Class 10th Science Chapter 13 – Our Environment | Environmental Problems and Pollution

Our Environment

Environmental Problems and Pollution

पर्यावरणीय समस्याएँ एवं प्रदूषण

Our Environment | Environmental Problems and Pollution

1. Introduction | परिचय

Environment includes all living and non-living components surrounding organisms and their interactions.

पर्यावरण में जीवों के चारों ओर उपस्थित सभी जैविक और अजैविक घटक तथा उनके बीच होने वाली पारस्परिक क्रियाएँ शामिल होती हैं।

When human activities or natural processes introduce harmful substances or excessive energy into the environment and cause undesirable changes, the condition is called pollution.

जब मानव गतिविधियों या प्राकृतिक प्रक्रियाओं के कारण पर्यावरण में हानिकारक पदार्थ या ऊर्जा की अत्यधिक मात्रा प्रवेश करती है और अवांछित परिवर्तन होते हैं, तो इसे प्रदूषण (Pollution) कहा जाता है।

2. Major Environmental Problems

Environmental Problem	Main Concern
Air Pollution	Harmful gases and particles in air
Water Pollution	Contamination of rivers, lakes, groundwater and oceans
Soil Pollution	Accumulation of harmful chemicals and waste in soil
Noise Pollution	Excessive unwanted sound
Plastic Pollution	Persistent plastic waste in ecosystems
Climate Change	Long-term changes in Earth's climate
Deforestation	Loss and degradation of forest ecosystems
Biodiversity Loss	Decline in variety of living organisms

3. What is Pollution? | प्रदूषण क्या है?

Pollution is an undesirable change in the physical, chemical or biological characteristics of the environment that can adversely affect organisms and ecosystems.

प्रदूषण पर्यावरण के भौतिक, रासायनिक या जैविक गुणों में होने वाला ऐसा अवांछित परिवर्तन है जो जीवों और पारिस्थितिक तंत्रों को प्रभावित कर सकता है।

4. Types of Pollution

5. Air Pollution | वायु प्रदूषण

Air pollution occurs when harmful gases, particles or biological materials are present in the atmosphere at concentrations that can adversely affect living organisms, materials or the environment.

Major Sources

• Vehicle exhaust
• Industries and power plants
• Burning of fossil fuels
• Open burning of waste
• Construction activities and dust
• Some agricultural activities

Common Air Pollutants

Pollutant	Important Source / Effect
Particulate matter	Dust, combustion; can affect respiratory health
Carbon monoxide	Incomplete combustion; reduces oxygen transport in blood
Sulfur dioxide	Combustion of sulfur-containing fuels; irritant and acid-rain precursor
Nitrogen oxides	Combustion; contribute to smog and acid deposition
Ground-level ozone	Secondary pollutant formed by atmospheric reactions

6. Water Pollution | जल प्रदूषण

Water pollution occurs when harmful substances enter water bodies and alter water quality in ways that can harm organisms or limit human uses.

Major Causes

• Untreated sewage
• Industrial effluents
• Agricultural runoff
• Plastic and solid waste
• Oil and chemical contamination
• Excess nutrients

Important: Excess nutrients such as nitrogen and phosphorus can promote excessive algal growth. When large amounts of organic matter are decomposed, dissolved oxygen may decrease, creating stressful conditions for aquatic organisms.

7. Eutrophication | सुपोषण

Eutrophication is the enrichment of a water body with nutrients, particularly nitrogen and phosphorus, which can stimulate excessive growth of algae and aquatic plants.

8. Soil Pollution | मृदा प्रदूषण

Soil pollution occurs when harmful chemicals, waste or other contaminants accumulate in soil and adversely affect soil organisms, plants, animals or humans.

Sources

• Excessive or inappropriate use of pesticides and fertilizers
• Industrial waste
• Improper disposal of solid waste
• Mining activities
• Oil and chemical spills
• Persistent pollutants

9. Noise Pollution | ध्वनि प्रदूषण

Noise pollution refers to unwanted or excessive sound that can disturb communication, sleep, behaviour and health.

Sources

• Vehicle horns
• Traffic
• Construction
• Industrial machinery
• Loudspeakers
• Aircraft and other transport

10. Plastic Pollution | प्लास्टिक प्रदूषण

Plastic pollution occurs when plastic waste accumulates in terrestrial and aquatic environments. Many conventional plastics are persistent and do not readily undergo natural biological decomposition.

