Pollution

Pollution is the process of contaminating the environment in a way that is harmful to living organisms. It includes several types, such as water, air, and soil pollution.

Types of Pollution and Their Pollutants

Water and Soil Pollution

Pollutants found in soil and water include:

• Heavy metals (e.g., cadmium, iron, manganese)
• Phosphates from fertilizers, detergents, and sewage
• Nitrates from fertilizers and sewage
• Sewage and harmful microbes
• Acids from industrial discharges
• Oil spills from tankers

Effects of Pollutants

• Acidic substances: Make water corrosive and unsafe for drinking; kill aquatic organisms and plants.
• Nitrates: Cause eutrophication and can harm infants if consumed.
• Phosphates: Promote algae growth, leading to oxygen depletion and death of aquatic life.
• Heavy metals: Carcinogenic; may cause various cancers (e.g., liver, skin, lung).
• Sewage: May contain pathogens causing diseases like diarrhea.
• Oil: Harms aquatic life and birds by reducing oxygen in water.

Air Pollution

Air pollutants come from both natural (e.g., volcanoes, forest fires) and human sources (e.g., exhaust fumes, factories).

Common Air Pollutants and Their Effects

• Carbon monoxide: Produced from incomplete combustion; binds to hemoglobin, reducing oxygen transport.
• Sulphur dioxide: Comes from burning fossil fuels; causes respiratory issues and acid rain.
• Oxides of nitrogen: Produced by lightning and engines; causes lung damage and acid rain.
• Methane: A greenhouse gas from decomposition and cattle; highly flammable.
• Unburnt hydrocarbons: From engines; carcinogenic and contributes to smog.
• Ozone: Causes eye and throat irritation; harmful to plants.

Control Measures

• Use of catalytic converters in vehicles
• Burning fuels with low sulphur content
• Legislation to control pollution near water bodies
• Enforcing pollution control laws

Acid Rain

Formed when SO₂ and NO₂ react with water and oxygen, forming acids like H₂SO₄ and HNO₃.

Effects:

• Damages buildings and statues
• Harms trees and soil
• Makes water bodies too acidic for fish
• Aggravates respiratory problems

Control:

• Desulphurization of fuel gases
• Neutralizing soil with calcium hydroxide
• Using fuels with lower sulphur content

Photochemical Smog

Produced from the reaction between NO₂ and hydrocarbons in sunlight, creating ozone (O₃).

Effects:

• Reduces visibility
• Causes eye and respiratory irritation
• Damages plants

Ozone Layer Depletion

The ozone layer blocks harmful UV radiation. It is damaged by CFCs (chlorofluorocarbons) which release chlorine atoms that destroy ozone (O₃).

Control: Use of HCFCs instead of CFCs, which degrade more quickly.

Global Warming

Caused by the greenhouse effect — the trapping of heat by gases like CO₂ and CH₄. Excessive industrial emissions enhance this effect, leading to rising global temperatures.

Examples of Greenhouse Gases

1. Carbon Dioxide (CO₂): This gas occurs naturally and is also released during the combustion of hydrocarbons.
2. Methane (CH₄): Methane is emitted during fuel production and from decaying organic matter. It also occurs naturally.
3. Nitrous Oxide (N₂O): Produced from industrial and agricultural processes, and from the incomplete combustion of hydrocarbons.

Side Effects of Global Warming

• Melting of polar ice caps and glaciers
• Flooding of low-lying and coastal areas
• Alteration of climate patterns in various regions
• Changes in agricultural productivity and crop yield
• Increased evaporation of surface water, affecting water supply