Environmental Pollution

The intensive use and misuse of our soil, water and air resources due to population
pressures and increased standard of living, have increased the hazard of declining
productivity and increasing pollution. The environment problems like pollution, global
warming and climate change, acid rain, waste disposal, ozone layer depletion, resource
depletion, land degradation and loss of biodiversity affect every human, animal and nation
on this planet. As our actions have been not in favor of protecting this planet, we have seen
natural disasters striking us more often in the form of flash floods, tsunamis and cyclones.

Sources of pollution
There are two main sources of pollution, i.e. natural and anthropogenic or cultural (caused
by human being). Each of these two sources could be divided into point sources and non-
point or diffuse sources based on the ways and modes of affecting pollution.

Point source of pollution

Point source pollution is contamination that enters the environment through any clear,
specific location. Source of pollution is specific/single and identifiable such as a pipe or a
drain.

Examples
Major point sources include untreated industrial effluent, sewage plants, effluent treatment
plants, effluent from agricultural farm buildings, solid waste disposal sites, application of
plant growth regulators and pesticide stores.

Non-point source of pollution

The pollution is a non-point one if the source of pollution is not specific and non-
identifiable. Non-point sources cannot be monitored since it is difficult rather impossible
to locate. These pollutants cannot be measured in terms of effluent limitations.

Examples
These sources are mainly related to erosion of virgin lands, forests and other natural
vegetation, in-situ weathering of rocks or soils and minerals. These also include un-
scientific application of pesticides, fertilizers and farm applications of other agro-
chemicals, cultivation of marginal sloping lands, construction sites, transportation, strip
mining, piling of dust and litter on impervious surface in urban The worst non-point
pollution source is the aerial sprays of agrochemicals through air-planes even in developed
countries. Evaluation of non-point pollution effects on surface water and soil quality do
differ from the traditional and conventional approaches those were mainly designed for
point sources areas.

Major Environmental Issues

I-Water pollution
Water pollution is the contamination of water bodies (lakes, rivers, oceans and ground
water) due to direct and indirect discharge of pollutants that degrade water quality and
purity. A pollutant is a substance introduced into the environment that has undesired
effects, or adversely affects the usefulness of a resource.

Sources of water pollution

1. Sewage is another name for waste water from domestic and industrial processes.
The discharge of untreated industrial effluent may pollute water with detergents,
dyes, heavy metals (such as lead, cadmium etc.), pharmaceutical drugs, paper,
plastic and other wastes. The domestic sewage enters viruses into the environment
such as those causing hepatitis, typhoid etc.
2. Agricultural processes such as uncontrolled spreading of slurries and manure,
disposal of sheep dip, tillage, ploughing of the land, use of pesticides and fertilizers
and accidental spills from milk dairies.
3. Improperly built and maintained landfills.
4. A substantial amount of oil released into oceans and seas as a result of loss from
storage facilities, spillage during delivery and deliberate disposal of waste oil to
drainage systems.
5. Radioactive substances found in nuclear power plants, industrial, medical and other
scientific processes. They are also present in watches, luminous clocks, television
sets and x-ray machinery.
 6. River/ marine dumping of plastics, supermarket trolleys, bicycles, garden cuttings
and electronic waste. It not only causes water pollution; it also harms wildlife and
increases the risk of flooding.

II- Soil pollution

Soil pollution is any physical or chemical change in soil that adversely affects the health of
plants or other organisms living on and in it.

Sources of soil pollution

1. Industrial effluents like harmful gases and chemicals.

2. Use of chemicals in agriculture like pesticides, fertilizers and insecticides.
3. Use of pesticides in agriculture retains chemicals in the environment for a long time. These
chemicals also effect beneficial organisms like earthworm in the soil and lead to poor soil
quality.
4. Improper or ineffective soil management system.
5. Unfavorable irrigation practices.
6. Improper management and maintenance of septic system.
7. Sanitary waste leakage.
8. Toxic fumes from industries get mixed with rains causing acid rains.
9. Leakages of fuel from automobiles are washed off due to rains and are deposited in the
nearby soil.
10. Unhealthy waste management techniques release sewage into dumping grounds and nearby
water bodies.
11. Absence of proper garbage disposal system leads to scattered garbage in the soil. These
contaminants can block passage of water into the soil and affects its water holding capacity.
12. Unscientific disposal of nuclear waste contaminate soil and can cause mutations.

Land degradation

Land degradation is a process in which the value of the biophysical environment is affected by a
combination of human-induced processes acting upon the land. Land degradation leads to a
significant reduction of the productive capacity of land.
III- Air pollution
Air pollution is a broad term applied to all physical (particulate matter), chemical and biological
agents that modify the natural characteristics of atmosphere. OR

The introduction of organic and inorganic chemicals, particulate matter, smoke and or biological
materials into the atmosphere that could harm or discomfort the humans and other living
organisms or disturbs the natural composition and chemistry of air.

Sources of air pollution

There are two major sources of air pollution: i) Anthropogenic and ii) Natural sources.

Anthropogenic sources

1. Burning of Fossil Fuels which release sulfur dioxide, carbon dioxide, carbon monoxide
and nitrogen oxides.
2. Burning of crop wastes by farmers.
3. Aerosol sprays and refrigeration, which once depended on feron and other chlorofluoro-
carbons.
4. Arsenic and chlorine found in drinking water and inhaled in bathroom showers.
5. Dust and chemicals from mining operations.
6. Fumes from paint, varnish and other solvents.
7. Industrial activity in general. Industries release large amount of carbon monoxide,
hydrocarbons, organic compounds, and chemicals into the air thereby depleting the quality
of air.
8. Military actions, including the use and testing of nuclear bombs, poison gases and germ
warfares as well as the so called operation against terrorists.
9. Oil refining.
10. Rocketry, which produces many tons of exotic emissions quickly, some of these
deposited directly into the upper atmosphere.
11. Waste deposition in landfills, which generate methane.
12. Agricultural practices, especially rice culture, fish farming, use of insecticides and
pesticides, FYM storage and its soil application and N fertilizers. Ammonia is a very
 common by product from agriculture related activities and is one of the most hazardous
gases in the atmosphere.
13. Deforestation and other land degradation processes.

Natural sources
1.Dust from large areas of land with little or no vegetation, e.g., salt affected soils.
2.Methane emitted by the digestion of animals, usually cattle.
3.Pine trees, which emit volatile organic compounds (VOC) and oxygen.
4.Radon gas from earth minerals.
5.Smoke and carbon monoxide from wildfires.
6.Volcanic activity, which produce sulfur, chlorine and ash particles.
7.Submergence as result of floods.
8.Earthquakes and damaging buildings.
9.Emergent and uncontrolled explosions of fire arms.