Plastic can break into smaller pieces, including microplastics, but physical fragmentation is not the same as complete biodegradation.

11. Greenhouse Effect | ग्रीनहाउस प्रभाव

The greenhouse effect is a natural process in which certain atmospheric gases absorb and re-emit infrared radiation, warming Earth's surface and lower atmosphere.

The natural greenhouse effect is essential for life. The environmental concern is the additional warming associated with increased concentrations of greenhouse gases from human activities.

Important Greenhouse Gases

• Carbon dioxide (CO₂)
• Methane (CH₄)
• Nitrous oxide (N₂O)
• Water vapour
• Ozone

12. Global Warming | वैश्विक तापन

Global warming refers to the long-term increase in Earth's average surface temperature, primarily associated with the enhanced greenhouse effect caused by increased concentrations of greenhouse gases.

More greenhouse gases → More heat retained → Warming of the climate system

13. Climate Change | जलवायु परिवर्तन

Climate change refers to long-term changes in temperature, precipitation, atmospheric circulation and other characteristics of the climate system.

Potential impacts include:

• Changes in rainfall patterns
• More frequent or intense heat extremes in many regions
• Changes in glaciers and ice sheets
• Sea-level rise
• Changes in ecosystems and species distribution
• Impacts on agriculture and water resources

14. Ozone Layer and Ozone Depletion

The ozone layer in the stratosphere absorbs much of the Sun's harmful ultraviolet radiation.

Certain ozone-depleting substances, historically including chlorofluorocarbons (CFCs), can release reactive chlorine or bromine in the stratosphere and contribute to ozone depletion.

Do not confuse:
Stratospheric ozone → protective.
Ground-level ozone → air pollutant and component of photochemical smog.

15. Acid Rain | अम्लीय वर्षा

Acid deposition is associated mainly with sulfur dioxide and nitrogen oxides released from combustion and industrial activities. These substances can undergo atmospheric reactions and contribute to acidic precipitation.

SO₂ + atmospheric reactions → acidic compounds
NOₓ + atmospheric reactions → nitric acid-related compounds

Effects

• Acidification of lakes and soils
• Damage to sensitive vegetation
• Corrosion of materials
• Weathering of buildings and monuments

16. Smog | धूम-कुहरा

Smog is polluted air containing a mixture of gases and particles. Photochemical smog forms when sunlight drives chemical reactions involving nitrogen oxides and volatile organic compounds, producing secondary pollutants such as ground-level ozone.

17. Deforestation | वनों की कटाई

Deforestation means the long-term conversion or removal of forest cover for other land uses.

Effects

• Habitat loss
• Biodiversity decline
• Soil erosion
• Disturbance of the water cycle
• Loss of carbon storage
• Fragmentation of ecosystems

18. Biodiversity Loss | जैव विविधता का ह्रास

Biodiversity means the variety of life at genetic, species and ecosystem levels. Biodiversity loss occurs when populations decline, species disappear or ecosystems are degraded.

Major pressures include habitat destruction, pollution, overexploitation, invasive species and climate change.

19. Solid Waste Problem

Waste Type	Examples	Management
Biodegradable	Food waste, leaves	Composting / biological treatment
Recyclable	Paper, metal, suitable plastics	Segregation and recycling
Hazardous	Some chemicals, batteries	Special collection and treatment
Residual	Non-recoverable waste	Appropriate disposal

20. Pollution and Food Chains

Some pollutants can move from the environment into organisms and then through food chains. Persistent substances that accumulate in organisms may become more concentrated at higher trophic levels.

Pollutant → Producer → Primary Consumer → Secondary Consumer → Top Consumer

This increase in concentration across successive trophic levels is called biomagnification.

21. Environmental Pollution Flow Diagram

22. Prevention and Control of Pollution

Problem	Control Measures
Air Pollution	Clean energy, public transport, emission controls, dust management
Water Pollution	Treat sewage and industrial wastewater; prevent dumping
Soil Pollution	Responsible chemical use and proper waste management
Plastic Pollution	Reduce unnecessary plastic, reuse and recycle where possible
Noise Pollution	Control unnecessary horns, loudspeakers and machinery noise
Deforestation	Forest conservation, restoration and sustainable land use

23. Sustainable Development

Sustainable development means meeting present needs while maintaining the environmental and resource base needed by future generations.

