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Summary
Pollution happens in different forms like noise, air, water, soil, and radioactive. It comes from point sources, which are direct and easy to find, or non-point sources, which are indirect and harder to manage.
Noise pollution is unwanted sound that causes discomfort and can disturb activities like sleep or conversation. Traffic with many vehicles and loud horns is a big source of this noise. Factories with their machinery also create a lot of noise, and sometimes these are located near homes. Construction sites, where new buildings are made, are often very noisy. Loudspeakers used for events, religious functions, and advertising contribute to noise as well. Airports cause significant noise from airplanes, especially large jets when they take off and land. Even everyday household sounds from appliances or activities, various types of farm equipment, and defence operations like military exercises or shooting practices also add to the general noise pollution.
Air pollution occurs when the air gets contaminated with substances like dust, smoke, or harmful gases. This pollution affects the health of people, animals, and plants, and harms the environment. Air pollutants are either primary, meaning they are emitted directly from sources like ash from a volcano, or secondary, which form when primary pollutants react with other things in the air, like ozone. Some air pollution is natural, for example, from volcanic eruptions. However, many human activities cause air pollution. Vehicles such as cars and trucks are a major source, releasing gases like carbon monoxide. Industries also pollute the air with smoke and chemicals from their processes. Burning garbage in open areas releases harmful gases and smoke into the atmosphere. Sometimes, smoke and fog mix to create smog, which is common in winter and can cause breathing problems. Certain air pollutants can also mix with rain to form acid rain, which can damage plants and buildings.
Water pollution happens when harmful substances enter rivers, lakes, and oceans. One source is domestic wastewater from homes, which carries detergents, human waste, and plastics into water systems. Phosphates found in many detergents and fertilizers can cause a problem called eutrophication. This is when too many tiny water plants called algae grow very quickly, using up oxygen and harming fish and other aquatic life. Industrial waste is another major source of water pollution. Factories often release waste that contains dangerous heavy metals like lead, mercury, and cadmium, or other harmful chemical compounds. Lead can enter water from old pipes or industrial processes and is bad for health. Mercury, used in some industries, can build up in fish, and then in people who eat those fish.
Soil pollution makes the land dirty and unsafe for use. One cause is the excessive use of chemical fertilizers in farming. While these help crops grow, they can also poison the soil with their impurities or other harmful chemicals. Biomedical waste from hospitals, which includes items like needles, old medicines, and organic matter, can contaminate the soil and spread diseases if not disposed of correctly. Pesticides, which are chemicals used on farms to kill pests and weeds, also get into the soil. These chemical residues can stay in the soil for a long time and can sometimes get into the food grown on that land.
Radioactive pollution involves harmful radioactive materials. A small amount of radiation is natural, like cosmic rays that come from space, but these are usually not dangerous to us on Earth. Most harmful radioactive pollution is man-made. X-rays used in hospitals for medical checks can affect our bodies if there is too much exposure. Nuclear power plants produce radioactive waste from their fuel and cooling systems; this waste is very dangerous and needs to be stored very carefully. The testing of nuclear weapons releases large amounts of radioactive material into the air. This material can be carried far by the wind and then fall to the earth with rain, polluting both soil and water. It can then enter food chains and harm living things. Radioactive isotopes used in scientific research laboratories can also cause water pollution if their wastewater is not handled correctly.
Textbook solutions (Morning Star/Total)