Indoor air pollution

Lack of ventilation concentrates indoor air pollution to which humans are most exposed.
Background pollution comes from such ordinary sources as shower water mist (containing arsenic
and manganese), household cleaning products, painting materials (emitting VOC as they dry) and
spray of insecticides. Carbon monoxide is a quick and silent killer, often caused by faulty vents
and chimneys or smokestacks or by burning charcoal indoors.

IV- Climate change

Climate change is a broader term that refers to long-term changes in climate, including average
temperature and precipitation. Harmful effects of climate change include: melting of polar regions,
occurrence of new diseases and permanent inhibition in growth of certain plants essential for
human survival.

V- Green-house effect and Global warming

The greenhouse effect is a phenomenon that causes the earth temperature to increase. Carbon
dioxide and the other so called greenhouse gases, CH4, N2O, CFC emitted from the earth surface,
move to upper atmosphere, where they are heated by sun light. Energy from the sun’s radiation is
absorbed by these gases and emitted to the surface of earth, resulting an increase in the temperature
of earth surface.

Global warming is the increase of the earth’s average surface temperature due to a build-up of
greenhouse gases such as CO2, CH4, N2O, CFC in the atmosphere. As is customary in science, the
issue of global warming, attributed to greenhouse effect, has been disputed and defended during
the years. The greenhouse effect does not uniformly effect the whole earth, but only certain parts,
where the production of pollutant gases is most intense, such as in regions where large industrial
centers are located.

Pollutants promote global warming

1. Greenhouse gases
2. Most common CO2
3. Exhaust from cars, trucks and other auto-vehicles

Pollutants slow down global warming

Aerosols released from cars, trucks and smokestacks slow down process of global warming. The
aerosols are made up of different materials which mainly include mineral dust, sulfates, sea salt or
carbon. Some of these particles get into the atmosphere naturally. Computer models indicate that
tiny aerosols cause about half as much cooling as greenhouse gases cause warming in the world.

Sources of global warming

1. Discharge of greenhouse gases from smokestacks, vehicles and burning forests.

2. Burning of fossil fuels and deforestation resulting in higher carbon dioxide concentrations
in the air.
3. Release of methane from paddy rice fields, manures and landfill emissions.
4. Use of chlorofluorocarbons (CFCs) in refrigeration systems.
5. Agricultural activities, including the use of fertilizers that lead to higher nitrous oxide (NO)
concentrations.
2NO3 → 2NO2→NO→ N20→ N2
 VI-Ozone shield

Ozone is a form of oxygen with the formula of O3. Ozone is a normal constituent of the stratosphere
and is present as an invisible cloud at approximately 24 km above the earth, called the ozone layer,
shielding the earth from harmful radiations from the sun.

Sources of destruction of ozone shield

1. It is due more to the effects of industrial and especially transportation related air pollution
than to those of agricultural pollution of the air.
2. Supersonic air transport is suspected of contributing to the destruction of ozone, because
of CO2 and H2O emissions from combustion of hydrocarbon fuel.
3. Other gases responsible for decomposing ozone are N2O, NO, CH3, CH4, and gases from
organic synthetics, such as CFCl3 (Feron), and CFCs (Chlorofluorocarbons) used as
refrigerants and aerosols.

VII-Acid rain

Acid rain is a natural phenomenon occurring during any thunderstorm, accompanied by heavy
lightening, or it can also be the result of volcanic eruptions. In an unpolluted environment,
rainwater is slightly acidic, having a pH of about 5.7. The normal acidity of rain water is created
when atmospheric CO2 is dissolved in water in clouds, mist, or fog and is converted into a mild
acid (carbonic acid)

CO2 + H2O → H2CO3 (carbonic acid)

Small amount of nitric acid is also responsible for the acidity of normal rainwater, which is
produced by the oxidation of nitrogen in presence of water during lightning storms.

2 N2 + 5O2 + 2H2O→ 4 HNO3 (nitric acid)

Acid precipitation is rain and snow with a pH below 5.7.

VIII-Energy sources

Energy is the life line of the economy for any country. Energy is available in various forms-
gaseous, liquid and solid- from a variety of sources. The energy sources are generally classified
into two categories.
 1. Non-renewable energy sources
2. Renewable energy sources

Non-renewable sources

A non-renewable source can be defined as a resource that is not replaced on a continuous basis or
is replaced only very slowly, but dependent completely on natural processes. The following energy
sources can be considered non-renewable:

 Petroleum (oil)
 Coal
 Natural gas
 Uranium and thorium (nuclear energy)

Renewable sources

Renewable energy source is considered as any resource that is available naturally on a continuous
basis or can be continually generated over a short period of time; which may be on a daily basis,
or over several days, or over several years. The renewable energy sources are derived directly from
sun (Such as thermal, photo-chemical, photo-electric), indirectly from sun (such as wind,
hydropower, photosynthetic energy stored in biomass or from the natural phenomenon of the
environment (such as geothermal and tidal energy). The most common renewable energy sources
are:

 Solar energy
 Wind energy
 Hydropower energy
 Geothermal energy
 Ocean energy
 Biomass energy

Resource depletion and its causes

Resource depletion is the consumption of a resource faster than it can be replenished. The
following are the main causes of resource depletion.

1. Overconsumption, excessive or unnecessary use of resources.

 2. Overpopulation.

3. Pollution or contamination of resources.

4. Slash-and-burn agricultural practices, currently occurring in many developing countries.

5. Soil erosion.

6. Mining for fossil fuels and minerals.

7. Technological and industrial development.

8. Deforestation.

IX- Deforestation

Traditionally, deforestation refers to the destruction of forest cover to open new lands which is
true for humid regions.

Today, deforestation can also mean degradation of forest quality as suggested by the United
Nations Research Institute for Social Development. The forest quality pertains, for example to
forest density, tree species, genetic diversity, and ecological importance. The degradation of forest
quality is a slow process.

Causes of deforestation

1. The degradation of forest quality might be due to edge effects, fragmentation of habitats
and effects of grazing animals.
2. The forest destruction is a rapid process because of catastrophic wildfires, effect of acid
rain and urban development.

X- Biodiversity

The variation of many forms of living organisms within an ecosystem is called biological diversity
or biodiversity. Three types of biodiversity can be distinguished: terrestrial, fresh-water marine
biodiversity. Terrestrial biodiversity is well known of above three.

