Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

MODULE - 4

Environmental Science Senior Secondary Course

Contemporary
Environmental Issues

10

Notes

ENVIRONMENTAL POLLUTION
Developmental activities such as construction, transportation and manufacturing not only
deplete the natural resources but also produce large amount of wastes that leads to pollution
of air, water, soil, and oceans; global warming and acid rains
...
In this lesson you will study about the major causes
of pollution, their effects on our environment and the various measures that can be taken to
control such pollutions
...


10
...
A stone crusher
adds a lot of suspended particulate matter and noise into the atmosphere
...
Domestic sewage and run off from agricultural fields, laden with pesticides
164

MODULE - 4

Environmental Pollution
and fertilizers, pollute water bodies
...
These are only a few examples which show how human activities
pollute the environment
...
The agents which cause environmental
pollution are called pollutants
...


Contemporary
Environmental Issues

Notes

10
...
3 AIR POLLUTION
Air pollution is a result of industrial and certain domestic activity
...
Air pollution may be defined as the presence of
any solid, liquid or gaseous substance including noise and radioactive radiation in the
atmosphere in such concentration that may be directly and indirectly injurious to humans
or other living organisms, plants, property or interferes with the normal environmental
processes
...
Some of the major air pollutants, their
sources and effects are given in table 10
...

Table 10
...


Fly ash

Part of smoke released from
chimneys of factories and
power plants

Settles down on vegetation, houses
...
Leachates contain harmful
material

165

MODULE - 4
Contemporary
Environmental Issues

Notes

Environmental Science Senior Secondary Course
10
...
1 Particulate pollutants
Particulate matter suspended in air are dust and soot released from the industrial chimneys
...
001 to 500 µm in diameter
...
Particles which are more than 10µm in diameter settle
down
...
02 µm form persisent aerosols
...

• Fly ash
Fly ash is ejected mostly by thermal power plants as by products of coal burning operations
...
Fly
ash affects vegetation as a result of its direct deposition on leaf surfaces or indirectly
through its deposition on soil
...

• Lead and other metals particles
Tetraethyl lead (TEL) is used as an anti-knock agent in petrol for smooth and easy running
of vehicles
...
If inhaled it produces injurious effects on kidney and liver and interferes with development
of red blood cells
...
It
has long term effects on children as it lowers intelligence
...
They create physiological, biochemical and developmental disorders in plants
and also contribute towards reproductive failure in plants
...
2: Annual average concentration of pollutants in ambient air in
residential and industrial areas (year 2000) mg/m3 in 24 hours
SPM permissible- residential 140 – 200 mg/m3, industrial 360 – 500 mg/m3
City

Industrial area

Agra
Bhopal
Delhi
Kanpur
Kolkata

349
185
368
348
218

388
160
372
444
405

Nagpur

166

Residential area

140

157

MODULE - 4

Environmental Pollution

Contemporary
Environmental Issues

10
...
2 Gaseous pollutants
Power plants, industries, different types of vehicles – both private and commercial use
petrol, diesel as fuel and release gaseous pollutants such as carbon dioxide, oxides of
nitrogen and sulphur dioxide along with particulate matter in the form of smoke
...
Table 10
...


Notes

Table 10
...

• Smoge (skoke & fog) formation leads
to poor visibility and aggravates
asthma in patients
• Lung disorders

Textiles and carpet weaving
industries

Fig
...
1: A chimney billowing smoke- Diesel vehicle ( bus/truck) showing
exhaust smoke
167

MODULE - 4
Contemporary
Environmental Issues

Environmental Science Senior Secondary Course
10
...
3 Prevention and control of air pollution
(i) Indoor air pollution

Notes

Poor ventilation due to faulty design of buildings leads to pollution of the confined space
...
in rooms may give out volatile organic compounds (VOCs)
...
may release hazardous gases
...
This can result in hospital acquired
infections and is an occupational health hazard
...
Children and ladies exposed to
smoke may suffer from acute respiratory problems which include running nose, cough,
sore throat, lung infection, asthama, difficulty in breathing, noisy respiration and wheezing
...
But supply of electricity is limited
...
Improved
stoves for looking like smokeless chullahs have high thermal efficiency and reduced emission
of pollutants including smoke
...
Use of biogas and CNG (Compressed Natural Gas) need to be encouraged
...
Charcoal is a comparatively cleaner fuel
...
Segregation of
waste, pretreatment at source, sterilization of rooms will help in checking indoor air pollution
...
which is cheaper in addition to being environmentally friendly
...

