Environmental Pollution-
Causes, Effects and Control
Measures
Prepared by
M.SHANMUGARAJ M.E.,
V.S.V.N Polytechnic College,
Virudhunagar
Tamil Nadu
India
Definition
“Pollution is the effect of undesirable
changes in our surroundings that have
harmful effects on plants, animals and
human beings”.
Pollutant
Any thing (solid, liquid or gas) that
cause pollution is called pollutant
Eg. Lead, sulphuric acid, carbon
monoxide,
Degradable: Those can be readily broken down by natural
processes
Eg. Discarded vegetables
Non-degradable: Those can not be degraded by natural
processes
Eg.plastics
Air Pollution
Air pollution occurs due to the presence of
undesirable solid or gaseous particles in the
air in quantities that are harmful to human
health and environment
Component Symbol Volume
Nitrogen N2 78.084%
99.998%
Oxygen O2 20.947%
Argon Ar 0.934%
Carbon Dioxide CO2 0.033%
Neon Ne 18.2 parts per million
Helium He 5.2 parts per million
Krypton Kr 1.1 parts per million
Sulfur dioxide SO2 1.0 parts per million
Methane CH4 2.0 parts per million
Hydrogen H2 0.5 parts per million
Nitrous Oxide N2O 0.5 parts per million
Xenon Xe 0.09 parts per million
Ozone O3 0.07 parts per million
Nitrogen dioxide NO2 0.02 parts per million
Iodine I2 0.01 parts per million
Carbon monoxide CO trace
Ammonia NH3 trace
Types of pollutants
Primary pollutants
Pollutants that are emitted directly from identifiable sources –produced by both natural events or human activities
Eg. Dust storms, emission from vehicles
Secondary pollutants
When certain chemical
reactions take place
among the primary
pollutants
Eg. Sulphuric acid
Primary pollutants
Carbon oxides (CO2 and CO)
Nitrogen oxides
Sulphur oxides
Volatile organic compounds – hydro
carbons
Suspended particulate matter
TERM MEANING EXAMPLES
Aerosol Particles suspended on air Sprays from pressurized
cans
Mist Aerosol consisting of liquid droplets Sulfuric acid mist
Dust Aerosol of solid particles that are blown
into the air
Dust storm
Smoke Aerosol of solid and liquid particles
produced by chemical reactions such as
fires
Cigarette smoke
Fume Condensation of hot vapors of metals Zinc, lead fumes
Plume Smoke coming out of chimney
Fog Aerosol of water droplets
Smog Mixture of smoke and fog
Effects of air pollution
Prolonged smoking or exposure to air
pollutants can overload or break down the
natural defenses such as hair in our nose,
sticky mucas in the lining of the upper
respiratory tract causing diseases like lung
cancer, asthma, chronic bronchitis etc.,
Cigarette smoking is responsible for the greatest exposure
to carbon monoxide.Exposure to air containing even
0.001% of carbon monoxide for several hours can cause
collapse, coma and even death.
CO is attached to blood hemoglobin for a long time, it
accumulates and reduces the oxygen carrying capacity of
blood. This impairs perception and thinking, slows reflexes
and causes headaches, drowsiness, dizziness and nausea
and blurred vision.
Nitrogen oxides and suspended particles both can
irritate lungs, aggravate asthma or chronic
bronchitis and increase respiratory infections.
Many volatile organic compounds such as benzene
and formaldehyde and toxic particulates such as
lead and cadmium can cause mutations,
reproductive problems and cancer, breathlessness
and irritation of the eye, nose and throat.
Sulphur dioxide irritates respiratory tissues,
chronic exposure causes a condition similar
to bronchitis.
It also reacts with water, oxygen and other
materials to form sulphur containing acids –
The acids can become attached to particles
which when inhaled are very corrosive to
the lung.
Chronic exposure of the leaves to air
pollutants can break down the waxy coating
that helps prevent excessive water loss and
leads to damage from diseases, pests,
drought and frost.
It also affects photosynthesis, respiration
and other metabolisms.
Ozone depletion
The upper stratosphere consists of
considerable amounts of ozone which works
as an effective screen for UV light.
The ozone thus formed is constantly broken down by naturally occurring processes that maintain its balance in the ozone layer. But the presence of certain pollutants can accelerate the breakdown of ozone. (chloroflurocarbons, halons)
The Chloro-fluro-carbons (CFCs) are extremely stable, non-flammable, non-toxic and harmless to handle. It is ideal for air conditioners, refrigerators and fire extinguishers etc.
