Class 8 Pollution of Air and Water

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Class 8 Pollution of Air and Water

Pollution of Air and Water is the 18th chapter of the class 8 NCERT book. It makes the students aware about the pollution of air and water through human activities and how they affect our health. It also provides useful measures which can be taken in the day to day routine to counter them. In this blog, we will read some of the important notes on Class 8 Pollution of Air and Water.

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Notice Writing for Class 8

Brief notes on Class 8 Pollution of Air and Water

Air is a very important element in the atmosphere which makes this Earth livable for us. It consists of a mixture of gases which by volume are – about 78% of nitrogen, about 21% is oxygen and carbon dioxide, argon, methane, ozone and water vapors in very small quantities.

Air Pollution

Contamination of air by unwanted substances which have a harmful effect on both the living and the non-living is referred to as air pollution. A thick fog-like layer in the atmosphere especially during winters is smog which is made up of smoke and fog. Smoke contains oxides of nitrogen which combine with other air pollutants and fog to form smog. The smog causes breathing difficulties such as asthma, cough and wheezing in the children.

Class 8 Pollution of Air and Water
Credit: Medical News Today

Air Pollutants

The substances which contaminate air are called air pollutants. Sometimes, such substances may come from natural sources like smoke and dust arising from forest fires or volcanic eruptions or by certain human activities.

The sources of air pollutants are factories, power plants, automobile exhausts and burning of firewood and dung cakes.

  • The Vehicles produce high levels of pollutants like carbon monoxide, carbon dioxide, nitrogen oxides and smoke.
  • Carbon monoxide is also produced from incomplete burning of fuels such as petrol and diesel. It is a poisonous gas because it reduces the oxygen-carrying capacity of the blood.
  • Many industries like petroleum refineries are a major source of gaseous pollutants like sulphur dioxide and nitrogen dioxide. Sulphur dioxide is produced by the combustion of fuels like coal in power plants. It can cause respiratory problems and permanent lung damage.
  • Other kinds of pollutants are chlorofluorocarbons (CFCs) which are used in refrigerators, air conditioners and aerosol sprays. CFCs damage the ozone layer of the atmosphere which is very harmful. Less harmful chemicals are being used in place of CFCs these days.

Not only living organisms but non-living things like buildings, monuments and statues also get affected by air pollution. One such example of a famous monument being affected by air pollution is Taj Mahal which is one of the 7 wonders of the world.

Class 8 Pollution of Air and Water
Credit: Examrace

The industries located around Agra like rubber processing, automobile, chemicals and oil refinery have been responsible for producing pollutants like sulphur dioxide and nitrogen dioxide. These gases react with the water vapors present in the atmosphere to form sulphuric and nitric acid. This acid then mixes with rain making it acidic and it is called acid rain.

This Acid rain corrodes the marble of the monument through a phenomenon called the “Marble cancer”. Suspended particulate matter such as the soot particles emitted by oil refineries and other factories have contributed towards the yellowing of the marble of Taj Mahal. The Supreme Court has therefore taken steps to save the Taj by ordering industries to switch to cleaner fuels like CNG (Compressed Natural Gas) and LPG (Liquefied Petroleum Gas) and the automobiles to switch over to unleaded petrol in the Taj zone.

Green House Effect

The trapping of radiations by the earth’s atmosphere is similar to how the greenhouse traps heat to keep the plants inside the greenhouse warm. That is why it is also called the greenhouse effect. Without this process, life is not possible on the earth. But the excess of this phenomenon threatens and endangers life on Earth.

Greenhouse Gases

Gases like CO2, methane, nitrous oxide and water vapours also contribute to the greenhouse effect hence they are called greenhouse gases

Global Warming

The gradual increase in the average temperature of the Earth’s atmosphere is called global warming. Global warming can cause sea levels to rise and affect rainfall patterns, agriculture, forests, plants and animals.

Deforestation leads to an increase in the amount of CO2 by reducing the number of trees which consume CO2. Human activities contribute to the accumulation of CO2 in the atmosphere adding to the greenhouse effect and thus eventually Global Warming.

What can be done to reduce air pollution?

  • A decision was taken by the government to switch to fuels like CNG unleaded petrol in vehicles which have resulted in cleaner air for the country.
  • “Say no to crackers” campaign was organized by children from many schools and it made a big difference to the air pollution levels around Diwali.
  • Switching over to alternative fuels like solar energy, hydropower and wind energy instead of fossil fuels for our energy requirements could help a lot.
  • Small contributions on our part like Aforestation can help a lot. Van Mahotsav are organized every year in July when lots of trees are planted. So we can help plant trees and nurture the ones already present in the neighbourhood.

Water Pollution

Class 8 Pollution of Air and Water
Credit: NRDC

Water is another one of the most important elements which is required for sustenance of life on Earth. But clean water is what gives us life whereas contaminated water can give us diseases.

Potable Water

The water suitable for drinking is called potable water.

Water Pollution

The contamination of water by unwanted and harmful substances is called Water pollution.

Water Pollutants

The substances that pollute water like sewage, toxic chemicals, silt, etc. are called water pollutants.

