NOTES PREPARED BY
ASHAQ HUSSAIN BHAT
TEACHER SCHOOL
EDUCATION DEPARTMENT
JAMMU AND KASHMIR
CHAPTER 13
POLLUTION OF AIR AND WATER
KEYWORDS
Air pollution Contamination of air by impurities.
Pollutants: Substances, which contaminate the air and water.
Smog: Thick fog, like; layer in atmosphere, especially, in winters.
CFC: Choro fluoro carbons, used in refrigerators, are conditioners and aerosol sprays.
Acid Rain : Combination of acidic gases and rainwater
Green house effect: Trapping of radiations by the earth's atmosphere.
Global warming: Gradual increase in average temperature of earth.
Potable water: Water suitable or fit for drinking.
INTEXT QUESTIONS (PAGE 162)
Q.1 Define Air Pollution.
Ans. When air is contaminated by unwanted substances, which have a harmful effect on, both, the living and non-living things, it is referred to as air pollution.
Q.2. What are pollutants and name them?
Ans. The agent or substances, which cause pollution of air, water and land, are called pollutants. Carbon monoxide, Carbon dioxide, Nitrogen and smoke are the pollutants.
Q.3. Name the various sources of air pollutants.
Ans. The sources of air pollutants are factories, power plants, automobile exhausts and burning of firewood and dung cakes.
Q.4. Define Smog and what are its ill-effects.
Ans. A thick fog, like; layer in the atmosphere, especially, during winters is regarded as Smog. Smog is made up of smoke and fog. The smog causes breathing difficulties, such as, asthama, cough and Wheezing in children
INTEXT QUESTIONS (PAGE 164)
Q.1. What do you understand by Green House Effect?
Ans. The sun's rays warm the earth's surface. A part of the radiation that falls on the earth is absorbed by it and a part is reflected back into the space. A part of the reflected radiation is trapped by the atmosphere and are not allowed to go out of the earth's atmosphere. These trapped radiations further warm the earth. The trapping of radiations by the earth's surface is called the greenhouse effect.
Q.2. Define Global Warming and name the various gases which lead to Global Warming.
Ans. Increase in the concentration of CO₂ in the atmosphere leads to the enhancement in the natural greenhouse effect. As a result, the average temperature of the atmosphere is, gradually, increasing. This is called global warming. Besides CO₂, other gases like methane,nitrous oxide, water vapour also contribute to green house effect. They are also called Greenhouse gases.
Q.3. What are the ill-effect of global warming?
Ans. Increase of Greenhouse gases in the atmosphere is responsible for the global warming. The quantity of these gases, is increasing day by day in the atmosphere and the temperature is raising. If this is not checked in time, there will be great hazards such as, glacier will melt, lower area will get submerged in water, rainfall will be affected, sea level will raise affecting production of crops, forests etc. and it will also effect the life style of living organisms.
INTEXT QUESTIONS (PAGE 168)
Q.1. What are the factors responsible for pollution of the river?
Ans. Factors responsible for pollution of the river are:
(i) Many industries discharge harmful chemicals into rivers and streams
(i) Chemical fertilizers, pesticides and weedicides used in agriculture dissolve in water and are washed into rivers or other water bodies from the fields.
(ii) Throwing of large quantities of garbage and untreated sewage, into the rivers.
(iv) Washing, bathing and other activities at the bank of rivers.
Q.2. What steps can be taken to restore the river Ganga to its past glory?
Ans. Laws should be made and strictly implemented, so that polluted water is not disposed off, directly, into Ganga. Water treatment plants should be installed in all industrial areas.
Q.3. How would the disposal of garbage, etc. affect the living organisms in the river?
Ans. Disposal of garbage into the rivers pollutes the river water. When organisms cannot breathe and die ultimately. garbage rots, it produces poisonous and toxic gases, so that living
INTEXT QUESTIONS (PAGE 168)
Q.1. Why do we need to filter water before drinking?
Ans. Clean looking water may have disease carrying micro-organisms and dissolved impurities. So, it is essential to filter water before drinking.
Q.2. Where do you get your drinking water from?
Ans. We get our drinking water supply from the municipality.
Q.3. What will happen if we drink polluted water?
Ans. We will be caught by water borne diseases, if we drink polluted water.
INTEXT QUESTIONS (PAGE 170)
Q.1. Name some methods used for purification of water?
Ans. Boiling, filtering and chlorination are the methods used for purification of water.
Q.2. What are the common water borne diseases?
Ans. Diarrhoea, dysentry, cholera, jaundice etc. are some of the common water-borne diseases.
Q.3. How can you save water?
Ans. We could use only required amount of water for our daily use like bathing, washing clothes, shaving etc. Besides, we can think of ideas, like; resuming water used for washing for other household tasks, like; cleaning the houses, watering the gardens, washing our vehicles etc.