(c) installing devices which reduce release of pollutants
...
The medium of a filter
may be made of fibrous materials like cloth, granular material like sand, a rigid material
like screen, or any mat like felt pad
...

(ii) Electrostatic precipitators (ESP)- The emanating dust is charged with ions and the
ionized particulate matter is collected on an oppositely charged surface
...
ESPs are used in boilers, furnaces, and many other units of thermal power
plants, cement factories, steel plants, etc
...
‘Cyclone’ is a common inertial collector
used in gas cleaning plants
...
They remove aerosols from a stream of
gas either by collecting wet particles on a surface followed by their removal, or else
the particles are wetted by a scrubbing liquid
...

Gaseous pollutants can be removed by absorption in a liquid using a wet scrubber and
depends on the type of the gas to be removed e
...
for removal of sulphur dioxide alkaline
solution is needed as it dissolves sulphur dioxide
...
Silica gel can remove water
vapour
...

Apart from the use of above mentioned devices, other control measures are•

increasing the height of chimneys
...


•

shifting of polluting industries away from cities and heavily populated areas
...


(iv) Control of vehicular pollution
•

The emission standards for automobiles have been set which if followed will reduce
the pollution
...


•

In cities like Delhi, motor vehicles need to obtain Pollution Under Control (PUC)
certificate at regular intervals
...


•

The price of diesel is much cheaper than petrol which promotes use of diesel
...
05%
...
Addition of lead in petrol has been banned to prevent
emission of lead particles with the vehicular emission
...


INTEXT QUESTIONS 10
...
Define pollutant and pollution
...
Name any three devices that control pollution
...
State two means of controlling indoor air pollution
...
What is a PUC certificate?
______________________________________________________________

10
...
Chlorine from chemicals such as
chlorofluorocarbons (CFCs) used for refrigeration, air conditioning, fire extinguishers,
cleaning solvents, aerosols (spray cans of perfumes, medicine, insecticide) cause damage
to ozone layer chlorine contained in the CFCs on reaching the ozone (O3) layer split the
ozone molecules to form oxygen (O2)
...
There has been a reduction of ozone umbrella or shield
over the Arctic and Antarctic regions
...
This permits passage
of UV radiation on earth’s atmosphere which causes sunburn, cataract in eyes leading to
blindness, skin cancer, reduced productivity of forests, etc
...


10
...

Infra-red radiations trapped by the earth’s surface cannot pass through these gases and to
increase thermal energy or heat in the atmosphere
...
As this phenomenon of increase in temperature is observed in

170

MODULE - 4

Environmental Pollution
green houses, in the botanical gardens these gases are known as green house gases and
the heating effect is known as green house effect
...
This will melt the polar ice caps
and increase the sea level leading to coastal flooding, loss of coastal areas and ecosystems
like swamps and marshes, etc
...
6 NOISE POLLUTION
Noise is one of the most pervasive pollutant
...
Noise by definition is “sound without
value” or “any noise that is unwanted by the recipient”
...
It is
therefore of utmost importance that excessive noise is controlled
...
W
...
O
...
Anything above 80 dB is hazardous
...
4 gives the noise intensity in some of the common activities
...
4: Sources of some noises and their intensity
Source

Intensity

Source

Intensity

Quiet Conversation

20-30dB

Radio Music

50-60 dB

Loud Conversation

60 dB

Traffic Noise

60-90 dB

Lawn Mower

60-80 dB

Heavy Truck

90-100 dB

Aircraft Noise

90-120 dB

Space Vehicle

140-179 dB

Beat Music

120 dB

Launch

Motor Cycle

105 dB

Jet Engine

140 dB

10
...
1 Sources of noise pollution
Noise pollution is a growing problem
...
Sources of noise pollution are many and may be located indoors or outdoors
...
Noise pollution is
more in cities due to a higher concentration of population and industries and activities such
as transportation
...

