CHAPTER ONE

1.0     Introduction

1.1 Background Information

Pollution of the littoral waters of the Niger delta region of Nigeria has in recent times received much alteration because of the high degree of environment degradation and aquatic perturbations posed by petroleum exploration activities in the oil bearing states. Petroleum hydrocarbons from oil spills and human related activities are usually incorporated into sediments where they can persist for years, gradually releasing toxic substance such as heavy metals into the immediate and remote environment (O’Clar et al., 1996; Moles and Norcoss, 1998, Zabby and Babatunda, 2015). Heavy metals distribution in aquatic ecosystems. Present divergent dynamics depending on such factors as source, flow rates particle flux rate, sediment characteristics and ecology of organisms under study. In the Niger delta, most report agree that heavy metal concentration is low in surface water sample (Davies et al., 2004. Chindah et al., 2006) sediment on the other hand is believed to be the sink for heavy metals, which usually allows re-suspension anytime the river is disturbed (Babatunda et al., 2013). However, to better characterize the risk presented by metals in the environment to human and ecological receptors, most researchers use benthic organism as biomonitors of both the levels and long-term influences of heavy metals within an ecosystem (Phlilps and Rainbow, 1994, Horsfall et al., 1998)

Fishing is one of the major occupations of the people of Niger Delta region and various fisheries resource are important delicacies including Egeria radiate which is popular among artisanal fisheries. The importance of heavy metal contamination of aquatic ecosystem cannot be over emphasized as most of them can bioaccumulate and become significant along the food chain giving concern of seafood safety to consumers (Davies et al., ., 2006). Selfish, especially clams like E. radiate and Tympanotonus  species are used largely as a condiment in most meal eaten in the Niger delta and its environ  (Gomna and Rana, 2007, Babatunde et al., 2005) and may accumulate metals at levels which can become deleterious to human consumers.

Bivalves are widely used as bioindicators of heavy metals pollution of heavy metals pollution in costal waters because they are known to concentrate metals providing indications of the contamination of the environment over time. Ergeria Nwanbeze (2011) reported elevated concentration of heavy metals in tissue of E. radiata from some creeks in Delta state Nigeria above concentration in the environment in particularly Pb, Mn and Cd as higher than FAO/WHO acceptable limits of heavy metal contamination in fishes and shell fish. Similarly, Etim (1990) reported elevated heavy metal contamination in tissues of E. Radiata from Calabar River, Cross River, Nigeria, above the environmental concentration indicating that the animal bioaccumulated the metals. Indeed numerous studies around the world have demonstration their ability to concentrate trace elements even in areas far from anthropogenic source such as the anthracitic ocean (Maur et al., 1990, and Nigro 1992; Viarengo et al., 1993) with seasonal variations in the concentration at various stages of their live (Bryan, 1973) and in the bay of la Rocchelle in France (Bustamante and Miramand, 2005).

Various anthropogenic activities in Itu bridgehead waters can adversely alter the water and the sediment chemistry. This will end up having effects on benthic organism like Egaria radiata. Since this organism is a delicacy in the area analyze of heavy metal levels in it will help determine its suitability for consumption.

1.2 Aims and Objectives

1. To determine levels of cadmium (cd), chronmium (cr), lead (pb), and iron (fe) in the flesh of E radiata from ITU bridgehead
2. To compare the levels of heavy metals analysed to the WHO standard

• To ascertain consumption suitability of E. radiata from ITU bridgehead.