Important approaches include:

• Efficient use of resources
• Renewable energy
• Waste reduction
• Water conservation
• Forest conservation
• Protection of biodiversity
• Cleaner technologies

🧠 Golden Memory Points

🌬️ Air pollution → harmful gases + particles

💧 Water pollution → contamination of water

🌱 Soil pollution → harmful substances in soil

🔊 Noise pollution → unwanted/excessive sound

🧴 Plastic pollution → persistent plastic waste

🌡️ Global warming → long-term rise in average surface temperature

🌍 Climate change → long-term changes in climate system

🌳 Deforestation → loss/conversion of forest cover

🦋 Biodiversity → variety of life

♻️ Best approach → Reduce → Reuse → Recycle → Recover → Safe Disposal

24. 30 MCQs | Multiple Choice Questions

1. Which of the following is an environmental problem?

A. Air pollution

B. Photosynthesis

C. Respiration

D. Germination

Answer: A — Air pollution is an environmental problem caused by undesirable changes in air quality.

2. Which is a major source of air pollution?

A. Photosynthesis

B. Vehicle emissions

C. Seed germination

D. Pollination

Answer: B

3. Which gas is a greenhouse gas?

A. Oxygen

B. Nitrogen

C. Carbon dioxide

D. Argon

Answer: C

4. Water pollution can be caused by:

A. Photosynthesis

B. Pollination

C. Respiration

D. Untreated sewage

Answer: D

5. Excess nitrogen and phosphorus in water can cause:

A. Eutrophication

B. Pollination

C. Germination

D. Condensation

Answer: A

6. Which pollutant is associated with incomplete combustion?

A. Oxygen

B. Carbon monoxide

C. Nitrogen

D. Hydrogen

Answer: B

7. Acid deposition is strongly associated with:

A. Oxygen and hydrogen

B. Helium and neon

C. Sulfur dioxide and nitrogen oxides

D. Nitrogen and argon

Answer: C

8. Which layer contains the ozone layer that protects from much harmful UV radiation?

A. Troposphere

B. Mesosphere

C. Thermosphere

D. Stratosphere

Answer: D

9. Which is a major effect of deforestation?

A. Habitat loss

B. Increased biodiversity everywhere

C. Increased forest cover

D. Reduced soil erosion everywhere

Answer: A

10. Which term means the variety of life?

A. Pollution

B. Biodiversity

C. Eutrophication

D. Smog

Answer: B

11. Which is a persistent environmental waste problem?

A. Fresh leaves

B. Vegetable peels

C. Conventional plastic

D. Fruit pulp

Answer: C

12. Noise pollution mainly involves:

A. Excess nutrients

B. Harmful microbes

C. Soil chemicals

D. Unwanted or excessive sound

Answer: D

13. Global warming refers to:

A. Long-term increase in Earth's average surface temperature

B. Daily change in temperature

C. Cooling during winter

D. Formation of clouds

Answer: A

14. Which process removes carbon dioxide from the atmosphere biologically?

A. Respiration

B. Photosynthesis

C. Combustion

D. Decomposition only

Answer: B

15. Which practice helps reduce plastic pollution?

A. Littering

B. Burning plastic in the open

C. Reducing unnecessary plastic use

D. Dumping plastic into rivers

Answer: C

16. Photochemical smog formation is promoted by:

A. Darkness only

B. Pure oxygen

C. Rain alone

D. Sunlight-driven reactions involving pollutants

Answer: D

17. Which is a secondary air pollutant?

A. Ground-level ozone

B. Sand

C. Water vapour

D. Nitrogen

Answer: A

18. Soil pollution can result from:

A. Seed formation

B. Improper disposal of chemicals and waste

C. Photosynthesis

D. Pollination

Answer: B

19. Which is an important effect of excessive organic matter entering water?

A. Increased dissolved oxygen in every case

B. Instant purification

C. Oxygen depletion during decomposition

D. Formation of mountains

Answer: C

20. Which is an example of sustainable practice?

A. Wasting water

B. Uncontrolled deforestation

C. Open dumping

D. Efficient resource use

Answer: D

21. The natural greenhouse effect is:

A. Essential for maintaining Earth's temperature suitable for life

B. Always harmful

C. The same as ozone depletion

D. The same as acid rain

Answer: A

22. Which activity can contribute to deforestation?

A. Forest restoration

B. Conversion of forests to other land uses

