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EZEOHA UCHENNA M.
PG/M.Sc/09/54149
THE EFFECTS OF SOLID WASTE ON THE QUALITY OF SOIL IN UGWUAJI DUMP SITE
ENVIRONMENTAL STUDIES
ENVIRONMENTAL MANAGEMENT AND CONTROL
Paul Okeke
Digitally Signed by: Content manager’s Name DN : CN = Webmaster’s name O= University of Nigeria, Nsukka OU = Innovation Centre
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CERTIFICATION
The work embodied in the project report is original and has not been
submitted in part or in full for any other degree of this University or
any other University to the best of my knowledge.
This is to certify that EZEOHA UCHENNA M. a postgraduate student
of the Centre for Environmental Management and Control with Reg
No: PG/M.Sc/09/54149 has satisfactorily completed the
requirements for project research in partial fulfillment of the award of
Masters of Science (M.Sc) in Environmental Management and control.
------------------------------- ---------------------------------- Student Supervisor ------------------------------ ------------------------------------ External Examiner Head of Department
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DEDICATION
I dedicate this work to my mother late Mrs. Rebecca N. Ezeoha who
wrestled life and sacrificed all even her life to sustain my choice. To
her wherever she may be I love you mum.
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ACKNOWLEDGMENT
I will be failing in my duty if I do not give my thanks to those who
have helped and encouraged me in upgrading myself. My thanks goes
to Prof. Ifeoma Enemo (the Deputy Vice Chancellor Enugu Campus),
Barr.Samuel Nwatu(Uncle sam), Barr E.U Onyeabor for giving me
some of the materials I used .I thank Dr. E.O Nwosu and Barr
Ogbuabor Anukenyi.
I gratefully acknowledge Dr. K.C Ogboi, my supervisor for giving
thorough reading and valuable comments even when it seems am
sliding.
I wish to express my sincere thanks and ever gratitude to my mum
late Lady Rebecca Ezeoha, my father Ozo N.O Ezeoha and my siblings
Ada and Ifeoma.
My heartfelt thanks goes to Nnedinnma, Chiamaka, Nonso, Nkiru
and Chukwudi for all your love and kindness. I acknowledge my
friend and brother Chimezie Ogenna Nwodo, Don Juan Salutations
Sir!
I thank Chukwuma Nnaji, Onyinye Egbo for carefully typesetting and
arranging this work. Thank you onyi!
To all that I cannot remember now I say thank you very much.
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ABSTRACT
Solid waste is a major environmental threat to most Nigerian cities. The rapid population growth, industrialization and technological changes and patterns have increased solid waste challenges. These factors and several others such as inadequate infrastructures, weak environmental administration and management are responsible for ineffective waste management strategies. In developing countries, large amount of waste are dumped daily in open dumping site without proper management. Urban industries, agricultural activities, hospitals household and market activities in Enugu city generate immense solid waste daily. To take care of these, the state government provided a site in 1992 at Ugwuaji for disposing and managing the wastes.
However the standards of the dumpsite and the management strategies fall short of environmentally accepted standards. Expectedly, the soil quality and aesthetic appearance of the entire area has been grossly affected. The interest in this study is to assess the quality of the soil in the dumpsite in terms of its functional ability to support the ecosystem.
To do this, this study examined the heavy metal concentration in the study sample. Six heavy metal considered to be hazardous to human and environmental health were chosen for analysis. These include Lead, Cadmium, Copper, Iron, Manganese and Nickel. The six elements were analyzed in soil samples using Atomic Absorption Spectrophotometer (AAS) machine at Ecochem scientific Laboratory. Targeted sampling method was used in the collection of the soil samples from the dumpsite. The sampling depth was about 170-200m deep into the ground.
The study revealed that the soil is heavily contaminated with Lead (Pb), Cadmium (Cd), copper (cu) Iron (Fe), Manganese and Nickel (Ni) with contamination factor as 19.89, 16.26, 25.06, 270.5, 245.25 and 1.20 respectively. These heavy metals are very high from the waste dump when compared with NESREA heavy metal threshold limit. Further findings in the study revealed that heavy metal pollutants in Ugwuaji dumpsite decreases as the distance increased.
From the study, it is recommended that more adequate and environmentally friendly methods of waste disposal like the sanitary landfill be used in dumpsites. Also, appropriate policies and legislation should be put in place to regulate solid waste disposal practices so as to prevent contamination of the environment, especially soil, around these dumpsites.
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TABLE OF CONTENTS
Title Page i
Certification ii
Dedication iii
Acknowledgements iv
Abstract v
Table of Contents vii
CHAPTER ONE: INTRODUCTION
1.1 Background of the study 1
1.2 Statement of the problem 3
1.3 Aims and Objectives 4
1.4 Research Questions 5
1.5 Scope of The Study 5
1.6 Limitations 6
1.7 Significant of the study 6
CHAPTER TWO
2.1 Conceptual Framework 8
2.2 The System Turns in Form of 11
CHAPTER THREE: LITERATURE REVIEW
3.1 Soil Definition and Components 13
3.2 Soil Quality 15
3.3 Soil Functions 15
3.4 Soil Degradation Threat 16
3.5 The Concept of Soil Sustainability 17
3.6 Soil Forming Factors 17
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3.7 Soil Properties and Processes 21
3.8 Processes Controlling Chemical Fate in Soil 25
3.9 Soil Classification 28
3.10 The Mechanism of Nutrient Uptake 36
3.11 Uses of Soil 37
3.12 Soil Degradation 37
3.13 Health Effects 39
3.14 Ecosystem Effects on Soil 40
3.15 Heavy Metal Contamination 42
3.16 Laws and Conventions on Soil 47
CHAPTER FOUR: STUDY AREA
4.1 Brief History 50
4.2 Climatic Condition 51
4.3 Ugwuaji 53
CHAPTER FIVE: RESEARCH METHODOLOY
5.1 Introduction 55
5.2 Sample Size And How It Was Obtained 56
5.3 Sampling Techniques Used 57
5.4 Method of Data Collection 57
5.5 Method Of The Analysis 58
5.6 Experimental Procedure 58
5.7 Analytical Techniques 59
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CHAPTER SIX: DATA ANALYSIS, INTERPRETATION AND
DISCUSSION OF FINDINGS
6.1 Data Presentation 62
6.2 Data Analysis And Interpretation 64
6.3 Discussion of Findings 67
CHAPTER SEVEN: RECOMMENDATIONS AND CONCLUSION
Conclusion
References
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CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND OF STUDY
Solid waste is a major environmental threat to most Nigerian cities.
The rapid population growth, industrialization and technological
changes and patterns have increased solid waste challenges. These
factors and several others such as inadequate infrastructure, weak
environmental administration and management are responsible for
ineffective waste management services.
Solid waste generation and management are processes dependent
upon a number of factors. These factors are human, population,
economic growth of the society and her citizens, level of technological
development of the society, culture and habit of the citizens. The
generation of solid waste is one such problem created by rapid
population growth coupled with inefficient waste disposal technique
and worsened by inconsistent waste management policies.
Ojiaku (1994) reported that uncontrolled solid waste disposal on land
contaminate the soil and is highly related to health hazard,
consequently requires adequate mitigation measures.
Due to improvement of quality of life of Nigerians from the 1970's an
attitude of robust appetite for the consumption of all sorts of
artificially packaged food manufactured locally and abroad and the
increased industrial, clinical, agricultural and manufacturing
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activities brought about an increase in the generation of solid waste in
Nigeria.
Government, private firms, individuals, industries and market people
are experiencing difficulty in their commitment to control the degree
or amount of solid waste generated in Nigeria and ensure adequate
and efficient management of generated wastes. These bodies
mentioned have only paid lip services to the problem of solid waste
generation and its possible or more efficient way of managing such
waste to reduce or avoid its impact mostly on the quality of soil. Solid
waste has been creating unsightly condition especially in Enugu
urban where it has been a source of worry.
The environment of the city including it's streams, rivers and soil has
become a dumping site for solid waste. One could easily see the
menace of solid waste on the soil in the study area and it's far
reaching effects on the soil quality and human health. This soil may
show very high concentration of heavy metals as well as high nitrate
and nitrite concentration. The unending case of dumping solid waste
on the soil without proper management may eventually pollute and
degrade the soil.
The waste comprises of degradable and non-degradable materials like
kitchen waste, empty cans, textile materials, hospital waste, chemical
lumps from industries and factories, brewery wastes among others are
seen in many dumpsites.
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It is this callous attitude or feeling of (individual habit, improper
management, I don't care attitude) “after all it is not at my backyard”;
the concern for the health of the people and crop yield by ensuring
good, safe and quality soil for agriculture that gave rise to this
research work. The study is geared towards comparing and carrying
out a systematic soil quality examination and looking into the effect of
solid waste on soil quality in Ugwuaji area as well as examination the
parameters of soil pollution.
1.2 STATEMENT OF THE PROBLEM
Urban industries, agricultural activities, hospitals, household and
market activities in Enugu city generate immense solid waste daily.
Enugu state government provided a site in Ugwuaji for disposing and
managing the waste. The Ugwuaji area is an open dump located in the
outskirt of Enugu city. The management processes include
transportation and disposal of solid waste. The site has been in use
since 1992, but unfortunately the standards required of the Ugwuaji
site and its management strategies have not been met thus making
this study crucial. Dumping of all categories of waste and discharging
of sewage improperly on the site now pollutes the soil and defaces the
aesthetic value of the area. This stands out as a problem that needs
urgent research and implementation procedure.
Wastes are being disposed recklessly on the site without adequate
management and concern for the environment. Due to the
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uncontrolled dumping and disposal of solid waste in Ugwuaji site and
lack of expected management of solid waste in the area, it is expected
that the soil quality has been adversely affected. This project examines
the effects of solid waste on heavy metal
It is believed that the problem of improper solid waste management
might have affected the soil n the surrounding areas of ugwuaji site.
Thus there is an urgent need to investigate the effects on soil, the
extent to which it has reduced the soil quality in the area and other
cognate effects it posses to the environment. In line with the foregoing,
the challenge before the researcher is an empirical one. It entails
examining the impact of solid waste on the quality of soil in Ugwuaji
area and the remedial processes to be employed.
1.3 AIM AND OBJECTIVES
The aim of this study is to examine the effects of solid waste on
the quality of soil in Ugwuaji dump site. To achieve this, the following
objectives were addressed.
(i) To examine the level of various heavy metals found in soil
samples around the dumpsite
(ii) To determine the relationship between the levels of the various
heavy metals and distance from the dumpsite
(iii) To compare the heavy metal concentration in the dumpsite to
the NESREA threshold limit
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1.4 RESEARCH QUESTIONS
i. Are the selected heavy metals for investigation present in the
soil of the dumpsite?
ii. Does heavy metal concentration in the dumpsite differ from the
NESREA threshold limit?
iii. Does the effect of Heavy metals found in the dumpsite differ
with distance?
HYPOTHESIS
1. The concentration of heavy metals in soil of ugwuaji dump does
not differ with distance from the dumpsite.
2 There is no significant difference between heavy metal
concentration in the dumpsite and NESREA threshold limit
1.5 SCOPE OF THE STUDY
The study assessed the impact of solid waste on soil quality in
Ugwuaji dumpsite. It entailed carrying out laboratory investigations
on soil quality. To test the parameters affected by solid waste in
different soil samples within Ugwuaji dumpsite which is the study
area.some selected heavy metals were investigated to know the extent
of deposit on the soil which are Lead, Cadmium, Copper, Iron,
Manganese and Nisckel.
