ABSTRACT
This study was carried out to determine the level of heavy metals concentration in soil and settled dust samples in four (4) randomly selected auto-mechanic workshops at varying depths 0-5cm, 5-10cm, 10-15cm and 15-20cm respectively. A total of sixteen (16) soils samples were collected in four different mechanic workshops at Afikpo in Afikpo North L.G.A, Ebonyi State. Four control samples were also collected in a primary school which is about 3 to 4km away from the activities of the mechanic workshops. Four (4) settled dust samples were equally randomly collected from abandoned cars packed in the four selected mechanic workshops. The soil samples were analysed for heavy metal concentration, pH and electrical conductivity (EC). Four heavy metals (As, Cd, Hg and Pd) were determined using AAS method. The dust samples were analysed for only heavy metals concentration. The pH of the soils ranged between 4.29 and 5.78 in the mechanic workshops and 4.39 and 5.78 in the control soil, which is below the neutral level of 7.00. The electrical conductivity (EC) ranged between 46.40µscm-1 and 312.60µscm-1mechanic workshops and 50.80µscm-1and 81.00µscm-1for the control, which shows high conductivity values in the mechanic workshops in comparison with the control which indicates acidity and presences of soluble inorganic salts. Arsenic and Mercury were not detected in all the soil and dust samples from all the mechanic workshops and control. The heavy metal concentration (mg/kg) of Cd ranged from 2.18mg/kg and 97.67mg/kg in the mechanic workshops with the highest at Ndubuise Mechanic workshop (NDMWS). Pb was of higher concentration in all the mechanic workshops with the highest of 276.96mg/kg at Ebiri mechanic workshop (EBMWS). Generally, variations exist in the concentration within mechanic workshops at different depths. Comparison of the results of the mechanic workshops and the control, shows that the mechanic workshops were moderately contaminated (polluted) which may be due to the anthropogenic waste generated from the workshops. The concentration of Cd ranged from 43.63mg/kg to 3.45mg/kg in settled dust samples. Also, the concentration of Pb ranged from 252.21 mg/kg to 105.88 mg/kg. The obtained results indicate various levels of dust pollution by these metals in the mechanic workshops and so calls for concern due to the health implications of these metals.
TABLE
OF CONTENTS
Title
page i
Declaration ii
Certification iii
Dedication
iv
Acknowledgements v
Table
of Contents vi
List of
Tables ix
List of
Figures x
List of
Plates xi
List of
Acronyms xii
Abstract
xiii
CHAPTER 1: INTRODUCTION
1.1 Background of the Study 1
1.2 Statement of the Problem 4
1.3 Aim and Objectives of the Research 5
1.4 Significance of the Study 5
1.5
Scope and Delimitation of the Research 6
CHAPTER 2: LITERATURE
REVIEW
2.1 Heavy Metals 8
2.2 Cadmium 8
2.2.1 Natural and anthropogenic sources of cadmium 9
2.1.1b Sources of cadmium in the environment 10
2.1.1c Effects of cadmium on human health 10
2.2.2 Lead 11
2.2.2a Natural and anthropogenic sources of lead 11
2.2.2b Sources of lead in the environment 12
2.2.2c Effects of lead on human health 13
2.3.3 Arsenic 14
2.3.3a Natural and anthropogenic sources of arsenic 14
2.3.3b Effects of arsenic in the environment 15
2.3.3c Effects of arsenic on human health 16
2.4.4 Mercury 17
2.4.4a Natural and anthropogenic sources of mercury 17
2.4.4b Effects of mercury in the environment 18
2.4.4c Effects of mercury on human health 19
2.5.5 Copper 21
2.5.5a Natural and anthropogenic sources of copper 21
2.6.6 Chromium 21
2.6.6a Natural and anthropogenic sources of chromium 22
2.6.6b Effects of chromium on human health 22
2.7 Behaviour of Heavy Metals in the Environment 23
2.8 Some Studies on Heavy Metals Contamination
on Soil and Settled Dust 25
2.9 Soil and Soil Profile 29
2.9.9a Soil 29
2.9.9b Soil profile 29
2.9.9c Soil horizons 30
2.10 Properties of Soil 32
2.10.10a Soil pH
32
2.10.10b Oxidation
and reduction in soil 33
2.10.10c
Electrical conductivity 33
CHAPTER 3: MATERIALS AND
METHODS
3.1 Study Area Description 34
3.2 Materials Used 36
3.3 Samples Collection 36
3.3.1 Collection of soil samples and treatment 36
3.3.2 Collection of dust samples 37
3.4 Samples Digestion Procedures 38
3.4.1 Sample digestion procedures for soil samples 38
3.4.2 Sample digestion procedures for dust Samples 38
3.5 Determination of pH 39
3.6 Determination of Electrical Conductivity 39
3.7 Preparation of Stock Solution 39
3.8 Preparation of Heavy Metals Standard
Solution for AAS 39
3.9 Atomic absorption Spectro Photometry (AAS)
Analysis 41
3.10. Statistical Method of Analysis 41
3.10.1.