Multiple-Choice Questions
1. Direct sources of pollutants that are easy to identify, monitor and control:
(a) Direct sources
(b) Primary sources
(c) Point sources
(d) Secondary sources
Answer: (c) Point sources
2. Which amongst the following is not a source of Noise Pollution?
(a) Traffic
(b) Factories
(c) Defence
(d) Burning of Garbage
Answer: (d) Burning of Garbage
3. Ozone, ketones and sulphur oxides are examples of which amongst the following:
(a) Primary Pollutants
(b) Direct Pollutants
(c) Secondary Pollutants
(d) Natural Sources
Answer: (c) Secondary Pollutants
4. Suspended droplets, solid particles or mixtures of the two in the air:
(a) Gaseous air pollutants
(b) Natural air pollutants
(c) Primary pollutants
(d) Particulate air pollutants
Answer: (d) Particulate air pollutants
5. Which amongst the following is NOT a source of Air Pollution?
(a) Vehicular exhaust
(b) Biomedical Waste
(c) Industrial exhaust
(d) Burning of garbage
Answer: (b) Biomedical Waste
6. Motor vehicles fuel, burning of wood, coal and solid waste disposal are major sources of which pollutant?
(a) Carbon monoxide
(b) Nitrogen oxides
(c) Particulates
(d) Sulphur oxides
Answer: (a) Carbon monoxide
7. Rapid growth of algae when phosphates are discharged into waterways.
(a) Algae-Discharge
(b) Eutrophication
(c) Algae-Enrichment
(d) Phosphatic Algae
Answer: (b) Eutrophication
8. Which amongst the following is not a source of Radioactive Pollution?
(a) Nuclear weapons
(b) X-rays waste
(c) Pesticides
(d) Radioactive fallout from nuclear plants
Answer: (c) Pesticides
9. Construction sites are of source of which pollution?
(a) Noise due to construction equipment.
(b) Air due to the particulate matter released.
(c) Soil due to the excavation for the site.
(d) Only (a) and (b).
Answer: (a) Noise due to construction equipment.
Short Answer Questions
1. Name any three air pollutants and the sources of each of them.
Answer: Three air pollutants and their sources are:
- Carbon Monoxide (CO): Sources include gasoline fuel, motor vehicles fuel, burning of wood and coal, solid waste disposal, and industrial processes.
- Nitrogen Oxides (NOx): Primary sources are motor vehicles and power generation stations, combustion of organic matters, furnace stacks, and incinerators.
- Sulphur Oxides (SOx): Sources are mainly due to burning of coal, smelting operations, refineries, chemical plants, open burning of garbage, and municipal incinerators.
2. What are natural sources of air pollution? Name one industry which pollutes the atmosphere with gaseous as well as with particulate matter.
Answer: Natural sources of air pollution include volcanic eruptions, deflation of sand and dust, as well as forest or wild fires of natural vegetation, etc.
Industries such as chemical industries, paper and pulp mills, cotton mills, and petroleum refineries produce most air pollution. The smoke coming out from factories, which includes those like petroleum refineries, has small particles of dust, carbon, metals, other solids, liquids, and radioactive materials which get mixed in smoke and pollute the air, indicating both gaseous and particulate matter.
3. What is known as smog? What harm is done by smog especially in winter?
Answer: Smog is known as a combination of smoke and fog.
In winter, smog envelopes many cities, creating health hazards and traffic problems. Smog is harmful for health as it causes asthma, bronchitis, shortness of breath, eye and nose irritation, etc. Smog also reduces visibility and leads to problems in traffic movement.
4. Name three gases emitted during burning of garbage.
Answer: Three gases emitted during the burning of garbage are carbon dioxide, sulphur dioxide, and nitrogen oxides.
5. Mention any two sources of water pollution.
Answer: Two sources of water pollution are:
(i) Domestic
(ii) Industrial
6. Name two heavy metals from industries that pollute water.
Answer: Two heavy metals from industries that pollute water are cadmium and lead. Other examples include mercury, copper, and chromium.
7. Mention any two sources of soil pollution.
Answer: Two sources of soil pollution are:
(i) chemical fertilisers
(ii) biomedical waste
8. Why radioactive pollutants are very dangerous?
Answer: Radioactive pollutants are very dangerous because they are hazardous to living organisms. For example, X-rays, a form of radioactive pollution, can pass through genetic cells and affect the chromosomes, resulting in mutations. Additionally, radioactive particles from sources like nuclear weapons can be carried by wind, fall with rain, affect the soil, and reach water sources. Aquatic organisms can absorb and accumulate these radioactive materials, which are then passed on to human beings through food chains.