The study also looked at the soil quality standards for habitat and
agriculture, as well as for other land uses.
The collection of samples is limited to Ugwuaji dumpsite. The Enugu
agricultural soil was used as a control site while Ugwuaji soil was
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used as experimental site because of the bulk of solid waste deposited
on the soil of Ugwuaji dumpsite area. Hence the study was aimed at
determining the various pollutants in soil and comparing them with
NESREA threshold standards.
1.6 LIMITATIONS
This study was confined to the assessment of only six metals
considered to be lethal to human health and environment. This
restriction stem from the huge financial involvement and dearth of
specialized equipment needed to do some of the analysis and test
other heavy metals. For example atrazine analysis requires a costly
equipment which is beyond the means of the researcher.
1.7 SIGNIFICANCE OF THE STUDY
This study is consciously aimed at looking into the effect or impact of
solid waste on the quality of soil; its effects on the health of residents,
crop production, protection of the environment and the biodiversity
caused by improper disposal of solid waste.
Furthermore, the study will establish traces of effect, treatment
procedures, best disposal methods and permissible quality content as
recommended by W.H.O and other standard regulatory body(ies).
The study is significant because it will also bring awareness to the
public (Enugu urban and environs) the implications of reckless
disposal of solid waste, the effects of solid waste on soil quality and
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health and the proffered recommendations will go a long way in
designing appropriate solid waste management methods by eswama.
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CHAPTER TWO
2.1.1 CONCEPTUAL FRAMEWORK
A number of conceptual frameworks or concepts which are important
in soil pollution by solid waste and its effects on soil quality would be
addressed. For purposes of this research, concepts like the hydrologic
concept, hydro-geopollution, system thinking and externalities were
discussed. It explains either graphically or in a narrative form, the
main things to be studied-key factors, concepts and the presumed
relationship among them. The concept behind this research work is
developed within the hydrologic cycle, and the hydro-geopollution
cycle Egboke et al; (1989.) These two theories are inter related and
influence one another.
According to Hutchison and Ridgeway (1975), “The hydrologic cycle is
an obvious mode of transmission of enteric disease. Whenever or
whatever form it assumes, every drop of the world's water is locked up
into the hydrologic cycle”. What happens to one area affects the other.
Some of the evaporated water is turned as precipitation, part of
which rapidly evaporates back into the atmosphere, some drain into
lakes, streams, while some equally infiltrate into the soil.
Another concept which will be relevant in discussing this topic is the
hydro-geo pollution cycle. Rain carries pollutants into surface water
for possible evaporation back into the atmosphere or storage in rivers
and seas. Some of the fallouts infiltrate into the soil. Here, the
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moisture joins a complex hydrodynamic flow system to be transported
to the oceans or other surface water where evaporation may return the
water to the atmosphere. This process or cycle transports pollutants
from one point of the soil to other. While observing this concept.
(hydro-geo pollution). (Egboka et al 1989) explained these
pollutants/contaminants cyclic movement in the soil as hydro-
geopollution. This concept is simply interpreted when solid waste is
dumped in a particular point, one observes that it is being transported
from that point to another contaminating an area of the environment.
Pollutants and contaminants may be generated through natural or
anthropogenic (study of mankind) processes and circulated in the
environment ie biosphere, atmosphere. (Ajiwe et al, 2006).
The pollution at a point source or distribution source may spread and
threaten the public health of nearby and distant places unless its
spread is checked and controlled.
The concept of externalities is relevant in discussing the topic.
Externality is something that while it does not monetarily affect the
producer of good, does influence the standard of living of society as a
whole. Economic externality referred to as spill over, exists whenever
one individual action affect the well being of another. Water pollution
by industries that add poisons to the water, which harm plants,
animals, and humans is a negative externality from industries.
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Though there may be positive externalities, we are much concerned
with the negative externalities which are more common. Pollution is a
very common negative externality. A company that pollutes loses no
money in doing so, but society must pay heavily to take care of the
problem caused by pollution. The problem is that companies do not
fully measure the economic cost of their action.
In the case of industries, hospitals and clinics, it has been noted that
practically all stages and operations from production are accompanied
by undesirable waste generation (solid waste). The undesirable
generation (externalities) of these waste become a spill-over on the
dumpsite. In this case, the environment and soil are affected.
The whole concept is diagrammatically represented in fig .11
System thinking is the human way of viewing the holistic entity of the
environment and deducing some thoughts out of it. (Ezeoha, 2012). It
can be described or interpreted in this form. Soil pollution is one of
the gravest problems existing on earth today. The earth and soil are
getting contaminated and polluted. Soil pollution is as a result of
many activities by mankind which end up contaminating the soil.
Such activities include industrial wastes, agricultural waste, improper
dumping of waste and poor waste management procedures.
Dumping of wastes like agricultural, industrial, garbage and domestic
wastes at ugwuaji dumpsite could release some toxins to the soil. The
toxins from the different wastes react and deposit on the soil.
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Plants/crops grow on the soil and the end product say “maize” is
produced. The plant absorbs those toxins and stores them.
Humans consume the maize and their heath is affected. Soil
contaminated by these pollutants such as heavy metals from
agricultural and Industrial wastes will produce unhealthy food. Heavy
metals enter the food chain and are consumed by humans. A
phosphate fertilizer which contains some amount of cadmium and
lead affects the human health.
Consequently, presence of such heavy metals have caused a
decrease in production of farm yields.
2.2 SOIL DEFINITION AND COMPONENTS
Soil is a natural body that consists of layers, composed primarily of
minerals, which differ from their parent materials in their texture,
structure consistency, color, chemical, biological and other physical
characteristics Soil is the end product of the influence of climate
(temperature, precipitation) relief (slope), organisms (flora and fauna),
Parent materials (original minerals) temperature and time. (Brady
1999).
Soil is referred to as regolith or loose rock material. Soil is altered from
its parent materials by the interactions between the lithosphere,
hydrosphere and biosphere. It is a mixture of mineral and organic
materials that are in solid gaseous and aqueous states. Soil forms a
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structure filled with pore spaces that can be thought of as a mixture
of solids water and air. Accordingly soils are often treated as a three
state system. Most soil have a density between I and 2g/cm3.
On a volume basis a good quality soil is one that is 75% minerals
(sand, silt, clay, 25% water, 25% organic material) .The mineral and
organic components are considered constant while the percentages
of water and air are the only variable parameters where the increase
in one is balanced by the reduction in the other.
Given time the simple mixture of sand, silt and clay will evolve into a
soil profile that consists of two or more layers called horizons that
differ in one or more properties such as texture, structure, color,
porosity, consistency and reaction. The pore space of soil is shared by
gases as well as water. The aeration of the soil influences the health
of the soils flora and fauna and the emission of greenhouse gases.
Of all the factors that influence the evolution of the soil, water is the
most powerful due to its effect on the solution and precipitation of
minerals, plant growth, the leaching of minerals from the soil profile
and the transportation and deposition of the very materials of which
soil is composed.
Soil colloidal particles (clay and humus) behave as a repository of
nutrients and moisture and buffer the variations of soil solution
ions”. Colloids act to store nutrients that might be leached and to
release those ions in response to soil pH. (Woodward 1984).
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Soil pH is a measure of the hydrogen ion (acid forming). Soil reactivity,
is a function of the soil materials, precipitation level and plant root
behavior. Soil PH affects the availability of nutrients.
2.3 THE CONCEPT OF SOIL SUSTAINABILITY
Sustainable soil use refers to the use of soil as a natural resources on
a way that does not exert any negative effects- that are irreparable
under rational conditions- either on the soil itself or any other
systems of the environment (Toth 2003, 2004).
The Alteration of soil characteristics by human impact may change
functional ability of the soil. The maintained, improved or degrade
quality thus depends on the human impact and soil characteristics
from the perspective of the soil function of interest.
Long term influence of human impact (by land use change,
degradation effects) on the ecological conditions of soil as well as the
seasonal soil use operations (drainage, cultivation, irrigation etc)
modify material and energy flow. When these process are traceable,
controllable, soil use and soil quality remains sustainable in long run.
(Brown. et al 1987).
2.4 SOIL FORMING FACTORS
Soil formation or pedogenesis is the effect of physical, chemical,
biological and anthropogenic processes on soil parent material. Soil
generics involve processes that develop layers or horizons in the soil
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profile. These processes involve additions, losses, transformations and
translocation of material that compose the soil. The alteration
and movement of materials within soil causes the formation of
distinctive soil horizons.
How the soil life cycle proceeds is influenced by at least five classic
soil forming factors that are dynamically intertwined in shaping the
way soil is developed: parental material, climate, topography (relief),
organisms and the passage of time. (Hans Jenny 2005).
(i) Parental Material: The material from which soil is formed is
called the parental material. Rock whether its origin is igneous,
sedimentary or metamorphic is the source of all soil mineral
materials. The formation of soil is dependent on their
transportation and deposition and the physical and chemical
weathering as original minerals are transformed into soil.
Typical soil minerals are
Calcite CaCo3
Quartz Sio2
Feldspar: KAIS; 3O8\Mica (biotite) K (Mgfe)3Alsi3O10(OH)2
Parental material may be classified according to how they came to be
deposited in place. They are Residuals: materials weathered in place
from primary Bedrock; transported material are these been deposited
by water, wind, ice, granit and cumulse material is organic matter
developed and accumulated in place.
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Cumulose parent material originates from deposited organic material
and includes peat and muck soils and results from plant residues that
have been preserved by low oxygen content of a high water table.
The parental materials weather in form of
(a) Physical disintegration: The first stage in the transforming
into soil material may result from the freezing of absorbed
water, causing the physical splitting of material, along a path
towards the centre of the rock. While temperature gradients can
cause exfoliation of shells of rock. Cycles of wetting and drying
cause soil particles to grind into finer particles or size as well
does the physical rubbing of material caused by water and
gravity.
(b) Climate is the dominant factor in soil formation, and soils show
the distinctive characteristics of the climate zone in which they
form. Mineral precipitation and temperature are the primary
climate influences on soil formation. The direct influence of
climate includes.
A shallow accumulation of line in how rainfall areas as caliche
• Formation of acid soils in humid areas
• Erosion of acid soils in humid areas
• Erosion of soils on steep hillsides
• Deposition of eroded materials downstream.
• Very intense chemical weathering, leaching and erosion in warm
and humid regions where soil does not freeze.
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Climate directly affects the rate of weathering and leaching. Soil is
said to be formed when detectable layers of clays, organic colloids,
carbonates, or soluble salts have been moved downward.
Wind moves sand and smaller particles, especially in arid regions
where there is little plant cover. The type and amount of precipitation
influence soil formation by affecting the movement of ions and
particles through the soil and aid in the development of different soil
profile. Soil profiles are more distinct in wet and cool climates, where
organic materials may accumulate, than those in wet, warm climates
where organic materials are rapidly consumed the effectiveness
of water in weathering parent rock materials depends on seasonal and
daily temperature fluctuations ( Hans, 2005 ).
Cycles of freezing and thawing constitute an effective mechanism that
breaks up rocks and other consolidated materials.
Climate indirectly influences soil formation by the effect of vegetation
covering biological activity, hence the rates of chemical reactions in
the soil.