Mean 41
3.10.2 Standard deviation 42
CHAPTER 4: RESULTS AND
DISCUSSION
4.1 Results 43
4.1.1 Distribution of metals in the soil from the
mechanic workshop
along with the Control 44
4.1.1.1
Cadmium (Cd): 44
4.1.1.2
Lead (Pb): 45
4.1.1.3
Arsenic and mercury: 45
4.2. Discussion 47
4.2.1. Heavy metals on soils 47
4.2.2. Effect of the auto mechanic workshops 53
4.2.3. Heavy Metals on settled dust 54
CHAPTER 5: CONCLUSION AND
RECOMMENDATIONS
5.1 Conclusion 60
5.2 Recommendations 61
References
Appendices
LIST
OF TABLES
2.1
Major health effects attributed to lead
explosive 13
2.2: Health
effects in environmentally exposed populations
attributed
to arsenic 16
4.1 The
Mean physico-chemical properties of the examined soils
in
the mechanic workshop along with the control. 43
4.2 Mean concentration of heavy metals
in soil of the mechanic
workshop
along with the control (Mg/Kg) 45
4.3 Mean
concentration of heavy metals in settled dust
from
the mechanic workshop (Mg/Kg) 46
4.4 Anova
table for Cd 56
4.5 Anova table for Pb 57
4.6 Anova
table for Cd in settled dust 58
4.7 Anova
table for Pb in settled dust 58
LIST OF FIGURES
2.1 Key processes that affect the speciation
and mobility
of mercury in aquatic environment. 19
2.2:
Routs of mercury explosive in humans. 20
2.3:
Behavior of heavy metals in the
environment 23
2.4:
A hypothetical model of the source of
occupational wastes
causing
soil pollution in mechanical villages. 24
2.5:
Diagram of soil profile 31
3.0: Map
of Ebonyi State showing Afikpo North L.G.A. 35
3.1:
Map of Afikpo showing sampling points
coordinates and distance 35
3.2: Grid map showing sampling points and
coordinates 37
4.1 A plot of mean values of pH 48
4.2 A plot of mean values of electrical
conductivity (EC) 49
4.3 A plot of mean values of cadmium (Cd) 51
4.4 A plot of mean values of lead(Pb) 51
4.5 A plot of overall mean (Cd and Pb) mechanic
workshops
against control mean (Cd and Pb) 53
4.6.
A plot of mean values of settled dust
for cadmium(Cd). 54
4.7.
A plot of mean values of settled dust
for lead(Pb). 55
LIST
OF PLATES
1 Collection of dust sample 38
LIST
OF ACRONYMS
ABMWS Abuja
Mechanic workshop
ABTMWS Abuja
Tipa mechanic workshop
NDMWS Ndubuise
mechanic workshop
EBMWS Ebiri
mechanic workshop
OHPS Ohabuike
primary school
Ss Some
of square
Ms Mean
square
Df Degree
of freedom
As Arsenic
Cd Cadmium
Hg Mercury
Pb Lead
CHAPTER
1
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Pollution is the introduction of contaminants into the natural
environment that causes adverse, change, instability, disorder, harm, or
discomfort to the ecosystem. The sources of pollution can be naturally or
anthropogenic occurring. Pollutants when occur naturally, are considered
contaminants when they exceed their natural levels (Almanac, 2010, Hill, 2010).