TEXTBOOK EXERCISE
Q.1. What are the different ways, in which water gets contaminated?
Ans. Water gets contaminated in different ways:
(i) Many industries discharge harmful chemicals into rivers and streams.
(ii) Chemical fertilizers, pesticides and weedi cides used in
agriculture dissolve in water and are washed into rivers or other water bodies from the fields.
(iii) Throwing of large quantities of garbage and untreated sewage, into the rivers.
(iv) Washing, bathing and other activities at the bank of rivers.
Q.2. At an individual level, how can you help reduce air pollution
Ans Air pollution can be reduced as under:
(i) By planting more trees.
(ii) By using smokeless stoves and LPG.
(iii) By using smokeless fuel, like; CNG in vehicles.
(iv) By avoiding the use of fossil fuels, like; coal and petroleum.
(v) By saying 'NO' to plastic bags.
(vi) By avoiding smoking.
(vii) By using public transport, as far as, possible.
(viii) By not burning dry leaves etc., but putting them in compost pits to make manure.
Q.3. Clear, transparent water is always fit for drinking. Comment.
Ans. Water, which looks clean, may still have disease - carrying micro- organisms and dissolved impurities. So, it is essential to purify water before drinking for example by boiling.
Q.4. You are a member of the municipal body of your town. Make a list of measures that would help your town to ensure the supply of clean water to all its residents.
Ans. List of measures to ensure the supply of clean water:
(i) Laws for industrial units should be strictly implemented so that polluted water is not disposed off directly into rivers and lakes.
(ii) Water treatment plants should be installed in all industrial areas.
(iii) Proper cleaning of the water tanks
(iv) Treatment of water before supplying it to households.
(v) The water supply pipes should not come in contact with the sewage pipes.
Q.5. Explain the differences between pure air and polluted air.
Ans. Pure air may contains all its constituent gases in fair ratio. Pure air does not possess, dust, smoke or harmful gases as sulphur dioxide carbon monoxide etc. While polluted air may contain dust, some and fair amount of harmful gases, like; sulphur, dioxide, carbon monoxide, smog etc. which leads to diseases like asthma, cough etc.
Q.6. Explain circumstances leading to acid rain. How does acid rain affect us?
Ans. The gases, like; sulphur dioxide and nitrogen dioxide react with the water vapour present in the atmosphere to form sulphuric acid and nitric acid. These come down with the rain making the rain acidic. This is called acid rain.
Harmful effects of Acid rain:
(i) Acid rain results in the corrosion of marble of the buildings, monuments and statues made of marble, slate or limestone.
(ii) It increases the corrosion of metals.
(iii) It is harmful to aquatic life.
(iv) It damages the leaves of plants and trees.
(v) It affects adversely the vegetation and reduces reproduction.
Q.7. Which of the following is not a greenhouse gas?
(a) Carbon Dioxide
(b) Sulphur dioxide
(d) Nitrogen
(c) Methane
Ans. (d) Nitrogen
Q.8. Describe the 'Green House Effect' in your own wards.
Ans. The sun's rays warm the earth's surface. A part of the radiation that falls on the earth is absorbed by it and a part is reflected back into the space. A part of the reflected radiation is trapped by the atmosphere and is not allowed to go out of the earth's atmosphere. These trapped radiations further warm the earth. The trapping of radiations by the earth's atmosphere is called the green house effect. Without this process life would not have been possible on earth, because of the low temperatures. CO, is one of the gases responsible for this effect. Other gases, like; methane, nitrous oxide, water vapour also contribute to this effect. These are also called Green House Gases. For example, the inside of a car with its windows closed is hotter than outside due to greenhouse effect. The window panes absorb infrared radiations of the sun making inside hotter because heat rays are absorbed by glass easily and are not allowed to reflect back.
Q.9. Prepare a brief speech on global warming that you have to make in your class.
Ans. Global Warming: Global warming as the name suggests is the continuous increase in the temperature of the earth (globe). It is caused by the pollution of air and excessive heat trapped by the green house gases, like; CO₂, methane, ozone, etc. The quantity of these gases is increasing day by day in the atmosphere. If this is not checked in time, we may have to face dire consequences, Such as, glaciers will melt, lower area will get submerged in water, rain fall will be affected, sea level will rise affecting production of crops, forests, etc and it will also affect the life-style of living organisms. So, immediate measures are to be taken to stop global warming.
Global warming has become a major concern for governments worldwide. Many countries have reached an agreement to reduce the emission of green house gases. The Kyoto protocol is such an agreement under the United Nations Convention, which has been signed by many countries.
Q.10. Describe the threat to the beauty of the Taj Mahal.