2.4.1 Topography
The topography or relief characterized by the indication of the surface
determines the rate of precipitation runoff and rate of formation and
erosion of the surface soil profiles. Steep slopes allow rapid runoff and
erosion of the top soil profile and little mineral deposition in lower
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profiles. Depressive allow the accumulation of water, minerals and
organic matter and in the extreme. The resulting soils will be saline
marshes or peat bogs. Intermediate topography affords the best
conditions for the formation of an agriculturally productive soil
(Nwaka,1995).
2.4.2 Time
Time is a factor in the interaction of all the above over time soils
evolve features dependent on the other forming factors. Soil formation
is a time responsive process that is dependent on how other factors
interplay with each other. Soil is always changing ( Wenzel, ) it takes
about 800-1000yrs for a 2.5cm thick layer of fertile soil to be formed
in a nature. For example, recently deposited material from a flood
exhibits no soil development because there have not been enough time
for the further disintegration of soil. Over a period of time from
hundreds to thousands of years the soil will develop a profile that
depends on the intensities of biota and climate (ibid)
2.5 SOIL PROPERTIES AND PROCESSES
Soil is a key component of the terrestrial ecosystem and is necessary
for the growth of plants. It is a three phase system comprising of solid
particles, which is basically the minerals and the organic matter, gas
which is a mixture of air and the volatile chemicals and liquids which
are made up of the soil solution and the immicible fluids (Jones and
Ghassemi, 1994).
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Soil is formed by the breakdown of large rocks to fine particles that
have greater surface areas. This breakdown is due to physical and
chemical processes. The soil formation processes is an interaction of a
number of factors namely, micro-organism, climate, topography,
parent material and time. The soil formation process releases plant
nutrients. In the early stages of soil formation, a number of soil
nutrients will be in deficiency. The major nutrients that are generally
in short supply of this stage are carbon, nitrogen, phosphorus and
sulphur. Since micro -organism play a critical role in the soil
formation process, the initial colonizers of the soil are the micro-
organisms that are capable of photosynthesizing, nitrogen fixing and
also capable of releasing nitrogen and sulphur from soluble forms.
The cyanobacteria, also known as blue-green algae are the most
predominant type and is involved in the microbal weathering of the
rocks into smaller particles. The establishment of vegetation lead to a
dynamic mixture of living and dead cells, soil organic matter and
mineral particles (Skidah and Irvine, 1998).
2.5.1 Soil Structure
The common definition of soil is the earth's surface layer that is
exploited by plants for their survival and growth. Soil is a three phase
system that comprises solid materials, air and solid liquids and a
complex heterogeneous medium. The mineral particles are of various
chemical composition and sizes. The other constituents include the
living population, plant roots and decomposing organic matter. Soil
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pore water, soil gases and dissolved materials complete the
composition of the soil. The major gases that are found in the soil are
these gases that are normally found in the outside atmosphere namely
nitrogen, oxygen and carbon dioxide. There are physical forces such
as drying, shrink-swell, freeze -thaw, root growth, compaction and
animal activity that act on the soil. These forces mould the soil into
aggregates and the structure of the soil is thereby defined. (Sikdah
and Irvine, 1998).
2.5.2 Key Soil Parameters
Soil pH
The soil pH refers to the hydrogen ions concentration that is in
dynamic equilibrium with negatively charged particles of the soil
particles. The chemical behavior of the contaminants especially
inorganic contaminants such as heavy metals is strongly dependent
on the soil pH of the body which they are to be extracted from (Jones
and Ghassemi, 1994). Normally, high soil pH or high alkalinity
hinders the mobility of heavy metals in the soil hence soils with high
pH are difficult to wash for heavy metal removal. Extreme pH ranges
negatively affects the effectiveness of in exchange and flocculation
processes. These extreme conditions also affect the microbial diversity
and activity by changes in the redox protentials that occur in the soil
(Jones and Ghassemi, 1994).
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2.5.3 Redox Conditions
Reduction - oxidation reactions are crucial in explaining both the
chemical and biological phenomenon that happens in the soil. The
redox equilibriums are controlled by the aqueous free - electron
activity that can be expressed as the Eh value. Large positive values of
Eh favour the existence of oxidized species while low values favour
the existence of reduced species. Redox conditions, together with the
pH are used to predict the dissolution behavior of metals through the
use of potential - pH diagrams (Habashi, 1999).
2.5.4 Moisture Content
Moisture content is the amount of water in the soil. The water is
available in the soil as water in the pores of the soil. Moisture content
is an important parameter because it affects the soil aeration, the
amount of water available to micro-organisms and the pH of the soil
solution. Water gets into the soil through three processes i.e the most
common way is rain or irrigation. The water is drawn into the soil by
gravity. This type of water is called gravitational water. As soon as it
drains out of the soil, the soil at that particular moisture content is
termed to be at its field capacity.
The second type of soil water is the hygroscopic water. This is when a
dry soil absorbs water from the outside atmosphere that is at a higher
humidity than the soil. Lastly, capillary water is the water available to
plants and microbial growth and is found in the pores of the soil.
29
Moisture content has been found to affect both soil washing and
bioremediation processes (Skidah and Irvine 1998).
2.5.5 Particle Size Distribution
This may be defined as percentage fraction of the different size ranges.
Soil particle size distribution is an important parameter in many
treatment technologies (Bhandan et al., 1994)
2.6 PROCESSES CONTROLLING CHEMICAL FATE IN SOIL
There are three important soil processes that control the distribution
and the form/nature of the chemicals in the soil namely biological,
chemical and physical processes. Biological processes obviously
involve the intervention of the soil micro-organisms with the
chemicals,chemical processes control the speciation and phase
distribution of the chemicals and lastly, physical processes controls
the movement of chemicals and liquids through the soil making them
a very important parameter in leaching (soil washing) process (Jones
and Ghassemi, 1994). A brief description of these processes will be
attempted.
2.6.1 Biological Processes
Apart from causing diseases to humans, micro-organisms,
particularly bacteria, actinomycetes, and fungi are responsible for a
number of important processes that happen in the soil. It is a known
fact that micro-organism are really important. They are responsible for
fixation of nitrogen into the soil that ensures plant growth. The micro-
30
organisms are also responsible for mineralisation and immobilization
of organic and inorganic plant nutrients. Apart from taking part in the
supply of essential nutrients to the plant, the micro-organisms also
play a sufficient role on the physical parameters of the soil such as
density, structure and porosity (Jones, and Ghassenin, 1994). The
chemical transformations that are achieved from microbial activity are
generally as a result of the search for energy and carbon sources by
the micro-organisms in order to build biomass.
2.6.2 Chemical Processes
The soil contains a complex mixture of chemicals and together with
the physical environment creates conditions that encourage a wide
variety of chemical reaction to occur. The processes can be categorized
into five group namely chemical degradation/transformation,
oxidation/reduction, solubility reactions, volatilization and
absorption/desorption (Jones and Ghassemi, 1994).
Oxidation/reduction reactions are probably the most important
reactions in the soil as far as soil washing is concerned. The oxidation
states affects the species present in solution and that affects
absorption and solubility reactions (Jones and Ghassemi, 1994).
Manganese is one of the many metals whose solubility depends on the
oxidation state. The redox states of the soil is dependent on the soil
properties that control the aeration and oxygen supply such as
moisture content porosity and texture (Jones and Ghassemi 1994).
Solubility processes involve the formation of solid phase compounds
31
that precipitate in the soil. It requires relatively more time and large
volumes of lixiviants to leach precipitates as compared to completely
soluble compounds. Chelating agents can be used to leach out the
metals.
The soil matrix has the ability to absorb chemical either from the gas
or liquid phase. Chemical absorption is simply the association of the
chemical with the solid phase thereby being removed from the liquid
or gaseous phase. Absorption occurs at the interface between the solid
and liquid/gas phase. The absorption capability of a soil comes from
the presence of functional groups at the surface of the soil particles.
These functional groups attract the changed ions in the soil solution.
Absorption is a competitive process and the ions compete for the
absorption sites (Jones and Ghassemi, 1994).
2.6.3 Physical Processes
Physical processes generally affect the transport of mass and energy
through the soil. The relevant physical processes are soil aeration and
heat flow, water storage and drainage and lastly solute transport. Soil
aeration affects soil washing and bioremediation processes because
oxygen supply affects the performance of micro-organisms and the
redox status of the soil. Chemicals are transported through the soil in
the vapour vase by diffusion and convection. Liquid phase diffusion
can be used to estimate the long term migration potential of a waste
from a dump site. Unfortunately, the diffusion is so slow that it
cannot be used in soil washing (Jones and Ghassemi, 1994).
32
2.7 SOIL CLASSIFICATION
Soil is generally classified by their particle size distributions. Particles
with the size range 0.05mm to 1mm are classified as sands, silts
range from 0.05 to 0.002 and clays below 0.002mm (McKinney 2004).
Other soils are also defined by the composition by the clay, silt and
sand. For example, a sandy loam is a soil that contains more of clay
and silt than sand and loamy sand contained more sand than clay
and silt.
2.7.1 Soil Structure
The clumping of the soil textural components of sand, silt and clay
forms aggregates and the further association of those aggregates into
larger units forms soil structures called peds. The adhesion of those
soil components by organic substances, iron oxides, carbonates, clays
and silica, and by the breakage of those aggregates due to expansion-
contraction, freezing-thawing, and wetting-drying cycles forms soil
into distinct geometric forms. These peds evolve into units that may
have various shapes, sizes and degrees of development. A soil clod is
not a ped but rather a mass of soil that results from mechanical
disturbance. The soil structure affects aeration, water movement,
conduction of heat, resistance to erosion and plant root growth. Water
has the strongest effect on soil structure due to its solution and
precipitation of minerals and its effect on plant growth. (Marshall &
Holmes, 1979).
33
Soil structure often gives clues to its texture, organic matter content,
biological activity, past soil evolution, human use, and chemical and
mineralogical conditions under which the soil formed. While texture,
is defined by the mineral component of a soil and is an innate
property of the soil and does not change with agricultural activities,
soil structure can be improved or destroyed by our choice and timing
of farming practices.(Young & Young, 2001)
2.7.2 Density
Density is the weight per unit volume of an object. Particle density is
the density of the mineral particles that make up a soil i.e. excluding
pore space and organic material. Particle density averages
approximately 2.65 g/cc (165 lbm/ft3). Soil bulk density, a dry weight,
includes air space and organic materials of the soil volume. A high
bulk density indicates either compaction of the soil or high sand
content. The bulk density of cultivated loam is about 1.1 to 1.4 g/cc
(for comparison water is 1.0 g/cc). A lower bulk density by itself does
not indicate suitability for plant growth due to the influence of soil
texture and structure (Bear 1972).
2.7.3 Porosity
Pore space is that part of the bulk volume not occupied by either
mineral or organic matter but is open space occupied by either air or
water. Ideally, the total pore space should be 50% of the soil volume.
The air space is needed to supply oxygen to organisms decomposing
organic matter, humus and plant roots. Pore space also allows the
34
movement and storage of water and dissolved nutrients.(Brady & Neil
1999).
