Environmental Pollution – Atmospheric, Water and Soil. Atmospheric Pollution – Tropospheric and Stratospheric. Tropospheric Pollutants – Gaseous Pollutants: Oxides of Carbon, Nitrogen and Sulphur, Hydrocarbons; Their Sources, Harmful Effects, And Prevention; Greenhouse Effect and Global Warming. Acid Rain; Particulate Pollutants: Smoke, Dust, Smog, Fumes, Mist; Their Sources, Harmful Effects, And Prevention. Stratospheric Pollution- Formation and Breakdown of Ozone, Depletion of The Ozone Layer – Its Mechanism and Effects. Water Pollution – Major Pollutants such as Pathogens, Organic Wastes, And Chemical Pollutants; Their Harmful Effects and Prevention. Soil Pollution – Major Pollutants Such as Pesticides (Insecticides. Herbicides and Fungicides), Their Harmful Effects and Prevention. Strategies to Control Environmental Pollution.

1. Environmental Pollution

1.1 Introduction

Environmental pollution is the effect of undesirable changes in our surroundings that have harmful effects on plants, animals, and human beings. A substance, which causes pollution, is known as a pollutant. Pollutants can be solid, liquid, or gaseous substances present in greater concentration than in natural abundance.

1.2 Atmospheric Pollution

Earth is surrounded by a thick envelope of gases called the atmosphere. The atmosphere is divided into different layers depending upon the distance from the sea level. The lowest part of the atmosphere in which human beings along with other organisms live is known as the troposphere. It extends up to the height of approx. 10 km from sea level. Above it, between 10 to 50 km above sea level lies the stratosphere. The troposphere is a turbulent and dusty zone containing air, water vapour, and clouds.

1.3 Water Pollution

Water pollution occurs when harmful substances often chemicals or microorganisms contaminate a stream, river, lake, ocean, aquifer, or other body of water, degrading water quality and rendering it toxic to humans or the environment.

1.4 Soil Pollution

Most of the soil pollution is caused by pesticides and other chemicals which are added to the soil to grow better crops. Often a pesticide poisons many more organisms than those intended. Some of these poisons pass through food chains and eventually reach harmful proportions.

2. Atmospheric Pollution

2.1 Strategies to Control Environmental Pollution

Waste Management

Nearby, there are lots of solid wastes. Besides household waste, we also have medical, agricultural, mining, and industrial waste. Improper disposal leads to environmental degradation. Therefore, care must be taken when disposing of these wastes to reduce pollution.

Two programmes are being implemented under the broad umbrella of the Swachh Bharat Abhiyan. These are Swachh Bharat Mission–Urban (SBM–U) and Swachh Bharat Mission Gramin (SBM–G). The SBM–U primarily aims at making Urban India free from open defecation and achieving 100% scientific management of solid waste in the country. The SBM–G targets to bring about an improvement in the general quality of life in rural areas by promoting cleanliness and hygiene and eliminating open defecation.

Collection and Disposal: Domestic wastes are collected in small bins, which are then transferred to community bins by private or municipal workers. From these community bins, these are collected and carried to the disposable site. At the site, garbage is sorted out and separated into biodegradable and non-biodegradable materials. Non-biodegradable materials such as plastic, glass, metal scraps etc. are sent for recycling. Biodegradable wastes are deposited in landfills and are converted into compost. All domestic wastes should be properly collected and disposed off. Poor management causes health problems leading to epidemics due to contamination of groundwater.

3. Tropospheric Pollutants

3.1 Tropospheric and Stratospheric Pollution

Tropospheric Pollution

It occurs when undesirable solid or gaseous particles are present in the air. The major gaseous and particulate pollutants present in the troposphere are as following:

1. Gaseous air pollutants: Oxides of sulphur, nitrogen and carbon, hydrogen sulphide, hydrocarbons, ozone, and other oxidants are referred as Gaseous air pollutants.

2. Particulate pollutants: These are dust, mist, fumes, smoke, smog etc.

Stratospheric Pollution:

Stratosphere is the region of earth’s atmosphere just above troposphere and below mesosphere. Considerable amount of ozone \left(O_3\right) is found in the upper stratosphere, which protects us from the harmful ultraviolet (UV) radiations coming from the sun. These radiations cause skin cancer in humans. Therefore, it is important to protect it.

3.2 Gaseous Pollutants

Oxides of Carbon:

1. Carbon monoxide: It is a colourless and odourless gas, highly poisonous to living beings because of its ability to block the delivery of oxygen to organs and tissues.

Source: Some of the sources of CO are

(i) Incomplete combustion of carbonaceous matter, automobile engines and in defective furnaces.

(ii) Incomplete combustion of fossil fuels, agricultural and slash matter.

(iii) Reaction of carbon dioxide and carbon at high temperatures in industrial processes.

C
O
2

+C
→


CO

(iv) Dissociation of carbon dioxide at high temperatures.

2C
O
2


→


2CO+
O
2

Single Correct Type Questions

1. The following do/does not cause water pollution

(a) Heavy metals such as Cd, Pb, Hg.
(b) Detergents
(c) Polychlorobiphenyls
(d) Freons

2. The statements that are TRUE:

(i) Methane leads to both global warming and photochemical smog.

(ii) Methane is generated from paddy fields.

(iii) Methane is a stronger global warming gas than .

(iv) Methane is a part of reducing smog.

Choose the most appropriate answer from the options given below.

(a) (i), (ii), (iii) only
(b) (i) and (ii) only
(c) (ii), (iii), (iv) only
(d) (i), (ii), (iv) only

3. Which among the following molecules represents PAN?

(a)

C{H}_{2}O

(b)

C
H
2

=CH–CHO

(c)

C
H
3

C
H
2

O− N=O

(d)

C
H
3

 −
C




| |




O




−OON
O
2

4. Gas released during Bhopal tragedy was

(a) Methyl isocyanate
(b) Potassium isothiocyanate
(c) Sodium isothiocyanate
(d) Ethyl isothiocyanate

5. Which of the following introduces particulate pollutants into the air?

(a) Hydrocarbons
(b) Hydrogen
(c) Sulphate
(d) Nitrogen

Single Correct Type Questions