Degradation of biodiversity

Degradation of biodiversity is the harmful decline of genetic diversity, species diversity and
ecosystem diversity. The issues on its degradation are also more closely related to the theme of
deforestation. For example, Species diversity in a forest is often considered an indicator of a
healthy biological ecosystem. The interaction between these plants and animals is so close that the
extinction of one species may have direct or indirect effect on other species.

Sources that contribute to degradation of biodiversity

1- Deforestation
2- Commercial hunting and harvesting
3- Destruction and alteration of habitat
4- Pest and predator control
5- The collection of animals and plants for human enjoyment, research and other purposes
6- Pollution
7- Biological factors
8- Multiplicity of factors
 Air Pollution, Its Causes, Effects and Solutions
Air pollution is one such form that refers to the contamination of the air, irrespective of indoors or
outside. A physical, biological or chemical alteration to the air in the atmosphere can be termed as
pollution. It occurs when any harmful gases, dust, smoke enters into the atmosphere and makes it
difficult for plants, animals and humans to survive as the air becomes dirty.

Air pollution can further be classified into two sections- Visible air pollution and invisible air
pollution. Another way of looking at Air pollution could be any substance that holds the potential
to hinder the atmosphere or the well-being of the living beings surviving in it. The sustainment of
all things living is due to a combination of gases that collectively form the atmosphere; the
imbalance caused by the increase or decrease of the percentage of these gases can be harmful for
survival.

Types of Pollutants

In order to understand the causes of Air pollution, several divisions can be made. Primarily air
pollutants can be caused by primary sources or secondary sources. The pollutants that are a direct
result of the process can be called primary pollutants. A classic example of a primary pollutant
would be the sulfur-dioxide emitted from factories

Secondary pollutants are the ones that are caused by the inter mingling and reactions of primary
pollutants. Smog created by the interactions of several primary pollutants is known to be as
secondary pollutant.

Causes of Air pollution:

1. Burning of Fossil Fuels: Sulfur dioxide emitted from the combustion of fossil fuels like coal,
petroleum and other factory combustibles is one the major cause of air pollution. Pollution emitting
from vehicles including trucks, jeeps, cars, trains, airplanes cause immense amount of pollution.
We rely on them to fulfill our daily basic needs of transportation. But their overuse is killing our
environment as dangerous gases are polluting the environment. Carbon Monoxides caused by
improper or incomplete combustion and generally emitted from vehicles is another major pollutant
along with Nitrogen Oxides, that is produced from both natural and manmade processes.

2. Agricultural activities: Ammonia is a very common by product from agriculture related

activities and is one of the most hazardous gases in the atmosphere. Use of insecticides, pesticides
and fertilizers in agricultural activities has grown quite a lot. They emit harmful chemicals into the
air and can also cause water pollution.

3. Exhaust from factories and industries: Manufacturing industries release large amount of
carbon monoxide, hydrocarbons, organic compounds, and chemicals into the air thereby depleting
the quality of air. Manufacturing industries can be found at every corner of the earth and there is
no area that has not been affected by it. Petroleum refineries also release hydrocarbons and various
other chemicals that pollute the air and also cause land pollution.

4. Mining operations: Mining is a process wherein minerals below the earth are extracted using
large equipment. During the process dust and chemicals are released in the air causing massive air
pollution. This is one of the reason which is responsible for the deteriorating health conditions of
workers and nearby residents.

5. Indoor air pollution: Household cleaning products, painting supplies emit toxic chemicals in
the air and cause air pollution. Have you ever noticed that once you paint walls of your house, it
creates some sort of smell which makes it literally impossible to breath?

Suspended particulate matter popular by its acronym SPM, is another cause of pollution. Referring
to the particles afloat in the air, SPM is usually caused by dust, combustion etc.

Effects of Air pollution:

1. Respiratory and heart problems: The effects of Air pollution are alarming. They are known
to create several respiratory and heart conditions along with Cancer, among other threats to the
body. Several millions are known to have died due to direct or indirect effects of Air pollution.
Children in areas exposed to air pollutants are said to commonly suffer from pneumonia and
asthma.
2. Global warming: Another direct effect is the immediate alterations that the world is witnessing
due to Global warming. With increased temperatures worldwide, increase in sea levels and melting
of ice from colder regions and icebergs, displacement and loss of habitat have already signaled an
impending disaster if actions for preservation and normalization aren’t undertaken soon.

3. Acid Rain: Harmful gases like nitrogen oxides and sulfur oxides are released into the
atmosphere during the burning of fossil fuels. When it rains, the water droplets combine with these
air pollutants, becomes acidic and then falls on the ground in the form of acid rain. Acid rain can
cause great damage to human, animals and crops.

4. Effect on Wildlife: Just like humans, animals also face some devastating effects of air pollution.
Toxic chemicals present in the air can force wildlife species to move to new place and change their
habitat. The toxic pollutants deposit over the surface of the water and can also affect sea animals.

5. Depletion of Ozone layer: Ozone exists in earth’s stratosphere and is responsible for protecting
humans from harmful ultraviolet (UV) rays. Earth’s ozone layer is depleting due to the presence
of chlorofluorocarbons, hydro chlorofluorocarbons in the atmosphere. As ozone layer will go thin,
it will emit harmful rays back on earth and can cause skin and eye related problems. UV rays also
have the capability to affect crops.

When you try to study the sources of Air pollution, you enlist a series of activities and interactions
that create these pollutants. There are two types of sources that we will take a look at: Natural
sources and Man-made sources.

Natural sources of pollution include dust carried by the wind from locations with very little or no
green cover, gases released from the body processes of living beings (Carbon dioxide from humans
during respiration, Methane from cattle during digestion, Oxygen from plants during
Photosynthesis). Smoke from the combustion of various inflammable objects, volcanic, etc. along
with the emission of polluted gases also make it to the list of Natural sources of Pollution.

While looking at the man-made contributions towards air pollution, smoke again features as a
prominent component. The smoke emitted from various forms of combustion like in bio, factories,
vehicles, furnaces etc. Waste used to create landfills generate methane, that is harmful in several
ways. The reactions of certain gases and chemicals also form harmful fumes that can be dangerous
to the well-being of living creatures.

Solutions for Air Pollution:

1. Use public mode of transportation: Encourage people to use more and more public modes of
transportation to reduce pollution. Also, try to make use of carpooling. If you and your colleagues
come from the same locality and have same timings, you can explore this option to save energy
and money.

2. Conserve energy: Switch off fans and lights when you are going out. Large amount of fossil
fuels is burnt to produce electricity. You can save the environment from degradation by reducing
the amount of fossil fuels to be burned.

