Environmental Pollution: AHSEC Class 11 Environment

Leave a Comment

Get summay, questions, answers, solutions, notes, extras, PDF, competency-based questions of chapter- 5/unit I, Environmental Pollution: AHSEC Class 11 Environmental Education, which is part of the present syllabus. These solutions, however, should only be treated as references and can be modified/changed. 

Summary

Environmental pollution is a great problem facing the world. It is the degradation of our environment caused by human actions. Fast-growing populations, expanding industries, and the clearing of forests have created imbalances in nature. Our search for economic growth has led to the careless use of natural resources. The problem began as the human population increased. A simple way to think about this is through the story of Adam and Eve, who ate an apple and threw away the peels, starting the first pollution. As societies developed with industries, cities, and modern farming, the problem grew much worse. The Earth can only absorb a certain amount of waste. Today, the amount of pollution we create is more than the land, air, and water can handle.

Pollution is an unwanted change in the physical, chemical, or biological properties of our air, water, and soil. The word itself comes from a Latin term meaning “to make dirty.” These changes can harm humans, animals, and other living things. Pollution can be categorized by the part of the environment it affects, such as air, water, or soil pollution. It can also be categorized by the type of pollutant, like noise, thermal, or radioactive pollution. Pollutants are harmful substances. Primary pollutants are released directly from a source, like smoke from a factory. Secondary pollutants are formed when primary pollutants react with each other in the environment.

Air pollution is the presence of harmful substances in the atmosphere. These include dust, smoke, and poisonous gases. The sources can be natural, like volcanic eruptions, or man-made, like emissions from vehicles and factories. These pollutants can cause headaches, breathing difficulties, and other serious health issues. Water pollution is the contamination of water bodies like rivers and lakes. It is caused by waste from homes, industries, and farms. Drinking polluted water can lead to dangerous diseases such as typhoid and cholera. Keeping drinking water sources clean is necessary for good health. Simple methods like filtration and boiling can help make water safer.

Soil pollution happens when toxic chemicals from industrial waste and pesticides get into the soil. This reduces the soil’s fertility and can contaminate the food grown in it. Noise pollution is unwanted and disturbing sound from sources like traffic, machinery, and loudspeakers. It can harm our hearing and cause stress. Solid waste pollution comes from all the trash discarded by households, businesses, and industries. The text describes this waste as “materials in the wrong place,” which means an item becomes waste only when its owner no longer finds it useful. Improper disposal of this waste pollutes the land, attracts disease-carrying pests, and can leak harmful liquids into the ground.

Textual/Exercise

1. What do you mean by environmental pollution? Name the different types of pollution.

Answer: Environmental pollution is the unfavourable alteration of our environment, largely because of anthropogenic or human activities. More precisely, pollution is an undesirable change in physical, chemical, and biological characteristics of air, water, and soil that may harmfully affect man, animal, other living organisms, or property.

Different types of pollution can be categorized in the following ways:

According to the environment affected:

a. Air pollution
b. Water pollution
c. Soil pollution

According to the pollutant:

a. Thermal pollution
b. Noise pollution
c. Radioactive pollution
d. Solid waste pollution
e. Oil pollution
f. Industrial pollution
g. Marine pollution

2. What is air pollution? Identify the sources of air pollution.

Answer: Air pollution may be defined as the presence of one or more pollutants or contaminants like dust, smoke, mist, odour, and suspended particulate matter (SPM) in the atmosphere, which are injurious to human beings, plants, and other animals, or which unreasonably obstruct the comfortable enjoyment of life and property.

The major sources of air pollution can be of two types:

Natural sources:

a. Volcanic eruption: releasing poisonous gases like SO₂, H₂S, CO etc.
b. Forest fires: liberating very large quantities of smoke and particulate matter.
c. Decomposition of organic and inorganic substances: Methane gas and carbon dioxide are released into the air.
d. Dust: Dust is always present in the atmosphere in varying amounts.
e. Pollen grains of flowers: Pollens or aeroallergens enter the atmosphere from weeds, grasses, and trees, mainly responsible for causing allergy.
f. Fungal spores: Micro-organisms such as algae, fungi, bacteria, yeasts, rusts, spores etc., are present as variable particles in the atmosphere.
g. Radioactive materials: The radioactive minerals present in the earth’s crust and the action of cosmic rays from outer space on gaseous constituents of the atmosphere are mainly responsible for the radioactivity of the atmosphere.