One big example of water pollution in our country is pollution of Ganga. A study by the (WWF) World Wide Fund for Nature found that river Ganga is one of the 10 most endangered rivers in the world and the pollution levels in it have been rising steadily for many years. The towns and cities through which the river flows throw large quantities of garbage, untreated sewage and many other harmful things directly into the river. In fact the river has been declared ‘dead’ at many places where the pollution levels are so high that aquatic life could not survive.

The Ganga Action Plan was launched in 1985 to reduce the pollution levels in the river. The increasing population and industrialization have already damaged this beautiful river beyond repair and therefore the Government of India launched another initiative known as (NMCG) National Mission for Clean Ganga in 2016.

Causes of Water Pollution

  • Many industries like oil refineries, paper factories, textile and sugar mills and chemical factories discharge harmful chemicals into rivers and streams, causing the pollution of water. This is called chemical contamination of water. The chemicals released into the water include arsenic, lead and fluorides which lead to toxicity in plants and animals. There are regulations to prevent this and industries are supposed to treat the waste produced before discharging it into water but the rules are not followed very often. The soil is also affected by the impure water causing changes in acidity, growth of worms, etc in the soil.
  • All the chemicals in weedicides and pesticides dissolve in water and are washed into water bodies from the fields and even seep into the ground and pollute groundwater. These chemicals in the water bodies act as nutrients for algae to flourish which serve as nutrients for algae to flourish. A lot of oxygen is used up by these unwanted processes which results in a decrease in the oxygen level and can kill aquatic organisms.
  • Untreated sewage with food wastes, detergents, micro-organisms etc. when thrown directly into the water bodies also causes water pollution. Water contaminated with sewage may contain bacteria, viruses, fungi and parasites which can cause diseases like cholera, typhoid and jaundice.
  • Hot water can also become a pollutant. When released into the rivers power plants and industries it can raise the temperature of the water body which adversely affects the animals and plants living in it because they are used to a certain temperature of water. Sudden fluctuation in the temperature affects the flora and fauna negatively and can even kill it.

How to Make Water Safe

  • Filtering- A popular household filter is a candle type filter.
  • Boiling- Many households use boiling for obtaining safe drinking water. Boiling kills the germs present in the water and makes it safe for drinking.
  • Chlorination– It is a commonly used chemical method for purifying water done by adding chlorine tablets or bleaching powder to the water. But more chlorine tablets than specified should not be used because they are harmful.
  • Water treatment plants– Laws should be strictly implemented so that polluted water isn’t disposed off directly into rivers and lakes. Water treatment plants should be installed in all the industrial areas.
  • At an individual level one should consciously save water and not waste it. Reduce, reuse and recycle should be used diligently as a method. Reusing water used for washing and for other household tasks, water used for washing vegetables can be used to water plants in the garden, while brushing your teeth or washing utensils the taps should be turned off. Leaving the tap running can waste several liters of water. Using simple methods in our everyday routine can help in saving water.

FAQs

Explain the difference between clean air and polluted air?

Clean air consists of a mixture of gases which by volume are – about 78% of nitrogen, about 21% is oxygen and carbon dioxide, argon, methane, ozone and water vapors in very small quantities. Whereas polluted air contains unwanted substances called air pollutants which have a harmful effect on both the living and the non-living.

What are air pollutants class 8?

The substances which contaminate air are called air pollutants. Sometimes, such substances may come from natural sources like smoke and dust arising from forest fires or volcanic eruptions or by certain human activities.

What is air pollution and water pollution?

Contamination of air by unwanted substances which have a harmful effect on both the living and the non-living is referred to as air pollution. The contamination of water by unwanted and harmful substances is called Water pollution.

What are the different ways in which water gets contaminated?

Water can be contaminated by the things given below –
Many industries like oil refineries, paper factories, textile and sugar mills and chemical factories discharge harmful chemicals into rivers and streams, causing the pollution of water. This is called chemical contamination of water. The chemicals released into the water include arsenic, lead and fluorides which lead to toxicity in plants and animals. There are regulations to prevent this and industries are supposed to treat the waste produced before discharging it into water but the rules are not followed very often. The soil is also affected by the impure water causing changes in acidity, growth of worms, etc in the soil.
All the chemicals in weedicides and pesticides dissolve in water and are washed into water bodies from the fields and even seep into the ground and pollute ground water. These chemicals in the water bodies act as nutrients for algae to flourish which serve as act as nutrients for algae to flourish. A lot of oxygen is used up by these unwanted processes which results in a decrease in the oxygen level and can kill aquatic organisms.
Untreated sewage with food wastes, detergents, micro-organisms etc. when thrown directly into the water bodies also causes water pollution. Water contaminated with sewage may contain bacteria, viruses, fungi and parasites which can cause diseases like cholera, typhoid and jaundice.
Hot water can also become a pollutant. When released into the rivers power plants and industries it can raise the temperature of the water body which adversely affects the animals and plants living in it because they are used to a certain temperature of water. Sudden fluctuation in the temperature affects the flora and fauna negatively and can even kill it.

Also Read:

Class 8 Science
Science Projects for Class 8
Class 8 English
NCERT Class 8 Maths Syllabus
List of NCERT Books Class 8

Hope these notes on Class 8 Pollution of Air and Water and extra questions helped you in understanding the chapter better. If you need help with other science chapters or with any other subject check our other blogs at Leverage Edu. We hope that these notes will help you get better marks in your exams. All the best!

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