Thesis Abstract

Abstract
Heavy metal pollution in freshwater ecosystems is a significant environmental concern due to its potential impacts on aquatic organisms and human health. This study focused on the bioaccumulation of heavy metals in the freshwater clam, Egeria radiata, from the Itu Bridge Head area in Itu Local Government Area, Akwa Ibom State. The research aimed to assess the levels of heavy metals in the clam species and evaluate the potential risks associated with human consumption of contaminated clams from this region. Sampling was conducted at various locations along the Itu Bridge Head area, and Egeria radiata specimens were collected for analysis. The concentrations of heavy metals, including lead (Pb), cadmium (Cd), mercury (Hg), arsenic (As), and chromium (Cr), were determined in the soft tissues of the clams using atomic absorption spectrophotometry. The bioaccumulation factors of the heavy metals in the clams were calculated to understand the accumulation patterns in the organisms. The results revealed varying levels of heavy metal contamination in Egeria radiata from the study area. Lead and cadmium concentrations exceeded the permissible limits set by regulatory bodies, indicating potential risks to both the clams and consumers. The bioaccumulation factors indicated that Egeria radiata has the capacity to accumulate heavy metals, especially lead and cadmium, in their tissues, highlighting their role as bioindicators of metal pollution in freshwater ecosystems. The study underscores the importance of monitoring heavy metal pollution in freshwater environments, particularly in vulnerable species like Egeria radiata, which can serve as sentinels for environmental contamination. The findings also emphasize the need for regulatory measures to mitigate metal pollution in the Itu Bridge Head area to protect both aquatic organisms and human health. In conclusion, the bioaccumulation of heavy metals in Egeria radiata from the Itu Bridge Head area poses potential risks to both the clams and consumers. Continued monitoring and assessment of heavy metal pollution in freshwater ecosystems are crucial for implementing effective management strategies to safeguard environmental and public health.

Thesis Overview

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

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