SOIL POLLUTION

A SEMINAR REPORT

BY

ABOLARINWA MERCY AYOMIDE

(FPA/ST/19/2-0020)

SUBMITTED

THE DEPARTMENT OF SCIENCE TECHNOLOGY

SCHOOL OF SCIENCE AND COMPUTER STUDIES

FEDERAL POLYTECHNIC ADO-EKITI

EIKITI STATE

IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR

THE AWARD OF NATIONAL DIPLOMA

IN

SCIENCE LABORATORY TECHNOLOGY

AUGUST, 2021.

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 ABSTRACT

The problem of soil pollution in developing countries cannot be considered in isolation from

perhaps the more pressing issues related to soil degradation generally. That phenomenon is now

a major preoccupation in the developing countries as soil degradation i.e. the denudation of the

productivity of soils especially in arid and semi-arid regions becomes acute.

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 INTRODUCTION

Soil pollution is defined as the build-up in soils of persistent toxic compounds, chemicals, salts,

radioactive materials, or disease causing agents, which have adverse effects on plant growth and

animal health.

Soil is the thin layer of organic and inorganic materials that covers the Earth's rocky surface. The

organic portion, which is derived from the decayed remains of plants and animals, is

concentrated in the dark uppermost topsoil. The inorganic portion made up of rock fragments,

was formed over thousands of years by physical and chemical weathering of bedrock. Productive

soils are necessary for agriculture to supply the world with sufficient food.

There are many different ways that soil can become polluted, such as:

Seepage from a landfill

Discharge of industrial waste into the soil

Percolation of contaminated water into the soil

Rupture of underground storage tanks

Excess application of pesticides, herbicides or fertilizer

Solid waste seepage

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The most common chemicals involved in causing soil pollution are:

Petroleum hydrocarbons

Heavy metals

Pesticides

Solvents

TYPES OF SOIL POLLUTION

 Agricultural Soil Pollution

Pollution of surface soil

Pollution of underground soil

 Soil pollution by industrial effluents and solid wastes

Pollution of surface soil

Disturbances in soil profile

 Pollution due to urban activities

Pollution of surface soil

Pollution of underground soil

CAUSES OF SOIL POLLUTION

Soil pollution is caused by the presence of man-made chemicals or other alteration in the natural

soil environment. This type of contamination typically arises from the rupture of underground

storage links, application of pesticides, and percolation of contaminated surface water to

subsurface strata, oil and fuel dumping, leaching of wastes from landfills or direct discharge of

industrial wastes to the soil. The most common chemicals involved are petroleum hydrocarbons,

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solvents, pesticides, lead and other heavy metals. This occurrence of this phenomenon is

correlated with the degree of industrialization and intensities of chemical usage.

A soil pollutant is any factor which deteriorates the quality, texture and mineral content of the

soil or which disturbs the biological balance of the organisms in the soil. Pollution in soil has

adverse effect on plant growth.

POLLUTION IN SOIL IS ASSOCIATED WITH:

 Indiscriminate use of fertilizers

 Indiscriminate use of pesticides, insecticides and herbicides

 Dumping of large quantities of solid waste

 Deforestation and soil erosion

 INDISCRIMINATE USE OF FERTILIZERS

Soil nutrients are important for plant growth and development. Plants obtain carbon, hydrogen

and oxygen from air and water. But other necessary nutrients like nitrogen, phosphorus,

potassium, calcium, magnesium, sulfur and more must be obtained from the soil. Farmers

generally use fertilizers to correct soil deficiencies. Fertilizers contaminate the soil with

impurities, which come from the raw materials used for their manufacture. Mixed fertilizers

often contain ammonium nitrate (NH4NO3), phosphorus as P2O5, and potassium as K2O. For

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instance, As, Pb and Cd present in traces in rock phosphate mineral get transferred to super

phosphate fertilizer. Since the metals are not degradable, their accumulation in the soil above

their toxic levels due to excessive use of phosphate fertilizers, becomes an indestructible poison

for crops.