Man-made sources:

a. Deforestation
b. Burning of fossil fuels
c. Emission from vehicles
d. Rapid industrialization
e. Modern agricultural practices

3. Mention few effects of air pollution on human health.

Answer: A few effects of air pollution on human health are:

• Sulphur-dioxide can cause chest constriction, headache, vomiting, and death from respiratory ailments.
• Nitrogen oxides can cause headaches, drowsiness, irritated lungs, and colds in children.
• Carbon monoxide causes nausea, reduces the oxygen-carrying capacity of the blood, and can lead to headaches, drowsiness, and an irregular heartbeat.
• Suspended particulate matter (SPM), ash, and soot can cause eye irritation, emphysema, and cancer.
• Volatile Organic Compounds (VOC) may cause irritation in mucous membranes, headache, and fatigue.
• Asbestos can cause lung diseases and lung cancer.

4. What is water pollution? What are the effects of water pollution on human health?

Answer: Water pollution can be defined as an alteration in the physical, chemical, and biological characteristics of water that may cause harmful effects on man and other aquatic biota. It is also the addition of an excess of undesirable substances to water that makes it harmful to man, animal, and aquatic life or otherwise causes a significant departure from the normal activities of various living organisms in or around water.

The effects of water pollution on human health include the introduction of a variety of intestinal pathogens like bacteria, viruses, and parasites. These can cause diseases ranging from mild gastroenteritis to severe and fatal dysentery, cholera, or typhoid. When drinking water is contaminated with sewage, gastroenteritis and infectious hepatitis may occur in epidemic proportions. Other diseases like rashes, fever, myocarditis, meningitis, and respiratory diseases are also likely. Protozoic diseases like amoebiasis and giardiasis may also occur through sewage contamination of water sources.

5. What is soil pollution? How can it be controlled?

Answer: Soil pollution occurs when the soil is contaminated by the dumping of various types of domestic and industrial wastes and the application of pesticides in agricultural fields. The addition of different types of toxic materials to the soil makes it polluted and decreases its fertility.

Soil pollution can be controlled in the following ways:

a. Industrial effluents should be properly treated before discharging them on the soil.
b. Solid wastes should be properly segregated as biodegradable and non-biodegradable wastes at the source and then disposed of by adopting effective scientific methods.
c. The use of bio-fertilizers should be encouraged instead of chemical fertilizers.
d. The application of pesticides should be controlled.
e. Bioremediation can be adopted for the degradation of toxic chemicals present in the soil.
f. Necessary enactment of laws should be made for panel action against those who are involved in polluting soil.
g. Awareness should be created among the people.

6. What are solid wastes? How are they classified? Give examples.

Answer: Solid wastes are all the wastes produced by household, commercial, institutional, agricultural, mining, and industrial activities and are discarded as useless or unwanted.

They are classified based on their source of production. They are produced by household, commercial, institutional, agricultural, mining, and industrial activities. They can also be segregated as biodegradable and non-biodegradable wastes.

Examples of solid wastes include wastes from industries, hospitals and nursing homes, and domestic waste.

7. Discuss the environmental effects of solid wastes.

Answer: Solid waste has the potential to degrade the air, water, and soil. The environmental effects are:

• Improper handling of solid wastes poses potential risks to the health of workers and the general public.
• Improper storage and disposal provide conditions for the breeding of disease vectors, primarily flies and rats, which can lead to health hazards like plague, dengue, and cholera.
• Garbage burning contributes significantly to urban air pollution.
• Using water polluted by solid waste for bathing, irrigation, and drinking can cause diseases like skin infections.
• It causes aesthetic damage, such as the ugliness of street litter and the destruction of the beauty of the countryside by uncontrolled dumping.
• Leachate, a liquid that oozes from a refuse dump, can enter surface water or groundwater, transferring pollution to water bodies.
• The inefficient burning of waste can cause air pollution.
• Open dumps are malodorous places where disease-carrying vermins like rats and flies proliferate.
• Methane gas is released into the air from the decomposition of solid wastes by micro-organisms.
• Hazardous materials dissolved in leachate can contaminate underground water and soil strata.

8. Mention two methods of solid waste management.

Answer: Two methods of solid waste management are:

• Solid wastes should be properly segregated as biodegradable and non-biodegradable wastes at the source and then disposed of by adopting effective scientific methods.
• Determining a substitute technology toward the recycling of solid wastes, with due consideration given to economic constraints and environmental aspects.

