Rajasthan Board RBSE Class 8 Science Notes Chapter 16 Air and Water Pollution and its Control
Fast growing population, deforestation, increasing automobiles, Industrial development, increasing number of industries, increasing industrial domestic waste have degraded the quality of environment. It has resulted into accute problems like air and water pollution. If it wouldn’t be controlled then a time will come when we will not get clean air and water or potable water. There are some questions related to surroundings which should be sincerely think and answer.
- Why traffic policeman standing at crossing wear mask?
- Why black smoke is emitted from brick plants?
- Why we cough when pass from a crowdy place?
- Why we feel pleasant in gardens?
- Is there any change in quantity of smoke in the atmosphere?
Air is essential for life, it is important for all living beings. Air is a mixture of different gases. In its composition 78% is nitrogen, 21% oxygen and 1% other gases are present like – Carbon dioxide, argon, methane, water vapour etc. In nature exchange between animals and plants keeps the composition of air balanced but there are some natural and man made reasons like – volcanoes, forest fire, increasing industries, transportation, mining etc.
These reasons are responsible for increasing harmful gases, dust particles and smoke continuously in the air. All these combinedly putting an adverse effect on health of all living beings. It is called air pollution or air which is not fit to live. In short quantitative change in quality and composition of air is called air pollution.
Causes of Air Pollution:
- Automobiles: All vehicles produce poisonous gases like – Carbon-monooxide, sulphur dioxide, Nitrogen oxide etc. due to burning of fuels. They make air polluted.
- Industries: Wastes produced through chemicals, iron and fertilizers, cement, sugar industries make the air polluted.
- Agricultural activities: Use of insecticides, pesticides, weedi acides mix with air and make it polluted.
- Domestic Pollution: Use of wood and dungcakes for cooking food, waste left in open cause air pollution.
- Individual habits: Smoking cigars and cigarettes.
- Natural sources: Volcanoes, land explosions, sand storm etc.
- Accidents: Cause due to the carelessness of human like – explosion at atomic plant, fire in war material, leakage of gas in industries make the atmosphere very harmfully polluted.
- Deforestation: Due to deforestation atmosphere is polluted as disbalance of gases.
- Increase in Population: Rapid increase in population is one of the factors of pollution. Pollutants-Substances which cause environmental degradation are called pollutants like (CO) carbon monoxide present in smoke emitted out of automobiles, CO2 (Carbon-dioxide) (NO2) Nitrogen oxide etc.
Air Pollutants and their ill Effects:
- Due to half or incomplete combustion of petrol and diesel, CO, a poisonous gas is produced. It decreases the capacity of oxygen carrying in blood.
- Tetra ethyl lead present in petrol is a dangerous pollutant. It is one of the factors of cancer and tuberculosis.
- In winters a thick layer of smog is formed it is formed due to fog and smoke. It contains NO2 which causes asthma, cough and disorder of respiration.
- From Petrol Refineries we released NO2 and SO2 pollutants as gas waste products. Fuel used in power plants also produce SO2. These pollutants are harmful and cause diseases related to lungs.
- Chloro-Floro Carbon (CFC) is a type of air pollutant. It is used in Refrigerators and Air conditioners. It harms the Ozone layer of atmosphere. It protects us from ultraviolet rays of to the sun. Due to excess dissolution of CFC in air the hole in the ozone layer is increased and created an acute problem.
- Gases emitted out of industries like – SO2, Cl2, NH2, N2O cause burning in eyes and throat diseases.
- Manufacturing industries of Aluminium and Super phosphate produce poisonous gases which cause many diseases.
- Air pollution also cause harm to plants. SO2 even causes death of plants.
Nitrogen, Sulplyjr and Carbon-dioxide form Sulphuric acid, Nitric acid, Nitrous acid, Sulphurous acid, Carbonic acid, by reacting with water. They convert rain into acid rain and fall on earth. Due to acid rain monuments like Taj Mahal is deteriorating. This event is called marble cancer. It also deteriorates buildings, monuments, bridges, sculptors, railing and railway lines. Ponds become acidic, pH of soil become low. It effects the absorption of minerals by the plants from soil and it become infertile. It causes burning in eyes and skin. It damaged membranes of plants and animals.
Measures Taken By Supreme Court To Conserve Historical heritage:
- Orders are given to industries to use CNG and LPG fuels.
- Order to use lead free petrol by vehicles in area of Taj mahal.
Green House Effect (effect on plants nursery):
To increase the plants, agriculture and gardens, glass houses are built in cold regions. These are called Green Houses. In these houses light of sun enters but do not come out. Hence green houses remain warm. Earths atmosphere also works as green house.
