Effect of Pollution and its Control

Air Pollution

Dry air has 78% N2, 21% O2, 0.03% CO2 and the rest other gases are about 1%. Air pollution is principally caused by man. Due to human activities, the amount of solid waste or concentration of gases other than O2 increase in the air and disturb the natural composition of air. This phenomenon is referred to as air pollution. Air pollution is one of the most dangerous and common kind of environmental pollution that is reported in most industrial towns and metropolitans. Motor vehicles are the major problems of the world which cause air pollution.

Sources of Air Pollutants:

Major source of air pollution is the burning of fossil fuels such as coal, petroleum and natural gases and biological decomposition of organic matter. The fossil fuels are utilized mainly in various industrial processes, thermal power stations, automobiles, domestic combustion, etc. 

Major Air Pollutants:

1) Carbon Oxides: Carbon monoxide, carbon dioxide are example of carbon oxide. Carbon dioxide released by complete combustion of fossil fuels (Coal, Oil etc) in biological respiration. Carbon monoxide is formed by incomplete burning of fossil fuels in automobiles.

2) Sulphur Oxides: Sulphur dioxide, sulphur trioxide are the sulphur oxides. These are released on combustion of petroleum products by the automobiles and burning of coal. Industries and power plants emit large quantity of sulphur dioxide.

3) Nitrogen Oxides: Nitric oxide, nitrogen dioxide and nitrous oxide are the nitrogen oxides. These are released by automobiles, industries and power plants.

4) Hydrocarbons: These are chiefly benzene, benzpyrene and methane. These are mostly discharged by automobiles and industries.

5) Smog: A mixture of smoke and fog is called smog. The incomplete combustion of petrol causes smoke, when it combines with water vapour, it gives rise to smog. These are quite harmful and frequently combine with nitrogen dioxide and produce photochemical smog.

6) Metals: These include chiefly lead, nickel, cadmium, mercury, tin, arsenic, titanium, etc. present in air as solid particles or liquid droplets or gases. These are mostly produced by metallurgical processes, automobiles, industries, etc.

7) Particulate Matter: These are fly, ash, dust, grit and other suspended particulate matter (SPM) released from power plants and industries. Cement factories emit plenty of dust which is a potential health hazard. There are many kinds of biological particulate matter suspended in the air. Tese are bacteria, fungal spores and pollen grains.

Effects of Air Pollution:

1) According to WHO report (1996) about 40,000 people die every year due to air pollution.

2) Carbon dioxide causes difficulty in breathing when present in large amount. The increased amount of carbon dioxide in atmosphere causes the global warming which is called green house effect.

3) Carbon monoxide combines with haemoglobin about 210 times faster than oxygen and reduces oxygen carrying capacity of haemoglobin. It causes headache, dizzines, nausea, difficulty in breathing etc.

4) Oxides of sulphur and nitrogen form acidic solutions when they dissolve in water and causes acid rain.

5) Sulphur dioxide causes intense irritation to eyes and respiratory tract. It also causes chest constriction, headache, vomiting and death from respiratory ailments. Sulphur dioxide damage crops and other plants. 

6) Photochemical smog causes irritation of eye, nose and throat. It also causes asthma and lung disorders. It bleaches and blazes the important leafy plants.

7) Nitrogen oxides cause defoliation and necrosis of plants. They also cause eye irritation, pulmonary troubles etc. High concentration of nitrogen oxides (about 15 to 50 ppm) injures lungs, liver and kidney.

8) Lead impairs the functioning of the brain and nervous system.

9) Cadmium brings about respiratory disease, high blood pressure and kidney damage.

10) Mercury damages nervous system, liver and eyes.

11) The particulate matter causes respiratory diseases and cancer. The biological particulate matter causes allergy and bronchial disorders.

12) Hydrocarbons like ethylene cause premature leaf fall, flower and bug shedding, curling of petals etc. They also cause carcinogenic effects on lungs.

Control Measures: It is not easy to check the environmental pollution. At present air pollution becomes a major problem for the world. However, some devices have been developed to check the air pollution, which include:

• The effluents from industries must be pretreated before discharging in the atmosphere.
• The industrial smokes must be filtered before releasing into atmosphere.
• The particulate matters from gases and liquids are separated by various devices. In this respect cyclones (centrifugal devices), electrostatic precipators are very useful.
• Scrubbers are special devices, which are useful in removing particulate matters and also sulphur dioxide gases.
• In the exhaust system of automobiles catalytic converters are used to convert carbon monoxide and hydrocarbons to carbon dioxide and water and nitrogen oxides to nitrogen gases.
• As the vehicles are major problems of air pollution, catalytic converters and lead free gasoline must be used.
• Prevention and control of pollution act should be strictly employed on national and international level. 
• Alternate source of energy such as solar energy, wind energy, electricity should be used in place of petroleum products, coal, wood, etc.