9. What is noise pollution? Write two probable effects of it on human health.

Answer: Noise pollution is any unwanted electromagnetic signal that produces a displeasing effect and which interferes with human communication, comfort, and health. It is the unwanted sound dumped into the environment without regard to the adverse effect it may have.

Two probable effects of noise pollution on human health are:

• Auditory effects: The most acute and immediate effect is the impairing of hearing, which may cause auditory fatigue and finally lead to deafness.
• Non-auditory effects: It can cause mental anxieties, mental stress, and psychological disorders. It also affects human health by disrupting comfort and working efficiency.

10. What measures can be taken to keep drinking water sources clean and safe?

Answer: To keep drinking water sources clean and safe, the following protective measures should be adopted:

(a) Location: Water sources should be on a higher location, at least 10m to 15m away from polluting sources like latrines, soak pits, garbage, etc.
(b) Platform: A cement concrete platform around the tube wells and ring wells, extending 1m in all directions and having a gentle slope outwards towards a drain, should be built. These platforms should be free from cracks and damages.
(c) Drain: Water sources should have sound drainage systems to check stagnancy. Waste water should not be allowed to accumulate in these areas.
(d) Covering: The mouth of a ring well should always be covered at all times to prevent foreign materials from entering it.
(e) Lining: The lining of a ring well should be built of stones set in cement up to a depth of at least 6m so that water enters from the bottom and not from the sides.

Extra/additional questions and answers

1. Define pollution?

Answer: Pollution is an undesirable change in the physical, chemical, and biological characteristics of air, water, and soil that may harmfully affect man, animals, other living organisms, or property.

2. How can pollution be categorized according to the environment?

Answer: According to the environment, pollution can be categorized into three types when different segments of the environment are affected. These are:

• Air pollution
• Water pollution
• Soil pollution

3. List the different types of pollution based on the pollutant.

Answer: Based on the pollutant, pollution may be of different types such as:

• Thermal pollution
• Noise pollution
• Radioactive pollution
• Solid waste pollution
• Oil pollution
• Industrial pollution
• Marine pollution

4. Distinguish between a pollutant and a contaminant with examples.

Answer: A pollutant is a substance present in nature in greater than natural abundance due to human activities, which ultimately has a detrimental effect on the environment. Examples include carbon monoxide, sulphur dioxide, arsenic, and lead.

A contaminant is a substance that does not occur in nature but is introduced by human activities into the environment. A contaminant is also considered a pollutant. Examples are fluorine from chlorofluorocarbons, food additives, and paints.

5. Differentiate between primary and secondary pollutants with suitable examples.

Answer: Primary pollutants are those that are released directly from an identifiable source and exist as such in the environment. Examples of primary pollutants are oxides of sulphur, oxides of nitrogen, and hydrocarbons.

Secondary pollutants are derived from primary pollutants through chemical reactions or by natural causes. For example, when hydrocarbons and nitrogen oxides react in the presence of sunlight, they form peroxy acetyl nitrate (PAN), which is a secondary pollutant.

6. What are the natural and anthropogenic causes of environmental pollution?

Answer: The natural causes of environmental pollution include earthquakes, volcanoes, eruptions, excessive rainfall (floods), landslides, storms, and the weathering of rocks.

The anthropogenic, or man-made, causes include population increase, deforestation, industrial and automobile exhausts, the burning of fossil fuels, war, and construction works.

7. Define air pollution.

Answer: Air pollution may be defined as the presence of one or more pollutants or contaminants like dust, smoke, mist, odour, and suspended particulate matter (SPM) in the atmosphere, which are injurious to human beings, plants, and other animals, or which unreasonably obstruct the comfortable enjoyment of life and property.

8. Describe the various natural sources of air pollution.

Answer: The various natural sources of air pollution include volcanic eruptions, which release poisonous gases like SO₂, H₂S, and CO. Forest fires liberate large quantities of smoke and particulate matter. The decomposition of organic and inorganic substances releases methane and carbon dioxide. Dust is always present in the atmosphere. Pollen grains from flowers, weeds, and trees enter the atmosphere and can cause allergies. Fungal spores from micro-organisms like algae and bacteria are also present. Finally, radioactive materials from the earth’s crust and cosmic rays contribute to air pollution.

9. What is mainly responsible for the radioactivity of the atmosphere?

Answer: The radioactivity of the atmosphere is mainly caused by radioactive minerals present in the earth’s crust and the action of cosmic rays from outer space on the gaseous constituents of the atmosphere.

