopy. The results revealed that the dissolved heavy metal concentrations in water ranged from undetectable to 4.57 μg/L for copper (Cu) and also from undetectable to 0.25 μg/L for lead (Pb) but dissolved nickel (Ni) and zinc (Zn) concentrations were totally undetectable in water samples of Lake Hawassa water. The contents of investigated heavy metals in fish samples ranged between 1.80 - 4.8 μg/g for Copper (Cu), <1.95 – 2.23 μg/g for lead (Pb), <0.29 - 0.68 μg/g for nickel (Ni) and 21.4 – 40.70 μg/g for zinc(Zn). The highest accumulations of copper (Cu) and zinc (Zn) in edible muscle of Nile Tilapia were observed at Referral H. site. The highest accumulation of lead (Pb) and nickel (Ni) were observed at Tikur Wuha site and at Dorie Basana respectively Among the detected metals, zinc (Zn) showed a maximum accumulation in the edible muscle of Nile Tilapia fish from Lake Hawassa, the next was copper (Cu) and then lead (Pb) and the least was nickel (Ni). The concentrations of the metals (copper (Cu), lead (Pb), nickel (Ni) and zinc (Zn) in water of Lake Hawassa were far below the recommended limit by WHO, US EPA and FAO. The accumulations of copper (Cu) and zinc (Zn) in fish analysed in this study were below the recommended limit of FAO/WHO and EU, the levels of nickel (Ni) in the edible muscle of Nile Tilapia fish were also far below the maximum limit of USFDA. However the levels of lead (Pb) at Tikure Wuha exceeded the recommended limit of FAO/WHO and EU.
Description: A Thesis Submitted to the School of Graduate Studies of the Addis Ababa University in Partial Fulfillment of the Degree of Mater of Science in Environmental Science
URI: http://hdl.handle.net/123456789/3391
Appears in:Thesis - Environmental Sciences

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