Water Pollution:

Water is one of our most precious resources. It is more abundant than anything else. It is the major constituent of protoplasm and is necessary for life activities. "Water is the soul of nature, its pollution will destroy the world." Water is used for diverse purposes in the country which can be conveniently grouped into five sectors mainly domestic, industrial, transportation, power generation and irrigation. But due to industrial growth, urbanization and domestic uses many unwanted substances are introduced in water and it is polluted. Polluted waters are turbid, bad smelling, unpleasant and unfit for drinking, bath and other purposes. They cause mainly diseases and are harmful to human beings.

Water Pollutants and their Sources:

1) Industrial Pollution: Most of the rivers and freshwater streams are seriously polluted by industrial toxins or wastes. The industrial wastes include metals (copper, zinc, lead, mercury, etc.), detergents, petroleum, acids, alkalines, phenols, carbamates, oils, greases, toxins, acids, salts, dyes, cyanides, etc.

2) Agricultural Pollution: When in insecticides, pesticides, fungicides and herbicides are used extensively for the eradication of insects and pests, these are washed off along with rains and taken to aquatic systems and pollute the same. These include DDT, BHC, aldrin, dieldrin, malathion, endrin, toxaphene, etc.

3) Thermal Pollution: Various industrial processes may utilize water in cooling process, which result in thermal pollution of water resources. Many fish require about 10 centigrade temperature for successful reproduction, which can be disturbed in thermal pollution. A temperature rise of 10 centigrade will double the rate of many chemical reaction, thus thermal pollution can exert a disruptive effect on aquatic ecosystem.

4) Sewage: It is the domestic and insutrial water borne wastes. Sewage includes human excreta, paper, cloth, soap, animal wastes, dissolved organic compounds like carbohydrate, protein, urea, etc. Due to uncontrolled dumping of sewage in water the water becomes polluted. The self-purifying ability of water is lost and water becomes unfit for drinking and other domestic uses. Sewage dumping causes severe water pollution problems in following ways:

1. Pathogenic Microbes: Sewage wastes may contain many pathogenic microbes such as bacteria, viruses, protozoans etc. which are a threat to human health.
2. Eutrophication: The eutrophication is a natural process which literally means " well nourished or enriched". Due to accumulation of high amounts of nutrients from domestic waste, phosphate, nitrates, animal wastes and detergents, the water bodies become rich in nutrients , especially phosphate and nitrate ions. Excessive nutrient levels in aquatic system leads to maximum growth or 'bloom' of micro-organisms and aquatic vegetation. This situation of an ecosystem is called eutrophication. The excessive growth og micro-organism and aquatic vegetation cause unpleasant odor, clogging pipes, in terfering with fishing and navigation. It also causes death of most fishes due to lack of oxygen.

5) Oil Pollution: Oil leaked or spilled from oil tanker float over the sea water and pollute the water. It damages marine ecosystem. 

Biological Oxygen Demand (BOD)

The amount of oxygen needed by bacteria for biological oxidation in any unit volume of water is known as biological oxidation demand. BOD is used as a measure of degree of water pollution and waste level. More the demand more is the degree of pollution.

Effects of Water Pollution:

1. Polluted water is unstable for human consumption.
   
2. The microorganisms present in polluted water cause many diseases such as typhoid, cholera, dysentery, diarrhoea, etc.
3. The higher concentration of heavy metal such as mercury, lead, arsenic, cadmium, copper, zinc causes several diseases. These include abdominal pain, headache, diarrhoea, chest pain, damage of brain, liver and kidney, lung cancer, coma, vomiting, etc.
4. Mercury is highly toxic to aquatic life and human life and can produce nervous disorders.
5. Oil pollution in sea water causes death of sea birds and fishes. It also kills most of the plants and animals in sea especially in the coastal areas.
6. Thermal pollution effects both flora and fauna of aquatic system. It causes death of fish. Hot water increased BOD which speed up the metabolism.
7. Free chlorine, phenol, hydrogen sulphide, ammonia and microorganisms cause unpleasant odors.
8. Fine suspended matter causes turbidity of water and it becomes unfit for drinking.