3. Understand the concept of Reduce, Reuse and Recycle: Do not throw away items that are of
no use to you. In-fact reuse them for some other purpose. For e.g. you can use old jars to store
cereals or pulses.

4. Emphasis on clean energy resources: Clean energy technologies like solar, wind and
geothermal are on high these days. Governments of various countries have been providing grants
to consumers who are interested in installing solar panels for their home. This will go a long way
to curb air pollution.

5. Use energy efficient devices: CFL lights consume less electricity as against their counterparts.
They live longer, consume less electricity, lower electricity bills and also help you to reduce
pollution by consuming less energy.
 WATER POLLUTION: Its Causes, Impacts and Remedies
Water pollution: an introduction

Over two thirds of Earth's surface is covered by water; less than a third is taken up by land. As
Earth's population continues to grow, people are putting ever-increasing pressure on the planet's
water resources. In a sense, our oceans, rivers, and other inland waters are being "squeezed" by
human activities-not so they take up less room, but so their quality is reduced. Poorer water quality
means water pollution.

How serious is the problem? According to the environmental campaign organization

WWF: "Pollution from toxic chemicals threatens life on this planet. Every ocean and every
continent, from the tropics to the once-pristine polar regions, is contaminated."

What are the main types of water pollution?

When we think of Earth's water resources, we think of huge oceans, lakes, and rivers. Water
resources like these are called surface waters. The most obvious type of water pollution affects
surface waters. For example, a spill from an oil tanker creates an oil slick that can affect a vast
area of the ocean.

Not all of Earth's water sits on its surface, however. A great deal of water is held in underground
rock structures known as aquifers, which we cannot see and seldom think about. Water stored
underground in aquifers is known as groundwater. Aquifers feed our rivers and supply much of
our drinking water. They too can become polluted, for example, when weed killers used in people's
gardens drain into the ground. Groundwater pollution is much less obvious than surface-water
pollution but is no less of a problem.

Surface waters and groundwater are the two types of water resources that pollution affects. There
are also two different ways in which pollution can occur. If pollution comes from a single location,
such as a discharge pipe attached to a factory, it is known as point-source pollution. Other
examples of point source pollution include an oil spill from a tanker, a discharge from a smoke
stack (factory chimney), or someone pouring oil from their car down a drain. A great deal of water
pollution happens not from one single source but from many different scattered sources. This is
called nonpoint-source pollution.
When point-source pollution enters the environment, the place most affected is usually the area
immediately around the source. For example, when a tanker accident occurs, the oil slick is
concentrated around the tanker itself and, in the right ocean conditions, the pollution disperses the
further away from the tanker you go. Sometimes pollution that enters the environment in one place
has an effect hundred or even thousands of miles away. This is known as transboundary
pollution. One example is the way radioactive waste travels through the oceans from nuclear
reprocessing plants in England and France to nearby countries such as Ireland and Norway.

How do we know when water is polluted?

Some forms of water pollution are very obvious: everyone has seen TV news footage of oil slicks
filmed from helicopters flying overhead. Water pollution is usually less obvious and much harder
to detect than this. But how can we measure water pollution when we cannot see it? How do we
even know it's there?

There are two main ways of measuring the quality of water. One is to take samples of the water
and measure the concentrations of different chemicals that it contains. If the chemicals are
dangerous or the concentrations are too great, we can regard the water as polluted. Measurements
like this are known as chemical indicators of water quality. Another way to measure water quality
involves examining the fish, insects, and other invertebrates that the water will support. If many
different types of creatures can live in a river, the quality is likely to be very good; if the river
supports no fish life at all, the quality is obviously much poorer. Measurements like this are called
biological indicators of water quality.

What are the causes of water pollution?

Most water pollution doesn't begin in the water itself. Take the oceans: around 80 percent of ocean
pollution enters our seas from the land. Virtually any human activity can have an effect on the
quality of our water environment. When farmers fertilize the fields, the chemicals they use are
gradually washed by rain into the groundwater or surface waters nearby. Sometimes the causes of
water pollution are quite surprising. Chemicals released by smokestacks (chimneys) can enter the
atmosphere and then fall back to earth as rain, entering seas, rivers, and lakes and causing water
pollution. That's called atmospheric deposition. Water pollution has many different causes and
this is one of the reasons why it is such a difficult problem to solve.
Sewage

With billions of people on the planet, disposing of sewage waste is a major problem. According
to 2013 figures from the World Health Organization, some 780 million people (11 percent of the
world's population) don't have access to safe drinking water, while 2.5 billion (40 percent of the
world's population) don't have proper sanitation (hygienic toilet facilities); although there have
been great improvements in securing access to clean water, relatively little progress has been made
on improving global sanitation in the last decade. Sewage disposal affects people's immediate
environments and leads to water-related illnesses such as diarrhea that kills 760,000 children under
five each year. (Back in 2002, the World Health Organization estimated that water-related diseases
could kill as many as 135 million people by 2020.) In developed countries, most people have flush
toilets that take sewage waste quickly and hygienically away from their homes.

Nutrients

Suitably treated and used in moderate quantities, sewage can be a fertilizer: it returns important
nutrients to the environment, such as nitrogen and phosphorus, which plants and animals need for
growth. The trouble is, sewage is often released in much greater quantities than the natural
environment can cope with. Chemical fertilizers used by farmers also add nutrients to the soil,
which drain into rivers and seas and add to the fertilizing effect of the sewage. Together, sewage
and fertilizers can cause a massive increase in the growth of algae or plankton that overwhelms
huge areas of oceans, lakes, or rivers. This is known as a harmful algal bloom (also known as an
HAB or red tide, because it can turn the water red). It is harmful because it removes oxygen from
the water that kills other forms of life, leading to what is known as a dead zone. The Gulf of
Mexico has one of the world's most spectacular dead zones. Each summer, according to studies by
the NOAA, it grows to an area of around 5500 square miles (14,000 square kilometers), which is
about the same size as the state of Connecticut.

Waste water

A few statistics illustrate the scale of the problem that waste water (chemicals washed down drains
and discharged from factories) can cause adverse effects. Around half of all ocean pollution is
caused by sewage and waste water. Each year, the world generates perhaps 5–10 billion tons of
industrial waste, much of which is pumped untreated into rivers, oceans, and other waterways.
Chemical waste

Detergents are relatively mild substances. At the opposite end of the spectrum are highly toxic
chemicals such as polychlorinated biphenyls (PCBs). They were once widely used to
manufacture electronic circuit boards, but their harmful effects have now been recognized and
their use is highly restricted in many countries. Nevertheless, an estimated half million tons of
PCBs were discharged into the environment during the 20th century. In a classic example of
transboundary pollution, traces of PCBs have even been found in birds and fish in the Arctic. They
were carried there through the oceans, thousands of miles from where they originally entered the
environment. Although PCBs are widely banned, their effects will be felt for many decades
because they last a long time in the environment without breaking down.