9. In cities flyovers are constructed with large sheets of fibre glass on the outer side of the flyovers. Give reason.
Answer: Large sheets of fibre glass are fixed on the outer sides of flyovers to reduce noise pollution. These sheets act as sound barriers that absorb or deflect the noise produced by the heavy traffic moving on the flyovers, thereby protecting the people living or working nearby from the harmful effects of constant noise.
10. How does lighting of crackers cause pollution?
Answer: Lighting of crackers releases a variety of pollutants into the air, such as smoke, dust, and harmful gases including sulphur dioxide and nitrogen oxides. These pollutants contribute to air pollution and can cause breathing problems, eye irritation, and other health issues, especially for people with respiratory conditions.
Structured Questions
1. With reference to noise pollution, answer the following:
(a) When does sound become a source of noise pollution?
Answer: Sound becomes unwanted and a source of noise pollution when it interferes with normal activities such as sleeping, conversation or disrupts one’s quality of life. Noise Pollution refers to an unwanted sound which produces unpleasant effects and discomfort.
(b) How does traffic contribute to noise pollution?
Answer: Traffic contributes to noise pollution as the rapidly increasing number of vehicles on the roads are a big source of noise pollution. Increasing traffic jams in congested areas lead to repeated hooting of horns by impatient drivers causing noise pollution.
(c) Why are the construction sites considered as worse than factories in their contribution to noise pollution?
Answer: Noise from construction sites is generally far worse than noise originating from factories because construction itself causes high noise emissions and the equipment used is inherently noisy.
(d) How do the airplanes cause noise pollution? Why is there more noise pollution during landing as compared to during take-off?
Answer: Airplanes cause noise pollution, a problem that has mainly arisen because of the widespread use of heavy long-range jet aircraft. Noise made by jet planes is more disturbing than that of the old propeller driven aircraft because it is of far higher pitch. Jet noise is caused by the violent mixing of the jet of gases from the engine with the surrounding air. It is at maximum level during take-off when the engine delivers maximum thrust, and reduces rapidly as the aircraft climbs.
During landing, the main source of high-frequency noise is the sound made by the air compressor and turbine blades. Aircraft pass close to the ground for quite a distance during the landing operation, and this noise often constitutes a more sustained environmental nuisance than the intense noise of shorter duration produced during take-off, which can be perceived as more noise pollution during landing.
2. Air pollution is the contamination of air by pollutants. In this context answer the following:
(a) Based on their origin, how can air pollutants be classified?
Answer: Based on their origin, air pollutants are classified into:
(a) Primary Pollutants: The pollutants that are emitted directly from the sources and are found in the atmosphere in the form in which they are emitted are known as primary pollutants, such as: ash, smoke, dust, radioactive compounds, oxides of sulphur and nitrogen, etc.
(b) Secondary Pollutants: The pollutants that are formed in the atmosphere by chemical interactions between primary pollutants and atmospheric constituents are known as secondary pollutants. Examples of secondary pollutants are Sulphur trioxide, Ozone, Peroxyacetyl Nitrate (PAN), ketones, etc.
(b) How does the use of automobiles cause air pollution?
Answer: The use of automobiles causes air pollution as vehicles are mainly responsible for more than 80 per cent of total air pollution. The major pollutants released from automobiles, locomotives, aircraft, etc., include carbon monoxide (CO), unburnt hydrocarbons and nitrogen monoxide. In the major metropolitan cities like Delhi, Mumbai and Kolkata, vehicular exhaust accounts for 75 per cent of all CO, 45 per cent of all hydrocarbons, 40 per cent of all oxides and 30 per cent of all suspended particulate matter. Air pollution is also caused by the gaseous and volatile hydrocarbons such as, methane, acetylene and ethylene. Some hydrocarbons like ethylene, which undergo chemical reactions in the presence of sunlight and nitrogen oxide form photochemical oxidants (like ozone) that are harmful. Fuel combustion in automobiles also produces nitrogen dioxide.
(c) How do industries pollute the air?
