Pollution of Air and Water

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1. Fill in the blanks.

 a. Carboxyhaemoglobin (COHb).

 b. Suspended particulate matter (SPM)

c. Sulphur dioxide 

d. Ozone layer

e. Carbon dioxide

2. Answer in one word.

a. Oxides 

b. Dust storm 

c. Wind energy 

d. Marble

3. State True or false.

a. True 

b. False 

c. True 

d. False 

e. True

Assessment Zone

A. Choose the correct answer.

1. b 

2. d 

3. c

4. d 

5. c 

6. b

B. Fill in the blanks.

1. Carbon dioxide 

2. Emphysema, bronchitis and asthma

3. Thermal pollution 

4. Filtration

C. State True or false.

1. True 

2. True 

3. False 

4. False 

5. False

D. Match the following:

1.d 

2. e 

3. c 

4. a 

5. b

E. Answer the following questions in brief.

1. Air pollution can be defined as the presence of toxic chemicals or compounds in the air

that pose a health risk.

2. Dust storms in desert areas and smoke from forest fires contribute to the air pollution.

The other natural source of air pollution is volcanic activity, which at times adds great

amount of ash and toxic fumes into the atmosphere.

3. SPM stands for suspended particulate matter. These are minute solids present in the

air in the form of smoke or dust.

Particulate matter can be divided into two types—

a. Coarse particles are formed from sources such as road dust, sea spray and

construction activities.

  b. Fine particles due to fuel is burnt in automobiles and power plants .

4. Lead can be emitted in the atmosphere from the automobile exhausts. It can be

dangerous to human beings and inhaling it can result in severe health problems.

Exposure to lead can increase the chance of having heart attacks or strokes.

5. The ozone layer is important to all living things because it absorbs harmful UV

radiation and acts as a shield. Exposure to UV radiation causes skin cancer and eye

damage .

6. Oil leakage from ships leave a certain amount of oil in the water which causes water

pollution. This endangers the life of marine plants and animals.

7. Four source of water pollution:

    a. Domestic sewage

    b. Agricultural runoff

    c. Industrial effluents

    d. Thermal pollution

  8. Global warming is a gradual increase in the overall temperature of the Earth’s

atmosphere generally attributed to the greenhouse effect caused by increased levels of

carbon dioxide .

9. Power plants and some other factories use the water from streams or lakes as a

coolant. The hot water is then returned to the water bodies thereby increasing their temperature. This is called thermal pollution.

  10. Chlorine or chlorine compounds such as bleaching powder or sodium hypochlorite in

calculated amounts are added to water to kill harmful germs in it .

F.  Answer the following questions in detail.

1.  This is an organic compound that contains carbon, chlorine and fluorine.

Chlorofluorocarbons (CFCs) cause damage to the ozone layer that protects the Earth

from the Sun’s ultraviolet (UV) radiation. The ozone layer is important to all living

things because it absorbs harmful UV radiation and acts as a shield.

 Exposure to UV radiation causes skin cancer and eye damage. Use of CFCs in

refrigerators, air conditioners, aerosols and industrial solvents has been restricted in

many countries to prevent the ozone layer from getting damaged.

2.  Acid rain occurs when sulphur dioxide and nitrogen oxides, added in air due to burning

of fossil fuels and other sources, combine with water vapour in the atmosphere and fall

as rain, snow or fog.

 As these oxides are highly acidic, the rain that falls becomes acidic. These gases can also

be emitted from natural sources such as volcanoes. Acid rain causes extensive damage

to water, forest, soil resources and human health.

It reacts with marble and so affects all buildings, monuments and statues made of

marble. The beautiful marble structure of Taj Mahal is slowly getting eroded by sulphur

dioxide fumes released into the atmosphere .

3.  Smog is formed when various gases, water vapour and smoke settle on dust particles.

Gases that are responsible in the formation of smog are produced when fuels are burnt.

Smog reduces visibility and forms a layer of haze in the atmosphere.

It adversely affects our lungs. It causes shortness of breath, pain when inhaling deeply,

wheezing and coughing. It can cause eyes and nose irritation. Smog causes diseases

such as emphysema, bronchitis and asthma.

4. Water pollution is the contamination of water bodies by discharge of undesirable

substances that are toxic and poisonous. These undesirable substances are generally

called water pollutants. Pollutants also seep down and affect groundwater.

Steps to Prevent Water Pollution

  •  Do not bathe and wash clothes near the water bodies such as rivers and oceans.

    •  Do not throw litter into rivers, lakes or oceans.

    •  Industrial wastes should be treated before discharging them into the rivers and

lakes.

  •  Excreta of humans and animals along with organic wastes should be used in biogas

plant to produce fuel and manure.

  •  Chemical fertilisers and pesticides should be replaced by bio fertilisers and

biopesticides.

5.  Power plants and some other factories use the water from streams or lakes as a

coolant. The hot water is then returned to the water bodies thereby increasing their

temperature. This is called thermal pollution. This also reduces the oxygen content

of water. The increased temperature and reduced supply of oxygen affect aquatic life,

causing the death of plants and animals.

6.  The water supplied to our homes may contains impurities and is not fit for drinking

purpose. In villages and small towns, people use groundwater for various activities. This

water is not suitable for drinking, and it needs pre-treatment before its use. Therefore,

we need to filter water before drinking

Methods to purify water at home

Boiling: This process is used to treat only small quantities of water. The bacteria

and germs get killed when the water is heated to its boiling point and boiled at this

temperature for some time. This renders it safe for drinking.

 Chemical treatment: Water can be purified by the addition of disinfectants in correct

proportion. This kills the germs and other harmful bacteria. Water treated with

chemicals should be boiled before drinking.

 Water purifying gadgets: Modern purifying gadgets such as water filters have the

ceramic candles with fine pores for removing suspended impurities. When water is

poured over these candles, the suspended impurities in the water do not pass through

the pores. Some purifiers use activated charcoal and ultraviolet rays along with ceramic

filters to purify water. The water thus purified is safe for drinking.

  7. Lakes turn green when water bodies become rich in nutrients leading to massive growth

of unwanted water plants especially weeds and algal blooms. These unwanted plants

use almost all the dissolved oxygen in water. Due to lack of oxygen in water, most

aquatic forms die in that water body.

  8. Purification of water at large scale is done in the water treatment plant. Water from

a river is made free from large entities such as leaves, twig and other impurities by

passing it through the screen filters. This water is then sent to a water treatment plant

for purification. At the water treatment plant, muddy water is made to stand in large

tanks for a long time. This method helps settle the heavy impurities at the bottom of

the tank. Later, alum is added in water to remove some of the suspended impurities.

These impurities along with some bacteria become heavy when coagulated with alum

and settle down in the tank. The clearwater above is sent for filtration. It is the method

in which the water passes through layers of gravel, pebbles, broken bricks, charcoal and

sand. Charcoal is used to remove the coloring matter while the sand traps the remaining

suspended impurities.

Water that comes out from the filter is free from impurities. Chlorination is a process

of adding either liquid chlorine or chlorine compounds such as bleaching powder

or sodium hypochlorite in calculated amounts to water to kill harmful germs in it.

Chlorinated water is then tested for purity in the water testing laboratory and is

pumped into the public water supply.

  9. CNG is safer option, as CNG-powered vehicles emit a lot less carbon monoxide, nitrogen

oxides—a primary component of smog—and particulates, which can trigger a range of

health problems.

G. Complete the crossword with the help of the clues provided.

 ACROSS

2. Fertilisers 

5. Pollutant

DOWN

1. Chlorination 

3. Potable 

4. Boiling