C. Wildlife protection

D. Afforestation

Answer: B

23. Which pollutant can contribute to acid rain?

A. Oxygen

B. Nitrogen

C. Sulfur dioxide

D. Helium

Answer: C

24. Biomagnification is associated with:

A. Rapid decomposition of leaves

B. Photosynthesis

C. Water evaporation

D. Increase of certain persistent substances along trophic levels

Answer: D

25. Which is the first preferred step in waste reduction?

A. Reduce unnecessary consumption

B. Dump waste

C. Mix all waste

D. Burn everything

Answer: A

26. Which of the following can reduce water pollution?

A. Dumping sewage into rivers

B. Treating sewage before discharge

C. Throwing plastic into lakes

D. Releasing untreated industrial effluent

Answer: B

27. Which environmental problem is directly related to loss of species and habitats?

A. Noise pollution

B. Eutrophication

C. Biodiversity loss

D. Acid rain only

Answer: C

28. Which statement about ozone is correct?

A. All ozone is harmful

B. All ozone is beneficial

C. Ozone never reacts chemically

D. Stratospheric ozone protects while ground-level ozone can be harmful

Answer: D

29. Which approach best supports sustainable waste management?

A. Reduce, reuse and recycle where appropriate

B. Throw waste into water bodies

C. Burn all waste in open areas

D. Mix hazardous and household waste

Answer: A

30. Which combination represents major environmental pressures?

A. Photosynthesis and respiration

B. Pollution, habitat loss and climate change

C. Germination and pollination

D. Digestion and excretion

Answer: B

25. 30 Subjective Questions with Answers

2 Marks 1. Define environmental pollution.

Environmental pollution is an undesirable change in the physical, chemical or biological characteristics of the environment that can adversely affect organisms or ecosystems.

2 Marks 2. Name four major types of pollution.

Air pollution, water pollution, soil pollution and noise pollution.

2 Marks 3. What is air pollution?

Air pollution is the presence of harmful gases, particles or other contaminants in the atmosphere at levels that can cause adverse effects.

2 Marks 4. What is water pollution?

Water pollution is contamination of water that changes its quality and can harm aquatic organisms or make the water unsuitable for particular uses.

2 Marks 5. What is global warming?

Global warming is the long-term increase in Earth's average surface temperature, primarily associated with increased concentrations of greenhouse gases.

2 Marks 6. What is biodiversity?

Biodiversity is the variety of life at genetic, species and ecosystem levels.

3 Marks 7. State three causes of air pollution.

Vehicle emissions, industrial combustion and open burning of waste are major causes.

3 Marks 8. State three causes of water pollution.

Untreated sewage, industrial effluents and agricultural runoff are important causes.

3 Marks 9. What is eutrophication?

Eutrophication is nutrient enrichment of a water body, particularly by nitrogen and phosphorus, leading to excessive growth of algae and aquatic plants.

3 Marks 10. What is acid rain?

Acid rain refers to precipitation made more acidic by atmospheric reactions involving pollutants such as sulfur dioxide and nitrogen oxides.

3 Marks 11. What is noise pollution?

Noise pollution is unwanted or excessive sound that can disturb communication, sleep, behaviour and health.

3 Marks 12. Give three effects of deforestation.

Habitat loss, soil erosion and biodiversity decline are major effects.

4 Marks 13. Explain four harmful effects of air pollution.

Air pollution can affect respiratory health, damage vegetation, reduce visibility and contribute to atmospheric problems such as smog and acid deposition.

4 Marks 14. Explain four causes of water pollution.

Untreated sewage, industrial wastewater, agricultural runoff and improper disposal of solid waste can contaminate water bodies.

4 Marks 15. Explain the effects of plastic pollution.

Plastic can persist in the environment, accumulate on land and in water, harm wildlife through ingestion or entanglement and fragment into smaller particles.