Control of Water Pollution:

1. Adequate Sewage Treatment: Sewage should be treated well before dumping in rivers or oceans. Sewage treatment includes three steps: (i) Removal of the solid wastes. (ii) Removal of biodegradable pollutants. It is done by using chlorine to kill pathogenic bacteria and germs of diseases. (iii) Lastly the removal of the chemicals present in water.
   
2. Recycling: The best method of prevention and control of water pollution is the recycling. Here the waste matter and water are recycled for further use.
3. Limiting the level of pollutant discharge. The amount of pollutant discharge should not exceed the self-purifying ability of water.
4. Application of suitable antipollution measures by industries. 
5. Management of aquatic bodies: Aquatic bodies should be well manage for proper utilization, so as to reduce water pollution.
6. Restriction on the excessive use of pesticides, insecticides, fungicides, etc. Biological and genetical control methods should be adopted for the eradication of insect pests.
7. Treatment of Industrial Effluents: The industrial effluents should be pretreated and rendered harmless before their dumping into aquatic system.

Soil Pollution:

Land and soil are very essential for the survival and maintenance of living organisms including man. Soil supports vegetation on which every living animal depends. However, like air and water, soil may also get polluted. There are many natural and synthetic materials that can adversely affect the physical, chemical and biological properties of soil and seriously affect its productivity. Therefore, any substance that reduces the productivity of soil is called pollutant and such soil is called polluted soil.

Causes of Soil Pollution:

The soil pollution is usually caused by solid wastes and chemicals.

1. Domestic wastes: These are kitchen, packing and building material like containers of tin, plastics, polythenes, glass, paper cardboard, rubber, cloth, leather, etc. All these wastes are thrown out as garbage. Some of them are easily degradable by the activity of micro organisms in nature and the materials are recycled, but some are not easily degraded like metals, plastics, nylons and polythenes.
2. Industrial wastes: It includes concrete, tin, iron, lead, aluminium etc. Many of the chemicals released by industries such as radioactive minerals, sulphur penetrate the soil and the soil becomes unproductive.
3. Agricultural chemicals: Excessive use of pesticides, herbicides, insecticides and fertilizers in agricultural practices may inhibit processes of soil formation and reduce the fertilityof soil.
4. Acid rains: It affects the physico-chemical composition of soil.
5. Manure: The excretary products of human and livestock used as manure also pollute the soil.
6. Salinization: Increase in the concentration of soluble salt causes salinization which reduces the productivity of soil.

Effects of Soil Pollution:

1. Acid rain and other chemicals reduces the fertility of the soil.
   
2. The structure and fertility of soil are greatly effected by soil pollution.
3. Several chemicals are absorbed by the plants, that effect the entire food chains.
4. Salinity of the soil reduces fertility and degrades the quality of the soil.
5. Wastes contain several disease germs which contaminate the soil, crops and vegetables causing several types of health hazards.
6. Excessive use of pesticides, herbicides and fertilizers cause death of micro organisms, animals and certain plants.

Control of Soil Pollution:

1. Recycling and proper utilization of garbage and wastes in energy production. For example fuel wood preparation from garbage. Paper making from paper wastes.
   
2. Controlled use of herbicides, fungicides and pesticides.
3. Pneumatic pipes should be laid foe collection and disposal of wastes.
4. Biological and genetic control should be used for pests control.
5. Animal refuge should be used for production of biogas.
6. By limiting the wastes disposal in land resources.
7. Garbage should be buried under the soil.

 Pesticides:

The chemical compounds which are used to kill pests are called pesticides. Any organism such as fungi, insects, rodents and plants that destroy plants, foods or livestock is called pest. Pesticides include herbicides, insecticides, fungicides and rodenticides. Now a days, pesticides have become inseparable part of agricultural system. Without pesticides the production will decline and the storage would be more difficult. But most of the pesticides are violent poisonous and their handling is hazardous. The selective action of pesticides is never perfect and many non-target organisms are affected by their toxicity. The pesticides are not usually decomposed in the environment (i.e. they are not biodegradable), so that they persist in the environment and may accumulate in living organisms. The most widely used pesticides are DDT, BHC, Chlordane, Aldrin, Dieldrin, Endrin, Parathion, Malathion, Heptachlor, Toxaphene etc. They are not readily degraded. Their concentration go on increasing in water and soil with further application. In ecosystem it gets entry into the bodies of plants and animals in the course of food chain. The accumulation of chemicals in larger concentration in organisms is called bio-accumulation.