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18. Pollution of Air and Water

This chapter talks about pollution of air and water that impacts our environment. Our environment today is not what it used to be. The quality of air & water is falling further impacting our lives. We dread to imagine a time when clear air & water may no longer be available.

Clean air is very important for us as we cannot survive even for a few minutes without air.

Air is a mixture of gases. It contains the following gases

  1. Nitrogen 78%
  2. Oxygen 21%
  3. Carbon dioxide
  4. Argon
  5. Methane
  6. Ozone
  7. Water vapour

When air is contaminated by unwanted substances which have a harmful effect on both the living & the non-living, it is called as Air Pollution.

18.1                 How does Air get Polluted?

The substances which contaminate the air are called Air Pollutants.

Air Pollutants are being added to the atmosphere from many sources

  • Natural sources like smoke & dust arising from forest fires & volcano eruptions.
  • From factories
  • From power plants
  • Automobile exhausts
  • Burning of firewood & dung cakes.

18.2                 Pollutants present in the air

  • Vehicular emissions produce high levels of pollutants like Carbon monoxide, CO2, Nitrogen Oxide & Smoke.
  • Incomplete burning of fuels like petrol & diesel produces Carbon monoxide.
  • Chlorofluorocarbon (CFLs) used in refrigerators, air-conditioners & aerosol sprays
  • Sulphur dioxide is produced by combustion of fuels like coal in power plants.
  • Automobiles which burn diesel & petrol also produce tiny particles which remain suspended in air for long periods
  • Petroleum refineries release gaseous pollutants like SO2 & No2

Harmful Effects of Pollutants

  • Many respiration problems are caused by air-pollution.
  • Carbon-monoxide a poisonous gas reduces the oxygen carrying capacity of blood.
  • Smog, which is made up of smoke & fog causes breathing difficulties such as asthma, cough & wheezing in children.
  • Sulphur dioxide can cause respiratory problems including permanent lung damage.
  • The suspended particles in aie, when inhaled, cause diseases.

18.3                 Impact of Air Pollution on Taj Mahal

Taj Mahal, India’s most famous tourist attractions is getting discoloured due to air pollution. This is because he industries located in & around Agra like rubber processing, automobile, chemical & the Mathura Oil Refinery are producing pollutants like SO2 & NO2. These gases react with water vapour in the atmosphere to form sulphuric Acid & Nitric Acid. The acids drop down with rain making the rain acidic. This is called Acid Rain.

18.3.1             Marble Cancer

Acid Rain corrodes the marble of the monument. This phenomenon is also called Marble Cancer.

18.3.2                 Saving Taj

To save Taj, following steps have been taken –

  • Industries to switch over to cleaner fuel like CNG & LPG.
  • Automobiles should switch over to unleaded petrol.

18.4                 Green House Effect

Sun warms the earth’s surface. A part of the radiation that falls on the earth is absorbed by it & a part is reflected back into space. A part of the reflected radiation is trapped by the atmosphere. The trapped radiations further warm the earth. This is called as Green House Effect. Without this process, life would not have been possible on the earth. But now it threatens life. Co2 is one of the gases responsible for this effect.

Co2 is one of the components of air. But if there is excess of Co2 in the air, it acts as a pollutant. This is because Co2 is constantly being released due to human activities. On the other hand, forest cover is also decreasing. Plants utilize Co2 from the atmosphere for photosynthesis, thus decreasing the amount of Co2 in the air. Deforestation leads to an increase in the amount of Co2 in the air because the no. of trees which consume Co2 is reduced. Co2 traps heat & does not allow it to escape into space.

As a result, the average temperature of earth’s atmosphere is gradually increasing. This is called as Global Warming.

18.4.1             Green House Gases

Besides, Co2, Methane, nitrous oxide & water vapour are also part of green house gases.

18.4.2             Kyoto Protocol

Kyoto Protocol is the agreement that many countries to reduce the emission of green house gases.

18.5                 What can be done to reduce Air Pollution?

Following steps are being taken to reduce air pollution –

  1. Switch to cleaner fuels like CNG & unleaded petrol.
  2. Promotion of ‘Say No to Crackers’ campaign brought down air pollution levels around Diwali.
  3. Alternative fuels instead of fossil fuels to be used such as Solar energy, wind energy & hydropower.
  4. Plant more trees & nurturing the one already present in the neighbourhood.
  5. Instead of burning dry leaves, better option is to put them into a compost pit. This can be used as a manure.

18.6                 Water Pollution

Water is becoming scarce due to increase in population, industries & agricultural activities.

When harmful substances such as sewage, toxic chemicals, silt etc get mixed with water, the water becomes polluted. The substances that pollute water are called Water Pollutants.

18.6.1             How Water gets polluted?

Ganga is the most famous river of India. It is the lifeline for most of the northern, central & eastern Indian population.

It has been found out by World Wide Fund for Nature (WWF) that Ganga is one of the ten most endangered rivers in the world. This stage has come because the towns & cities, through which the river flow, throw large quantities of garbage, untreated sewage, dead bodies & many other harmful things directly into the river.

An ambitious plan to save the river, called the Ganga Action Plan was launched in 1985.

18.6.2             Factors that pollute rivers

  • People bathe, wash clothes & defecate in the river.
  • People throw garbage, flowers, idols of gods & non-biodegradable polythene bags into the river.
  • Industries like fertilizer, detergent, leather & paint industries discharge toxic chemical waste into the river. This causes chemical contamination of water.
  • Although, pesticides & weedicides are important for the protection of crops, but these chemicals dissolve in water & are washed into water bodies form the fields. They also seep into the ground to pollute ground water.

18.6.3             How does increased pollutant level in water bodies decrease oxygen levels?

When excessive quantities of chemicals get washed from the fields & get into water bodies, they act as nutrients for algae o flourish. Once these algae die, they serve as food for decomposes like bacteria. A lot of oxygen in the water body gets used up. This results in a decrease in the oxygen level which may kill aquatic organisms.

18.6.4             What is Potable water & how is Water Purified?

Water which is suitable for drinking is called Potable Water. It is essential to purify water before drinking water can be made safe for drinking by the following methods-

  • By filtering the water. This is a physical method of removing impurities.
  • By boiling as boiling kills the germs present in water.
  • Chlorination is a commonly used chemical method for purifying water. It is done by adding chlorine tablets or bleaching powder to the water.

18.6.5             What can be done?

Laws for industrial units should be strictly implemented so that polluted water is not disposed off directly into rivers & lakes. Water treatment plants should be installed in all industrial areas.

At our individual levels, we should consciously save water & not waste it. We should

  • Reduce Wastage
  • Reuse
  • Recycle to save water

In all, we should realize our responsibility & start using environment friendly processes