There are four categories of pores:
Very fine pores: < 2 microns
Fine pores: 2-20 microns
Medium pores: 20-200 microns
Coarse pores: 200 microns-0.2 mm
In comparison, the root hairs are 8 to 12 microns in diameter. When
pore space is less than 30 microns, the forces of attraction that hold
water in place are greater than those acting to drain the water. At that
point, soil becomes water logged and it cannot breathe. For a growing
plant, pore size is of greater importance than total pore space. A
medium textured loam provides the ideal balance of pore sizes. Having
large pore spaces that allow rapid air and water movement is superior
to smaller pore space but has a greater percentage pore space. Tillage
has the short term benefit of temporarily increasing the number of
pores of largest size but in the end those will be degraded by the
destruction of soil aggregation (ibid).
2.7.4 Temperature
Soil temperature regulates germination, root growth and availability of
nutrients. Soil temperatures range from permafrost at a few inches
below the surface to 38 C (100 F) in Hawaii on a warm day. The color
of the ground cover and insulating ability has a strong influence on
soil temperature. Snow cover and heavy mulching will reflect light and
35
slow the warming of the soil, but at the same time reduce the
fluctuations in the surface temperature.
Most often, soil temperatures must be accepted and agricultural
activities adapted to them to:
i. Maximize germination and growth by timing of planting.
ii. Optimize use of anhydrous ammonia by applying to soil below
10 C (50 F).
iii. Prevent heaving and thawing of frosts from damaging shallow
rooted crops.
iv. Prevent damage to soil by freezing of saturated soils.
v. Improve uptake of phosphorus by plants.
Otherwise soil temperatures can be raised by drying soils or using
clear plastic mulches. Organic mulches slow the warming of the soil.
2.7.5 Soil Color
Soil color is often the first impression one has when viewing soil.
Striking colors and contrasting patterns are especially noticeable.
Color is determined by organic matter content, drainage conditions,
and the degree of oxidation. Soil color, while easily discerned, has
little use in predicting soil characteristics. It is of use in distinguishing
boundaries within a soil profile, the origin of a soil's parent material,
as an indication of wetness and waterlogged conditions, and as a
qualitative means of measuring organic, salt and carbonate contents
of soils. Color is recorded in the munsell color system as for instance
10YR3/4 (Brady Nyle & Ray R. Weil 2006).
36
Soil color is primarily influenced by soil mineralogy. Many soil colors
are due to various iron minerals. The development and distribution of
color in a soil profile result from chemical and biological weathering,
especially redox reactions. As the primary minerals in soil parent
material weather, the elements combine into new and colorful
compounds. Iron forms secondary minerals with a yellow or red color,
organic matter decomposes into black and brown compounds, and
manganesse, sulphur and nitrogen can form black mineral deposits.
(Ibid)
2.7.6 Soil Water
Water affects soil formation, structure, stability and erosion but is of
primary concern with respect to plant growth. Water is essential to
plants for four reasons:
i. It constitutes 85%-95% of the plants protoplasm.
ii. It is essential for photosynthesis.
iii. It is the solvent in which nutrients are carried to, into and
throughout the plant.
iv. It provides the turgidity by which the plant keeps itself in proper
position at lower levels, and possibly leaving the soil sterile in
the case of extreme rainfall and drainage.
In a loam soil, solids constitute half the volume, air one-quarter of the
volume, and water one-quarter of the volume of which only half of that
water will be available to most plants.
37
2.7.7 Water Retention Forces
Water is retained in a soil when the adhesive force of attraction of
water for soil particles and the cohesive forces water feels for itself are
capable of resisting the force of gravity that tends to drain water from
the soil. When a field is flooded, the air space is displaced by water.
The field will drain under the force of gravity until it reaches what is
called field capacity at which point the smallest pores are filled with
water and the largest with water and air. The total amount of water
held when field capacity is reached is a function of the specific surface
area of the soil particles. As a result, high clay and high organic soils
have higher field capacities. The total force required to pull, or push
water out of soil is given the term suction and usually expressed in
units of bars (105 pascal) which is just a little less than one-
atmosphere pressure. Alternatively, the terms tension or moisture
potential may be used.
2.7.8 Soil Atmosphere
The atmosphere of soil is radically different from that of the
atmosphere above. The consumption of oxygen by microbes and plant
roots and their release of carbon dioxide decreases oxygen and
increases carbon dioxide concentration. Atmospheric CO2
concentration is 0.03% but in the soil pore space it may range from 10
to 100 times that level. In addition the void is saturated with water
vapor. Adequate porosity is necessary not just to allow the penetration
of water but also to allow gasses to diffuse in and out. Movement of
38
gasses is by diffusion from high concentrations to lower. Oxygen
diffuses in and is consumed and excess levels of carbon dioxide,
which can become toxic, diffuse out with other gasses as well as
water. Soil texture and its structure strongly affects soil porosity and
gas diffusion. Platy and compacted soils impede gas flow and a
deficiency of oxygen may encourage anaerobic bacteria to reduce
nitrate to N2, N2O, and NO, which is then lost to the atmosphere.
Aerated soil is also a net sink of methane CH4 but a net producer of
greenhouse gases when soils are depleted of oxygen and subject to
elevated temperatures.
2.7.9 Soil Reaction (pH)
Soil reactivity is expressed in terms of pH and is a measure of the
acidity and alkalinity of the soil. More precisely, it is a measure of
hydrogen ion concentration in an aqueous solution and ranges in
value from 0-14 (acidic to basic) but practically speaking for soils, Ph
ranges from 3.5 to 9.5 as pH values beyond those extremes are toxic
to life forms.
It has been shown that the lower the pH, the greater the percentage
removal of metallic contaminants from the soil (Semer and Reddy,
1995) Neale et al. (1997) and du plessis (2006), managed to show that
the recovery of metal increased as the pH is lowered. However,
extreme pH ranges are not desired as they hinder ion exchange and
flocculation processes.
39
Plants differ in their nutrient needs and the effect of pH is to remove
from the soil or make available certain ions. High acid soils tend to
have toxic amounts of aluminum and manganese. Plants that need
calcium need moderate alkalinity but most minerals are more soluble
in acid soils. Soil organisms are hindered by high acidity and most
agricultural crops do best on mineral soils of pH 6.5 and organic soils
of pH of 5.5.
In high rainfall areas, soils tend to acidity as the basic cations are
leached away by rain allowing the soil colloids to become saturated
with hydrogen ions from naturally acid rain leaving the soil sterile.
2.7.10 Soil Nutrients
There are sixteen nutrients essential for plant growth and
reproduction. They are carbon, hydrogen, oxygen, nitrogen,
phosphorus, potassium, sulfur, calcium, magnesium, iron, boron,
manganese, copper, zinc, molybdenum, and chlorine. Nearly all plant
nutrients are taken up in ionic forms from the water part of the soil
solution as cations or as anions. Plants release bicarbonate and
hydroxyl (OH-) anions or hydrogen cations in an effort to cause
nutrient ions to be freed from sequestration on colloids and so force
them into the soil solution. Nitrogen ions and cations are stored in soil
organic material and are made available to the plant roots by that
material's decomposition by micro-organisms. (USDA, 2012).
40
2.8 THE MECHANISM OF NUTRIENT UPTAKE
All the nutrients with the exception of carbon are taken up by the
plant through its roots. All those taken through the roots, with the
exception of hydrogen which is derived from water, are taken up in the
form of ions. Carbon, in the form of carbon dioxide, enters primarily
through the stomata of the leaves and where the plant releases oxygen
as a byproduct of photosynthesis. All the hydrogen utilized by the
plant originates from soil water and results in the release of further
oxygen. Plants may have their nutrient needs supplemented by
spraying a water solution of nutrients on their leaves, but nutrients
are typically received through the roots by:
i. Mass flow.
ii. Diffusion.
iii. Root interception.
The nutrient needs of a plant may be carried to the plant by the
movement of the soil solution of water in a what is called mass flow.
The absorption of nutrients by the roots from the water with which it
is in contact, causes the concentration of nutrients in that area to be
depleted. Nutrients then diffuse from areas with higher concentration
to lower concentration, thereby bringing more nutrients near the
roots. Plants also send out roots constantly to seek new sources of
nutrients in a process called root interception. Meanwhile older less
effective roots die back. Water is lifted to the leaves where it is lost by
transpiration and in the process, it brings with it soil nutrients. A
41
corn plant will use one quart of water per day at the height of its
growing season.
2.9 USES OF SOIL
Soil is used in agriculture, where it serves as the anchor and primary
nutrient base for plants; however, as demonstrated by hydroponics, it
is not essential to plant growth if the soil-contained nutrients could be
dissolved in a solution. The types of soil and available moisture
determine the species of plants that can be cultivated.
Soil is the basis of life and living space for humans, animals, plants
and microorganisms. Soil is part of the ecological balance, particularly
with it's water and nutrient cycles. Soil are for filtering, buffering and
transformation activity between the atmosphere and ground water.
(Sheals J. G. 1969).
2.10 SOIL DEGRADATION
Soil degradation is defined as a process that lowers the current
and/or the potential capability of the soil to produce goods or services.
Six specific processes are recognized as the main contributors to soil
degradation: Water erosion, wind erosion, water logging and excess
salts, chemical degradation, physical degradation and biological
degradation. Soil degradation now affects one-third of the world's
soils, which are used for agriculture, particularly the soils which are
physically and chemically unsuitable for agriculture, grazing and
other purposes. The dominant process is erosion by wind and water,
42
accounting for 83% of the area affected by soil degradation in the
world.
It has been demonstrated that land use system are affected in all eco-
regions and in most countries, although the impact differs depending
on the type, the severity and extent of soil degradation (Bridgets et
al.)
2.11 Soil Pollution
Soil pollution is defined or can be described as the contamination of
soil of a particular region. Soil pollution mainly is a result of
penetration of harmful pesticides and insecticides, which on one hand
serve whatever their main purpose is, but on the other hand bring
about deterioration in the soil quality, thus making it contaminated
and unfit for use later.
In a general sense, soil pollution definition is the presence of toxic
chemicals (pollutants or contaminants) in soil in high enough
concentrations to be of risk to human health and/or ecosystem.
Additionally, even when the levels of contaminants in soil are not of
risk, soil pollution may occur simply due to the fact that the levels of
the contaminants in soil exceed the levels that are naturally present in
soil (in the case of contaminants which occur naturally in soil).
Soil contamination or soil pollution is caused by the presence of
xenobiotic (human-made) chemicals or other alteration in the natural
soil environment.
43
There are many different ways that soil can become polluted, such as:
(a) Seepage from a landfill
(b) Discharge of industrial waste into the soil
(c) Percolation of contaminated water into the soil
(d) Excess application of pesteicides, herbicides or fertilizers
(e) Solid waste seepage.
The most common chemicals involved in causing soil pollution are
petroleum hydrocarbon, heavy metals, pesticides and solvents
2.12 HEALTH EFFECTS
Contaminated or polluted soil directly affects human health through
direct contact with soil or via inhalation of soil contaminants which
have vaporized; potentially greater threats are posed by the infiltration
of soil contamination into groundwater aquifers used for human
consumption, sometimes in areas apparently far removed from any
apparent source of contamination aboveground Health consequences
from exposure to soil contamination vary greatly depending on
pollutant type, pathway of attack and vulnerability of the exposed
population. Chronic exposure to chromium, lead and other metals,
petroleum, solvents, and many pesticide and herbicide formulations
can be carcinogenic, can cause congenital disorders, or can cause
other chronic health conditions. Industrial or man-made
concentrations of naturally-occurring substances, such as nitrate and
ammonia associated with livestock manure from agricultural
44
operations, have also been identified as health hazards in soil and
groundwater. (Baselt, Randall. C. 2008).