Halons are similar to the CFCs dangerous to ozone layer.
The CFCs and Halons migrate into the upper atmosphere after they are released. As they are heavier than air, they are carried by air currents and reach upper atmosphere. This is a slow process and even take few to many years.
In the stratosphere unfiltered UV radiation severs the chemical bonds releasing chlorine from CFCs.
This attacks the ozone molecule resulting in its splitting into oxygen molecule and an oxygen atom.
Thus leading to ozone depletion.
Effects of ozone depletion
On human- sunburn, cataract, skin cancer, weakens the immune system
Food production – uv radiation causes reduction in photosynthesis – reduces nutrient contents and the growth of plants
On materials- damages paints and fabrics causing them to fade faster.
On climate- global warming – Green house effect-
increase in concentration of certain gases like carbon di oxide, nitrogen oxides, methane, CFCs trap heat in the form of infra red radiation near the earth’s surface- Green house effect
Effects of Green house effect
Polar ice caps will melt causing rise in
ocean levels.
Fall in agricultural produce.
Changes in habitats – climatic conditions.
Smog is a type of large-scale outdoor
pollution. It is caused by chemical reactions
between pollutants derived from different
sources, primarily automobile exhaust and
industrial emissions. Cities are often centers
of these types of activities, and many suffer
from the effects of smog, especially during
the warm months of the year.
Control measures
Proper fuel and exhaust system in vehicles
Use of dry and wet collectors, filters,
electrostatic precipitators.
Providing greater height to the stacks –
discharge pollutants away from the ground.
Substitution of raw materials that cause
more pollution.
Water pollution
71% of earth’s surface is covered by water-but
only a tiny fraction is available as fresh water.
97% of total water is found in oceans and 3% is
fresh water.
Out of this 2.997% is locked in ice caps. The only
0.003% of total volume is available as soil
moisture, ground water, water vapour, water in
lakes, streams, rivers and wetlands.
Definition
When the quality or composition of
water changes directly or indirectly as
a result of man’s activities such that it
becomes unfit for any purpose it is
said to be polluted.
Types of water
Surface water- water found in streams,
rivers and lakes etc.
Ground water- that percolates into ground
Aquifers- porous water-saturated layers of
sand, gravel or bedrock through which
ground water flows. It is replenished
naturally by rainfall.
Point source – source is known-
eg. Municipal and industrial discharge pipes
Non-point source- source is unknown-
eg.agricultural runoff, acid rain
Sources of Water
Pollution
Water soluble radioactive isoptopes –
radioactive wastes- ionizing radiation cause
birth defects, cancer and genetic disorders.
Hot water- thermal plants, nuclear power
stations, power plants release water-
Oil-leakage
Water soluble inorganic chemicals-acids, salts and compounds of toxic metals such as mercury and lead.
Organic compounds-oil, gaseoline, plastics, pesticides, cleaning solvents, detergents etc.
Sediment of suspended water- insoluble particles of soil and other solids that become suspended in water
Industrial EffluentsWater is discharged from industries after having been used in production processes. This waste water may contain acids, alkalis, salts, poisons, oils and in some cases harmful bacteria.
Mining and Agricultural WastesMines, especially gold and coal mines, are responsible for large quantities of acid water.
Agricultural pesticides, fertilizers and herbicides may wash into rivers and stagnant water bodies.
Sewage Disposal and Domestic WastesSewage as well as domestic and farm wastes were often
allowed to pollute rivers and dams.
Causes of water pollution
Disease causing agents – bacteria, viruses,
protozoa and parasitic worms enter water from
domestic sewage and untreated human and animal
wastes.
Oxygen depleting wastes- large populations of
bacteria use up the oxygen present in water to
degrade wastes. The amount of oxygen required
to break down a certain amount of organic matter
is called Biological Oxygen Demand(BOD).
If too much organic waste is added, all the
available oxygen is used up and causes
organisms like fish to die.
Anaerobic bacteria begin to break down the
wastes producing chemicals that have a foul
and unpleasant odour.
Inorganic plant nutrients-water soluble nitrates
and phosphates that cause excessive growth of
algae and other aquatic plants- called
eutrophication.
Biomagnification- pesticides- reach water-
phytoplanktons-herbivorous fish-carnivorous fish-
water birds-animals-human beings.