Radioactive waste

People view radioactive waste with great alarm-and for good reason. At high enough
concentrations it can kill; in lower concentrations it can cause cancers and other illnesses. The
biggest sources of radioactive pollution in Europe are two factories that reprocess waste fuel
from nuclear power plants: Sellafield on the north-west coast of Britain and Cap La Hague on the
north coast of France. Both discharge radioactive waste water into the sea, which ocean currents
then carry around the world. Countries such as Norway, which lie downstream from Britain,
receive significant doses of radioactive pollution from Sellafield. The Norwegian government has
repeatedly complained that Sellafield has increased radiation levels along its coast by 6–10 times.
Both the Irish and Norwegian governments continue to press for the plant's closure.

Oil pollution

When we think of ocean pollution, huge black oil slicks often spring to mind, yet these spectacular
accidents represent only a tiny fraction of all the pollution entering our oceans. Even considering
oil by itself, tanker spills are not as significant as they might seem: only 12 percent of the oil that
enters the oceans comes from tanker accidents; over 70 percent of oil pollution at sea comes from
routine shipping and from the oil people pour down drains on land. However, what makes tanker
spills so destructive is the sheer quantity of oil they release at once — in other words, the
concentration of oil they produce in one very localized part of the marine environment. The biggest
oil spill in recent years (and the biggest ever spill in US waters) occurred when the tankerExxon
Valdez broke up in Prince William Sound in Alaska in 1989. Around 12 million gallons (44 million
liters) of oil were released into the pristine wilderness—enough to fill your living room 800 times
over! Estimates of the marine animals killed in the spill vary from approximately 1000 sea otters
and 34,000 birds to as many as 2800 sea otters and 250,000 sea birds. Several billion salmon and
herring eggs are also believed to have been destroyed.

Plastics

If you've ever taken part in a community beach clean, you'll know that plastic is far and away the
most common substance that washes up with the waves. There are three reasons for this: plastic is
one of the most common materials, used for making virtually every kind of manufactured object
from clothing to automobile parts; plastic is light and floats easily so it can travel enormous
distances across the oceans; most plastics are not biodegradable (they do not break down naturally
in the environment), which means that things like plastic bottle tops can survive in the marine
environment for a long time. (A plastic bottle can survive an estimated 450 years in the ocean and
plastic fishing line can last up to 600 years.)

While plastics are not toxic in quite the same way as poisonous chemicals, they nevertheless
present a major hazard to seabirds, fish, and other marine creatures. For example, plastic fishing
lines and other debris can strangle or choke fish (This is sometimes called ghost fishing). About
half of all the world's seabird species are known to have eaten plastic residues. In one study of 450
shearwaters in the North Pacific, over 80 percent of the birds were found to contain plastic residues
in their stomachs

Other forms of pollution

These are the most common forms of pollution—but by no means the only ones. Heat or thermal
pollution from factories and power plants also causes problems in rivers. By raising the
temperature, it reduces the amount of oxygen dissolved in the water, thus also reducing the level
of aquatic life that the river can support.

Another type of pollution involves the disruption of sediments (fine-grained powders) that flow
from rivers into the sea. Dams built for hydroelectric power or water reservoirs can reduce the
sediment flow. This reduces the formation of beaches, increases coastal erosion (the natural
destruction of cliffs by the sea), and reduces the flow of nutrients from rivers into seas (potentially
reducing coastal fish stocks). Increased sediments can also present a problem. During construction
work, soil, rock, and other fine powders sometimes enters nearby rivers in large quantities, causing
it to become turbid (muddy or silted). The extra sediment can block the gills of fish, effectively
suffocating them. Construction firms often now take precautions to prevent this kind of pollution
from happening.

What are the effects of water pollution?

Some people believe pollution is an inescapable result of human activity: they argue that if we
want to have factories, cities, ships, cars, oil, and coastal resorts, some degree of pollution is almost
certain to result. In other words, pollution is a necessary evil that people must put up with if they
want to make progress. Fortunately, not everyone agrees with this view. One reason people have
woken up to the problem of pollution is that it brings costs of its own that undermine any economic
benefits that come about by polluting.

Take oil spills, for example. They can happen if tankers are too poorly built to survive accidents
at sea. But the economic benefit of compromising on tanker quality brings an economic cost when
an oil spill occurs. The oil can wash up on nearby beaches, devastate the ecosystem, and severely
affect tourism. The main problem is that the people who bear the cost of the spill (typically a small
coastal community) are not the people who caused the problem in the first place (the people who
operate the tanker). Yet, arguably, everyone who puts gasoline (petrol) into their car—or uses
almost any kind of petroleum-fueled transport—contributes to the problem in some way. So oil
spills are a problem for everyone, not just people who live by the coast and tanker operates.

Sewage is another good example of how pollution can affect us all. Sewage discharged into coastal
waters can wash up on beaches and cause a health hazard. People who bathe or surf in the water
can fall ill if they swallow polluted water—yet sewage can have other harmful effects too: it can
poison shellfish (such as cockles and mussels) that grow near the shore. People who eat poisoned
shellfish risk suffering from an acute—and sometimes fatal—illness called paralytic shellfish
poisoning. Shellfish is no longer caught along many shores because it is simply too polluted with
sewage or toxic chemical wastes that have discharged from the land nearby.

Pollution matters because it harms the environment on which people depend. The environment is
not something distant and separate from our lives. It's not pretty shoreline hundreds of miles from
our homes or a wilderness landscape that we see only on TV. The environment is everything that
surrounds us that gives us life and health. Destroying the environment ultimately reduces the
quality of our own lives—and that, most selfishly, is why pollution should matter to all of us.

How can we stop water pollution?

There is no easy way to solve water pollution; if there were, it wouldn't be so much of a problem.
Broadly speaking, there are three different things that can help to tackle the problem—education,
laws, and economics—and they work together as a team.

Education

Making people aware of the problem is the first step to solving it. In the early 1990s, when surfers
in Britain grew tired of catching illnesses from water polluted with sewage, they formed a group
called Surfers against Sewage to force governments and water companies to clean up their act.
People who've grown tired of walking the world's polluted beaches often band together to organize
community beach-cleaning sessions. Anglers who no longer catch so many fish have campaigned
for tougher penalties against factories that pour pollution into our rivers. Greater public awareness
can make a positive difference.

