Pollution Chapter Notes | Geography Class 9 ICSE PDF Download

Picture a world where the air, water, and soil we depend on are tainted with harmful substances, threatening the health and survival of humans, animals, and the environment as a whole. Pollution refers to undesirable changes in the physical, chemical, or biological characteristics of our surroundings, disrupting ecosystems and their natural balance. Pollutants, the substances responsible, are released into the biosphere, adversely affecting the environment’s normal functioning. From natural sources like volcanic eruptions and forest fires to human activities such as industrial emissions, vehicle exhausts, and burning farm waste, pollution stems from both nature and anthropogenic sources like thermal power plants, chimneys, and stoves. This chapter explores the alarming world of pollution, its types, causes, and impacts, guiding us toward a cleaner, healthier planet!

Pollution

• Pollution is the introduction of harmful or toxic substances into the environment, causing unfavorable changes to our surroundings.
• Pollutants are unwanted chemicals or materials in the environment that have harmful effects on plants, animals, and human health.

Types of Pollutants

• Pollutants are classified based on three criteria: degradation, origin, and existence in nature.

1. On the Basis of Degradation
Biodegradable Pollutants:These are broken down by biological or microbial actions.

• Examples: Sewage, paper.
• Concept Example: Kitchen waste like vegetable peels decomposes naturally in a compost pit due to microbial action, turning into fertile soil.

Non-Biodegradable Pollutants:These do not decompose or break down very slowly.

• Examples: Plastic, glass.
• Concept Example: A plastic bottle thrown in a park may take hundreds of years to decompose, harming wildlife and polluting the soil.

2. On the Basis of Origin in the Environment
Primary Pollutants:These are directly released into the environment.

• Examples: Sulphur dioxide (SO₂), methane (CH₄).
• Concept Example: Sulphur dioxide emitted from factory chimneys directly pollutes the air, causing respiratory issues.

Secondary Pollutants:These form when primary pollutants react with environmental components.

• Example: Peroxyacetyl nitrate forms when hydrocarbons react with sunlight.
• Concept Example: Vehicle exhausts release hydrocarbons, which combine with sunlight to form harmful peroxyacetyl nitrate, contributing to smog.

3. On the Basis of Existence in Nature

Quantitative Pollutants:Naturally occurring substances that become harmful when their levels increase.

• Examples: Carbon dioxide (CO₂), nitrogen.
• Concept Example: Excess CO₂ from burning fossil fuels increases global warming, disrupting climate patterns.

Qualitative Pollutants: Substances introduced by human activities, not naturally present.

• Examples: Pesticides, chemical fertilizers.
• Concept Example: Pesticides sprayed on crops can wash into rivers, poisoning aquatic life.

Characteristics

• Biodegradable Pollutants: Decompose through microbial action, e.g., sewage, paper.
• Non-Biodegradable Pollutants: Resist decomposition or degrade very slowly, e.g., plastic, glass.
• Primary Pollutants: Directly emitted into the environment, e.g., sulphur dioxide, methane.
• Secondary Pollutants: Formed by reactions of primary pollutants, e.g., peroxyacetyl nitrate.
• Quantitative Pollutants: Naturally present but harmful in excess, e.g., carbon dioxide, nitrogen.
• Qualitative Pollutants: Human-introduced substances, e.g., pesticides, chemical fertilizers.

Five Major Kinds of Pollution

• The five main types of pollution are air pollution, water pollution, soil pollution, noise pollution, and radioactive pollution.

Differences Between Biodegradable and Non-Biodegradable Pollutants

Biodegradable Pollutants:

• Decompose naturally into the soil.
• Do not pose a major threat to the environment.
• Examples: Paper, egg shells.

Non-Biodegradable Pollutants:

• Do not decompose or take a long time to break down.
• Pose a serious threat to the environment due to persistence.
• Examples: Metal cans, plastic products.

Kinds of Pollution

Air Pollution

• Air pollution occurs when harmful substances or particles are present in the air, affecting the atmosphere negatively.

Types of Air Pollutants:

• Natural pollutants: Pollen grains, bacteria.
• Suspended particles (aerosols): Fog, fumes, haze, dust, mist.
• Gases: Carbon monoxide (CO), sulphur dioxide (SO₂), hydrogen sulphide (H₂S), released by industries, vehicles, and fossil fuel burning.

Smog:

• A mixture of fog, smoke, and dust particles.
• Forms in areas with many industries or heavy vehicle traffic.

Concept Example: In cities like Delhi, industrial emissions and vehicle exhausts combine with fog to form smog, reducing visibility and causing health issues.

Water Pollution

• Water pollution is the contamination of water bodies by harmful substances, making them unsafe for human and aquatic life, as per the World Health Organization.

Types of Water Pollutants:

• Biological pollutants: Viruses, protozoa, fungi, bacteria, algae.
• Organic chemical agents: Gasoline, pesticides, insecticides, oil.
• Inorganic chemical agents: Acids, nitrates, phosphates, salts.
• Physical pollutants: Suspended solid particles, heat.

Concept Example: Factory waste containing nitrates dumped into a river can cause algal blooms, depleting oxygen and killing fish.

Soil Pollution

• Soil pollution is the change in soil’s natural properties due to human activities, reducing its quality and productivity.

Types of Soil Pollutants:

• Organic pollutants: Human and animal waste, food waste, poultry waste, food processing waste.
• Inorganic pollutants: Metallic waste, chemical fertilizers, detergents, oil, heavy metals, which do not degrade easily.
• Radioactive substances: Highly toxic with long-lasting effects on soil.

Concept Example: Excessive use of chemical fertilizers on farmland can alter soil pH, reducing its fertility and affecting crop growth.

Noise Pollution

• Noise pollution is any loud, unwanted sound that causes stress or irritation.

Main Sources:

• Transportation (vehicles, trains, airplanes).
• Loudspeakers.
• Industrial activities.
• Festivals and wedding celebrations.

Concept Example: Constant honking in a busy market can cause stress and disturb concentration for nearby residents.

Effects of Noise Pollution

• Can lead to hearing loss or sleep disturbances.
• May cause hypertension, depression, or panic attacks in people exposed regularly.
• Can increase heart rate or cause heart palpitations.
• May result in migraine headaches, nausea, or dizziness.

Radioactive Pollution

• Radioactive pollution is the release of radioactive substances into air, water, or soil, mainly due to human activities.
• Radioactive waste is highly dangerous, persists in the environment, and is difficult to dispose of safely.

Types of Environmental Radiation:

• Natural radiation: Cosmic rays from space, terrestrial radiation from Earth’s isotopes.
• Man-made radiation: From nuclear weapon production and nuclear power plants.

Effects:

• Unsafe disposal causes environmental pollution.
• Harms human health, plants, and animals.

Concept Example: The Chernobyl nuclear disaster on April 26, 1986, released radioactive gases, killing many and damaging plant and animal life in the area.