Pollution: A Rising Environmental Problem

ICSE Class 10 Biology • Chapter 14

1. Definitions

Pollution: The addition of any such constituent to air, water, or land which alters its natural quality and is harmful to ecosystems.
Pollutant: Any constituent of air, water, or land which adversely modifies their quality.

Sources: Automobile exhaust, Industrial smoke, Burning of garbage.

Effects:

Respiratory Diseases: Asthma, Bronchitis.
Acid Rain: Oxides of Sulphur and Nitrogen dissolve in rain water ($\text{H}_2\text{SO}_4$, $\text{HNO}_3$). Damages monuments (Taj Mahal) and soil fertility.
Global Warming: Greenhouse gases ($\text{CO}_2$, Methane) trap heat, raising earth's temperature. Climate change.
Ozone Depletion: CFCs (Chlorofluorocarbons) destroy ozone layer. increased UV radiation $\rightarrow$ Skin cancer.

Practice Q1: Acid Rain

CONCEPT CHECK Which gases are primarily responsible for Acid Rain?

Ans: Sulphur Dioxide ($SO_2$) and Nitrogen Dioxide ($NO_2$).

Sources: Domestic sewage, Industrial effluents (Mercury, Lead), Oil spills, Agricultural runoff (Fertilizers).

Effects:

Eutrophication: Excess nutrients cause algal bloom $\rightarrow$ Oxygen depletion $\rightarrow$ Fish die.
Bio-magnification: Increase in concentration of toxic substances (like DDT) at successive trophic levels.
Water-borne Diseases: Cholera, Typhoid, Jaundice.

Practice Q2: Biological Magnification

BOARD QUESTION Explain the term Bio-magnification with an example.

Ans: The increase in concentration of non-biodegradable toxic substances (like DDT) at successive trophic levels in a food chain.

Sources: Plastics (Non-biodegradable), Industrial waste, Overuse of fertilizers/pesticides.

Control: 3Rs (Reduce, Reuse, Recycle). Composting.

Sources: Loudspeakers, Traffic, Industry.

Effects: Hypertension, Hearing loss, Stress.

Standards for emission control in vehicles. Stricter norms (BS-VI) act to reduce Sulphur and Particulate Matter.

A campaign by the Government of India to clean the streets, roads, and infrastructure of the country.

Practice Q3: Control Measures

APPLICATION Suggest one eco-friendly way to dispose of biodegradable kitchen waste.

Ans: Composting / Vermicomposting.

Q1: What is 'Acid Rain'?

Ans: Rainwater containing acids (Sulphuric/Nitric) formed by atmospheric pollutants ($SO_2, NO_2$). pH less than 5.6.