Laws

One of the biggest problems with water pollution is its transboundary nature. Many rivers cross
countries, while seas span whole continents. Pollution discharged by factories in one country with
poor environmental standards can cause problems in neighboring nations, even when they have
tougher laws and higher standards. Environmental laws can make it tougher for people to pollute,
but to be really effective they have to operate across national and international borders. This is
why we have international laws governing the oceans, such as the 1982 UN Convention on the
Law of the Sea (signed by over 120 nations), the 1972 London (Dumping) Convention, the
1978 MARPOL International Convention for the Prevention of Pollution from Ships, and the
1998 OSPAR Convention for the Protection of the Marine Environment of the North East Atlantic.
The European Union has water-protection laws (known as directives) that apply to all of its
member states. They include the 1976 Bathing Water Directive (updated 2006), which seeks to
ensure the quality of the waters that people use for recreation. Most countries also have their own
water pollution laws. In the United States, for example, there is the 1972 Clean Water Act and the
1974 Safe Drinking Water Act.

Economics

Most environmental experts agree that the best way to tackle pollution is through something called
the polluter pays principle. This means that whoever causes pollution should have to pay to clean
it up, one way or another. Polluter pays can operate in all kinds of ways. It could mean that tanker
owners should have to take out insurance that covers the cost of oil spill cleanups, for example. It
could also mean that shoppers should have to pay for their plastic grocery bags, as is now common
in Ireland, to encourage recycling and minimize waste. Or it could mean that factories that use
rivers must have their water inlet pipes downstream of their effluent outflow pipes, so if they cause
pollution, they themselves are the first people to suffer. Ultimately, the polluter pays principle is
designed to deter people from polluting by making it less expensive for them to behave in an
environmentally responsible way.

Our clean future

Life is ultimately about choices-and so is pollution. We can live with sewage-strewn beaches, dead
rivers, and fish that are too poisonous to eat. Or we can work together to keep the environment
clean so the plants, animals, and people who depend on it remain healthy. We can take individual
action to help reduce water pollution, for example, by using environmentally friendly detergents,
not pouring oil down drains, reducing pesticides, and so on. We can take community action too,
by helping out on beach cleans or litter picks to keep our rivers and seas that little bit cleaner. And
we can take action as countries and continents to pass laws that will make pollution harder and the
world less polluted. Working together, we can make pollution less of a problem-and the world a
better place.
 Soil Pollution and its Impact on Ecosystem
“The soil does not stay the same, but like anything alive, is always changing and telling its own
story. Soil is the substance of transformation”.

Introduction:
The planet Earth is suffering from an ever-escalating rate of pollution. It was not until the twentieth
century that mankind was seriously concerned about pollution. But now pollution has reached to
such a significant level that is influencing all ecological compartments. There are many types of
pollution. Among these most important are i.e. soil pollution, air pollution, noise pollution, and
water pollution. This chapter deals with soil pollution, its possible causes and adverse impact on
the ecosystem. Concerns about soil pollution have increased in the recent decades. Soil pollution
has deteriorated large areas of agricultural land around the globe.

Soil: “Soil is the unconsolidated upper part of the earth’s crust which serves as a natural medium
for the growth of plants. It is dynamic in nature and composed of mineral and organic materials,
water, air and living forms (plants and animals) that supports plant growth”.
1. Soil supports the growth of higher plants mainly by providing a medium for plant roots and
supplying nutrients.
2. Soil properties are the principal factor controlling the fate of water in hydrological system
3. Soil functions as nature’s recycling system.
4. Soils provide habitats for living organisms.
5. Soils markedly influence the composition and physical condition of the atmosphere.
6. In human-built ecosystem, soil plays an important role as an engineering
medium/materials.
> World Soil Day was established in 2002 by the International Union of Soil Sciences (IUSS) to
celebrate the importance of soil and its vital contributions to human health and safety.
> World Soil Day is annually held on December 5 to highlight soil's importance on Earth. World
Soil Day serves as a reminder to all of us that we owe our existence to the soil.
> The UN General Assembly recognized 2015 as the International Year of Soils to emphasize the
importance of soils beyond the soil science community.
Pollution: “It is any alteration of air, water or soil that harms health, survival, or activities of
humans and other living organisms”.

Soil Pollution: “Soil pollution is any physical or chemical change in soil that adversely
affects the health of plants or other organisms living on and in it”. Soil is polluted due to build-up
of persistent toxic compounds, chemicals, salts, radioactive materials, or disease causing agents,
which have adverse effects on plant growth and soil ecology.
Soil pollution occurs when the presence of toxic chemicals, pollutants or contaminants in the soil
is in high enough concentrations to be of risk to plants, wildlife, humans and of course, the soil
itself. Arable land is turning to desert and becoming non-arable at ever-increasing rates, due largely
in part to global warming and agricultural fertilizers and pesticides, lessening the hope that we can
feed our booming population. Within 40 years, there will be over 2 billion more people, which is
the equivalent of adding another China and India. Food production will have to increase at least
40% and most of that will have to be grown on the fertile soils that cover just 11% of the global
land surface. However, there is little new land that can be brought into production and existing
land is being lost and degraded. The United Nations Food and Agricultural Organization states
that annually, 75 billion tons of soil, the equivalent of nearly 10 million hectares, which is about
25 million acres, of arable land is lost to erosion, water-logging and salinity and another 20 million
hectares is abandoned because its soil quality has been degraded. Contact with contaminated soil
may be direct, from using parks, schools etc., or indirect by inhaling soil contaminants which have
vaporized or through the consumption of plants or animals that have accumulated large amounts
of soil pollutants, and may also result from secondary contamination of water supplies and from
deposition of air contaminants.