171

MODULE - 4
Contemporary
Environmental Issues

Notes

Environmental Science Senior Secondary Course
Outdoor sources of noise pollution include indiscriminate use of loudspeakers, industrial
activities, automobiles, rail traffic, aeroplanes and activities such as those at market place,
religious, social, and cultural functions, sports and political rallies
...
During festivals, marriage and
many other occasions, use of fire crackers contribute to noise pollution
...
6
...
Noise disturbs sleep, causes hypertension
(high blood pressure), emotional problems such as aggression, mental depression and
annoyance
...

10
...
3 Prevention and control of noise pollution
Following steps can be taken to control or minimize noise pollution•

Road traffic noise can be reduced by better designing and proper maintenance of
vehicles
...


•

Retrofitting of locomotives, continuously welded rail track, use of electric locomotives
or deployment of quieter rolling stock will reduce noises emanating from trains
...


•

Industrial noises can be reduced by sound proofing equipment like generators and
areas producing lot of noise
...
Use of horns, alarms, refrigeration units, etc
...
Use of fire crackers which are noisy and cause air pollution should be
restricted
...


INTEXT QUESTIONS 10
...
What is noise and in which units it is measured?
______________________________________________________________
2
...

______________________________________________________________
3
...

______________________________________________________________
172

Environmental Pollution

MODULE - 4
Contemporary
Environmental Issues

10
...

Water pollution is one of the most serious environmental problems
...

Agricultural run off laden with excess fertilizers and pesticides, industrial effluents with
toxic substances and sewage water with human and animal wastes pollute our water
thoroughly
...
Rivers, lakes, seas, oceans, estuaries and
ground water sources may be polluted by point or non-point sources
...
In contrast
non-point sources include discharge of pollutants from diffused sources or from a larger
area such as run off from agricultural fields, grazing lands, construction sites, abandoned
mines and pits, roads and streets
...
7
...

Sediments brought by runoff water from agricultural fields and discharge of untreated or
partially treated sewage and industrial effluents, disposal of fly ash or solid waste into or
close to a water body cause severe problems of water pollution
...

(i) Pollution due to pesticides and inorganic chemicals
•

Pesticides like DDT and others used in agriculture may contaminate water bodies
...
At higher trophic level they get concentrated
and may reach the upper end of the food chain
...
Arsenic pollution of ground water has
been reported from West Bengal, Orissa, Bihar, Western U
...
Consumption of such
arsenic polluted water leads to accumulation of arsenic in the body parts like blood,
nails and hairs causing skin lesions, rough skin, dry and thickening of skin and ultimately
skin cancer
...
Lead causes displexia, cadmium poisoning causes Itai – Itai disease
etc
...

Accidents of oil tankers spill large quantity of oil in seas which kills marine birds and
adversely affects other marine life and beaches
...
The waste heat from the boilers and heating processes
increases the temperature of the cooling water
...

This is thermal pollution
...
Unlike terrestrial ecosystems, the temperature
of water bodies remain steady and does not change very much
...
Hence discharge of hot
water from power plants adversely affects aquatic organisms
...
It requires only a slight deviation from this
limit to cause a thermal stress to these organisms
...
Their swimming efficiency declines
...
Their resistance to diseases and parasites decreases
...
One of the best methods of reducing
thermal pollution is to store the hot water in cooling ponds, allow the water to cool before
releasing into any receiving water body
10
...
2 Ground water pollution
Lot of people around the world depend on ground water for drinking, domestic, industrial
and agricultural uses
...
However, human
activities such as improper sewage disposal, dumping of farm yard manures and agricultural
chemicals, industrial effluents are causing pollution of ground water
...
10
...
7
...
The enrichment of water bodies
with nutrients causes entrophication of the water body
...
The excessive nutrient
enrichment in a water body encourages the growth of algae duckweed, water hyacinth,
phytoplankton and other aquatic plants
...
As more plants grow and die, the dead and decaying
plants and organic matter acted upon by heterotrophic prtozoans and bacteria, deplete the
water of dissolved oxygen (DO)
...
The sudden and explosive growth of phytoplankton and
algae impart green colour to the water is known as water bloom, or “algal blooms”
...
This phenomenon of nutrient enrichment of a water body is called eutrophication
...
7
...
It may also contain rain water and surface runoff
...
The
treatment involves three stages: primary, secondary and tertiary
...