10. List the man-made sources of air pollution.

Answer: The man-made sources of air pollution are:

• Deforestation
• Burning of fossil fuels
• Emission from vehicles
• Rapid industrialization
• Modern agricultural practices

11. Explain the various pollutants emitted by vehicles.

Answer: The principal pollutants emitted by vehicles are carbon monoxide (CO), hydrocarbons (HC), oxides of nitrogen (NOx), and suspended particulate matter (SPM). Petroleum-based vehicles also emit polynuclear aromatic hydrocarbons and aldehydes. Depending on the fuel’s sulphur content, sulphur dioxide (SO₂) may also be emitted. Additionally, exhaust from petrol vehicles can contain lead particles and compounds, while diesel vehicles contribute more NOx and particulate matter.

12. Which vehicles contribute more NOx and particulate matter?

Answer: Diesel vehicles contribute more NOx and particulate matter.

13. How does rapid industrialization contribute to air pollution?

Answer: Rapid industrialization contributes to air pollution as industrial processes from chemical plants, metallurgical plants, paper mills, and petroleum refineries produce about 20% of air pollution. In factories and mines, workers are exposed to toxic substances that can lead to deadly diseases like silicosis and pneumoconiosis from inhaling substances such as cotton dust, flour dust, asbestos dust, and silica dust.

14. What are sinks of atmospheric gases? Explain with examples.

Answer: A sink is a medium capable of retaining and interacting with a long-lived pollutant. Oceans and vegetation are the most important sinks for most atmospheric gases. For example, gases in the atmosphere diffuse to the surface of the oceans and are absorbed. Plants can also take up atmospheric gases. Other examples include limestone, which acts as a sink for atmospheric acids, and some soil micro-organisms, which are major sinks for carbon monoxide.

15. What is indoor air pollution? Mention its sources and effects.

Answer: Indoor air pollution is a major health problem recognized as significant pollution at homes and offices in urban areas. Its sources include air conditioners, gas stove smoke, building materials, furnishing, photocopies, paper products, carpets, and adhesives.

The effects of indoor air pollution can include allergy, asthma, and diseases of the skin, lungs, and respiratory tract. Prolonged exposure to oxides of nitrogen from gas stoves may damage the lungs and increase susceptibility to respiratory infections.

16. Define water pollution.

Answer: Water pollution is the alteration in physical, chemical, and biological characteristics of water that may cause harmful effects on man and other aquatic life.

17. List the various identified sources of water pollution.

Answer: The identified sources of water pollution include domestic wastes, industrial effluents, agricultural wastes, and run-off from urban areas. Other sources are soluble effluents, oil spills, seepage pits, refuse dumps, solid wastes, thermal pollutants, radioactive nuclides, particulates and atmospheric gases, and infectious agents.

18. How does contamination of drinking water by sewage pose a health risk?

Answer: Contamination of drinking water by sewage is a widespread danger because it introduces a variety of intestinal pathogens like bacteria, viruses, and parasites. These pathogens cause diseases ranging from mild gastroenteritis to severe and fatal dysentery, cholera, or typhoid. When drinking water is contaminated with sewage, infectious hepatitis can also occur. Other possible diseases include rashes, fever, meningitis, and respiratory diseases, as well as protozoic diseases like amoebiasis.

19. What are water-borne diseases? List some common examples.

Answer: Water-borne diseases are caused by ingesting water that has been contaminated by human activities or animal excreta containing pathogenic micro-organisms.

Some common water-borne diseases are:

• Typhoid
• Cholera
• Dysentery
• Diarrhoea
• Giardiasis
• Gastroenteritis
• Polio

20. What is safe water? When is water considered unfit for drinking?

Answer: Safe water is water that is suitable for household activities and personal cleanliness. For drinking, a chemical test must be carried out to ensure it is safe. Highly sophisticated water is essential for special activities like medical dialysis.

Water is considered unfit for drinking if it is untreated. It is also unfit if samples are found to be highly coloured with an objectionable taste, highly turbid, have a high iron content, or if its quality parameters are above the permissible level.

21. What is soil?

Answer: Soil is the uppermost part of the earth’s crust and is a mixture of organic material, weathered rock, and other materials necessary for plant growth.

22. What is soil pollution? What are its main sources?

Answer: Soil pollution occurs when various types of domestic and industrial wastes, pesticides, and other toxic materials are added to the soil, making it polluted and decreasing its fertility.