The over use of NPK fertilizers reduce quantity of vegetables and crops grown on soil over the

years. It also reduces the protein content of wheat, maize, grams, etc., grown on that soil. The

carbohydrate quality of such crops also gets degraded. Excess potassium content in soil

decreases Vitamin C and carotene content in vegetables and fruits. The vegetables and fruits

grown on over fertilized soil are more prone to attacks by insects and disease.

 INDISCRIMINATE USE OF PESTICIDES, INSECTICIDES AND HERBICIDES

Plants on which we depend for food are under attack from insects, fungi, bacteria, viruses,

rodents and other animals, and must compete with weeds for nutrients. To kill unwanted

populations living in or on their crops, farmers use pesticides. The first widespread insecticide

use began at the end of World War II and included DDT (dichlorodiphenyltrichloroethane) and

gammaxene. Insects soon became resistant to DDT and as the chemical did not decompose

readily, it persisted in the environment. Since it was soluble in fat rather than water, it

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biomagnified up the food chain and disrupted calcium metabolism in birds, causing eggshells to

be thin and fragile. As a result, large birds of prey such as the brown pelican, ospreys, falcons

and eagles became endangered. DDT has been now been banned in most western countries.

Ironically many of them including USA, still produce DDT for export to other developing

nations whose needs outweigh the problems caused by it.

The most important pesticides are DDT, BHC, chlorinated hydrocarbons, organophosphates,

aldrin, malathion, dieldrin, furodan, etc. The remnants of such pesticides used on pests may get

adsorbed by the soil particles, which then contaminate root crops grown in that soil. The

consumption of such crops causes the pesticides remnants to enter human biological systems,

affecting them adversely.

An infamous herbicide used as a defoliant in the Vietnam War called Agent Orange (dioxin),

was eventually banned. Soldiers' cancer cases, skin conditions and infertility have been linked to

exposure to Agent Orange.

Pesticides not only bring toxic effect on human and animals but also decrease the fertility of the

soil. Some of the pesticides are quite stable and their bio- degradation may take weeks and even

months.

Pesticide problems such as resistance, resurgence, and health effects have caused scientists to

seek alternatives. Pheromones and hormones to attract or repel insects and using natural enemies

or sterilization by radiation have been suggested.

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 DUMPING OF SOLID WASTES

In general, solid waste includes garbage, domestic refuse and discarded solid materials such as

those from commercial, industrial and agricultural operations. They contain increasing amounts

of paper, cardboards, plastics, glass, old construction material, packaging material and toxic or

otherwise hazardous substances. Since a significant amount of urban solid waste tends to be

paper and food waste, the majority is recyclable or biodegradable in landfills. Similarly, most

agricultural waste is recycled and mining waste is left on site.

The portion of solid waste that is hazardous such as oils, battery metals, heavy metals from

smelting industries and organic solvents are the ones we have to pay particular attention to.

These can in the long run, get deposited to the soils of the surrounding area and pollute them by

altering their chemical and biological properties. They also contaminate drinking water aquifer

sources. More than 90% of hazardous waste is produced by chemical, petroleum and metal-

related industries and small businesses such as dry cleaners and gas stations contribute as well.

Solid Waste disposal was brought to the forefront of public attention by the notorious Love

Canal case in USA in 1978. Toxic chemicals leached from oozing storage drums into the soil

underneath homes, causing an unusually large number of birth defects, cancers and respiratory,

nervous and kidney diseases.

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 DEFORESTATION

Soil Erosion occurs when the weathered soil particles are dislodged and carried away by wind or

water. Deforestation, agricultural development, temperature extremes, precipitation including

acid rain, and human activities contribute to this erosion. Humans speed up this process by

construction, mining, cutting of timber, over cropping and overgrazing. It results in floods and

cause soil erosion.