Ans. Case Study: The Taj Mahal
Over the past 2 decades, India's most famous tourist attraction, Taj Mahal located at Agra, has become a matter of concern. Experts have warned that air pollution is discoloring its white marble. The industries located in and around Agra, like; rubber processing, automobiles, chemicals and especially, the Mathura oil refinery have been responsible for producing pollutants, like; sulphur dioxide and nitrogen dioxide. Acid rains have resulted in corrosion of the marble of the monument- The phenomenon is also called 'Marble cancer'. Suspended particulate matter, such as, the soot particles emitted by the Mathura oil refinery, has contributed to the yellowing of the marble.
The Supreme Court has taken several steps to save the Taj. It has ordered the industries to either switch to cleaner fuels like CNG (Compressed Natural Gas) and LPG (Liquefied Petroleum Gas). Moreover, the automobiles should switch over to unleaded petrol in the Taj Zone.
Q.11. Why does the increased level of nutrients in the water affect the survival of aquatic organisms?
Ans. The ponds look green due to lot of algae growing them. This is caused by excessive quantities of chemicals, like; nitrates and phosphates, which are present in fertilizers. These act as nutrients for algae to flourish. Once these algae die, they serve as food for decomposers, like; bacteria. They use up a lot of oxygen. This results in a decrease in the oxygen level, which is harmful for the survival of other aquatic organisms.
SOME ADDITIONAL SHORT ANSWER TYPE QUESTIONS
Q.1. Give the constituent of air.
Ans. The air consists of a mixture of gases. By volume about 78% of this mixture is nitrogen and about 21% is oxygen. Carbon dioxide, argon, methane, ozone, water vapour are also present in very small quantities.
Q.2. Is Hot water also a pollutant, Comment
Ans. Hot water can also be a pollutant. This is, usually, water from power plants and industries. It is released into the rivers. It raises the temperature of the water body. Adversely, affecting the animals and plants living in it.
Q.3. How is CO, added to the atmosphere in excess?
Ans. On one hand, CO, is continuously being released because of human activities and on the other hand, forest area is decreasing. Plants utilize CO₂ from the atmosphere for photosynthesis, thereby decreasing the excess of CO₂ in the air. Deforestation leads to an increase in the amount of CO₂ in the air because the number of trees, which consume CO₂ becomes lesser. Human activity is thus contributed to the accumulation of CO₂ in the atmosphere.
Q.4. State, why a car parked in the sunshine with its windows closed is found much more hot inside than outside ?
Ans. The inside of a car with its windows closed is hotter than outside due to greenhouse effect. The window panes absorb infrared radiations of the sun making inside hotter because hot rays are absorbed by glass, easily, and are not allowed to reflect back.
Q.5. What are aerosols? How are these dangerous ?
Ans. Nitric oxide and nitrogen dioxide gases are produced during some biological processes and also by the combustion of carbonaceous matter and motor fuels. Nitric oxide (NO) is less toxic and nitrogen dioxide is very toxic. Oxides of nitrogen also damage leaves of certain plants. Oxides of nitrogen are also responsible for acid rain and for formation of smog.
Q.6. What is smog ?
Ans. When fumes from industries, automobiles and homes do not raise high into theatmosphere but condense over water droplets of smoke and fog, the coloured blanket so formed is called smog. Smoke + Fog + Fumes Smog
Q.7. "Hot water can also be a pollutant" explain. How?
Ans. Hot water is, usually, water from power plants and industries. It is released into rivers. It raises the temperature of the water body, adversely affecting the animals and plants living in it.
Q.8. What do you mean by water pollution ?
Ans. Destruction of purity of water by the addition of harmful substances is called pollution of water. Such, impure water is called polluted water. The substances responsible for the pollution of water are called pollutants.
Q.9. Can ground water get polluted by sewage? How?
Ans. Yes, the polluted sewage mixes with well water by seeping and makes the well water polluted with bacteria, viruses, fungi and parasites which cause diseases like cholera, typhoid and jaundice.
Q.10.Are non-living things also affected by air pollution ?
Ans. Yes, the air pollution is affecting not only living beings, but also the non-living things. An example of this is discolouring the white marble of Taj Mahal due to air pollution. Similarly, many other buildings, monuments and statues are also getting affected.
Q.11. What is ozone? How is it helpful for our environment?
Ans. Ozone is a gas which is very helpful for environment of our earth. It forms a protective layer around the atmosphere of earth. It does not allow the ultraviolet rays of the sun from reaching the earth. U.V. rays can cause great damage to our earth. So, ozone is of great help for our earth.
Q.12. What is ozone hole or depletion of ozone layer?
Ans. A gas named ozone forms a protective layer around the atmosphere of the earth. It protects the earth from the ultra- violet rays of the suns, but, some chemicals used in refrigeration cause damage to this layer. CFCs cause tearing away of this layer. This is called depletion of ozone layer. At some points this are called ozone holes. layer is depleted completely and holes are created. These holes
Q.13. In what way chloro-fluoro carbons are harmful ?