The main sources of soil pollution are industrial wastes, urban wastes, agricultural practices and wastes, municipal wastes, radioactive pollutants, and biological agents.

23. Explain the effects of sewage sludge and fertilizers on the environment.

Answer: Sewage sludge contains many types of pathogenic micro-organisms that can cause various soil-transmitting diseases, such as giardiasis and tetanus.

Nitrogen and phosphorus from fertilizers in the soil can reach nearby waterbodies through agricultural run-off. This process causes eutrophication, which is the excessive growth of plant life in the water.

24. Why are radioactive wastes in soil an extremely difficult public health problem?

Answer: Radioactive wastes in soil are an extremely difficult public health problem because radioactive elements like radium, uranium, and plutonium can remain active in the soil for thousands of years. Since these wastes are produced in huge quantities and have high activation energy, they create a very challenging and long-term health risk.

25. Define noise pollution.

Answer: Noise pollution is any unwanted electromagnetic signal that produces a displeasing effect and interferes with human communication, comfort, and health.

26. What are the sources of noise pollution? Distinguish between natural and man-made sources.

Answer: The sources of noise pollution can be natural or man-made.

The natural source of noise pollution is thunder.

Man-made sources are caused by human activities and include automobiles like trucks and buses, trains, aeroplanes, industries, factories, loudspeakers, musical instruments, sirens, and explosions. Firecrackers used during festivals also produce noise that exceeds permissible levels.

27. Differentiate between the auditory and non-auditory effects of noise pollution.

Answer: The auditory effects of noise pollution are the most immediate and involve the impairing of hearing. This can cause auditory fatigue and, in severe cases, may lead to deafness.

The non-auditory effects are also serious and include interference with speech communication, annoyance leading to ill temper, mental anxieties, mental stress, and violent behaviour. Noise pollution affects human health and disrupts comfort and working efficiency.

28. What are solid wastes? Why have they become a serious threat in recent years?

Answer: Solid wastes are all the wastes produced by household, commercial, institutional, agricultural, mining, and industrial activities that are discarded as useless or unwanted.

They have become a serious threat in recent years due to rapid urbanization, industrialization, population growth, and increasing economic standards, which have all led to a greater generation of waste.

29. Explain in detail the various man-made sources of air pollution.

Answer: The major man-made or anthropogenic sources of air pollution include deforestation, the burning of fossil fuels, vehicular emissions, rapid industrialization, and modern agricultural practices.

Deforestation is occurring on a large scale due to population increase, fuel requirements, and developmental projects, leading to consequences like global warming and climate change.

Vehicular emissions are considered the most dangerous form of air pollution. The principal pollutants emitted by vehicles are Carbon monoxide (CO), Hydrocarbons (HC), Oxides of nitrogen (NOx), and Suspended particulate matter (SPM). Petrol-based vehicles also release lead particles.

The burning of fossil fuels like coal, wood, and petroleum in industries and thermal power plants produces smoke containing fine particles, coarse particles, nitrogen oxides, halogens, and radioactive substances.

Rapid industrialization, involving chemical plants, smelters, and refineries, produces about 20% of air pollution and exposes workers to toxic substances that can lead to deadly diseases.

30. What are the causes of environmental degradation?

Answer: Different types of pollution, fast depleting forest resources, rapid population explosion, expanding industrialization, unplanned urbanization, mining, soil erosion etc have created ecological imbalances in recent years. Man’s quest for economic development has been mainly responsible for the ruthless exploitation of natural resources.

31. What is the term pollution?

Answer: The word pollution is derived from the Latin word pollutionem, meaning to make dirty. It is the unfavourable alteration of our environment, largely because of anthropogenic or human activities. More precisely, pollution is an undesirable change in the physical, chemical, and biological characteristics of air, water, and soil that may harmfully affect man, animal, other living organisms, or property.

32. What is a Pollutant and a contaminant?

Answer: A pollutant is a substance present in nature in greater than natural abundance due to human activities, which ultimately has a detrimental effect on the environment. Examples include Carbon monoxide, sulphur dioxide, arsenic, fluorides, lead, and cadmium.

A contaminant is a substance which does not occur in nature but is introduced by human activities into the environment. A contaminant is also a pollutant. Examples include Fluorine from chlorofluorocarbons, food additives, and paints.