Forests and grasslands are an excellent binding material that keeps the soil intact and healthy.

They support many habitats and ecosystems, which provide innumerable feeding pathways or

food chains to all species. Their loss would threaten food chains and the survival of many

species. During the past few years quite a lot of vast green land has been converted into deserts.

The precious rain forest habitats of South America, tropical Asia and Africa are coming under

pressure of population growth and development (especially timber, construction and agriculture).

Many scientists believe that a wealth of medicinal substances including a cure for cancer and

aids, lie in these forests. Deforestation is slowly destroying the most productive flora and fauna

areas in the world, which also form vast tracts of a very valuable sink for CO2.

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 POLLUTION DUE TO URBANISATION

 POLLUTION OF SURFACE SOILS

Urban activities generate large quantities of city wastes including several Biodegradable

materials (like vegetables, animal wastes, papers, wooden pieces, carcasses, plant twigs, leaves,

cloth wastes as well as sweepings) and many non-biodegradable materials (such as plastic bags,

plastic bottles, plastic wastes, glass bottles, glass pieces, stone / cement pieces). On a rough

estimate Indian cities are producing solid city wastes to the tune of 50,000 - 80,000 metric tons

every day. If left uncollected and decomposed, they are a cause of several problems such as

Clogging of drains: Causing serious drainage problems including the burst / leakage of drainage

lines leading to health problems.

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Barrier to movement of water: Solid wastes have seriously damaged the normal movement of

water thus creating problem of inundation, damage to foundation of buildings as well as public

health hazards.

Foul smell: Generated by dumping the wastes at a place.

Increased microbial activities: Microbial decomposition of organic wastes generate large

quantities of methane besides many chemicals to pollute the soil and water flowing on its surface

When such solid wastes are hospital wastes they create many health problems: As they may have

dangerous pathogen within them besides dangerous medicines, injections.

 POLLUTION OF UNDERGROUND SOIL

Underground soil in cities is likely to be polluted by

Chemicals released by industrial wastes and industrial wastes

Decomposed and partially decomposed materials of sanitary wastes

Many dangerous chemicals like cadmium, chromium, lead, arsenic, selenium products are likely

to be deposited in underground soil. Similarly underground soil polluted by sanitary wastes

generate many harmful chemicals. These can damage the normal activities and ecological

balance in the underground soil

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CAUSES IN BRIEF:

Polluted water discharged from factories

Runoff from pollutants (paint, chemicals, rotting organic material) leaching out of landfill

Oil and petroleum leaks from vehicles washed off the road by the rain into the surrounding

habitat

Chemical fertilizer runoff from farms and crops

Acid rain (fumes from factories mixing with rain)

Sewage discharged into rivers instead of being treated properly

Over application of pesticides and fertilizers

Purposeful injection into groundwater as a disposal method

Interconnections between aquifers during drilling (poor technique)

Septic tank seepage

Lagoon seepage

Sanitary/hazardous landfill seepage

Cemeteries

Scrap yards (waste oil and chemical drainage)

Leaks from sanitary sewers

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EFFECTS OF SOIL POLLUTION

 Agricultural

 Reduced soil fertility

 Reduced nitrogen fixation

 Increased erodibility

 Larger loss of soil and nutrients

 Deposition of silt in tanks and reservoirs

 Reduced crop yield

 Imbalance in soil fauna and flora

 Industrial

 Dangerous chemicals entering underground water

 Ecological imbalance

 Release of pollutant gases

 Release of radioactive rays causing health problems

 Increased salinity

 Reduced vegetation

 Urban

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

 Clogging of drains

 Inundation of areas

 Public health problems

 Pollution of drinking water sources

 Foul smell and release of gases

 Waste management problems

ENVIRONMENTAL LONG TERM EFFECTS OF SOIL POLLUTION

When it comes to the environment itself, the toll of contaminated soil is even direr. Soil that has

been contaminated should no longer be used to grow food, because the chemicals can leech into

the food and harm people who eat it.