Chronic exposure to benzene at sufficient concentrations is known to
be associated with higher incidence of leukemia. Mercury and
cyclodienes are known to induce higher incidences of kidney damage,
some irreversible. PCBs and cyclodienes are linked to liver toxicity.
Organophosphates and carbamates can induce a chain of responses
leading to neuromuscular blockage. Many chlorinated solvents induce
liver changes, kidney changes and depression of the central nervous
system. There is an entire spectrum of further health effects such as
headache, nausea, fatigue, eye irritation and skin rash for the above
cited and other chemicals. At sufficient dosages a large number of soil
contaminants can cause death by exposure via direct contact,
inhalation or ingestion of contaminants in groundwater contaminated
through soil. (Article on soil contamination in China).
2.13 ECOSYSTEM EFFECTS ON SOIL
The effects of pollution on soil are quite alarming and can cause huge
disturbances in the ecological balance and health of living creatures
on earth. Some of the most serious soil pollution effects are:
i. Decrease in soil fertility and therefore decrease in the soil yield.
How can one expect contaminated soil to produce healthy
crops?
45
ii. Loss of soil and natural nutrients present in it. Plants also
would not thrive in such soil, which would further result in soil
erosion (Micheal Hogan 1973).
iii. Disturbance in the balance of flora and fauna residing in the
soil.
iv. Increase in salinity of the soil, which therefore makes it unfit for
vegetation, thus making it useless and barren.
v. Generally crops cannot grow and flourish in polluted soil. Yet, if
some crops manage to grow, they would be poisonous enough to
cause serious health problems in people consuming them.
vi. Creation of toxic dust is another potential effect of soil pollution.
vii. Foul smell due to industrial chemicals and gases might result in
headaches, fatigue, nausea, etc., in many people.
viii. Soil pollutants would bring in alteration in the soil structure,
which would lead to death of many essential organisms in it.
This would also affect the larger predators and compel them to
move to other places, once they lose their food supply.
Effects occur to agricultural lands which have certain types of soil
contamination. Contaminants typically alter plant metabolism, often
causing a reduction in crop yields. This has a secondary effect upon
soil conservation, since the languishing crops cannot shield the
Earth's soil from erosion. Some of these chemical contaminants have
long half-lives and in other cases derivative chemicals are formed from
decay of primary soil contaminants (Micheal Hogan et al (1973).
46
2.14 HEAVY METAL CONTAMINATION
The main threats to human health from heavy metals are associated
with exposure to lead, cadmium, mercury and arsenic. These metals
have been extensively studied and their affects on human health
regularly reviewed by international bodies such as the WHO. Heavy
metals have been used by men for thousands of years. Although
several adverse effects of heavy metals have been known for a long
time, exposure to heavy metal continues and is even increasing in
some part of the world, in particular less developed countries.
Cadmium compounds are currently mainly used in re-chargeable
nickel-cadmium batteries. Cadmium emissions have increased
dramatically during the 20th century, one reason being that cadmium
containing compounds are rarely re-cycled but often dumped together
with household waste. The general population is exposed to lead from
air and food in roughly equal proportion. Children are particularly
susceptible to lead exposure due to high gastrointestinal uptake and
the permeable blood brain barrier. Recent data indicate that they may
be neurotoxin effects of lead of lower levels of exposure than
previously anticipated (Jarup, 2003).
Exposure to arsenic is mainly via intake of food and drinking water.
Food being the most important source in most populations
Chromium (Cr)
Chromium is a chemical element which has the symbol Cr and atomic
number 24. it is the first element in group 6. A hard metal that takes
47
high polish and has a high melting point. Chromium was regarded
with great intrest because of its high corrosion resistance and
hardness. A major development was the discovery that steel could be
made highly resistant to corrosion and discolourtion by adding
chromium to form stainless steel. This application long with chrone
plating are currently the highest volume uses of the metal.
Trivalent chronmium (cr (III) is required in trace amount for sugar and
lipid metabolism.In large amount and different forms,chromium can
be toxic and carcinogenic.the most prominent of the toxic chromium
is the haxavalent chromium (cr(vi) often seen in production sites and
required environmental clean up (Sabina C. et al 2005).High
concentration of chromium III in the cell leads to DNA damage
(Eastmond, D. et al (2005). Chromium and compounds are often
found in soil and groundwater at abandoned industrial sites.
Lead (Pb)
Lead in a chemical element in the carbon group with symbol Pb and
atomic number 82. Lead is a soft, malleable poor metal. It is also
encountered as one of the heavy metals. Metallic lead has a bluish
white color after being freshly cut. Lead is used in building
construction, lead-acid batteries, bullets, and shots and as a radiation
shield. Lead has the highest atomic number of all the stable elements.
Lead at certain contact degrees, is a poisonous substance to animals
as well as for human beings. It damages the nervous system and
causes brain disorder. Excessive lead also cause blood disorders in
48
mammals. Lead is a neurotoxin that accumulates both in soft tissues
and bones. Lead poisoning has been documented from ancient Rome,
Ancient Greece and China (ibid)
Iron (FE)
Iron is a chemical element with symbol Fe and atomic number 26. It is
a metal in the first transition series. It is the most common element
(by mass) forming the planet earth as a whole, forming much of earths
outer and inner core. It is the fourth most common element in the
earth crust. Iron exists in a wide range of oxidation states, -2 to 6.
Elemental iron occurs in meteoroids and other low oxygen
environments, but is reactive to oxygen and water.
Iron metals has been used since ancient times, large amount of
ingested iron can cause excessive levels of iron in the blood. High
blood levels of free ferrous iron react with peroxides to product free
radicals which are highly reactive and can damage DNA, Proteins,
lipids and other cellular components. Thus, iron toxicity damages
cells of the gastrointestinal tract. Iron typically damages cells in the
heart, liver, and causes coma, shock, liver failure coagulopathy and
even death (ibid).
Manganese
Manganese is mostly found in the earth's surface as the mineral
pyrolusite, manganese dioxide (Mn02). Mn is not found as a five metal
in nature but in minerals such as oxides, silicates, and carbonate.
South Africa is one of the major manganese producing countries along
49
with Autralia, Brazil, Gabon, India and Rusia. Pyrolusite is leached
under reducing condition, usually in the presence of a reducing agent
such as the ferrous iron to achieve high dissolution according to the
reaction.
Mm02 + 2 fe2 + 4H Mn2 + 2Fe2 + 2H20 Equation……………(1)
MnO2 can also be leached using a combination of sulphric acid and
oxalic acid. The oxidic acid acts as a reducing agent (Habashi, 1999).
At High pH, the leaching of manganese stops and it precipitates as a
hydroxide.the other method the leaching pyrolusite involves the use of
hydrogen halides as lixivants. The most common is hydrochloric acid
leaching. This process was developed by a Belgian company,
Metallurgic Hoboken over pelt (MHO). The process involved crushing
the of manganese and leaching with hydrochloric acid.
The simplified reaction can be presented as:
MnO2 + 4HCl = MnCl 2 + 2H2O + Cl2 ---------equation 3-2.
The reaction represented by equation 3.2 progresses very well to the
right under strongly acidic condition. The reaction mechanisms is
believed to involve part of the modules ie MnO2 to act as an oxidizing
agent and oxides part of the chloride to chlorine and therefore, it is
reduced to the more soluble manganeous state. However, the high
solubility of metal chlorides as compared to the sulphide posses a
challenge in the later stage of precipitation to recover the metals from
the solution. Another manganese ore rhodochrosite (MnCo3), can be
50
leached easily with sulphoric acid and the reaction is as shown in
equation 3-3:
MnCo3 + H2So4 MnSo4 + Co2 + H20 ……………..equation 3-3.
Generally, Mn in the + 2 oxidation state, is very soluble in acidic
condition.
Nickel (Ni)
Nickel is found in the earth's crust as oxides and sulphides. It can
occur in a number of oxidation states but only to N1(II)is stable over a
wide range of pH and redox condition. Nickel suphides dissolves in
dilute sulphric acid in the absence of oxiding agents as shown in
equation 3-4 (Gupta and Mukherjee, 1990, Habasie 1999).
Nis + H2 S04 NiSo4 + H2S………………….. equation 3-4
In industrial applications, however, the nickel sulphides are leached
under oxygen pressure to achieve high rates of dissolution. Although
the NiS have been the major sources of nickel, the oxides (lateritic)
represents 85% of the known Nickel reserves in the world. The lateritic
ores are subjected to a combination of pyro-and hydrometallurgical
processes to extract the nickel and any associated cobalt. Lateritic
ores are of two types, the limonitic and silicate. The limonitic ore is
difficult to treat by direct atmosphere leaching using sulpheric acid
hence it is treated at temperatures above 2000c in autoclaves. Efforts
to leach the lateritic ores without involving pressure resulted in the
development of a process that involved subjecting the ore to selective
reduction with gaseous, liquid or solid reductants in the temperature
51
range of 600 to 8250c. The resultant reduced ore is then leached with
dilute sulphric acid at pH 2.5 to 4 at a temperature of approximately
80c. This technique is known as the IRAL process and was renowned
for the reduction in the acid consumption as compared to the
pressure leaching. The silicate type lateritic ores are associated with
large quantities of MgO and are unsuitable for sulphuric acid pressure
leaching. This ore is reduced by roasting followed by leaching with the
ammonia-ammonium salt (Guptas and Mukkerjee, 1990; Habashri,
1999).
2.15 LAWS AND CONVENTIONS ON SOIL
There are so many laws and conventions protecting the environmental
which look at soil and its conservation. Among such laws and
conventions are those stated below:
According to the law of pollution (adopted on 1 July 2001) several
regulations concerning soil quality has been adopted.
1 Cabinet of ministers regulations no 483 adopted on 20 November
2001 “INVENTORY AND REGISTRATION OF CONTAMINATED AND
POTENTIALLY CONTAMINATED AREAS
2 Cabinet of ministers regulations No 804 adopted on October 25,
2005 “QUALITY STANDARDS FOR SOIL AND GROUND”
In 2002 the lativa city organized on environmental monitoring
program which its aim is the establishment of the environmental
monitoring system according to EU directives, to ensure general
52
public, policy makers, experts both on national and international level
with reliable, goal oriented and qualitative environmental information.
The Montevides programme III is a programme for the development
and periodic review of environmental law for the first decade of the
21st century was adopted by the governing council of the UNITED
NATIONS ENVIRONMENT PROGRAMME (UNEP) in February 2001
(precision 21/23 of 2001 Governing Council). The programme
includes a specific objective for soils (objective 12) as part of the new
UNEP strategic environmental law programme. The programme
generally includes not only development of international agreements,
but also international guidelines, principles and standards, as well as
the provision of assistance to develop capacity to formulate and
implement these. The programme supports a general initiative for soil
legislation reforms including undertaking actions to
i. Improve the effectiveness of environmental law on soils
ii. Improve the conservation and management of soil
iii. Forge better links between environmental law on soils and other
fields of environmental law.
Objective 12 thus reads: to improve the conservation, rehabilitation
and sustainable use of soils. Strategy of objective: To promote the
development and implementation of laws and policies for enhancing
the conservation, sustainable use and where appropriate
rehabilitation of soils.