Pollution is a serious problem the world over in which millions of
world inhabitants suffer health related problems from waste generated from
anthropogenic activities. In recent years pollution has increased considerably
as a result of an increasing human activity such as burning of fossil fuels,
industrial and automobile exhaust emissions
(Amusan et
al., 2003, Kanchev et al., 2005).
These activities are identified to be introducing
a number of toxic metals into the environment (Amusan et al., 2003). Some of these harmful or toxic chemical compounds
that are released into the atmosphere or environment is carbon monoxide,
sulphur dioxide, carbon dioxide, and particulate matter, which include lead
from gasoline additives, zinc, copper and cadmium from tyreabrasion,
lubricants, and other industrial emissions (Kanchev et al., 2005). Heavy metalscontribute a greater part of these
harmful or toxic chemicals released into the environment.
Heavy metals are chemical elements mostly with density greater
than 4g/cm3 found in all kinds of soils, rocks and water in terrestrial and
freshwater ecosystems (Lacatusu, 1998, Duffus, 1980, Martin et al., 1982). They occur in typical
background concentrations in the ecosystem. They come from different sources in
urbanized areas; including vehicle emissions, industrial discharges and
manufacturing, and other activities (Harrison et.al.,1981, Alloway, 1990,
Thorton, 1990, Adentuji and Odetokun, 2011, Asamoah-Boateng,2009). Heavy metals
are simply metals or metalloids with a potential negative health effect or of
environmental concern. These elements include vanadium, iron, manganese, cobalt,
copper, zinc, selenium, strontium, lead, molybdenum, etc.
The release of heavy metals into air, water and soil is one of the
most significant environmental problems caused by anthropogenic activities such
as urban road construction, quarrying, agriculture, waste incinerations, sewage
disposal, auto-mechanic workshops, bush burning, etc. (Alloway, 1995, Akoto et al., 2008). Some of the well known or
most occurring toxic metallic elements with regards to potential hazards
incontaminated soils are; arsenic (As), cadmium (Cd), iron (Fe), mercury (Hg)
and lead(Pb) (Alloway, 1995). Their presence has been considered as useful
indicators for contamination in surface soil, sediments and dust environments
(Harrikumar et al., 2010).
Heavy metals are used in so many industrial applications as in the
manufacturing of batteries, alloys, electroplated metal parts, etc., with the
products find in our homes and actually add to our quality of life when
properly used. Nutritionally, trace quantities of some of these heavy metals
such as; iron, copper, manganese, and zinc are essential for a healthy life (infinitehealthresources.com).
Heavy metal pollutants are non-degradable and severely inhibit the
biodegradation of organic contaminants in the environment, and will becomes
threaten to humans and other biological life at any high levels upon acute and
chronic exposure (Tam and Wong, 2000,Yuan et al., 2004, Mohiuddin et al., 2010,
Brinkmann, 1994, Sheppard, 1998). Their accumulations not only contaminate the
surface environment but also contributes to air pollution, as they may become
airborne and eventually enter the drainage system to affect aquatic ecosystems.
In general, the presence of heavy metals in high concentrations in the environment
results in health hazards such as adverse effects of the nervous system, blood
formation, renal and reproductive systems. Others include; reduced
intelligence, attention deficit and behavioral abnormality, as well as its
contribution to cardiovascular diseases in adults and children (Adelekan and
Abegunde, 2011). For children, ingestion of contaminated soil is found to be
the most significant pathway into the body (Chaney et al., 1989, EPA, 1997).
According to Adewole and Uchegbu, (2010), auto-mechanic activities
are one of the major sources of heavy metal contamination of the ecosystem in
Nigeria. This could also be true for Ghana as a developing country since the
mode of activities in both countries is quite similar. Auto-mechanic workshops
are establishments offering miscellaneous repair services (Udebuani et al., 2010) ranging from simple and
fast oil change to complex engine rebuilding. They also provide body repair and
painting services. The operational processes by auto-mechanic workshops often
involve the use of highly toxic and hazardous materials such as solvents,
paints, and primers. It also involves battery charging, welding and soldering,
automobile body works, painting/spraying and etc.