Answer: Industries pollute the air as industries such as chemical industries, paper and pulp mills, cotton mills and petroleum refineries produce most air pollution. The cement factories emit dust, which is a potential health hazard. The smoke coming out from the factories has small particles of dust, carbon, metals, other solids, liquids and radioactive materials which get mixed in smoke and pollute the air. The burning of sulphur in coal or heavy oil in thermal power plants releases SO₂ in the air. Sulphur dioxide (SO₂) combines with oxygen and water to form sulphuric acid (H₂SO₄) in the atmosphere which is a health hazard and also produces acid rain.
(d) Mention any three air pollutants and two sources of each.
Answer: Three air pollutants and two sources of each are:
- Carbon Monoxide (CO): Sources are gasoline fuel and motor vehicles fuel.
- Nitrogen Oxides (NOx): Sources are motor vehicles and power generation stations.
- Sulphur Oxides (SOx): Sources are burning of coal and smelting operations.
3. With reference to the sources of water pollutants answer the following questions:
(a) What are the domestic sources of water pollution?
Answer: Domestic sources of water pollution originate from man’s use of water for drinking, preparation of food, bathing, and cleaning the house. Most of this used water is drained out through municipal drains and poured into a river or lake. This domestic wastewater, when mixed with other wastes such as plastic, detergents, animal dung and human faecal material, is known as municipal waste, which is a source of water pollution.
(b) Why is it harmful to dispose of household detergents in water bodies?
Answer: It is harmful to dispose of household detergents in water bodies because many detergents contain phosphates. When phosphates are discharged into waterways, their remnants promote rapid growth of algae. Such an enrichment process is known as ‘eutrophication’. Aquatic weeds multiply rapidly in many water bodies, and they interfere with fishing, navigation and irrigation.
(c) In what way does the industrial waste pollute water?
Answer: Industrial waste pollutes water because industries dealing with chemicals, pulp and paper, food processing, etc., produce waste material such as heavy metals or synthetic organic compounds. These pollutants reach water bodies either through direct discharge or by leaching from waste dumps. Heavy metals such as cadmium, lead, mercury, copper, chromium, etc., get into water. For example, lead can enter water from mining and smelting of lead-bearing ores, lead plumbing, and disposal of lead-zinc batteries. Mercury, used in plastic and chemical industries, can accumulate in aquatic environments and pass on to humans through fish.
(d) What are the sources of radioactive pollution? Describe each of them.
Answer: The two main sources of radioactive pollution are natural sources and man-made sources.
(a) Natural Sources: These sources are cosmic rays with energetic radiations reaching the earth from outer space. Though they are a major hazard in space, they are not dangerous for organisms on earth.
(b) Man-made Sources: The following man-made sources cause radioactive pollution:
- (i) X-rays waste: The use of X-rays is common for detecting skeletal disorders. Cancer patients undergo radium and other isotope radiations. The X-rays pass through genetic cells and affect the chromosomes, resulting in mutations.
- (ii) Radioactive fallout from nuclear plants: In a nuclear power establishment, both fuel elements and coolants are sources of radiation pollution. Radioactive wastes from atomic reactors are hazardous to living organisms. Even if radioactive wastes are buried underground they may escape into the surroundings. Inert gases escape as vapours and pollute the environment.
- (iii) Nuclear Weapons: Testing of nuclear weapons involves using radioactive substances like Uranium 235 and Plutonium 239 for fission. The radioactive waste emitted during these tests makes the surrounding materials radioactive. Radioactive particles are carried away to distant places by wind. They are brought down by rain. Raindrops containing these radioactive particles fall on earth, and affect the soil causing soil pollution. From the soil, the radioactive materials reach water sources, where the aquatic organisms absorb and accumulate them through the food chains and pass them on to human beings.
- (iv) Radioactive Isotopes: Radioactive isotopes are used in research laboratories. When the wastewater from these laboratories reaches the rivers, streams, lakes, etc., through the sewers they cause water pollution.
Thinking Skills
1. Of all the different types of pollution, noise pollution is the most subtle but with many harmful effects. Do you agree with this statement? Give reasons to support your answer.