Ans. Chloro-fluoro carbons deplete the ozone layer in the atmosphere radiations. which protects earthy organisms from harmful ultraviolet
Q.14. How does carbon monoxide act on humans?
Ans. Hemoglobin of the blood absorbs carbon monoxide. This in turn reduces oxygen carrying capacity of blood. Non-availability of sufficient oxygen to the tissues results in death.
Q.15. What is potable water? What will happen if we drink polluted water?
Ans. By potable water we mean water which is suitable for drinking. If we drink polluted water we will be caught by water borne diseases like diarrhea, dysentery, cholera, jaundice etc.
ADDITIONAL LONG ANSWER TYPE QUESTIONS
Q.16. What is air pollution? Write its causes.
Ans. When air is contaminated by unwanted substances, which have a harmful effect on both the living and non-living, it is called air pollution.
Causes of air pollution:
(i) Vehicles: Vehicles produce high level of pollutants, like; carbon dioxide carbon monoxide, nitrogen oxides and smoke. Carbon monoxide is produced from incomplete burning of fuels, such as, petrol and diesel. It is poisonous gas. It reduces the oxygen carrying capacity of the blood.
(ii) Industrial emissions : Different poisonous and dangerous gases are emitted by factories, industries using coal and petroleum products, as, fuel. These fuels emit various poisonous gases.
(iii) Natural pollutant: Natural sources, like; forest fire and volcanic eruptions produce smoke and dust particles.
(iv) Human activities: Uses of fuels, like; cow dung, coal, wood also produce air pollution. Agricultural practices, like; burning chaff after cultivation also pollute air.
Q.17. What steps do you suggest for minimising the air pollution around you?
Or
How should air pollution be controlled?
Ans. (1) Use of plastic bags should be banned.
(ii) Recycling plants for paper, tree, leaves etc. should be set up at convenient places.
(iii) Diesel or petrol run vehicles should be changes to CNG at affordable cost, simultaneously increasing CNG filling facilities.
(iv) Smoking should be discreet.
(v) Use of aerosols should be minimised.
(vi) Plantation of trees at available space should be encouraged.
Q.18. What is green house effect? How does it cause global warming?
Ans. The process of trapping of radiation by the earth's atmosphere is called green house effect.
By this process, the warming of earth takes places. Without this process life would not have been possible on earth, but now in threatens life.
CO₂, methane, nitrous oxide, and water vapour are called green house gases because they all contribute towards this effect.
CO, is one of the components of air. As the amount of CO₂ increase in the atmosphere due to which more green house effect takes place. As a result, the average temperature of the earth's atmosphere is gradually increasing. This is called global warming.
Q.19. What is water pollution? How is water pollution caused?
Ans. The mixing of harmful substances, such as, sewage, toxic chemicals, slit, etc. in water is called water pollution.
Causes of water pollution :
(i) Domestic discharges : The sewage from homes are collected and disposed off in nearby rivers, which cause water pollution.
(ii) Industrial discharges: Various harmful and toxic chemicals are discharged by various industries, directly, into the water. These chemicals spoils the water and make it unfit for drinking.
(iii) Religious rituals: Various religious rituals are also cause the causing water pollution. water pollution. Dispersion of dead bodies or remains in river is activities are also cause water pollution.
(iv) Human activities: The bathing, washing and other human
Q.20. How can water pollution be controlled?
Ants. Water pollution can be controlled in various ways and by human beings only:
(1) Human and animal excreta should be prevented from mixing in water sources. For this pit latrines should be build.
(ii) Dead bodies on human and animals should not be thrown into rivers.
(iii) Industrial chemical wastes should be treated chemically into harmless compounds before throwing into the water.
(iv) Excreta and garbage should be recycle in biogas plant.
(v) We should not wash clothes and take bath in river water.
(vi) Sewage water should be treated before releasing them into water.
Q.21. Identify the sources for water pollution in your neighbourhood.
Ans.
(i) People go to toilet in open fields. The catties leave their dung. All these substances in the rainy season washes away into nearby river and ponds. These substances contain micro-organisms which are responsible to cause the various diseases.
(ii) Fertilizers are extensively used to increase the production. These are carried by rain water to the river and pond. This renders the water polluted.
(iii) The villagers people take bath in the water sources and also they let their animals to take bath near the water sources. Thus, this water becomes polluted.
Q.22. What is potable water? How is water purified for drinking?
Ans. By Potable Water we mean water which is suitable for drinking. Water obtained from sources is not pure. It needs purification before being supplied for drinking purposes. Water is first pumped from a source such as river or lake and is collected in a reservoir.The water is then cleaned in water works by allowing it to filter through layers of gravel and sand it. It removes the dirt from water. Then water is treated with some chemicals like chlorine to kill the germs. The water is then supplied to localities where it is to be used for drinking purposes.
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