33. What is Deforestation?

Answer: Forests are one of the most important natural resources on this earth. Covering the earth like a green blanket, these forests not only produce innumerable material goods but also provide several environmental services which are essential for life. However, it is a matter of concern that almost everywhere the forest cover has declined to a great extent. Deforestation is ongoing due to population increase, shifting cultivation, fuel requirements, raw materials for industries, developmental projects, growing food needs, and overgrazing. This has far-reaching consequences such as global warming and climate change, loss of soil fertility, and loss of biodiversity.

34. What are Vehicular emissions?

Answer: Vehicular emission is the most dangerous form of air pollution. Despite introducing stringent laws, adopting new standards, changing fuel characteristics, and modifying vehicle design, studies reveal that vehicular pollution is increasing day by day. The principal pollutants emitted by vehicles are:

• Carbon monoxide (CO)
• Hydrocarbons (HC)
• Oxides of nitrogen (NOx)
• Suspended particulate matter (SPM)

Petroleum-based vehicles also emit polynuclear aromatic hydrocarbons and aldehydes in trace amounts. Depending on the sulphur content of the fuel, varying amounts of sulphur dioxide (SO₂) may also be emitted. Additionally, exhaust gases from petrol-based fuel vehicles contain lead particles and sometimes lead compounds due to the addition of tetraethyl lead. Diesel vehicles contribute more NOx and particulate matter.

35. What are the sinks of atmospheric gases?

Answer: Oceans and vegetation are the most important sinks for most atmospheric gases. A sink is a medium capable of retaining and interacting with a long-lived pollutant. The gases widely dispersed in the troposphere find oceans as ready sinks, where they diffuse to the surface, cross the gas-liquid interface, and go into the bulk of the oceans.

Plants are also capable of taking up atmospheric gases without active metabolism and some can metabolise the gas, creating a concentration gradient for further absorption. Other sinks include limestone, which acts as a sink for atmospheric acids, and some soil micro-organisms, which are major sinks for carbon monoxide (CO).

36. What are indoor air pollutants?

Answer: Indoor air pollution has been recognized as a significant pollution problem at homes and offices in urban areas. Pollution from air conditioners, gas stove smoke, building materials, furnishing, and photocopies are increasingly found to cause allergy, asthma, and diseases of the skin, lungs, and respiratory tract. Prolonged exposure to oxides of nitrogen from gas stoves may damage the lungs and increase susceptibility to respiratory infections. Volatile Organic Compounds (VOC) like formaldehyde from paper products, carpets, floor coverings, adhesives, and resins may cause irritation in mucous membranes, headache, and fatigue.

37. What are the environmental effects of solid wastes?

Answer: Solid waste can degrade the air, water, and soil, posing risks to health and the environment. Direct risks mainly concern workers who need protection from skin contact with waste. For the general public, the main health risks are indirect, arising from the breeding of disease vectors like flies and rats due to improper storage and disposal. This can lead to health hazards like plague, dengue, and cholera. Garbage burning contributes to urban air pollution, and using water polluted by solid waste can cause skin infections.

Other environmental damage includes the ugliness of street litter and the destruction of the countryside’s beauty. A more serious issue is the transfer of pollution to water bodies when leachate from a refuse dump enters surface or groundwater. Inefficient burning of waste can cause air pollution, and industrialization introduces hazardous wastes whose improper disposal can result in the death of humans and other animals.

38. Distinguish between a Pollutant and a Contaminant.

Answer: A pollutant is a substance present in nature, in greater than natural abundance due to human activities, which ultimately has a detrimental effect on the environment. Examples include Carbon monoxide, sulphur dioxide, arsenic, fluorides, lead, and cadmium.

On the other hand, a contaminant is a substance which does not occur in nature, but is introduced by human activities into the environment. A contaminant is also a pollutant. Examples include Fluorine from chlorofluorocarbons, food additives, and paints.

39. Distinguish between Primary pollutants and Secondary pollutants.

Answer: Primary pollutants are released directly from an identifiable source and exist as such in the environment. Examples include oxides of sulphur, oxides of nitrogen, and hydrocarbons.

Secondary pollutants are derived from the primary pollutants by chemical reactions or by natural causes. For example, hydrocarbons and nitrogen oxides react in the presence of sunlight to form peroxy acetyl nitrate (PAN), which is a secondary pollutant.

40. Distinguish between Natural and Anthropogenic causes of environmental pollution.

Answer:

41. Distinguish between Natural and Man-made sources of air pollution.

Answer: The major sources of air pollution can be of two types: natural and man-made.