At each stage the chemicals are concentrated
resulting biomagnifiction. Eg.DDT
Soil pollution
Soil is s thin covering over the land
consisting of a mixture of minerals, organic
materials, living organisms, air and water.
Under ideal climatic conditions soft parent
material may develop into a centimeter of
soil in 15 years.
Soil profile
The top layer – O horizon- freshly fallen and decomposed leaves, twigs, animal wastes, fungi and other organic materials- brown or black in colour
Uppermost layer- A horizon-partially decomposed organic matter and inorganic mineral particles –darker and looser
B horizon – subsoil contains less aquatic material and fewer organisms than A zone.
C horizon – weathered parent material
Causes of soil degradation
Erosion
By wind and water accelerated by human
activities such as farming, construction,
overgrazing by livestock, burning of grass
cover, deforestation.
Excess use of fertilizers
Fertilizers, insecticides, herbicides,
pesticides, fungicides, rodenticides
Soil fertility is lost
Kill beneficial insects
Integrated Treatment
Methods
Continuous contour trenches or benches
Live check dams – planting grass, shrubs
and trees etc.
Bund constructed out of stones.
Earthen check bund- local soil,across the
stream
Integrated Pest Management
Organic farming
Use of biofertilzers
Earthworms- vermicomposting
Pest control through microbes – Bacillus
thrungiensis, Azadirachta indica- Neem
Marine Pollution
The introduction of substances to the
marine environment directly or
indirectly by man resulting in adverse
effects
Causes
Direct discharge of wastes into sea –
sewage
Washed off materials- fertilizers, pesticides
Petroleum, oils washed off from roads
Spill of Toxic substances from ships
Offshore oil exploration and extraction
Effects of marine pollution
Eutrophication-phytoplankton blooms
Oil slick – affect plants and fish
Destroys flora and fauna
Control Measures
Introduction of sewage treatment plants
Primary treatment-physical process such as
screening and sedimentation to remove
pollutants that will settle, float etc.
Secondary treatment- to remove BOD
Control measures for oil
pollution
Process of emulsification through chemical
dispersants-sprayed on the oil.
Biological methods- use of bacteria
dB Environmental condition
0 Threshold of hearing
10 Rustle of leaves
20 Broadcasting studio
30 Bedroom at night
40 Library
50 Quiet office
60 Conversational speech
70 Average radio
74 Light traffic noise
90 Subway train
100 Symphony orchestra
110 Rock band
120 Aircraft takeoff
146 Threshold of pain
Decibel levels of common sounds dB
Ambient noise levels dB
Zone Day time Night time
Silent zone 50 40
Residential zone 55 45
Commercial zone 65 55
Industrial zone 70 70
Safe time exposure in dBDuration
(hrs/minutes/seconds)
dB
8 hrs 90
4 93
2 96
1 99
30 minutes 102
15 102
7 108
4 111
2 114
1 117
30 seconds 120
Instantaneous rupture of
membrane
150
Effects of noise pollution
Physical damage to ear- temporary thresh
hold shift-TTS – hearing loss
Mental fatigue
Control techniques
Reduce noise at source
Block the path of noise
Increase the path length and
protect the recipient
Thermal Pollution
Sources- discharge of warm water into river
Effects-changes the ecological balance of river
Death of fish
Effect on plants
Control- passing the heated water through a cooling pond or cooling tower after it leaves the condenser
Nuclear hazards
Nuclear fission –splitting of the nucleus of
the atom – resulting energy is used for a
variety of purposes
Hot water
Uranium waste – ionizing material
Effects of nuclear pollution
Lethal
Mutation
Plants and animals
Marine organisms-fish
Skin diseases, cancer, eye disorders etc.,
Role of an individual in
prevention of pollution Develop respect to all forms of life
Try to plant trees where ever you can
Reduce the use of paper and wood products where ever possible – use recycled paper
Do not buy furniture, doors etc., made from teak – forest based
Help in restoring a degraded area
Join in an aforestation program
Advocate organic forming
Avoid use of pesticides
Reduce fossil fuel – coal, petrol etc. save petrol
Shut of the lights and fans when not needed- save
electricity
Do not use aerosol spray products
do not pour chemicals, paints pesticides in the
drain
Use rechargeable batteries
Do not use cans, avoid plastics – plastic
carry bags
Recycle paper, aluminum, plastics
Set up compost bin in your garden
Start community composting
Keep you and your place clean