sedimentation, 2
...
filtration, 4
...
softening and
6
...
The first four steps are of primary treatment
...
Secondary treatment removes
organic solids, left out after primary treatment, through their microbial decomposition
...
The tertiary
treatment is meant to remove nutrients, disinfect for removing pathogenic bacteria, and
aeration removes hydrogen sulphide and reduce the amount of carbon dioxide and make
water healthy and fit for aquatic organisms
...
The residue obtained
from primary treatment one known as sludge
...
7
...
However, the
availability of water is limited but an ever increasing water withdrawal from different sources
175

MODULE - 4
Contemporary
Environmental Issues

Notes

Environmental Science Senior Secondary Course
such as rivers, lakes and ground water is depleting these sources and deteriorating their
water quality
...

This involves recycling of waste water for certain uses with or without treatment
...
Thus the waste water is recovered and
repetitively recycled with or without treatment by the same user
...
7
...
Control of water pollution
The following measures can be adopted to control water pollution:
(a) The water requirement should be minimized by altering the techniques involved
...

(c) Recycling of water after treatment should be practiced to the maximum extent possible
...


INTEXT QUESTIONS 10
...
Name the metals which when in excess in drinking water cause Minamata and Itai itai
diseases
...
When fertilizers and sewage enter a water body phytoplankton and algae grow rapidly
...

______________________________________________________________
3
...

______________________________________________________________
4
...

To what extent does this raise the water temperature of the river?
______________________________________________________________
5
...
What effect does thermal pollution have on metabolism of aquatic animals?
______________________________________________________________
7
...

______________________________________________________________
176

Environmental Pollution

MODULE - 4
Contemporary
Environmental Issues

10
...
Generally polluted water also pollute soil
...
Fly ash,
iron and steel slag, medical and industrial wastes disposed on land are important sources
of soil pollution
...
Acid rain
and dry deposition of pollutants on land surface also contribute to soil pollution
...
10
...
8
...
The discarded bags block drains and
sewage systems
...
on which cows and dogs feed may
die due to the choking by plastic bags
...

Industrial sources – It includes fly ash, chemical residues, metallic and nuclear wastes
...
find their way into the soil and are
known to create many health hazards including cancer
...
Fertilizers in the run off water from these fields can cause eutrophication in water
bodies
...

10
...
2 Control of soil pollution
Indiscriminate disposal of solid waste should be avoided
...
Sewage should be treated properly before
using as fertilizer and as landfills
...
The industrial wastes prior to disposal should be properly treated
for removing hazardous materials
...


INTEXT QUESTIONS 10
...
Define soil pollution
...
Why are plastic bags a big environmental nuisance?
______________________________________________________________
3
...
What is this substance
used for?
______________________________________________________________

10
...
There are
many sources of radiation pollution such as nuclear wastes from nuclear power plants,
mining and processing of nuclear material etc
...

10
...
1 Radiation
Radiation is a form of energy travelling through space
...
Radiations can be
categorized into two groups namely the non-ionizing radiations and the ionizing radiations
...
These waves
have energies enough to excite the atoms and molecules of the medium through which they
pass, causing them to vibrate faster but not strong enough to ionize them
...

Ionizing radiations cause ionization of atoms and molecules of the medium through which
they pass
...
Electrically charged
particles produced in the nuclear processes can have sufficient energy to knock electrons
out of the atoms or molecules of the medium, thereby producing ions
...
An example of this would be when a gamma ray passes
through a cell, the water molecules near the DNA might be ionized and the ions might react
with the DNA causing it to break
...
The ionizing radiations cause damage to
biological systems and are, therefore, pollutants
...
9
...
Large amounts of radiation can kill cells that can dramatically affect the exposed
organism as well as possibly its offspring
...
A
large enough dose of radiation can kill the organism
...
Somatic damage refers to damage to cells that are
not associated with reproduction
...
This damage can
also result in cancer and death
...
This damage can subsequently cause genetic damage from gene mutation
resulting in abnormalities
...

10
...
3 Radiation dose
The biological damage caused by the radiation is determined by the intensity of radiation
and duration of the exposure
...
In studying the effects of radiation exposure in humans, it is
important to realize that the biological damage caused by a particle depends not only on
the total energy deposited but also on the rate of energy loss per unit distance traversed by
the particle (or “linear energy transfer”)
...