Natural sources of air pollution include:

• Volcanic eruption: releasing poisonous gases like SO₂, H₂S, CO etc.
• Forest fires: liberating very large quantities of smoke and particulate matter.
• Decomposition of organic and inorganic substances: releasing Methane gas and carbon dioxide into the air.
• Dust: which is always present in the atmosphere in varying amounts.
• Pollen grains of flowers: which enter the atmosphere from weeds, grasses and trees and are mainly responsible for causing allergy.
• Fungal spores: Micro-organisms such as algae, fungi, bacteria, yeasts, rusts, spores etc. are present as variable particles in the atmosphere.
• Radioactive materials: The radioactive minerals present in the earth crust and action of cosmic rays from outer space on gaseous constituents of the atmosphere are mainly responsible for radioactivity of the atmosphere.

Man-made sources of air pollution include:

• Deforestation
• Burning of fossil fuels
• Emission from vehicles
• Rapid industrialization
• Modern agricultural practices

42. Distinguish between Outdoor air pollutants and Indoor air pollutants.

Answer: Outdoor air pollutants are found in the open environment. The sources of the highest amount of these pollutants are vehicles. Outdoor pollutants include immoderate chemical substances, particulates, sulphur-di-oxide, carbon monoxide and carbon-di-oxide, ozone, and lead.

Indoor air pollution is recognized as significant pollution at homes and offices in urban areas. It comes from sources like air conditioners, gas stove smoke, and building materials. Furnishing and photocopies are increasingly found to cause allergy, asthma, and diseases of the skin, lungs, and respiratory tract. Volatile Organic Compounds (VOC) like formaldehyde from paper products, carpets, floor coverings, adhesives, and resins may cause irritation in mucous membranes, headache, and fatigue.

43. Distinguish between the health risks of Microbial contamination and Chemical contamination in drinking water.

Answer: The most common and widespread health risk associated with drinking water is microbial contamination. Faecal pollution leads to the introduction of intestinal pathogens like bacteria, viruses, and parasites, causing diseases from mild gastroenteritis to severe and fatal dysentery, cholera, or typhoid. When drinking water is contaminated with sewage, gastroenteritis and infectious hepatitis may occur in epidemic proportions. Other diseases like rashes, fever, myocarditis, meningitis, and respiratory diseases are also likely.

On the other hand, chemical contamination does not cause immediate, acute health problems unless present in massive quantities through an accident. However, after a prolonged period of exposure, these contaminants can do considerable harm by being cumulative poisons and carcinogens.

44. Distinguish between Auditory and Non-auditory effects of noise pollution.

Answer: Auditory effects of noise pollution are the most acute and immediate. They involve the impairing of hearing, which may cause auditory fatigue and finally lead to deafness.

Non-auditory effects are also equally serious. They include interference with speech communication, annoyance leading to ill temper, mental anxieties, mental stress, bickering, and violent behaviour. Noise pollution affects human health, disrupts comforts and working efficiency, and excessive noise pollution causes psychological disorder.

45. Distinguish between Air pollution and Water pollution.

Answer: Air pollution is defined as the presence of one or more pollutants or contaminants like dust, smoke, mist, odour, and suspended particulate matter in the atmosphere, which are injurious to human beings, plants, and other animals or which unreasonably obstruct the comfortable enjoyment of life and property.

Water pollution, on the other hand, is the alteration in physical, chemical, and biological characteristics of water that may cause harmful effects on man and other aquatic biota. It is also defined as the addition of an excess of undesirable substances to water that makes it harmful to man, animal, and aquatic life.

46. Distinguish between Soil pollution and Noise pollution.

Answer: Soil pollution occurs when the soil is contaminated with toxic materials. It is caused by the dumping of domestic and industrial wastes and the application of pesticides in agricultural fields. This pollution affects soil fertility and ultimately affects human health.

Noise pollution is the unwanted sound dumped into the environment without regard to the adverse effect it may have. It is also defined as any unwanted electromagnetic signal that produces a displeasing effect and interferes with human communication, comfort, and health.

47. Distinguish between Water pollution and Soil pollution.

Answer: Water pollution is the alteration in the physical, chemical, and biological characteristics of water that may cause harmful effects on man and other aquatic life. It is caused by the addition of excess undesirable substances to water from sources like domestic wastes, industrial effluents, and agricultural wastes.

Soil pollution, on the other hand, affects the uppermost part of the earth’s crust. It is caused by the dumping of various types of domestic and industrial wastes and the application of pesticides in agricultural fields, which make the soil polluted by adding different types of toxic materials.