4 Marks 16. Explain the role of greenhouse gases.

Greenhouse gases absorb and re-emit infrared radiation. The natural greenhouse effect keeps Earth warm enough for life, while increased concentrations of greenhouse gases enhance heat retention and contribute to global warming.

5 Marks 17. Explain the major causes and effects of soil pollution.

Soil pollution can result from improper waste disposal, excessive or inappropriate chemical use, industrial waste, mining and chemical spills. It can affect soil organisms, plant growth, food quality and groundwater.

5 Marks 18. Explain eutrophication and its effects.

Excess nitrogen and phosphorus enter a water body and stimulate algal growth. When the algae die, microbial decomposition can consume dissolved oxygen. Low oxygen can stress or kill aquatic organisms and alter the ecosystem.

5 Marks 19. Explain acid rain and its effects.

Sulfur dioxide and nitrogen oxides can undergo atmospheric reactions to form acidic compounds. Acid deposition can acidify soils and water bodies, damage sensitive vegetation and corrode materials.

5 Marks 20. Explain the difference between global warming and climate change.

Global warming specifically refers to the long-term increase in Earth's average surface temperature. Climate change is broader and includes long-term changes in temperature, rainfall, atmospheric circulation, sea level and other aspects of the climate system.

5 Marks 21. Explain how deforestation affects ecosystems.

Deforestation removes or fragments habitats, reduces biodiversity, increases soil erosion and alters water and carbon cycles. It can also reduce ecosystem services and carbon storage.

6 Marks 22. Explain the different types of environmental pollution.

Air pollution involves harmful substances in the atmosphere; water pollution involves contamination of water; soil pollution involves harmful substances in soil; noise pollution involves excessive unwanted sound. Plastic pollution is associated with persistent plastic waste. Each can affect organisms and ecosystems in different ways.

6 Marks 23. Explain the causes, effects and prevention of air pollution.

Causes include vehicle emissions, industrial combustion, fossil-fuel use and open burning. Effects include respiratory problems, reduced visibility, damage to vegetation and atmospheric pollution. Prevention includes cleaner energy, emission controls, public transport, efficient vehicles and dust management.

6 Marks 24. Explain the causes, effects and control of water pollution.

Causes include sewage, industrial effluents, agricultural runoff and solid waste. Effects include disease risks, ecological damage, eutrophication and oxygen depletion. Control requires sewage treatment, industrial wastewater treatment, responsible agricultural practices and prevention of waste dumping.

6 Marks 25. Explain the relationship between pollution and food chains.

Pollutants released into air, water or soil can enter organisms. Persistent pollutants may accumulate in organisms and move through food chains. Some can become increasingly concentrated at higher trophic levels, producing biomagnification.

5 Marks 26. Write five measures for controlling environmental pollution.

1. Use cleaner energy.
2. Treat sewage and industrial wastewater.
3. Reduce unnecessary plastic and other waste.
4. Promote recycling and proper waste segregation.
5. Protect forests, wetlands and biodiversity.

4 Marks 27. Why is biodiversity important?

Biodiversity supports ecosystem functioning, food webs, nutrient cycling, genetic resources and ecosystem services. Greater biodiversity can also increase ecological resilience to disturbances.

5 Marks 28. Explain the importance of sustainable development.

Sustainable development seeks to meet present needs without undermining future generations' ability to meet their needs. It promotes efficient resource use, pollution reduction, conservation and long-term environmental protection.

6 Marks 29. Explain how an individual can contribute to pollution control.

Individuals can reduce unnecessary consumption, use public transport or shared mobility, conserve electricity and water, segregate waste, avoid littering, reuse products, recycle suitable materials and support environmentally responsible practices.

6 Marks 30. Explain the major environmental challenges facing ecosystems.

Major challenges include pollution, climate change, habitat loss, deforestation, biodiversity loss, plastic waste, overexploitation and invasive species. These pressures can interact and reduce ecosystem stability. Conservation, sustainable resource use, pollution control and habitat protection are important responses.

26. Assertion–Reason Questions

1. Assertion: Excess nutrients can cause eutrophication.
Reason: Nitrogen and phosphorus can stimulate excessive algal growth.

Answer: Both Assertion and Reason are true, and the Reason correctly explains the Assertion.

2. Assertion: Untreated sewage can cause water pollution.
Reason: Sewage may contain organic matter, nutrients and disease-causing organisms.