Radiation effects and radiation doses
A traditional unit of human-equivalent dose is the rem, which stands for radiation equivalent
in man
...
At higher doses (up to 100 rem), the cells might

179

MODULE - 4
Contemporary
Environmental Issues

Notes

Environmental Science Senior Secondary Course
not be able to repair the damage, and the cells may either be changed permanently
or die
...

At even higher doses, the cells cannot be replaced fast enough and tissues fail to function
...
” This is a condition that results after high
doses is given to the whole body (>100 rem)
...
The effects of atomic explosions in Nagasaki and Hiroshima are still not forgotten
...

Accidents at nuclear power plants
Nuclear fission in the reactor core produces lot of heat which if not controlled can
lead to a meltdown of fuel rods in the reactor core
...

To prevent this type of accidents and reactor blow up, the reactors are designed to
have a number of safety features
...
S
...
) in 1979, at
Chernobyl (U
...
S
...
) in 1986
...
The leakage from Three Mile Island reactor was apparently low and
no one was injured immediately
...
People of the city had to be evacuated to safer places
and the plant had to be closed down
...
Accidents
with nuclear submarines also points to the same
...
5
1
...
State the use of absorbed dose of radiation
...
How much of radiation can damage internal organs upon its exposure for a few days
...


•

Pollution in effect is an undesirable byproduct of industrialization and urbanization
...


•

There are six types of pollutions: air pollution, water pollution, noise pollution, soil
pollution, thermal pollution, radiation pollution etc
...


•

Air pollutants are of two types (1) suspended particulate matter, and (2) gases like
carbon dioxide CO2, NOx etc
...


•

Segregation of waste, pretreatment at source, sterilization of rooms will help in checking
indoor pollution
...


•

Use of chlorofluorocarbons cause damage of ozone layer which has resulted in its
thinning over the Arctic and Anctartic regions, is know as ozone hole
...


•

Noise like other pollution is a by product of industrialization, urbanization and modern
civilization
...


•

Addition of undesirable substances in water is called water pollution
...


•

Notes

Power plants and various industries used lot of water for cooling purposes and hot
water is discharged into rivers, streams or oceans
...

181

MODULE - 4

Environmental Science Senior Secondary Course

Contemporary
Environmental Issues
•
•

Nutrient enrichment of a water body is called eutrophication
...


•

Addition of substances which adversely affect the quality of soil or fertility is known as
soil pollution
...


•

Notes

Improper sewage disposal, dumping of farm yard manures and agricultural chemicals,
industrial effluents are causing pollution of ground water
...
Radiation can be grouped into
non-ionizing radiation and the ionizing radiations
...
Define the terms pollution and pollutant
...
List the environmental problems faced by women inside the rural households
...

3
...
Manufacture of chlorofluorocarbons is to be phased out as per ‘Montreal protocol’
...
Describe an environmental friendly method to profitably dispose off human waste and
cattle waste
...
Chemical fertilizers are useful to crops
...
What steps can be taken to reduce pollution due to particulate matter from industries?
8
...
What is a medical waste? Why it is called hazardous waste? What is the safe way to
dispose medical waste
...
Suggest the way to improve the water quality it has undergone primary treatment?
11
...
What are ionizing and non-ionizing radiations? Give examples
...
List the possible damages caused to humans by radiation pollution
...
How can cancer be caused by radiation?

MODULE - 4
Contemporary
Environmental Issues

15
...


ANSWER TO INTEXT QUESTIONS

Notes

10
...
(a) Agents which cause environmental pollution are called pollutants
...

2
...
Refer to text
4
...

10
...
Decibels (Db)
2
...
Better designing and proper maintenance of vehicle, use of noise abatement measures,
appropriate insulation and introduction of noise regulation for take off aircrafts, use of
electric locomotives, using of sound proofing equipment
...
3
1
...
Eutrophication
3
...

4
...

5
...

6
...

7
...
4
1
...

2
...


183

MODULE - 4
Contemporary
Environmental Issues

Environmental Science Senior Secondary Course
3
...

10
...
Non-ionizing radiations

Notes

2
...

3
...


184



---