Extra/additional Fill in the Blanks

1. The word pollution is derived from the Latin word ______ meaning ‘to make dirty’.

Answer: pollutionem

2. Pollution is an undesirable change in the physical, chemical, and biological characteristics of air, water, and ______.

Answer: soil

3. A substance present in nature in greater than natural abundance due to human activities, which has a detrimental effect, is called a ______.

Answer: pollutant

4. Pollutants that are released directly from an identifiable source are known as ______ pollutants.

Answer: primary

5. Hydrocarbons and nitrogen oxides reacting in sunlight to form peroxy acetyl nitrate (PAN) is an example of a ______ pollutant.

Answer: secondary

6. A substance which does not occur in nature but is introduced by human activities into the environment is called a ______.

Answer: contaminant

7. Earthquakes, volcanoes, and landslides are examples of ______ causes of environmental pollution.

Answer: natural

8. Deforestation, industrial exhausts, and burning of fossil fuel are examples of ______ causes of environmental pollution.

Answer: anthropogenic

9. Air pollution is defined as the presence of pollutants like dust, smoke, mist, or suspended ______ matter (SPM) in the atmosphere.

Answer: particulate

10. A natural source of air pollution is ______ eruption, which releases poisonous gases like SO₂ and CO.

Answer: volcanic

11. ______ grains from flowers are a natural source of air pollution that can cause allergies.

Answer: Pollen

12. The principal pollutants emitted by vehicles include carbon monoxide, hydrocarbons, oxides of nitrogen, and suspended ______ matter (SPM).

Answer: particulate

13. Exhaust gases from petrol vehicles contain lead particles due to the addition of ______ lead to the fuel.

Answer: tetraethyl

14. ______ vehicles contribute more NOx and particulate matter compared to petrol vehicles.

Answer: Diesel

15. Burning of fossil fuels in thermal power plants produces about 2/3 of the ______ dioxide present in the air.

Answer: sulphur

16. Industrial processes like chemical and metallurgical plants produce about ______% of air pollution.

Answer: 20

17. A ______ is a medium, such as an ocean or vegetation, which is capable of retaining and interacting with a long-lived pollutant.

Answer: sink

18. Major carbon monoxide (CO) sinks are some soil ______.

Answer: micro-organisms

19. Dust, smoke, fumes, and flyash are examples of ______ particulates.

Answer: solid

20. ______ are the sources of the highest amount of outdoor air pollutants.

Answer: Vehicles

21. Volatile Organic Compounds (VOC) like ______ from paper products and carpets can cause irritation in mucous membranes and headaches.

Answer: formaldehyde

22. Carbon monoxide is dangerous because it reduces the ______ carrying capacity of blood.

Answer: oxygen

23. Asbestos, used in pipe insulation and vinyl tiles, is known to cause lung diseases and lung ______.

Answer: cancer

24. One of the key principles for preventing air pollution is that a raw material for feedstock should be ______ rather than depleting.

Answer: renewable

25. Water for human consumption must be free from ______ micro-organisms.

Answer: pathogenic

26. ______ pollution of water leads to the introduction of intestinal pathogens like bacteria, viruses, and parasites.

Answer: Faecal

27. The most common and widespread health risk associated with drinking water is ______ contamination.

Answer: microbial

28. Diseases caused by the ingestion of contaminated water, such as cholera and typhoid, are known as ______ diseases.

Answer: water borne

29. The bacterium that causes cholera is ______ cholerae.

Answer: vibrio

30. Hardness in water can be softened by ______, a process which also kills bacteria.

Answer: boiling

31. To protect a ring well, its lining should be built of stones set in cement up to a depth of at least ______ meters.
Answer: 6

32. ______ is the uppermost part of the earth’s crust, formed from weathered rock and organic matter.

Answer: Soil

33. Nitrogen and phosphorus from fertilizers that run off into waterbodies can cause ______.

Answer: eutrophication

34. The use of ______ can be adopted for the degradation of toxic chemicals present in soil.

Answer: bioremediation

35. The natural source of noise pollution mentioned in the text is ______.

Answer: thunder

36. The most acute and immediate auditory effect of noise pollution is the impairing of hearing, which can cause auditory ______.

Answer: fatigue

37. An apt definition of solid waste is “materials in the wrong ______”.

Answer: place

38. The liquid that oozes and seeps through a solid waste heap is called ______.

Answer: leachate

39. In open dumps, ______ gas is released into the air due to the decomposition of solid wastes by micro-organisms.

Answer: methane