Pollution indices of trace metals in surface sediments from ibeno, akwa ibom state, nigeria

Thesis Overview

<p> </p><p><strong>1.0 &nbsp; &nbsp; INTRODUCTION</strong></p><p>Sediment is the loose sand, clay, silt and other soil particles that is deposited at the bottom of body of waste or accumulated at other depositional sites, sediments can emanate from the erosion of bedrocks and soil or from the decomposition of plants and animals (Taylor <em>et al</em>., 2009).</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Mucha <em>et al</em>; (2003) opines that sediments are the ultimate sink of contaminants in the aquatic system. Information glean from the study of sediment provides a better view on the impact of distinct human activity on the other ecosystem. Sediment load and composition is highly reflective of the type and intensity of agricultural land used which is lead in determining the health and survival of aquatic organisms. It’s composition provides best natural archives of recent environmental changes.</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; According to Martins <em>et al</em>. (1997) sediments besides being a habitat, it is also a major source of nutrient for aquatic organisms, hence an assessment of the concentration of metal contaminants and extent to which these metals has pollute the sediments is imperative.</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Multi-elemental analysis of sediments may reveal the presence of heavy metals which are contaminants and may have toxic influence on ground water and surface water and also on plants, animals and humans (Suciv <em>et al</em>. 2008). Accumulation of trace metals occur in upper sediment in aquatic environment by biological and geochemical mechanisms may become toxic to sediment-dwelling organisms and fish, resulting in death, reduce growth, or impaired reproduction and lower species diversity (Praleena <em>et al</em>., 2007). These elements also occur naturally in rocks forming minerals and ore minerals; here they can reach the environment from natural processes (Akinmosin <em>et al</em>., 2009).</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Heavy metals may accumulates to a toxic level in sediments without visible signs. This occur from normal geological phenomenon such as ore formation, weathering of rocks and leaching or due to increased population, urbanization, industrial activities agricultural practices, exploration and exploitation of natural resources (Ajayi and Osibanjo, 1981).</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Sediment analysis is vital to assessing qualities of total ecosystem of water body in addition to water sample analysis practiced for many years, because it reflects the long term quality situation independent of the current imputs (Adeyamo <em>et al</em>., 2008). Because sediments are also an important biological habitat, uptake of toxicants into the food web are influenced by toxicant concentration in sediments. Toxicant concentration and sediment toxicity may be analyzed, but these analysis fail to account for the influence that contaminated sediments has on the overlying water column of effect toxicant mixtures in the sediments has on benthic organisms.</p><p><strong>1.1 &nbsp; &nbsp; TOXIC METALS</strong></p><p>Toxic metals comprise a group of minerals that have no function in the body and in fact are very harmful to plant, animal and human beings. This is due to their industrial use for the past 300 years. The burning of fossil fuels without scrubbers and improper incineration of waste materials worldwide. Toxic metals are now everywhere on planet earth.</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Toxic metals effect on biochemical reaction in soils and sediments may vary with pH, organic matter content, particle size distribution, vegetation and total hydrocarbon content (Esser <em>et al</em>., 1991) worldwide increasing level of industrialization and urbanization has lead to environmental pollution (Filazi <em>et al</em>., 2003). With the rapid industria-lization and economic development, toxic metals are continuing to be introduced to soils and sediments via several pathways including fertilization, irrigation, rivers, runoff atmospheric deposition, and point sources where metals are produced as a result of mining, refining and refinishing by product.</p> <br><p></p>