ABSTRACT
Ten representative soil samples were collected along major
gutters within Nkpor metropolis. The soil samples were digested using mixtures
of HF and aqua regia in ratio1:1. The heavy metals contents of the digested
soil samples were determined via Flame Atomic Absorption Spectrophotometer
FAAS. Sample A had the highest concentration of heavy metal and the trend was
Ni > Cr > Hg > Zn > As ~ Cd, it was followed by sample B with Ni
> Cr > Zn > Zn > Cd >g > As, sample C had Ni>Cr
>Zn>Hg>Cd>As, sample E had Ni > Zn > Cd > Cr > Hg >
As. While sample D had Cr > Ni > Zn > Cd > Hg > As. Also the
results of the sequential extraction of each soil sample indicated that Ni had
the highest percentage bioavailability (49.61%), Hg (47. 72%), Cr (42. 19%), Zn
(39.66%), Cd (35.10%), As (0.00%). The high concentration of Hg, Cr and Cd in
most areas of the metropolis indicated gross contamination, which could have
resulted from human activities, hence the need to adequately monitor the
release of these toxic metals to the environment.
CHAPTER ONE
INTRODUCTION
1.0 GENERAL INTRODUCTION
Minerals, metals and metalloids, toxic or essential, are
present in soils or sediments in various forms with varying bioavailability,
toxicities and mobilities. Heavy metals are natural components of the earth’s
crust and the ecosystem with variations in concentration. They cannot be
degraded or destroyed and they enter our bodies via food, drinking water and
air [1].
Unlike organic contaminants, most metals do not undergo
microbial or chemical degradation and the total concentration of these metals
in soils persist for a long time after their introduction [2].
These metals are a cause of environmental pollution
(heavy-metal pollution) from a number of sources. For example lead in petrol,
industrial effluents and leaching of metal ions from the soil into lakes and
rivers by acid rain [3].
Living organisms require varying amounts of “heavy metals”.
Iron, cobalt, copper, manganese, molybdenum and zinc are required by humans.
Excessive levels can be damaging to the organisms. Other heavy metals such as
mercury, plutonium and lead are toxic metals that have no beneficial effect on
organisms and can cause serious illnesses (3).
Therefore, with greater public awareness of the implications
of contaminated soils on humans and animal health, there has been increasing
interest among scientific communities in the development of technologies to
determine the total concentrations of these elements of interest in the soil as
well as their chemical forms.
The use of sequential extraction techniques to fractionate
metals in soils and evaluate their potential effects has become very useful and
well recognized (4)
1.1 SCOPE OF STUDY
This
research covers the analysis of six heavy metals in each of the five selected
drainage pathways or gutters in Nkpor. The heavy metals are mercury (Hg)
Nickel; (Ni), Zinc (Zn), Arsenic (As), Cadmium (Cd), Mercury (Hg)
Soil
samples were collected from each of the drainage systems as follows:
Five soil samples each along Nkpor/Enugu Old Road,
Nkpor/Obosi Road (site for Geolis Cables Industry), Limca Road Nkpor, New
Market Road Nkpor and Nkpor/Enugu Express Road.
The samples will be collected at a distance of 10 meters
each to avoid bias. A total of 25 soil samples will be analysed to determine
the total concentration of each metal in each sample.
1.2 AIMS AND OBJECTIVES OF STUDY
Heavy metal content of soil sample in some selected drainage
systems in Nkpor will be investigated. As earlier on stated, heavy metals are
dangerous because they tend to bioaccumulate i.e increase in their
concentration over time. Also heavy metals can enter water supply by industrial
and consumer waste or even from acidic rain and release heavy metal into
streams, lakes, rivers and ground water.
Hence, the study will help in assessing the potential
environmental impacts of these metals by determination of their concentrations
in soils as well as the chemical form of these metals in the soil.
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Item Type: Project Material | Size: 52 pages | Chapters: 1-4
Format: MS Word | Delivery: Within 30Mins.
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