Sun rays penetrates in the atmosphere and reaches to the surface of the earth and make it warm, some part of radiations is absorbed by the earth and some reflects back to the universe, some part of it remains in the atmosphere. These radiations increase the temperature of the environment. It is called green house effect. CO2 is responsible for this effect. It is beneficial for us, without this, life is not possible on earth, but now a days it has become dangerous. When CO2 is increased in atmosphere then it works as pollutant. CO2absorbs heat and not allow it to enter in the atmosphere. Now the average temperature is increasing in the atmosphere. It is called Global warming. Beside CO2, Methane, nitrous oxide and water vapour are also called green house gases.
Global warming, an acute crisis: It is a cause of melting of world glaciers, It may result into increase in sea level at many places, coastal regions are submerged. Its broad effects could be seen on rain, agriculture, forests, plants and animals. We still have enough time to control this effect otherwise at the end of century temperature could raise upto 2°C which is a dangerous level. Many countries have sign an agreement to decrease the amount of emission of such gases of green house gases.
Steps for Air Pollution Control:
- Gas absorber should have chimneys of all industries.
- Pollutant particles should be removed through filters.
- Time-to-time combustion engine should be checked.
- Ideal fuels should be used, so less smoke and harmful gases would emit.
- Waste gases and smoke should be oxidized so there would be less pollution.
- Industries should be established away from city.
- Deforestation should be banned.
- More and more plantation should be done.
- Public awareness programmes should be conducted, for environmental cleanliness.
- To drive automobiles lead less petrol, CNG and LPG should be used.
- Crackers should be banned on Diwali to decrease pollution.
- Government should carry out monitoring of air’s quality regularly.
- Wind energy, solar energy and hydro power should be used as alternate source of energy.
- Lakh of plants should be planted in the month of July under forest or Van mahotsav.
- The use of vehicles should be less and use of bicycles should be encouraged.
- By putting garbage into compost pit.
Contamination of water with the substances harmful for life is called water pollution.
Causes of Water Pollution:
- Water becomes polluted when industrial waste, garbage, polythene and other waste mixes with water.
- Dirty water of rural drains mixes with pond water and rivers.
- Washing clothes, bathing, washing utensils, dumping garbage, giving bath to animals, dispose of solid and liquid waste, cleaning of vehicles in ponds and rivers make water polluted.
- Pesticides and chemical fertilizers used increase growth of crops when reaches to rivers along with rain water they become polluted.
- Polluted water makes oceanic water polluted. Atomic test domestic oceans radiations of these explosions make oceanic water pollute.
Effect of water pollution:
Solid waste deposited in water make water polluted. This polluted water contains various, microbes, fungi, parasites etc. Such water can cause infections and diseases like Cholera, Diarrhea, skin diseases etc. Polluted water decreases the supply of oxygen to aquatic plants and animals, it puts an adverse effect on their growth. Hence their number is decreasing day-by-day. Polluted water makes soil polluted, it decreases its fertility.
Oil refineris, paper industries, textile and sugar industries emit chemicals in which poisonous substances like – lead, arsenic, fluoride are present. These mixes with soil and produce toxicity in animals and plants. Hot water expelled by electric plants and industries, increases the temperature of ponds and put an adverse effect on aquatic life. Pesticides and insecticide dissolved water reach to the underground and makes it polluted.
Measures to control water pollution:
- Waste from the industries should not disposed in rivers.
- According to the laws passed by the governments. These wastes should be treated in treatment of plants and then should be drained. These laws should be followed strictly.
- Atomic explosions should be banned in oceans.
- Washing clothes, bathing of animals, washing utensils in rivers should be banned.
- Solid and liquid waste should not be passed near banks of rivers and ponds.
- Water supply sources should be checked and cleaned regularly.
- Domestic waste should be dumped at right place in options.
- At every rural and tehsil level water purifier plants should be installed so pollutants from water should be removed.
Special studies of water pollution:
Ganga is one of the holy rivers among famous rivers of India. It is also called Gangamata. Ganga water remains pure (potable) if kept for many days. It nourishes the population of North and east India. According to the study of WWF (World Wildlife Federation) Ganga is one of the ten rivers of the world whose existence is in danger.
Those cities which are located on the banks of river Ganga, are dumping garbage, treated waste, dead bodies, flowers, pooja material, polythene directly in this river. Hence it is polluting day by day. In 1985 to save this river, Ganga river plan was started but increasing population and industrialization both have already harmed this river. At present Govt, has started an integrated plan ‘Namami Ganga’ for its conservation. But to make it successful participation of all Government departments and people is must.
Chemicals like – Nitrates, Phosphate present in the solid waste work as nutrients for algae, hence number of algaes increase in a large amount in ponds. The excess growth of algae is called algae bloom. They utilize excess amount of oxygen resulting in low level of oxygen in the ponds. Hence aquatic organisms die.
Purification of water:
Potable water is called purified water. 25% of population in the world do not get potable water. Hence before discharging polluted water in ponds and rivers it should be treated with physical and chemical treatment. In public water distribution system water is treated before supplying in homes.
Methods to purify water:
- Domestic filter (candle filter)
- By the use of Potash alum.
- By putting lime, potassium permanganate in wells to make water free from worms.
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