Other Treaties and Conventions protecting the soil are
53
i. 10th international soil conservation organization conference May
1999 (USA)
ii. 17th world congress of soil sciences Aug 2002 (Thailand)
iii. 11th international soil conservation organization conference Oct
2002 (Argentina)
ii. - World international meeting in Berlin Sept 2011 tagged
“protecting soil for our common future”.
54
CHAPTER THREE
LITERATURE REVIEW
3.1 For the realization of topic of research, relevant information in
scientific area was collected through studies of diverse literature from
textbooks, journals and internet websites. Substantial knowledge was
gathered and a review of what other scientists have written on
- Improper and indecent disposal of solid waste on soil leads to
spread of some communicable diseases and spoils the biosphere
(soil and water) as a whole. marthandon 2007.
Luczkiewicz, 2006, soil and ground water contamination as a
result of sewage sludge on land application assessed leaching of
chemical compounds and heavy metals and trace element ( Cu,
Cr, Ni, Zn, and Pb) from sewage sludge and their migration
through the soil profile. He discovered that nitrogen compounds
such as nitrate (NNoz) and ammonium as well as some heavy
metals (Ni and Cd) originating from sewage sludge can reach
deeper than 0.8m and cause contamination of potential shallow
aquifers.
- Landfills are the major pollution causing source in urban
environment. The leachate generated from the landfills and
open dumps pollute the soil, ground water and creates health
risk. The health risks are also associated with physical
disturbances of landfill. The generation of leachate and soil and
the groundwater contamination is widely studied throughout
the world. Sabahi et al; 2009 studied the composition of landfill
55
leachate and groundwater pollution at ibb landfill, Yemen. They
found that some bore wells were contaminated with landfill
leachates where the concentration of physio-chemical
parameters is above the standard acceptable level.
Another study in Guwahati city of India studied the impact of
municipal solid waste dumping on the soil quality. It was observed
that the experimental values for the physiochemical parameters
increase for soils treated with solid waste in comparison to the control
soil Goswami and Sarma, 2008.
In furtherance of the studies in this area of research,Chen et al 2009
studied the heavy metal contents and chemical specifications in
sewage – irrigated soils from the eastern suburb of Beijing, China.
They reported that the accumulation of heavy metals in agricultural
sewage where irrigated soils has originated increased concern. Some
of the heavy metals analysed with total concentration and chemical
specification were cd, cr, cu, zn and ni.
In another report by Bradford et al 2003 in hubli Dharwad India
looked at wastewater irrigation and its implications for health and
livelihoods. They reported there are adverse health implications
including bacterial contamination of vegetables.
Amusa et al 2005 carried out the investigation of soils and crop
uptake of heavy metals in municipal waste dump in Nigeria. It was
found that crops which grow on the dumpsite and its surrounding
accumulates higher metal contents than those in normal agricultural
56
soils. It was equally observed that crops differ in their ability to uptake
those heavy metals.
In another research by Oyelola and Babatunde, 2008 (a) reported the
effect of soil waste and heavy metals in Olysosun dumpsite soil in
Lagos State Nigeria. The result showed that solid waste are
contributing significantly to the metal concentrations in the dump soil
samples
Adedosu et al 2013 in a study conducted in a landfill at Olusosun
gota Lagos observed that heavy metals Fe, Zn, Cu, Pb and Cd in soil
ranged from a certain degrees. These levels for all metals were far
higher in varying degrees than background levels, suggesting serious
anthropogenic influence from the landfill.
Mor et al in a research conducted in a functional dumpsite in Lagos
observed that the uncontrolled dumpsite and waste dumpsite threaten
the groundwater supply as movement of leachate from dumpsite
penetrate through the soil and the aquifers pose a risk to the
environment and human health. Consequent upon the report and
research about the impact of solid waste on soil, Su, 2008 observed
that the presence of and potential exposures of the community to
ground water contamination through the soil percolation may
contribute to the predilection of human health impacts, from simple
poisoning to cancer, heart diseases and teratogenic abnormalities.
57
3.2 SOIL QUALITY
Soil quality is often cited as a state indicator that describes the quality
of the soil/ (Bouma 1997, Karlen et al 1997). Soil quality is an
account of the ability of soil to provide ecosystem and social services
through its capacities to perform its functions and response to
external influences. The term soil quality (SQ) encompasses a broad
spectrum of features and considers functional ability together with the
response properties of the soil S.Q therefore provide a complex
information on the functional ability of the soil (Bouma 1997, Karlen
et al 1997).
3.3 SOIL FUNCTIONS
Soil, a non renewable natural resource, has several functions in the
biosphere and for humans. It is a reactor, transformer and integrator
of material and energy from other natural resources (solar radiation,
astrosphere, surface and subsurface waters, biological resources), a
medium for biomass production; storage of water, nutrient and heat;
natural filter and detoxification and buffering system; and important
gene- resevior and or medium of past and present human activities
(Blum 2005, Nortchiff 2002, Varallyay 1997). Soil functions are
general or specific capabilities of soil for various agricultural,
environmental, landscape and urban applications. Specific soil
functions are manifold and may be grouped according to the principal
purpose.
58
In the soil protection strategy (EC 2006a) the main functions are
identified as
- Biomass production
- Storing, filtering and transforming nutrients and water.
- Acting as a platform for most human activities
- Providing raw materials
- Acting as a carbon pool
- Storing geological and archaeological heritage.
These functions are performed on different levels and are determined
by inherent soil characteristics (e.g. texture, organic matter content,
ph, porosity e.t.c) and external environmental (climate, terrain,
hydrological, biological) and anthropogenic(soil use and management)
factors.
To access the performance of soil functions, different purpose specific
measurement and modeling techniques can be applied. Land
evaluation is one of the traditional tool.
3.4 SOIL DEGRADATION THREAT
Soil is essentially a non renewable resource with possible high rate of
degradation and extremely slow rate of regeneration process.
Degradation deteriorates soil quality by partially or entirely damaging
one or more of its functions (Blum 1988). Risk of soil degradation
depends on soil and terrain properties which make the soil inherently
59
receptive of degradation. Van Camp et al (2004) provides substantial
knowledge towards identifying and describing hazards (threats) to soil
The main threats to soil functioning abilities are identified as Decline
in organic matter; Soil erosion; Compaction; Salinisation; Landslides;
Contaminations ; Floods and sealing.
KNOWELDGE GAP
So many scholarly work has been written on this subject area of the
environment as we all know is a complex weave of physical, chemical
and biotic factors which interact with each other and impact upon all
living things and surrounding. These impacts as it concerns the
quality of soil, effect on underground water and human health has
been discussed extensively as it relates to dumping waste.
Interestingly and regrettably research on this impact of open dump on
soil quality as distance increases away from the dumpsite is yet to see
much relevance. Moreso the depth and speed at which the heavy
metals runs down to the underground aquifer is yet to have enough
literature.The system of plant intake of this heavy metals within and
away from the dumpsites barely has been written on.
60
CHAPTER FOUR
STUDY AREA
4.4 Geographic location
It has an Area of 7.161km2 (2,764,9 sq.m) and has total population of
about 5,590,513 according to National population commission data
(2004). Enugu state is a mainland state in southeastern Nigeria,it's
capital is Enugu from which the state was created in 1991 from the
old Anambra state derives it's name. The principal cities in the state
are Enugu, Agbani, Awgu, Udi, Oji River and Nsukka. Within her
territory are numerous streams and rivers of which the major ones are
the Oji River, Adada River. Ekulu River, Nyama River, Ajalli River.
About 60% of her population engages in farming and irrigation
thereby making use of the rivers.
The state shares borders with Abia state, Imo state to the south,
Ebonyi, state to the east, Benue state to the north east, Kogi state to
the north west and Anambra state to the west.
4.5 CLIMATIC CONDITION
Enugu has good soil, land and climatic conditions all year round,
sitting at about 23 meters above sea level and it's soil is well drained
during the rainy seasons. The mean temperature in Enugu state in
the hottest month of February is about 87. 16f (30.64°c) while the
lowest temperature comes around November reaching 60.54f.(15.8C)
61
TRANSPORTATION SYSTEM IN ENUGU
The main forms of transportation in the city are taxi cabs and buses.
Okada (motorcycles), once served as public transportation in the city
until the state government banned them from this use in April 2009.
Most transport enters and leaves the city through Enugu's Ogbete
Motor Park, Garki Motor Park serves as a transport pick-up point as
well. Unregistered taxis are known as Kabu Kabu and are
differentiated with registered ones through the lack of yellow paint on
the unregistered vehicles. In 2009, Enugu introduced a taxi job
scheme under 'Coal City Cabs' to help in the eradication of poverty in
the city. 200 registered Nissan Sunny taxis, provided by the state
government; and 200 registered Suzuki taxis, provided by the
Umuchinemere Pro-Credit Micro Finance Bank, were given out on
loan to unemployed citizens in the city who will operate as taxi drivers
and will own the vehicles after payments are completed. 20 buses with
the capacity for 82 passengers seated and standing were introduced
as Coal City Shuttle buses on 13 March 2009 to run as public
transport for Enugu urban. Enugu's economy in the early
20th century depended on coal mining in the Udi plateau; this
industry was the pushing force towards the city's growth. The Nigerian
Coal Corporation has been based in Enugu since its creation in 1950
where it controlled coal mining. With the creation of the Eastern Line,
Enugu was connected with the sea via Port Harcourt to its south and
later connected to the city of Kaduna to Enugu's north.] The Biafran
62
war brought widespread devastation that forced a decline in coal
production from damage or destruction of equipment. As of 2005 coal
mining is no longer the major source of income and mines lay unused.
Other minerals mined in Enugu include iron ore, limestone, fine clay,
marble, and silica sand. Trades and services, agricultural activities,
transportation business has been on the increase.
ECONOMIC ACTIVITIES IN ENUGU
Economically, Enugu is predominantly rural and agrarian, with a
substantial proportion of its working population engaged in farming,
although trading (18.8%) and services (12.9%) are also important. In
the urban areas trading is the dominant occupation, followed by
services. A small proportion of the population is also engaged in
manufacturing activities, with the most pronounced among them
located in Enugu, Oji, Ohebedim and Nsukka. The state boasts of a
number of markets especially at each of the divisional headquarters,
prominent of which is the Ogbete Main market in the State capital,
Enugu. There is also one of the largest grains market East of the
Niger, the Orie Orba Market which plays host to most farmers from
the North Central States of Benue, Kogi, Nassarawa and Plateau who
use the market to dispose their produce for consumers in South-East
and South-Southern Nigeria . Every four days, grains and other farm
produce are found in large quantities and at highly competitive prices.
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Moreso industries are beginning to come up fast in Enugu state like
Innoson industries, arab contractors and pharmaceutical companies
whose products are on daily use In Enugu state.
4.6 UGWUAJI
Ugwuaji is a community in Enugu South L.G.A of Enugu State. It is
one of the communities that made up the Nkanu clan and its creation
was dated some 200 years ago. The community has its importance
because of its large hectares of land for farming and its cultural
heritage. It has an area of 67km and a total population of about
33,000 according to Enugu South indigene registration (2006)
Ugwuaji community has about 6 villages which are Isiagu Ugwuaji,
Umunnagingene, Ndiaga Ugwuaji, Obeagu Uno, Obeagu Ugwuaji and
in Ugwuaji.