Answer: Yes, I agree that noise pollution is the most subtle type of pollution, yet it has many harmful effects. Unlike air or water pollution, noise pollution doesn’t leave visible traces, which makes it harder to notice or measure. However, its impact on daily life and health can be quite serious.
Noise pollution comes from many common sources such as traffic, factories, construction sites, loudspeakers and airports. It disrupts normal activities like sleeping and conversation, and causes irritation, stress, and even hearing loss. For example, the noise from construction sites is often more intense than that from factories because of the heavy machinery used. Airports near residential areas also expose people to constant jet noise, which can be disturbing due to its high pitch and intensity during take-off and landing.
Household items like mixers, televisions, and even crying infants contribute to the background noise that can affect one’s mental well-being. The subtle nature of noise pollution means we often ignore it, but over time, the cumulative effects can be damaging to our physical and mental health.
2. Pollution in the cities is the price of growing affluence. Give your views on the above statement with examples.
Answer: I believe this statement is true to a large extent. As cities develop and become more affluent, the demand for vehicles, factories, electricity, and modern conveniences also increases. These developments, while improving the standard of living, often come at the cost of polluting the environment.
For example, vehicles are a major source of air pollution in cities. In places like Delhi and Mumbai, vehicular exhaust contributes to the majority of carbon monoxide and suspended particles in the air. Industrial activities that support urban development also release harmful gases and dust into the atmosphere.
As people gain more wealth, consumption of goods also rises, leading to increased garbage and waste. The burning of garbage in open spaces or municipal incinerators releases toxic gases into the air. Similarly, water bodies become polluted when domestic and industrial waste is discharged untreated.
Thus, while affluence brings comfort and progress, it also leads to environmental degradation unless sustainable practices are adopted. Growing affluence should be balanced with responsibility towards the environment.
Practical Work
Find out the percentage of pollutants released into the air by automobiles in your city. Do you think introduction of CNG in some of the cities has been helpful in reducing pollution levels?
Answer: Do it yourself. Here are the instructions:
- Collect data on air pollution sources in your city from reliable sources such as local government environmental departments or pollution control boards. Focus on identifying what percentage of air pollution is caused by vehicles.
- Note key pollutants released by vehicles, such as carbon monoxide (CO), unburnt hydrocarbons, and nitrogen oxides (NOx). Mention that vehicles are responsible for more than 80% of total air pollution in urban areas.
- Visit a nearby traffic-heavy area to observe and document the number of vehicles, types of fuel used, and any visible pollution (like smog or soot).
- Interview residents or shopkeepers in high-traffic areas to gather their views on vehicular pollution and any health effects they’ve experienced.
- Analyse the role of CNG (Compressed Natural Gas) in reducing pollution. Focus on how its introduction has helped lower levels of harmful emissions in cities where it’s used.
- Compare pollution levels before and after the introduction of CNG in cities like Delhi. Use charts or graphs to show the difference if data is available.
- Conclude by summarising whether CNG has been effective, based on the evidence you gather.
- Include photographs or newspaper clippings, if possible, to support your findings.
Extras
Additional MCQs
1. What describes unwanted sound that interferes with normal activities?
A. Acoustic noise
B. Noise pollution
C. Sound disturbance
D. Auditory interference
Answer: B. Noise pollution
52. Which radioactive pollution arises from nuclear plant accidents?
A. Cosmic rays
B. Nuclear fallout
C. X-ray waste
D. Industrial effluent
Answer: B. Nuclear fallout
Additional Assertion and Reason
1. Assertion (A): Direct sources of pollutants are easy to identify, monitor and control.
Reason (R): Point sources are direct sources of pollutants.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R does not explain A.
(c) A is true but R is false.
(d) A is false but R is true.
Answer: (a) Both A and R are true and R is the correct explanation of A.
18. Assertion (A): Radioactive fallout from nuclear plants is a source of radioactive pollution.
Reason (R): In a nuclear power establishment, both fuel elements and coolants are sources of radiation pollution.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R does not explain A.
(c) A is true but R is false.
(d) A is false but R is true.
Answer: (a) Both A and R are true and R is the correct explanation of A.
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