ASSESSMENT OF HEAVY METALS IN WILD AND FARMED AFRICAN CATFISH CLARIAS GARIEPINUS (BURCHELL, 1822) IN SELECTED RIVERS AND FISH FARMS

Project Abstract

<p> </p><div><p><strong>ABSTRACT</strong></p><p>The presence and bioaccumulation pattern of some heavy metal concentrations in wild and</p><p>farmed African catfish, <em>Clarias</em>&nbsp;<em>gariepinus</em>&nbsp;(Burchell, 1822) muscles collected from selected</p><p>rivers and fish farms in Kaduna State, Nigeria, were assessed. Fish and water samples used for</p><p>the assessment were collected during the wet and dry seasons from River Kaduna, River</p><p>Galma in Zaria; and from two fish farms in Sabon Tasha, Kaduna and Dakace, Zaria. Physico-</p><p>chemical parameters, such as Puissance Hydrogen (pH), temperature, Turbidity etc., were also</p><p>analysed. The analyses of heavy metals, Iron (Fe), Lead (Pb), Nickel (Ni), Cadmium (Cd) and</p><p>Mercury (Hg), in all water and <em>Clarias</em>&nbsp;<em>gariepinus</em>&nbsp;muscle samples was carried out in the</p><p>Multi-User Science Research Laboratory, Department of Chemistry, Ahmadu Bello</p><p>University, Zaria, using Thermo-element Solar S4 Atomic Absorption Spectrophotometer</p><p>(AAS), while the Varian Generation Accessory (VGA 77) with closed end cell was used for</p><p>Hg determination. The results obtained were subjected to t-test analysis to determine the level</p><p>of significance (p &lt; 0.05) between the means, while Pearson correlation coefficient was</p><p>employed to determine the relationships. pH was highest in River Kaduna during the wet</p><p>season, in the upstream (7.04), while there was a dip in the downstream (6.67) during the dry</p><p>season. Seasonal variations in temperature were evident, as the ranges obtained in the rivers</p><p>were from 27.03°C – 30.68°C and the farms ranged from 23.76°C – 27.42°C, which were</p><p>within World Health Organization (WHO) recommended threshold (30°C – 36°C). Dissolved</p><p>Oxygen (DO) varied widely in the rivers (5.11mg/l – 7.04mg/l) as well as in the farms</p><p>(9.29mg/l – 10.74mg/l). Total dissolved solids (TDS)obtained in this study were all very high</p><p>(Rivers 54.91mg/l – 82.09mg/l, Farms 28.43mg/l – 42.03mg/l), but were all lower than the</p><p>WHO standardindicativeofportability (1000 – 1600mg/l). Heavy metal concentrations in</p><p>water samples and heavy metal bio-accumulation in both wild and farmed <em>C.</em>&nbsp;<em>gariepinus</em></p><p>muscles showed irregular distributions with descending order ofFe &gt;Pb&gt;Hg&gt;Ni &gt; Cd. Fe</p><p>vii</p></div><p><br></p><p>levels were the highest in both rivers water samples (3.23mg/l), closely followed by Pb (0.78)</p><p>and Hg (0.69mg/l), while the farms also had Fe as the dominant element (1.31mg/l), with Pb</p><p>(0.26mg/l) and Hg (0.09mg/l), respectively. Both water bodies had Ni concentration (0.2mg/l)</p><p>higher than the WHO limits of 0.02mg/l, while the farms‟ concentration (0.03mg/l) was</p><p>slightly higher than WHO threshold limit. In the muscle of <em>C.</em>&nbsp;<em>gariepinus</em>, Fe concentrations</p><p>were also high in rivers (3.53mg/kg), while the Farms was 1.44mg/kg, all above the FAO</p><p>recommended limit (0.5mg/kg) in fish. Generally, only Cd didnot exceed the maximum</p><p>permissible limits in the tissues of<em>C.</em>&nbsp;<em>gariepinus</em>. However, with Fe, Hg, Pb and Ni all higher</p><p>than the acceptable limits, most especially in the rivers, this could pose a serioushealth risk to</p><p>consumers. Thus, a close periodical and regular monitoring of heavy metal pollution in the</p><p>water bodies is strongly advocated.</p> <br><p></p>

Project Overview

<p> </p><div><p><strong>1.0</strong>&nbsp; &nbsp; &nbsp; &nbsp;<strong>INTRODUCTION</strong></p><p><strong>1.1</strong>&nbsp; &nbsp; &nbsp; &nbsp;<strong>Background</strong>&nbsp;<strong>of</strong>&nbsp;<strong>the</strong>&nbsp;<strong>Study</strong></p><p>In recent years the concentrations of toxic metals in many ecosystems are reaching</p><p>unprecedented levels. The increasing use of metals in industry and mining activities have led</p><p>to serious environmental pollution through effluents and emanations (Güven <em>et</em>&nbsp;<em>al.,</em>&nbsp;1999).</p><p>Under certain environmental conditions, heavy metals may accumulate and cause serious</p><p>ecological damage. The aquatic ecosystem is often seen as the ultimate recipient of almost</p><p>everything including heavy metals (Ogoyi <em>et</em>&nbsp;<em>al.,</em>&nbsp;2011). Pollution of heavy metals in aquatic</p><p>environment is a growing problem worldwide and currently it has reached an alarming rate.</p><p>There are various sources of heavy metals; some originates from anthropogenic activities like</p><p>draining of sewage, dumping of hospital wastes and recreational activities. Conversely,</p><p>metals also occur in small amounts naturally and may enter into aquatic system through</p><p>leaching of rocks, airborne dust, forest fires and vegetation (Fernandez and Olalla, 2000). As</p><p>heavy metals cannot be degraded, they are continuously being deposited and incorporated in</p><p>water, sediment and aquatic organisms (Linnik and Zubenko, 2000), thus causing heavy</p><p>metal pollution in water bodies.</p><p>Heavy metal is any metallic chemical element that has a relatively high density and is toxic or</p><p>poisonous at low concentrations (Ngumbu, 2014). Examples of heavy metal include mercury,</p><p>cadmium, arsenic chromium, thallium and lead. As trace elements, some heavy metals (e.g.</p><p>copper, iron, zinc, manganese and selenium) are essential to maintain the metabolism of the</p><p>human body. However, at higher concentrations they can lead to poisoning (Lenntech, 2014).</p><p>Heavy metals can enter the human food through water, air, soil, plants and animals. The</p><p>pollution of the environment by heavy metals is viewed as an international problem because</p><p>1</p></div><p><br></p><div><p>of its effects. In recent years, the pollution of aquatic environment with heavy metals has</p><p>become a worldwide problem because of their potential toxic effect and also most of them</p><p>accumulate in tissues and organs of aquatic organism (Goldstein and Hewitt,</p><p>1990andGledhill <em>et</em>&nbsp;<em>al.,</em>&nbsp;1997).</p></div> <br><p></p>