The community has borders with Emene and Abakpa. Ugwuji has
good soil and climatic conditions all year round, sitting at about 23
meters above sea, level and its soil well drained during the rainy
season. The mean temperature of Ugwuaji is same with Enugu state.
In the hottest month of February is about 37.16F (304c) while the
lowest temperature come around November reaching 60. 54f . Within
her territory are streams and river which are Ini stream, Atafu stream
and Onungene streams. About 90% of her population engages in
farming and irrigation using those stream.
FOLLOWED BY MAP OF ENUGU STATE
64
CHAPTER FIVE
RESEARCH METHODOLOY
5.8 INTRODUCTION
This chapter presents the research methodology/technique used in
investigating the effect of solid waste on soil quality in Ugwuaji Area. It
describes how the surveys were conducted, as well as the sampling
method and analytical techniques used.
SOURCES OF DATA
The data for the study was derived from the secondary and primary
sources.
Secondary Data
These are data obtained from materials which have been previously
documented and that relates to the study. Such documents are:
(1) Related research reports in the field of study
(2) Documents from Ministry of Agriculture, Ministry of
Environment Enugu State
(3) Journal of soil quality treatment and procedures
(4) Textbooks, library, internet, Encyclopedias
(5) World Health Organization (WHO) document and soil quality
standards.
(6) NESREA environmental chart sheet
65
Primary Data
The primary data provide first hand information in the field. They will
be obtained through collection of different soil samples from the study
Area.
Soil samples was collected from 6 different dump stations namely
A- Site where they is no waste Dump about 500m away
B- Asbestos Dump
C- Clinical waste dump
D- Metal scraps dump
E- Household waste
F- Sewage/ leachate.
For soil sample collection, clean new polyethene bags was used for
collection. For easy of identification, the bags were labeled with names
of the sampling stations and date of collection.
5.9 SAMPLE SIZE AND HOW IT WAS OBTAINED
Six soil samples were used as a case study for the purpose of this
research work and they are:
i. Soil sample from low heaped dump
ii. Soil sample from high heaped dump
iii. Soil sample collected from each of the dump with 50ft
progression out the main dump.
66
The soil samples were collected and analysed in soil laboratory of
ecochem scientific limited.
Parameters tested and analysed were
Heavy Metals
i. Lead
ii. Cadmium and compounds
iii. Hexavalent chromium
iv. Iron
v. Manganese
vi. Nickel, soluble salt
(B) Pesticide
Vii Atrazine
5.10 SAMPLING TECHNIQUES USED
Targeted sampling method was used in collection of the samples from
dump site for this research work. Samples were collected from the
main dump and as the distance increases away from the dump. The
soil sampling depth was about 170-200mm deep into the ground.
5.11 METHOD OF DATA COLLECTION
Data used in this research work are mainly data derived from
laboratory analysis carried out on each of the soil samples and testing
different parameters and variation of quality for the different samples
collected.
67
5.12 METHOD OF THE ANALYSIS
The experiment was carried out with the soil samples.
Soil Sample Analysis
Soil samples were collected from the main dump sites and 50ft
progression outside the dumpsite.
5.13 EXPERIMENTAL PROCEDURE
The samples were dried in an oven at 105oc to a constant weight and
sieved through a 2mm mesh to remove large debris, gravel sized
materials and other unwanted materials. A portion (0.5g) of the sieved
samples were measured after homogenization and ground with a
laboratory mortar and pestle. The ground samples were transferred
into a 250ml beaker. A portion (10ml) of 1:1 nitric acid was measured
into the beaker and covered with a water glass.
The beaker was placed on a steam bath at 99oc and left for1 hour. The
samples were removed from the steam bath and allowed to cool for 10
mins after which 2ml of distilled water and 3ml of 30% hydrogen
peroxide was added to the sample, the beaker was covered with watch
glass and placed on steam bath and allowed to digest until the sample
appearance remained unchanged. The samples were filtered through a
Whatman No.1 filter paper and the solution made up to 50ml mark
with distilled water. The samples were subsequently analysed for lead,
cadmium, copper, iron, manganese and nickel using Atomic
68
absorption spectrophotometer (AAS) machine to analyze and the result
of the various heavy metals determined and data recorded.
Conversions: A *50ml=mg/kg. 0.5g
Where A is concentration in PPM
5.14 ANALYTICAL TECHNIQUES.
Two-way analysis of variance
In statistics, the two-way analysis of variance (ANOVA) test is an
extension of the one-way ANOVA test that examines the influence of
different categorical independent variables on one dependent variable.
While the one-way ANOVA measures the significant effect of one
independent variable, the two-way ANOVA is used when there is more
than one independent variable and multiple observations for each
independent variable. The two-way ANOVA can not only determine the
main effect of contributions of each independent variable but also
identifies if there is a significant interaction effect between the
independent variables.
As with other parametric tests, we make the following assumptions
when using two-way ANOVA:
i. The errors of populations from which the samples are obtained
must be normally distributed.
ii. Sampling is done correctly. Observations for within and between
groups must be independent.
iii. The variances among populations must be equal
(homoscedastic).
69
iv. Data are interval or nominal.
ANALYTICAL TECHNIQUE USED IN HYPOTHESIS TWO
T test
A t-test is any statistical hypothesis test in which the test statistic
follows a Student's t distribution if the null hypothesis is supported. It
can be used to determine if two sets of data are significantly different
from each other, and is most commonly applied when the test statistic
would follow a normal distribution if the value of a scaling term in the
test statistic were known. When the scaling term is unknown and is
replaced by an estimate based on the data, the test statistic (under
certain conditions) follows a Student's t distribution.
Uses
Among the most frequently used t-tests are:
• A one-sample location test of whether the mean of a population
has a value specified in a null hypothesis.
• A two-sample location test of the null hypothesis that the means
of two populations are equal. All such tests are usually called
Student's t-tests, though strictly speaking that name should
only be used if the variances of the two populations are also
assumed to be equal; the form of the test used when this
assumption is dropped is sometimes called Welch's t-test. These
70
tests are often referred to as "unpaired" or "independent
samples" t-tests, as they are typically applied when the
statistical units underlying the two samples being compared are
non-overlapping
Paired sample t-test
In testing the null hypothesis that the population mean is equal to a
specified value µ0, one uses the statistic
where is the sample mean, s is the sample standard deviation of the
sample and n is the sample size. The degrees of freedom used in this
test are n − 1. Although the parent population does not need to be
normally distributed, the distribution of the population of sample
means, , is assumed to be normal. By the central limit theorem, if
the sampling of the parent population is random then the sample
means will be approximately normal.[11] (The degree of approximation
will depend on how close the parent population is to a normal
distribution and the sample size, n.)
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CHAPTER SIX
DATA PRESENTATION, ANALYSIS, AND DISCUSSION OF
FINDINGS
6.4 DATA PRESENTATION
The data presented in this study are the result of laboratory analysis
of soil sample collected within the dump site and some distance away
from the dump site. This distance as measured are 20ft, 50ft, 100ft,
150ft and 200ft.The sample collected and analyzed in the laboratory
help the study to establish the impact of solid waste on soil quality in
the study area.
In addition, the study also presented the result of accepted
permissible standard of heavy metal as recommended by National
Environmental standard and Regulatory Enforcement Agency
(NESREA). This is the acceptable thresh-hold limit for heavy metals
discharge in the soil for Nigerian environment.
The soil samples laboratory result and NESREA Permissible limit for
heavy metals were presented in form of tables, multiple bar, graphs
and pie charts.
72
Table I: Percentage concentration of oxides of elements detected
in soil from various study locations(mg/kg)
Study location Pb Cd Cu Fe Mn Ni
0 19.89 16.26 25.06 270.5 245.25 1.02
20 19.35 15.72 25.01 272.45 244.78 0.59
50 10.24 8.57 9.77 180.91 170.61 0.25
100 6.82 2.52 8.35 105.63 150.55 0.11
150 1.2 1.88 3.1 98.47 82.52 0
200 1.17 0.95 1.22 70.52 45.25 0
Source: Author's Soil Laboratory Analysis 2012.
HEAVY METAL
NESREA
LIMIT(mg/kg)
Lead (Pb) 40
Cadmium (Cd) 3
Copper (Cu) 100
Iron (Fe) 0.3
Manganese (Mn) 0
Nickel (Ni) 0.05
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Table 2: National Standards and Regulatory Enforcement Agency
(NESREA) Threshold Limit of Heavy Metal in the Soil
(Source: NESREA Gazette 2007)
6.5 Test of hypothesis
HYPOTHESIS ONE
Ho: The extent to which solid waste dump in Ugwuaji affect soil
quality is not high.
The two – way Anova was used in testing this hypothesis
Mean
square
Sum of
square
Df Error (ss) Fear F critical
32384.54 19437.2 5 94476.92 10.28332 2.420523
From the Analysis in the above the F calculated (10.28332) is greater
than F critical (2.420523)
Fcal > F critical
10.28332 > 2.420523
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Since the F calculated is greater than F critical; the null hypothesis is
rejected.
Therefore; The extent to which solid waste dump in Ugwuaji affect soil
quality is high.
The rejection of the two null hypothesis, is a clear indication that the
indiscriminate, and uncontrolled dumping of solid waste in Ugwuaji
affects the soil quality; also, the heavy metals are gradually moving
away from the dump site, to the farmlands close by.
Furthermore, manganese concentration was the highest as compared
to the rest of the dictated heavy metals, concentration of iron was
next, and the least concentration is Nikel. There was a decrease in
Mn, Fe, CU and Pb > Cd > Ni concentration, as they move away from
the dumpsite. The implication is that if left unchecked, and
uncontrolled will be more harmful.
6.2.2 Application t-Test for hypothesis two
HYPOTHESIS TWO
Ho: There is no significant difference between heavy metal
concentration in the dumpsite and Nesrea threshold limit
T-test was used in testing this hypothesis
75
Table showing values of analyzed heavy metals compared to NESREA
values. Data is presented as mean ± standard error of mean (SEM).
Values of P < 0.05 and P<0.001 are considered significant.
Heavy Metals Analysed
Observed Value (ppm)
NESREA values (ppm)
Significance (P value)
Lead 9.78 ± 3.42** 40.00 ± 0.00 0.000
Cadmium 7.65 ± 2.85 3.00 ± 0.00 0.164
Copper 12.14 ± 4.29** 100 ± 0.00 0.000
Iron 166.41 ± 36.42* 0.30 ± 0.00 0.006
Manganese 156.49 ± 33.54* 0.00 ± 0.00 0.006
Nickel 0.33 ± 0.16 0.05 ± 0.00 0.152
Key: * = p < 0.05
** = p < 0.001
From the analysis, there were observed differences between the
observed values of analyzed heavy metal when compared with the
NESREA values. Observe values for the soil levels of lead and copper
was found to be significantly (p < 0.001) lower than the NESREA
threshold limit. Observed levels of Iron and Manganese in soil sample
analyzed was found to be significantly higher (p < 0.05) than the
NESREA threshold limit. There was no significant difference (p > 0.05)
between the observed and NESREA threshold values for Cadmium.
This implies that to a significant extent, the soil around the dumpsite
is contaminated with heavy metals especially Iron and manganese.
76
Since there was significant difference between the observed value and
the NESREA value for some of the analyzed heavy metals, the null
hypothesis is rejected.
