POLLUTION OF AIR AND WATER

IMPORTANT TERMS

Potable Water              Water that is suitable for drinking by human beings.

Pollutants                     Substances that contaminate the air, water and soil.

Smog                          A fog-like layer in the atmosphere made up of smoke and fog.

Soot                           Fine black particles, chiefly composed of carbon.

Sewage                       Waste water generated from household activities such as bathing, washing clothes and dishes etc.

 

Eutrophication              The process of nutrient enrichment of water bodies and subsequent growth of plants on the surface of water.

Algal Bloom                  A rapid increase in the population of algae in water bodies due to an excess of nutrients in the water.

 

AIR POLLUTION AND ITS CAUSES

Air pollution is the contamination of air by unwanted substances which have a harmful effect on both the living and the non-living. The substances which contaminate the air are called air pollutants. Forest fires and volcanic eruptions are natural sources of air pollution.

Power Plants - Thermal Power plants burn fossil fuels to produce electricity. Fossil fuels such as coal pollute the air when they are burned. Coal contains sulphur, which produces sulphur dioxide upon burning.

Industries – Many industries are a source of gaseous pollutants such as sulphur dioxide and nitrogen Dioxide. They release smoke, which not only pollutes the air but also causes respiratory diseases.

Vehicles – Vehicles that are driven by petrol and diesel release pollutants into the air, mostly through the exhaust fumes. Pollutants produced by vehicle exhausts include carbon monoxide, hydrocarbons, nitrogen oxides, dust particles and sulphur dioxide.

 

EFFECTS OF AIR POLLUTION

Air pollution has long-lasting effects on global climate and environment.

Global Warming

Global warming is the unnatural increase in the Earth's surface temperature due to effect of greenhouse gases, such as carbon dioxide and methane. The possible effects of global warming are as follows:

• Melting of Polar ice caps
• Irregular weather pattern
• Rise in global sea level resulting in the flooding of low-lying coastal regions

 

Acid Rain

Acid rain is a rain or any other form of precipitation that is unusually acidic. When fossil fuel such as coal and petroleum are burnt, they produce air-polluting gases such as sulphur dioxide and nitrogen dioxide. These gases react with the water vapour in the atmosphere and eventually form dilute solutions of sulphuric acid and nitric acid. These acids mix with rain water and come down in the form of acid rain. It can have harmful effects on human beings, vegetation, aquatic animals and buildings.

 

Common Air Pollutants	Source	Effects
Carbon Monoxide	Incomplete burning of fuels	Reduces the oxygen-carrying capacity of the blood
Sulphur Dioxide	Combustion of fuels like coal in power plants	Dissolves in rainwater and forms acid rain; aggravates respiratory Diseases
Oxides of Nitrogen	Burning of fossil fuels	Worsen Asthma, Bronchitis
Particulate Matter	Automobile exhaust, burning of fossil fuels	Lead to respiratory diseases, hinder Photosynthesis
Chlorofluorocarbons (CFCs)	Used in refrigerators and AC	Damage the ozone layer

 

PREVENTION OF AIR POLLUTION

The use of public transport should be encouraged.

Use of unleaded petrol and CNG should be encouraged.

Regular pollution-check for all vehicles should be made mandatory.

 

GREENHOUSE EFFECT

The greenhouse effect is a natural process that warms the Earth's surface. When the Sun's energy reaches the Earth's atmosphere, some of it is reflected back to space and the rest is absorbed and re-radiated by greenhouse gases.

Major gases which contribute to the greenhouse effect are water vapor, carbon dioxide and methane.

WATER POLLUTION AND ITS CAUSES   

Water pollution is the contamination of water by chemical or biological constituents that make it unfit for drinking and other uses. The main causes of water pollution are:

Dumping of garbage, domestic sewage into water bodies

Dumping of untreated industrial effluent into water bodies

Washing clothes and bathing near water bodies

Oil spills from ferry boats and ships not only pollute the water but also harm the aquatic animals and destroy the marine life.

PREVENTION OF WATER POLLUTION

Washing clothes and bathing near water bodies should be avoided.

Use of eco-friendly fertilisers should be encouraged.

Domestic and industrial waste should be treated to remove toxic substances before releasing into water bodies

METHODS OF PURIFYING WATER

Sedimentation is a method of purifying water in which impure water is allowed to stand undisturbed in a container. The insoluble impurities are allowed to settle to the bottom as sediments

Decantation is a water purification process in which water is slowly transferred into another container after the process of sedimentation.

Filtration is a method of purifying water in which insoluble impurities are removed by passing the impure water through a filter or a filter paper.

Distillation is process to remove soluble impurities from water. It is the process of first converting a liquid into water vapour and then back to liquid, to purify it.

Chlorination is a method of purifying water, which includes adding small amounts of chlorine to the water. This destroys the harmful microorganisms and germs present in the water.

Boiling is one of the most effective methods of purifying water. Boiling the water at 100 degree Celsius for at least 10-15 minutes kills all the harmful microorganisms present in the water.

INTRESTING FACTS

• 80% of the water pollution is caused due to domestic sewage, like throwing garbage on open ground and water bodies.
• It is estimated that we breathe 20,000 liters of air each day, which means that the more polluted the air is, the more we breathe dangerous chemicals into our lungs.
• By the year 2100, the average temperature of the Earth will rise by 5.8 degrees as a result of global warming.
• Every year there are about 250 million cases of water-based diseases, resulting in roughly 8 to 10 million deaths.
• The hole in the ozone layer was discovered above the Antarctic in 1985. It has improved following a ban on the use of Chlorofluorocarbons (CFCs). 
• Approximately 30 million people including children in India suffer from Asthma.
• River Ganga and river Yamuna are ranked among the world’s 10 most polluted rivers.