RIGVEDA INTERNATIONAL SCHOOL

Pollution of Air and Water

 Global warming - The rise in overall temperature of the earth because of the green house
effect is referred as global warming.

 Air pollution

o The layer of air present around the earth is called atmosphere.

o Atmosphere is composed of 78% of nitrogen, 21% of oxygen, and 1% percent other gases
such as carbon dioxide, ozone, water vapour, methane, etc.

o The phenomenon of contamination of air with unwanted substances so that it becomes

harmful for living organisms and non-living substances is known as air pollution.

o The substances, which cause air pollution, are called air pollutants.

o Sources of air pollution are

o Power plants

o Factories

o Automobiles

o Burning of firewood

 Types of air pollutants

 Carbon monoxide

o It is a colourless poisonous gas.

o It is produced from incomplete burning of fossil fuels.

 Smog
o It is made up of smoke and fog.

 Sulphur dioxide
o It is produced from combustion of fuels.

 Nitrogen dioxide
o It is produced from incomplete burning of fuels.
 Chlorofluorocarbons (CFCs)
o They are released from refrigerators, air conditioners, and aerosol sprays.
o They cause damage to the ozone layer resulting in the formation of ozone hole.

 Suspended particulate matter

o It comprises of tiny particles, which remain suspended in air for a long time.
o They are produced during burning of fossil fuels in power plants, mining, steel making, and
other industrial processes.

 Types of air pollutants

 Carbon monoxide

o It is a colourless poisonous gas.

o It is produced from incomplete burning of fossil fuels.
o It reduces oxygen carrying capacity of the blood.

 Smog
o Smog is made up of smoke and fog.

 Sulphur dioxide

o It is produced from combustion of fuels.

o It causes respiratory problems including permanent lungs damage.
o It causes formation of acid rain.

 Nitrogen dioxide

o It is produced from incomplete burning of fuels.

o It causes respiratory problems.
o It causes formation of acid rain.

 Chlorofluorocarbons (CFCs)

o They are released from refrigerators, air conditioners, and aerosol sprays.
o They cause damage to the ozone layer resulting in the formation of ozone hole.

 Suspended particulate matter

o It comprises of tiny particles, which remain suspended in air for a long time.
o They are produced during burning of fossil fuels in the power plants, mining, steel making,
and other industrial processes.
o They reduce visibility and cause haze.
o They cause respiratory diseases on inhalation.

 Soot released from Mathura refinery has caused yellowing of the marble of Taj Mahal.
 Acid rain

o It is formed when sulphur dioxide and nitrogen dioxide present in air react with water
droplets to form nitric and sulphuric acid.
o When it rains, it brings these acids along with it, which causes damage to plants, animals,
and monuments.
o Acid rain has caused corrosion of the marble of Taj Mahal.

 Greenhouse effect

o Trapping of heat by gases (CO2) in the atmosphere.

o Gases that cause the greenhouse effect are responsible for increasing the temperature of
the Earth and thus contributing to the phenomenon called global warming.

 Causes of Green house effect

o A part of solar radiations cause warming of the earth’s surface.

o A part of solar radiation is reflected back, which is trapped by the earth’s atmosphere. This
phenomenon is called green house effect.

 Green house gases

o These are the gases, which trap the solar radiations, and in this way, are responsible for the
increase in the temperature of Earth.

o The examples include carbon dioxide, methane, nitrous oxide, and water vapours.
 Global warming

o The CO2 level in atmosphere is increasing due to various human activities such as
deforestation and burning of fossil fuels.

o Build up of CO2 in the atmosphere will result in a rise in the average temperature of earth’s
atmosphere, leading to global warming.

o Global warming will lead to melting of glaciers and increase in the sea level.

 Prevention of air pollution

o Use of clear fuels such as CNG, LPG, and unleaded petrol in public and private transport.

o Use of renewable sources of energy such as solar, wind, and hydel energy.

o Planting more and more trees to prevent pollution.

o Prevent burning of dry leaves and use them in composting.

o Kyoto protocol is an agreement between various countries for reducing green house
emission.

 The addition of harmful substances to water, as a result of which its physical, chemical, and
biological properties get altered, is called water pollution.

 Types of water pollutants

 Domestic sewage

o It is composed of food wastes, detergents, and disease-causing pathogens.

o The bacteria present in faecal matter of mammals indicate the pollution levels in a river
and if such water is consumed, it may cause various diseases.

 Industrial waste

o It is rich in toxic chemicals such as arsenic, fluorides, and lead.

o It causes toxicity in plants and animals.

o It affects the soil by causing changes in its acidity and growth of worms.

 Agricultural waste

o It is rich in agricultural pesticides and weedicides.

o It causes ground water pollution.

o It causes an increase in the population of algae in water.

o When these algae die, they are acted upon by decomposers, which use lots of oxygen
dissolved in water leading to depletion of dissolved oxygen.

o This results in the death of fish and other aquatic organisms.

 Release of Superheated Water

o The release of superheated water from some industries and nuclear power plants causes
thermal pollution of the water bodies.

o The abrupt change in the temperature of water body can kill the fish and other organisms
adapted to particular temperature range.

Methods of preventing water pollution

 Industrial waste must be chemically treated to remove harmful substances before dumping
into the water bodies.

 Disposal of human and animal excreta into water should be avoided.

 Sewage water must be treated before releasing into the rivers.

 Water pollution
o It is the mixing of harmful substances in water such as sewage and toxic chemicals so that
its physical and chemical properties get altered and it becomes toxic for living organisms.
o Substances that pollute water are called water pollutants.

 Sources of water pollution in Ganga river

o Untreated discharges from textile, paper and sugar mills, and oil refineries.

o Disposal of agricultural discharge from near-by fields, which are rich in pesticides and
weedicides, into the river.

o Flow of untreated domestic sewage into the river.

o Cremation of dead bodies into the river.

o Immersion of idols of gods and goddesses, flowers, garbage, and polythene bags into the
river.

 Ganga Action Plan aimed to reduce the pollution levels in the river.

 Conservation of water

o Reusing the waste water from the kitchen (water that has been used to wash vegetables,
etc.) to water the plants in the garden

o Turning the tap off while brushing or shaving

o Checking for leaky taps and fixing them up

o Rainwater harvesting

o Using improved farming and irrigation techniques

o Preventing pollution of water

o Conserving and replenishing ground water

o Proper removal of silt from water bodies

o Preventing cutting of trees

 Prevention of water pollution

o Proper treatment of industrial waste and domestic waste before their disposal into rivers.

o Strict implementation of environmental laws in industrial units.

o Reusing water used in kitchens (such as to wash vegetables) for watering plants.

o Getting the leaky taps checked and preventing wastage of water.

 Potable water

o Water that is fit for drinking is called potable water.

o Methods of obtaining potable water.

 Physical methods

o Sedimentation and filtration

o Boiling of water
o Use of domestic filters such as candle type filter

 Chemical method

o Use of chlorine tablets

o Infusion of ozone gas