There is significant difference between heavy metal concentration in
the dumpsite and NESREA threshold limit
6.3 DISCUSSION OF FINDINGS
This study concentrated on the impact of solid waste on soil quality in
Ugwuaji environs. It examines the type of heavy metal that
accumulates into the soil from the waste dump. The study looks at the
effect of heavy metal distribution in the soil within the waste
dumpsite.
Finally, the study, examine the relationship between those detected
heavy metal with different study locations and the distance from the
dumpsite.it equally looked at the National Environmental Standard
and Regulatory Enforcement Agency (NESREA) heavy metal threshold
limit. This will enable the study to assess the level of enforcement of
NESREA in waste management in Enugu.
Thus, the research findings include the following:
i. The soil is heavily contaminated with Lead (Pb), Cadmium (Cd),
Cupper (Cu), Iron (Fe), Manganese (Mn) and Nickel (Ni).
ii. Cadmium (Cd), Cupper (Cu), Iron (Fe) and Manganese (Mn) are
very high at the waste dump site when compared with NESREA
heavy metal threshold limit.
77
iii. The concentration to the chemical detected in the soil reduced
as distance in areas from the waste dump site. The chemical
includes Lead (Pb), Cadmium (Cd), Copper(Cu), Iron (Fe),
Manganese (Mn) and Nickel (Ni).
iv. There is an established discernable pattern of heavy metal
distribution in the study area.
v. Finally, the strength of relationship between various detected
heavy metal in the soil and NESREA heavy metal threshold limit
as established by R- square change is 1.00.The study was also
able to trace a reduction in concentration of heavy metals as
distance increases.
The reduction in concentration of detected heavy metal over distance
is as a result of leachate processes and rainfall factor. The heavy
metal penetrates into the soil through leaching process and rainfall
act as a catalyst that speeds up this action. This constitutes a serious
problem to the underground aquifer and soil micro-organism. The
study emphasized that water sample collected from hand-dug-
shallow-well located 10km away from waste dump is also seriously
contaminated. This is in alignment with the finding of Ogbuene et
al(2012). The heavy metals that reduce as distance increase from
waste dumpsite find its way into the soil and underground aquifer.
Rotich et al (2006) maintained that leachate can contaminate both
ground and surface water. During floods, water mixed with leachate
may flow out of the dumpsite and set into nearby ponds, streams, and
78
rivers. This of course poses health risk to the communities near the
dump, and those in the down stream who may be using the water for
various purposes.This is in line with Ugwuaji Area.
Also, Citamba (2007) opined that study carried out at Kariba showed
that waste sample taken from the vicinity of the dumpsite had a high
level of concentration of mercury (Hg) and lead (Pb). This study is in
line with the finding of this study.
The soil in Ugwuaji waste dump environment is currently deteriorated
with Lead (Pb), Cadmium (Cd), Cupper (Cu), Iron (Fe), Manganese (Mn)
and Nickel (Ni).
The rate of reduction in level of concentration as distance increase
shows that the soil is highly polluted with the metal detected. The
waste dump comprised of industrial waste, chemical waste, clinical
waste, household waste, commercial waste, abattoir waste among
others. These various chemical wastes react with each other, thus
deteriorating the environment so much. There is need for urgent
management strategy. The waste dump is currently seen as slow on-
set environmental hazard.
The study is in line with a research done by Md Sirajul and others in
Bangladesh. The study investigated that waste materials produced
tangible impacts on the soil quality while the sample contained
higher available sulphur and a marked increase in the concentration
of heavy metals in soil and the measured metals varied in the order of
79
iron(Fe)> Nickel (Ni)> Lead (Pb) > Copper (cu)> Cadmium (Cd). The
mean concentration of the heavy metals in the surface soil of the
dumped site were 0.40, 1.42, 0.46, 350.38 and 0.03ppm for copper,
nickel, lead, iron and cadmium respectively. These values were
attributed to the leachates percolated from the wastes.
Md Siragul also found that metal species were comparatively higher in
industrial effluents accumulations site and regarded it unsafe as
these heavy metals are eventually picked up by growing plants and
thereby entering the food chain. Md Sirajul assertions and findings is
along with what the researcher observed and investigated at the
Ugwuaji dumpsite. At Ugwuaji area the case is not different as plants
in process of taking up nutrient pick up those detected heavy metals
and store it in the food chain. The research put in thought this
concepts earlier in chapter 2 (system thinking) of this research work.
Another study conducted by Sultan et al examined how soil quality is
affected by heavy metal. The results suggests that soil contains much
higher values of heavy metal like Mercury, Manganese, Copper and
Zinc than world wide average soil values of 0.05,270.00 5.50, and
45.00ppm respectively. It was found that it might have considerable
negative effects on the soil quality, agricultural crops of the area and
thus harmful for human health. The higher concentrations just like
the research conducted in Ugwuaji suggest that they resulted due to
natural origin, human activities and solid waste dumping.
80
In a research conducted by Irshad(2013) in the department of
Environmental sciences University of Harpur Pakistan (2011), on
effects of solid waste on Heavy metal composition of soil at Nathiagali
Abbottbad dumpsite, the experiment concluded that the Waste
material produced tangible impacts on soil in Nathagali. The dumping
of waste resulted in a marked increase in concentration of metal
varied in order of Mn> Fe>Zn>Cu>Pb>Ni. The metals were found
higher on the site of waste accumulation and decreased with the
increasing distance from the dumpsite. The dumping place had the
highest concentration of heavy metals as compared to the nearby
soils. Metal concentrations were found in excess to the WHO quality
standards.
In line with the findings of Irshad(2013) in Pakistan, the research
work conducted in Ugwuaji is not different. It was equally found that
Dumping of waste resulted in a marked increase in concentration of
Pb, Cu, Ni, Mg, and Fe. The metals were equally found to decrease in
concentration as distance increases away from the main dumpsite.
Metal concentrations were observed to be in excess to the NESREA
threshold limit. Finally, the result of this study maintained that heavy
metals detected in the solid waste dump is higher than the
permissible limit by NESREA. The implication is that wastes are not
properly disposed. This constitutes serious environmental hazard. The
heavy metal can reach humans through bio- accumulation in plants
in the ugwuaji area including the underground water. The study was
81
also able to establish the discernible pattern of heavy metal
concentration in the soil. The area is currently heavily polluted with
Cu,Cd,Fe,Mn,Ni, and Pb. There is need for environmental
management practices in the area.
Therefore, an effective awareness, recycling and land filling techniques
for the solid waste management in the study area is urgently needed.
82
CHAPTER SEVEN
CONCLUSION
The above significant heavy metals (pb, cd, cu, mn, fe, ni) found in soil
sample in and around the dumpsite were traced from the poor
management and dumping of solid waste in the area and they are
toxic and very harmful to plants, animal and man. They are
carcinogenic, causes renal impairment, brain disorder and possibly
death with certain level of exposure. Although some of these heavy
metals such as copper are biologically essential and play an important
role in the growth of plants, animal and man if taken in moderate
quantity. They can also be toxic when found in high concentration.
Certainly, future studies should determine the health impact of heavy
metals on the human population living in the Ugwuaji including the
scavengers in the dumpsite area taking into consideration that such
heavy metals can accumulate in plants, making their way to human
through the food chain. All efforts should be made to determine the
accumulation rate of heavy metal on plants that grow in that area to
known its quality.
Finally adequate waste management practices should be put in place
to mitigate such environmental threats as seen in cause of this
research and future ones.
83
RECOMMENDATION
1. After the thorough work carried out on the research area,
putting into consideration the findings which is the end product
of this research, the researcher has gleaned some steps that can
be taken to ameliorate the impacts left by solid wastes to
achieve notable sustenance of the environment; hence, the
following recommendation.
2. There is urgent need to look into the waste dump site and
construct a standard environmental sanitary landfill than the
unpleasing open dumping practice at the Ugwaji dump.
3. Waste sorting policy should be introduced at point source to
separate wastes as degradable and non degradable. While
degradable domestic wastes can be used as manure in farm
land. Revitalizations and support of waste recycling and reuse
at the waste dump is important.
4. Waste management policy and Law that exist in Enugu need
appropriate implementation with honesty and truth. This Law
or legislation regulating open dumping disposal should strive to
make provision for the prosecution of an offender who embark
on careless disposal of waste in the environment.
5. Periodic soil evaluation and treatment especially before planting
to help rid it of the contamination by solid waste should be
84
considered. The various environmental agencies in Enugu state
should make efforts to provide soil treatment standard to help
remedy this situation.
6. There is need for community policing and vigilant in Ugwuaji to
help check indiscriminate dumping of waste in the site.If this
recommendations are considered, pollution of soil and
contamination by heavy metal would be reduced drastically.
85
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Environmental Quality Standards for Soil Pollution
Substance Target level of soil quality examined through leaching
and content tests
Cadmium 0.01 mg/l in sample solution and less than 0.4mg/kg
in rice for agricultural land
total cyanide not detectable in sample solution
organic phosphorus not detectable in sample solution
Lead 0.01 mg/l or less in sample solution
chromium (VI) 0.05 mg/l or less in sample solution
Arsenic 0.01 mg/l or less in sample solution, and less than 15
mg/kg in soil for agricultural land (paddy fields only)
total mercury 0.0005 mg/l or less in sample solution
alkyl mercury not detectable in sample solution
PCBs not detectable in sample solution
copper less than 125 mg/kg in soil for agricultural land
(paddy fields only)
dichloromethane 0.02 mg/l or less in sample solution
carbon tetrachloride 0.002 mg/l or less in sample solution
1,2-dichloroethane 0.004 mg/l or less in sample solution
1,1-dichloroethylene 0.02 mg/l or less in sample solution
cis-1,2-
dichloroethylene
0.04 mg/l or less in sample solution
1,1,1-trichloroethane 1 mg/l or less in sample solution
93
1,1,2-trichloroethane 0.006 mg/l or less in sample solution
trichloroethylene 0.03 mg/l or less in sample solution
tetrachloroethylene 0.01 mg/l or less in sample solution
1,3-dichloropropene 0.002 mg/l or less in sample solution
Thiuram 0.006 mg/l or less in sample solution
Simazine 0.003 mg/l or less in sample solution
Thiobencarb 0.02 mg/l or less in sample solution
Benzene 0.01 mg/l or less in sample solution
Selenium 0.01 mg/l or less in sample solution
94
RESEARCHER AT THE
DUMPSITE
95
INDUSTRIAL WASTE AT THE DUMP SITE
96
INDUSTRIAL WASTES FROM BREWERY DUMPED AT UGWUAJI
DUMPSITE
97
CLINICAL WASTES DUMPED AT UGWUAJI DUMPSITE
98
SCHEDULE IV
SOIL QUALITY STANDARDS
FOR CHEMICALS, PHARMACEUTICAL
During routine operations of these industry specifics, there may be
soil contaminations and the need to preserve the environment. The
soil quality levels listed below must not be exceeded with the tactility.
Parameter Guideline value (mg/kg dry weighty)
Aluminium ?? -
Arsenic 20
Barium 400
Cadmium 3 - cadmium
Chromium cr +6) 100
Cobalt 50
Copper 100
Head 164
Mercury 4 - copper
Molybdenum 40 - lead
Nickel 70
Tin 50
Zinc 421 - Nickel
Benzene 0.1
Tohene 0.1
Xylene 0.1
Source (scheduled regulations 7, 20(1), 21 (1), 22 (1)
Regulation 40 (2) Schedule XII
