Project Abstract

Abstract
Heavy metals are a major concern in aquatic environments due to their toxicity and persistence. The Akpabuyo Stream in Nigeria is an important water body that serves multiple purposes for the surrounding communities. This study aimed to investigate the distribution of heavy metals in the sediment of Akpabuyo Stream to assess the potential environmental impact. Sediment samples were collected from different locations along the stream and analyzed for heavy metal concentrations using atomic absorption spectrophotometry. The results showed varying levels of heavy metals in the sediment, with higher concentrations found near industrial and urban areas. Lead, cadmium, and chromium were among the metals detected in significant amounts, raising concerns about potential contamination sources. Spatial distribution mapping revealed hotspots of heavy metal accumulation in specific areas of the stream, indicating localized pollution sources. The sediment quality guidelines were used to assess the potential ecological risks associated with the heavy metal concentrations. The results indicated that certain areas of the stream exceeded the threshold limits for heavy metals, suggesting a risk to the aquatic ecosystem. Furthermore, sequential extraction analysis was conducted to determine the chemical forms of heavy metals in the sediment. The majority of the metals were found to be associated with the exchangeable and carbonate fractions, which are more bioavailable and pose a higher risk to aquatic organisms. This information is crucial for understanding the mobility and bioavailability of heavy metals in the sediment and their potential impact on the aquatic environment. Overall, this study highlights the presence of heavy metal contamination in the sediment of Akpabuyo Stream and underscores the need for effective management strategies to mitigate the environmental risks. Addressing the sources of heavy metal pollution and implementing remediation measures are essential for protecting the water quality and biodiversity of the stream. Future research should focus on monitoring the long-term trends of heavy metal distribution in the stream and evaluating the effectiveness of remediation efforts in reducing environmental risks.

Project Overview

1.1 INTRODUCTION

Heavy metals pollution of aquatic ecosystem is becoming a potential global problem, pollution typically refers to chemicals or other substance in concentration greater than it would occur under natural conditions. Water pollution is the introduction by man of substances into the aquatic environment resulting from deleterious effect as harm to human health (FAO 1990).The presence of increased level of heavy metals in the aquatic environment has been of much concern for the past decades due to adverse effect of some metals on living organisms in food chains leading to man. Pollutants are the cause of major water quality degradation around the world. Several toxic metals which are important to the environment and human health have been detected in aquatic media. These toxic metals include the non-essential meals and are no importance to humans (Borgman and Norwood 2002).

Trace amount of heavy metals are always present in fresh water from terrigenous sources such as weathering of rocks resulting into geo-chemical recycling of heavy metal elements in these ecosystem. Trace elements may be immobilised within the stream sediments and could be involved in absorption, co-precipitation and complex formation. Sometimes they are co-adsorbed with other elements as oxides, hydroxides of Fe, Mn, or may occur in particulate form.

Heavy metal may enter into aquatic ecosystem from anthropogenic sources, such as industrial wastewater discharge, sewage wastewater, fossil fuel combustion, and atmospheric deposition. Trace element in stream sediment compartment can be used to reveal the history and intensity of local and regional pollution. In this work, the of stream sediment contamination was assess using geo-accumulation index.

1.2 AIMS AND OBJECTIVES

The main objectives of the current study area are:

To assess the extent and degree of metals, and the origin of these metals, using the geo-accumulation index of the metals.

To determine the total content of heavy metals in surface sediments of Akpabuyo.

To estimate the anthropogenic input and to assess the pollution status on the area.

1.3 STUDY AREA

The study area which is located in Akpabuyo, Cross River State lies between longitudes 80 22I 30II E – 80 30I 0II E and latitude 40 52I 30II N – 40 57I 30II N (fig 2). With an area of 126,4032 Square Km. Although many stream samples where collected but few was selscted for the heavy metal analysis. The various Locations in Akpabuyo which sediment samples were collected and used to carry out the analysis are Esuk Mbat stream(L1), Esuk Ekpo Eyo Stream(L2), Ikot Akwa Stream(L3), Dan Archibong Stream(L4), Itu Stream(L5), Ikot Ndarake Stream(L6), Asioha Stream(L7), Ikot Ekpo Ene Stream(L8), Ekpene Ikot Imo Stream(L9), Ikot Nakanda(L10), and their following coordinate shown respectively (table 1.3) . It originate from a hilly region and flows through several villages and farmland.