If contaminated soil is used to grow food, the land will usually produce lower yields than it

would if it were not contaminated. This, in turn, can cause even more harm because a lack of

plants on the soil will cause more erosion, spreading the contaminants onto land that might not

have been tainted before.

In addition, the pollutants will change the makeup of the soil and the types of microorganisms

that will live in it. If certain organisms die off in the area, the larger predator animals will also

have to move away or die because they've lost their food supply. Thus it's possible for soil

pollution to change whole ecosystems

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EFFECTS OF SOIL POLLUTION IN BRIEF

 Pollution runs off into rivers and kills the fish, plants and other aquatic life

 Crops and fodder grown on polluted soil may pass the pollutants on to the consumers

 Polluted soil may no longer grow crops and fodder

 Soil structure is damaged (clay ionic structure impaired)

 Corrosion of foundations and pipelines

 Impairs soil stability

 May release vapours and hydrocarbon into buildings and cellars

 May create toxic dusts

 May poison children playing in the area

CONTROL OF SOIL POLLUTION

The following steps have been suggested to control soil pollution. To help prevent soil erosion,

we can limit construction in sensitive area. In general we would need less fertilizer and fewer

pesticides if we could all adopt the three R's: Reduce, Reuse, and Recycle. This would give us

less solid waste.

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 Reducing chemical fertilizer and pesticide use

Applying bio-fertilizers and manures can reduce chemical fertilizer and pesticide use. Biological

methods of pest control can also reduce the use of pesticides and thereby minimize soil pollution.

Reusing of materials

Materials such as glass containers, plastic bags, paper, cloth etc. can be reused at domestic levels

rather than being disposed, reducing solid waste pollution.

Recycling and recovery of materials

This is a reasonable solution for reducing soil pollution. Materials such as paper, some kinds of

plastics and glass can and are being recycled. This decreases the volume of refuse and helps in

the conservation of natural resources. For example, recovery of one tonne of paper can save 17

trees.

 REFORESTING

Control of land loss and soil erosion can be attempted through restoring forest and grass cover to

check wastelands, soil erosion and floods. Crop rotation or mixed cropping can improve the

fertility of the land.

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 SOLID WASTE TREATMENT

Proper methods should be adopted for management of solid waste disposal. Industrial wastes can

be treated physically, chemically and biologically until they are less hazardous. Acidic and

alkaline wastes should be first neutralized; the insoluble material if biodegradable should be

allowed to degrade under controlled conditions before being disposed.

As a last resort, new areas for storage of hazardous waste should be investigated such as deep

well injection and more secure landfills. Burying the waste in locations situated away from

residential areas is the simplest and most widely used technique of solid waste management.

Environmental and aesthetic considerations must be taken into consideration before selecting the

dumping sites.

Incineration of other wastes is expensive and leaves a huge residue and adds to air pollution.

Pyrolysis is a process of combustion in absence of oxygen or the material burnt under controlled

atmosphere of oxygen. It is an alternative to incineration. The gas and liquid thus obtained can

be used as fuels. Pyrolysis of carbonaceous wastes like firewood, coconut, palm waste, corn

combs, cashew shell, rice husk paddy straw and saw dust, yields charcoal along with products

like tar, methyl alcohol, acetic acid, acetone and a fuel gas.

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 Anaerobic/aerobic decomposition of biodegradable municipal and domestic waste is also

being done and gives organic manure. Cow dung which releases methane into the

atmosphere, should be processed further in 'gobar gas plants' to produce 'gobar gas' and

good manure.

NATURAL LAND POLLUTION:

Land pollution occurs massively during earth quakes, landslides, hurricanes and floods. All

cause hard to clean mess, which is expensive to clean, and May sometimes take years to restore

the affected area. These kinds of natural disasters are not only a problem in that t

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