Answer: Both Assertion and Reason are true, and the Reason correctly explains the Assertion.

3. Assertion: Ground-level ozone is always beneficial.
Reason: Ozone in the stratosphere absorbs ultraviolet radiation.

Answer: Assertion is false, but Reason is true.

4. Assertion: Deforestation can reduce biodiversity.
Reason: Deforestation can destroy or fragment habitats.

Answer: Both Assertion and Reason are true, and the Reason correctly explains the Assertion.

5. Assertion: Every environmental problem has only one cause.
Reason: Environmental problems often result from interactions among several factors.

Answer: Assertion is false, but Reason is true.

27. HOTS | Higher Order Thinking

HOTS 1: A lake receives untreated sewage and agricultural runoff. Predict two major ecological consequences.

Nutrient enrichment can promote algal blooms. Decomposition of excess organic matter can reduce dissolved oxygen and stress aquatic organisms.

HOTS 2: Why can replacing a plastic bag with a reusable bag reduce environmental pressure?

A reusable bag can be used many times, reducing the number of single-use bags produced and discarded, provided it is actually reused sufficiently.

HOTS 3: Why should air pollution and climate change not be treated as exactly the same problem?

They overlap in some sources, especially fossil-fuel combustion, but they are different concepts. Air pollution concerns harmful pollutants affecting air quality and health, whereas climate change concerns long-term changes in the climate system.

HOTS 4: Why can deforestation affect both biodiversity and climate?

Deforestation destroys habitats and can reduce biodiversity. It also releases stored carbon and reduces the capacity of forests to absorb carbon dioxide.

28. Quick Revision Chart

Topic	Key Point
Air Pollution	Harmful gases and particles in air
Water Pollution	Contamination of water
Soil Pollution	Harmful substances in soil
Noise Pollution	Unwanted/excessive sound
Eutrophication	Nutrient enrichment → algal growth → oxygen depletion risk
Acid Rain	Associated mainly with SO₂ and NOₓ atmospheric reactions
Global Warming	Long-term rise in average surface temperature
Climate Change	Long-term changes in climate system
Ozone Layer	Stratospheric ozone absorbs much harmful UV radiation
Deforestation	Forest loss/conversion and habitat destruction
Biomagnification	Increase of certain persistent substances at higher trophic levels

29. One-Minute Revision

🌍 Environment = Living + Non-living components + interactions.

🚗 Air pollution = harmful gases + particles.

💧 Water pollution = contamination of water.

🌱 Soil pollution = harmful contaminants in soil.

🔊 Noise pollution = unwanted/excessive sound.

🌿 Eutrophication = excess nutrients → algal growth → oxygen depletion risk.

🌧️ Acid rain = atmospheric acids associated mainly with SO₂ and NOₓ.

🌡️ Global warming = long-term increase in average surface temperature.

☀️ Ozone layer = protects against much harmful UV radiation.

🌳 Deforestation = habitat loss + biodiversity decline + ecosystem disruption.

🧴 Plastic pollution = persistent plastic waste.

♻️ Pollution control = Reduce + Reuse + Recycle + Treat + Conserve.

30. Final Summary | अंतिम सारांश

Environmental pollution is one of the major challenges affecting ecosystems and human societies. Air, water, soil, noise and plastic pollution can arise from different human activities. Other major environmental problems include deforestation, biodiversity loss and climate change.

पर्यावरणीय प्रदूषण पारिस्थितिक तंत्रों और मानव समाज के सामने प्रमुख चुनौतियों में से एक है। वायु, जल, मृदा, ध्वनि तथा प्लास्टिक प्रदूषण विभिन्न मानव गतिविधियों से उत्पन्न हो सकते हैं। वनों की कटाई, जैव विविधता का ह्रास और जलवायु परिवर्तन भी महत्वपूर्ण पर्यावरणीय समस्याएँ हैं।

CBSE Exam Key Point:
Pollution means an undesirable change in environmental conditions. Important topics include air pollution, water pollution, soil pollution, eutrophication, greenhouse effect, global warming, ozone depletion, acid rain, deforestation, biodiversity loss and waste management.

Our Environment | Environmental Problems and Pollution
CBSE Class 10 Science • Foundation • Competitive Preparation