Wastes from such activities include spent lubricants, worn-out
parts, metal scraps,stripped oily sludge and packaging materials (Loranger et al., 1994, EEA, 2007). The care finishing
process results in the improved look of the vehicle but generates hazardous wastes
that require appropriate disposal (Kostyantyn, 1997). Petrol, diesel, solvents,
grease, and lubricants can either be accidentally or deliberately released into
the environment.
As a result of frictional wear, the hydraulic fluids collect heavy
metal debris containing
Pb, Cd, Zn, Fe, Cu, etc. Usually an automobile waste will consist of auto body scraps
(Aland Zn), pieces of mild steel (Fe), electrical components and wires (Cu and
Pb). Many of these petroleum products are organic chemicals that can be highly
toxic and hazardous to soil, flora and fauna. The use of automobiles and its
repairs has generally led to heavy metals contamination in soil, which have
grave consequences for soil dwelling organisms(Adewoyin et al., 2013).
1.2 STATEMENT OF THE PROBLEM
Industrialization
in Nigeria is advancing at a fast rate. This has led to large increase in the
rate of urbanization and automobile mechanic village is also on the increase
due to the high level of car usage in Nigeria. Environmental pollution is on
the increase as a result of indiscriminate sitting of the automobile mechanic
village and motor park. Therefore, there are serious problems poised to the
environment and the health of humans. In Nigeria,
there are some information as applied to heavy metal pollution from
auto-mechanic workshops. The activities within the auto-mechanic workshops,
create the potential for the accumulation of heavy metals in the working
environment, near and far. These Auto-mechanic workshops are mostly located by
the road side, in the open and on bare soil.
The activities therein are done mostly in non-scientific ways.
Consequently, contaminants from fuel, lubricants, used batteries, etc. are
easily released into the environment. These contaminants have adverse effects
on soil, water and air quality in the general environment and even some
distance from the vicinity (Lacatusu, 1998; Ayodele and Abubakari,2001) of the
auto-mechanic workshops and poses health risk. It is therefore necessary to
determine pollution levels of heavy metals at auto-mechanic workshop sites. One
needs to also know the contributions from specific activities such as
auto-welding, auto-spraying, auto-electrical and auto-mechanical locations
within the auto-workshops. Assessment of health hazards will help established
the significance of environmental and health impact of heavy metals from
auto-mechanic workshops.
1.3 AIM AND OBJECTIVES OF THE RESEARCH
This
research work is concerned with the evaluation of heavy metals concentration in
the soil and settled dust of automobile mechanic workshops in Afikpo.
Some specific objectives
of this study are stated below:
1. To
determine heavy metals content of some soil samples obtained from certain
automobile mechanic workshops in Afikpo
2. To
determine the level of air born heavy metals from abandoned vehicles in the
automobile mechanic workshops studied.
3. To
statistically examine the relationship between the areas of research and
control site.
4. To contribute to the generation of data for the purposes of
regulations
5. To Make appropriate
recommendations.
1.4 SIGNIFICANCE OF THE STUDY
Heavy
metals pollution problems are in every nation around the globe and
contamination of land by these toxic metals has become a major public issue in
the world today. Therefore, this study will be significant in the following
ways;
-
It will help in producing
data about the toxic metalsin the various mechanic workshops under study
-
It will provide baseline
data that could be used to improve the health and safety of the environment
-
The information got from
this study would provide a basis for preventing further contamination and
provide some more scientific decontamination strategies.
-
The result of this study
shall guide as action plan towards the decontamination efforts of local
authorities and as well as the ministry of health
-
1.5 SCOPE AND
DELIMITATION OF THE RESEARCH
Out of the many auto-mechanic workshops within Afikpo, sampling
was done in four (4)auto-mechanic workshops. This was due to the fact that auto-mechanic
workshop owners were not ready to give permission to the researcher. The
research seeks to determine the heavy metal levels of soils and settled dust at
the auto-mechanic workshops and the health risk assessment associated with the
heavy metals. The period for sampling collection was from 3th February to 20th February,
2017. Fractionated size of 100 μm of the soil from the selected auto-mechanic
workshops were analyzed using atomic absorption spectrometry (AAS) technique.
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