ASSESSMENT OF HEAVY METALS IN WILD AND FARMED AFRICAN CATFISH CLARIAS GARIEPINUS (BURCHELL, 1822) IN SELECTED RIVERS AND FISHFARMS IN KADUNA STATE, NIGERIA
CHAPTER ONE
1.0 INTRODUCTION
1.1 Background of the Study
In recent years the concentrations of toxic metals in many ecosystems are reaching unprecedented levels. The increasing use of metals in industry and mining activities have led to serious environmental pollution through effluents and emanations (Güven et al., 1999). Under certain environmental conditions, heavy metals may accumulate and cause serious ecological damage. The aquatic ecosystem is often seen as the ultimate recipient of almost everything including heavy metals (Ogoyi et al., 2011). Pollution of heavy metals in aquatic environment is a growing problem worldwide and currently it has reached an alarming rate. There are various sources of heavy metals; some originates from anthropogenic activities like draining of sewage, dumping of hospital wastes and recreational activities. Conversely, metals also occur in small amounts naturally and may enter into aquatic system through leaching of rocks, airborne dust, forest fires and vegetation (Fernandez and Olalla, 2000). As heavy metals cannot be degraded, they are continuously being deposited and incorporated in water, sediment and aquatic organisms (Linnik and Zubenko, 2000), thus causing heavy metal pollution in water bodies.
Heavy metal is any metallic chemical element that has a relatively high density and is toxic or poisonous at low concentrations (Ngumbu, 2014). Examples of heavy metal include mercury, cadmium, arsenic chromium, thallium and lead. As trace elements, some heavy metals (e.g. copper, iron, zinc, manganese and selenium) are essential to maintain the metabolism of the human body. However, at higher concentrations they can lead to poisoning (Lenntech, 2014). Heavy metals can enter the human food through water, air, soil, plants and animals. The pollution of the environment by heavy metals is viewed as an international problem because of its effects. In recent years, the pollution of aquatic environment with heavy metals has become a worldwide problem because of their potential toxic effect and also most of them accumulate in tissues and organs of aquatic organism (Goldstein and Hewitt, 1990andGledhill et al., 1997).
However, the amount of absorption and bioaccumulation of the heavy metals depends on ecological, physical, chemical and biological condition and the kind of element and physiology of organisms (Jaffer et al., 1988). Heavy metals are considered the most important form of pollution of the aquatic environment because of their toxicity and accumulation by marine organisms (Eletta et al., 2003; Malik, 2004; Obasohan et al., 2006 and Igwemmar et al., 2013). There is increasing concern about the quality of foods in several parts of the world. The determination of toxic elements in food has prompted studies on toxicological effect of these elements in food. Fish as an important component of the human diet, is generally appreciated as one of the healthiest and often times referred to as the “cheapest” source of protein, as its amino acid compositions are richer in Cysteine than most of the other sources of protein (Eletta et al., 2003).
DOWNLOAD COMPLETE PROJECT MATERIALS
ASSESSMENT OF HEAVY METALS IN WILD AND FARMED AFRICAN CATFISH CLARIAS GARIEPINUS (BURCHELL, 1822) IN SELECTED RIVERS AND FISHFARMS IN KADUNA STATE, NIGERIA