Causes of Soil Pollution: Soil Pollution is a result of many activities by mankind which
contaminate the soil. The main sources of soil pollution include:
1. Industrial Activities: Industrial activities have been the biggest contributor to the problem in
the last century, especially since the amount of mining and manufacturing has increased. About
90% of the soil pollution is caused by industrial waste products. Most industries are dependent on
extracting minerals from the Earth. Whether it is iron ore or coal, the by products are contaminated
and they are not disposed of in a manner that can be considered safe. As a result, the industrial
waste lingers in the soil surface for a long time and makes it unsuitable for use. Some of the
important examples include:
i) Oil drilling and mining industries produce a lot of harmful waste, which finds its way into the
environment either as discharge during industrial processes or through leaching after disposal.
ii) Toxic fumes from the regulated landfills contain chemicals that can fall back to the earth in the
form of acid rain and can damage the soil profile. These pollutants entering the soil ultimately
affect plant and animal species and local water supplies and drinking water.
2. Agricultural Activities: Agriculture is also responsible for a high percentage of soil
contamination, mainly due to its use of harmful pesticides, herbicides, and fertilizers. Chemical
utilization has gone up tremendously since technology provided us with modern pesticides and
fertilizers. They are full of chemicals that are not produced in nature and cannot be broken down
by it. As a result, they seep into the ground after they mix with water and slowly reduce the fertility
of the soil. Other chemicals damage the composition of the soil and make it easier to erode by
water and air. Plants absorb many of these pesticides and when they decompose, they cause soil
pollution since they become a part of the land.
i) Pesticides and herbicides: Pesticides applied to plants can also leak into the ground, leaving
long-lasting effects. These chemicals seep into the ground after use, either directly or indirectly
(through the decomposing plants and animals they have been used on), contaminating the soil and
reducing its fertility and other health associated hazards.
ii) Fertilizers: Some of the harmful chemicals found in the fertilizers (e.g. cadmium in phosphate
fertilizers) may accumulate above their toxic levels, ironically leading to the poisoning of crops.
Heavy metals can enter the soil through the use of polluted water in watering crops, or through the
use of mineral fertilizers.
3. Urban activities: Human activities can lead to soil pollution directly and indirectly. Improper
drainage and increase run-off contaminates the nearby land areas or streams. Improper disposal of
trash breaks down into the soil and it deposits in a number of chemical and pollutants into the soil.
These may again seep into groundwater or wash away in local water system. Excess waste
deposition increases the presence of bacteria in the soil. Decomposition by bacteria generates
methane gas contributing to global warming and poor air quality. It also creates foul odors and can
impact quality of life.
4. Improper Waste Disposal: The waste we produce, be it industrial, agricultural, household
waste or sewage, needs to be disposed of somewhere, and unfortunately it’s very hard to dispose
of such waste without causing some form of pollution. Areas surrounding waste disposal sites (like
landfill, dumps, and sewage treatment plants) often show signs of soil contamination.
5. Accidental Oil Spills: Oil leaks can happen during storage and transport of chemicals. This can
be seen at most of the fuel stations. The chemicals present in the fuel deteriorates the quality of
soil and make them unsuitable for cultivation. These chemicals can enter into the groundwater
through soil and make the water undrinkable.
6. Acid Rain: Acid rain is caused when pollutants present in the air mixes up with the rain and fall
back on the ground. The polluted water could dissolve away some of the important nutrients found
in soil and change the structure of the soil.

Effects of Soil Pollution on the Ecosystem: “An ecosystem is a self-contained,

dynamic system made of a population of species in its physical environment”. This concept is used
to study the complex interactions between the organisms - plants, animals, bacteria, and fungi -
that make up the community. There are many different ways in which the community of organisms
interacts. For example, there is the food chain where each organism is in a producer, consumer,
predator, and prey relationship; there is the oxygen cycle and the water cycle that sustains the
organisms. When an ecosystem gets polluted, the natural balance in the system is disturbed and
this affects the organisms in different ways. It is important to know how a simple act like
introducing sewage water or toxic waste into a lake can threaten several life species and plants in
the area.
Soil contamination greatly affects the ecosystem; it slows down or stops plant growth, which
changes the structure of the soil and can lead to diminished soil fertility and even soil erosion.
When animals consume plants affected by soil contamination, they can experience harmful health
effects similar to those experienced by humans, which in the most extreme circumstances can wipe
out entire species.
1. Effect on Health of Humans: Contaminated soil poses significant risks to those who come in
contact with it, either directly or indirectly through other resources (contact with affected water
sources, or bioaccumulation through consumption of affected plants and animals). Crops and
plants grown on polluted soil absorb much of the pollution and then pass these on to us. This could
explain the sudden surge in small and terminal illnesses. Some of the examples include:
i) Chronic exposure to heavy metals, petroleum, solvents and agricultural chemicals can be
carcinogenic.
> For example, chlorinated solvents induce damages to liver, kidney, depression of the central
nervous system.
> The presence of heavy metals in soil in toxic amounts can cause irreversible developmental
damage in children. Although lead and mercury may be found naturally in soil, high concentrations
of either metal may cause damage to the developing brains of young children, which in turn may
lead to neurological problems.
> Chemical pollutants, such as DDT interfere with the human body’s reproductive and
developmental functions. These substances are known as endocrine disrupters.
> Many common soil pollutants are carcinogenic, or cancer-causing. According to the U.S.
Environmental Protection Agency (EPA), humans who are exposed to these pollutants are far more
likely to develop cancer than humans who are not exposed to them. For example, regular exposure
to benzene is known to cause leukemia in both children and adults. Exposure to polychlorinated
biphenyls (PCBs) is linked to liver cancer.
ii) While long term exposure to polluted soil can affect the genetic make-up of the body, causing
congenital illness and chronic health problems that cannot be cured easily. For example, exposure
to benzene for a long term is associated with higher incidence of leukemia. Similarly,
organophosphates can lead to chain of responses leading to neuromuscular blockage.
iii) Emissions of toxic gases and foul odor from the landfills pollute the environment and causes
serious health effects on some people. The unpleasant smell causes inconvenience to other people.
iv) The soil pollution can sicken the livestock to a considerable extent and cause food poisoning
over a long period of time.
v) The soil pollution can even lead to widespread famines if the plants are unable to grow in it.
2. Bioaccumulation: Soil that is not significantly polluted may still harm humans indirectly. One
way such soil pollution can harm humans is by bioaccumulation. Plants that are grown in lightly
polluted soil continuously absorb molecules of the pollutants. Since the plants cannot get rid of
these molecules, they accumulate in the plant, causing higher amounts of pollution to exist in the
plant than in the soil. Animals who eat many of these polluted plants take on all the pollution those
plants have accumulated. Larger animals who eat the plant-eating animals take on all the pollution
from the animals they eat. Humans who eat plants or animals that have accumulated large amounts
of soil pollutants may be poisoned, even if the soil itself does not contain enough pollution to harm
human health.
3. Effect on Growth of Plants: The ecological balance of any system gets affected due to the
widespread contamination of the soil. Most plants are unable to adapt when the chemistry of the
soil changes so radically in a short period of time. Fungi and bacteria found in the soil that bind it
together begin to decline, which creates an additional problem of soil erosion.
The fertility slowly diminishes, making land unsuitable for agriculture and any local vegetation to
survive. The soil pollution causes large tracts of land to become hazardous to health. Unlike
deserts, which are suitable for its native vegetation, such land cannot support most forms of life.
4. Decreased Soil Fertility: The toxic chemicals present in the soil can decrease soil fertility and
therefore decrease in the soil yield. The contaminated soil is then used to produce fruits and
vegetables which lacks quality nutrients and may contain some poisonous substance to cause
serious health problems in people consuming them.
5. Effects on Soil Micro-organisms: “Micro-organisms are organisms that are too small to be
seen with the human eye. They live on the top-most layer of soil. There are many micro-organisms
which live in the soil such as bacteria, fungi, algae, protozoa etc.”.
Micro-organisms are essential to healthy soil. Micro-organisms are responsible for the
decomposition and recycling of organic materials in the soil. They aid in the plant's absorption of
essential nutrients. Therefore, without micro-organisms, plants cannot reach their true potential.
An example of this is the nitrogen fixing bacteria, Bradyrhizobium, which lives in a nodule on the
soybean plant. It provides nitrogen to the plant and boosts growth. Polluted lands cannot support
most forms of life. The microorganisms found in the soil decline and create additional problems
of soil erosion. Among the different soil pollutants, pesticides are designed to kill bugs that are
harmful to plants. Pesticides kill specific pests on plants such as slugs, beetles and flying insects.
However, the chemicals used in most pesticides can kill more than just garden pests; they can kill
the helpful organisms that live in the soil. Some of these chemicals can remain in the soil for years,
effectively keeping necessary microorganisms from working the soil. Thus, the effects of
pesticides on soil microorganisms can cause a ripple effect that can last for years.
6. Changes in Soil Structure: The death of many soil organisms (e.g. earthworms) in the soil can
lead to alteration in soil structure. Apart from that, it could also force other predators to move to
other places in search of food.
7. Economic Losses: In addition to endangering plant and human health, soil pollution can also
cause economic damage. For example, in some parts of China, soil that is polluted with heavy
metals is nevertheless used to grow grain. The grain grown in these soils is often polluted with
heavy metals. According to China Dialogue, an estimated 12 million tons of polluted grain must
be disposed of each year, costing Chinese farmers up to 20 billion yuan, or about $2.57 billion
U.S.

Control Measures of Soil Pollution: A number of ways have been suggested to curb
the pollution rate. Attempts to clean up the environment require plenty of time and resources. Some
of the important steps to reduce soil pollution are:
1. Reducing the Use of Chemical Fertilizers and Pesticides: To increase agricultural yield, most
farmers took to using chemical fertilizers. No doubt that the yield did indeed increase, but at the
cost of the soil losing its fertility. To restore the fertility of the soil to what it was, will take a very
long time, however, one has to start at some point of time. Drastic measures are required for the
same. Farmers should be encouraged to start using bio fertilizers. The microorganisms in these
fertilizers will help in increasing the fertility of the soil.
Similarly, that along with fertilizers, farmers should shift to bio pesticides and fungicides, also
known as herbicides. These products will take a little longer to react, but they do not have adverse
effect on the soil. It is best to use manure both as a fertilizer as well as pesticide, as it has far less
side effects as opposed to its chemical counterpart. Thus, both chemical fertilizers and pesticides
should be replaced by organic fertilizers and pesticides.
2. Proper Disposal of Industrial Waste: If one has to look at the soil pollution facts, it will be
seen that toxic waste has a big role to play in soil pollution. Hence, industrial toxic waste should
be treated to reduce its toxicity before it is disposed off. At the same time, responsible methods
should be used for disposing off the waste. The best, however, is to avoid the use of harmful
chemicals unless they are of extreme importance. Similarly, excess wastes by man and animals
pose a disposal problem. Open dumping is the most commonly practiced technique. Organic
wastes in animal dung may be used to prepare compost manure instead of throwing them
wastefully and polluting the soil.
3. Proper Hygienic Condition: People should be trained regarding sanitary habits. A lot of
propaganda has been carried out about recycling waste, not many measures have been taken about
the same. If each family has to take it upon themselves to recycle waste, the land pollution caused
due to landfills will be reduced considerably. The land so saved can be used constructively for a
number of better tasks. Also, lavatories should be equipped with quick and effective disposal
methods.
4. Public Awareness: Informal and formal public awareness programs should be imparted to
educate people on health hazards by environmental education. For example, mass media,
educational institutions and voluntary agencies can achieve this.
5. Recycling and Reuse of Wastes: To minimize soil pollution, the wastes such as paper, plastics,
metals, glasses, organics, petroleum products and industrial effluents etc. should be recycled and
reused. Industrial wastes should be properly treated at source. Integrated waste treatment methods
should be adopted.
6. Avoiding Deforestation and Promoting Forestation: To prevent soil pollution, reforestation
measures have to be undertaken at rapid pace and deforestation should be banned. Soil erosion is
caused, when there are no trees to prevent the top layer of the soil from being transported by
different agents of nature like water and air. At the same time, measures should be taken to avoid
over cropping and over grazing, as it leads to flood and soil erosion and further deterioration of
the soil layer. Thus, agro-forestry/plantation programs should be encouraged.

Conclusion: 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 pollutants include a large variety of contaminants or chemicals (organic and inorganic), which
could be both naturally-occurring in soil and man-made. In both cases, the main soil pollution
causes are the human activities (i.e., the accumulation of those chemicals in soil at levels of health
risk is due to human activities such as accidental leaks and spills, dumping, manufacturing
processes, agricultural wastes like fertilizers and pesticides etc.). Accumulation due to natural
processes is also possible, but it has only been recorded in few cases (such as the accumulation of
higher levels of perchlorate in soil from Atacama Desert in Chile which is purely due to natural
processes in arid environments). Natural processes, however, may have an influence of the human
released toxic chemicals (pollutants) in the soil, overall decreasing or increasing the pollutant
toxicity and/or the level of contaminated soil. This is possible due to the complex soil environment
involving the presence of other chemicals and natural conditions which may interact with the
released pollutants.

Suggested Readings:
(1) Botkin, D.B., and E.A. Keller. 2014. Environmental Science: Earth as a living planet. 9th Ed.
John Wiley and Sons, NY, USA.

(2) Chiras, D.D. 2012. Environmental Science. 9th Ed. Jones and Bartlett Publishers, Ontario,
Canada.

(3) Ghafoor, A., G. Murtaza, M.Z. Rehman, M. Sabir, H.R. Ahmad, and Saifullah. 2012.
Environment Pollution: Types, Sources and Management. Allied Book Center, Lahore-Pakistan.

(4) Brady, N.C., and R.R. Weil. 2010. Elements of the Nature and Properties of Soils. 3 rd Ed.
Pearson Prentice Hall Publishing.