The world in which we live constitute our environment. High population and industrialisation has polluted the environment and has caused many problems. This chapter describes environment and its pollution.
Environment : The physical and biological world where we live is called our environment. It has three components : (i) Physical surroundings (ii) Living organisms (iii) Meteorological factors.
Abiotic Environment : It is the non-living environment which includes soil, water and air on the surface of the earth. The climatic factors such as sunlight, temperature, rainfall, humidity, atmosphere and wind speed are also considered to be a part of the abiotic environment.
Biotic Environment : It is the living part of the environment. These include plants, animals, human beings and micro-organisms like bacteria and fungi.
Socio-cultural Environment : It is the environment made by man through his various social and cultural activities through the ages. It includes several aspects of human life such as historical, regional, cultural, political, economical, educational, moral and aesthetic.
Inter-Relationship between Man and His Environment : There is a close relationship between man and his environment and both are influenced by each other. Every activity of a man has a direct or indirect impact on the environment. A large number of activities of the man are polluting the environment. In fact man is the main agent for polluting the environment.
Pollution : Any undersirable thing in physical, chemical or biological form present in air, water and land is called pollution.
Pollutant : The harmful substances, which make our environment impure and unhealthy are called pollutants.
Biodegradable Pollutants : Several types of organic wastes like excreta drained out of residential buildings are easily degraded by micro-organisms and are called biodegradable pollutants.
Non-biodegradable Pollutants : Many pollutants like compounds of aluminium, iron, mercury, phenolic compounds. DDT etc. either do not get degraded or degrade partially or take a very long time for degradation, and are called non-degradable pollutants. Plastic is one, very important of this kind.
Air Pollution : It may be defined as the occurrence or release into the atmosphere of any foreign material or gases which are harmful to man, vegetation, animals or buildings.
Air Pollutants : The particulate pollutants which are solid and liquid aerosol suspended in the atmosphere consitute the particulate matter. Smoke is a particulate pollutant. The smoke is formed by the combustion of coal in air. Automobiles run by petrol and diesel contain many different substances in their exhaust. Some of these particles, when emitted into the atmosphere, become air pollutants. The emission of soot from chimneys of factories cause pollution in the air. In most of the industries coal is used. The coal when burnt produces mainly carbondioxide. The jet aeroplene emission is an important source of fluorocarbon. Metal dusts such as lead, asbestos, and aromatic hydrocarbons pollute the air.
Effects of Air Pollution : Air pollution leads to many health hazards to man. The fluorocarbons deplete the ozone layer of the ionosphere. This may lead to entry of ultraviolet radiations into the human body. Lead poisoning may result in weakness and convulsions in the humans. Smoke particles blacken the surface of plants. This reduces the amount of sunlight reaching photosynthesising cells. A number of respiratory diseases such as bronchitis, asthma, emphysema may result due to air pollution.
Carbon Monoxide : CO is produced by the partial combustion of carbonaceous materials. Aircraft engines and spacecraft engines release large amount of CO into the atmosphere. Excessive presence of CO in the atmosphere results in global warming. It, when enters into human blood, combines with haemoglobin and forms carboxy haemoglobin. Thus the oxygen carrying capacity of haemoglobin is considerably reduced. In the absence of proper intake of oxygen the man may die.
Sulphur Dioxide : Sulphur dioxide is produced mainly from coal combustion and from fertilizer factories. Sulphur dioxide is irritant to eyes, nose and lungs.
Acid Rain : When coal is burnt, along with sulphur dioxide, carbon dioxide and nitrogen dioxide are released into the atmosphere. These three gases dissolved in water form sulphuric acid, carbonic acid and nitric acid respectively. These acids fall on earth as acid rain. When such acids percolate into the soil, the roots of the plant get damaged. These acids also damage the leaves. Further the acids make the soil more acidic and cultivation becomes impossible in the acidic soil.
Ways of Controlling Air Pollution
1. Trees should be planted on both sides of the roads.
2. Parks and gardens are to be laid out in the open.
3. Proper planning should be made while laying foundation for houses and colonies so that overcrowding can be avoided.
4. The authorities have to visit the petrol pumps frequently to check the adulteration of petrol.
5. Use of coal and oil in the factories should be minimised.
6. Use of steam engines in railways should be avoided.
Water Pollution : Water gets polluted when the waste materials such as waste products of refineries, chemical industries, tanning factories and waste water like sewage water are disposed off into it.
Water Pollutants : Water pollutants are of two types solid wastes and liquid wastes. Human and animal faecal matter, and dust are solid pollutants. Waste water from tanneries and industries are liquid pollutants. If chemicals are added in excess for purification of water, they become water pollutant. Acid rain also forms water pollutant.
Effects of Water Pollution
1. Water gets contaminated due to water pollution.
2. Normally, sewage is subjected to biological degradation resulting in the yield of carbon dioxide and water. But if there is large amounts of sewage, the dissolved oxygen will be used up. Then the water becomes septic and spoil the aquatic life.
3. Colour of the water will be changed with foul odour emanating.
4. Scum and sludge get collected and make the water unfit even for boating and other recreation purposes.
5. The waste from sanitoria and slaughter houses is discharged into river or pond and the water gets contaminated. This polluted water contains many pathogens like bacteria, viruses, etc. This contaminated water helps the growth of diseases causing germs. These pathogenic germs will cause diseases such as jaundice, typhoid, cholera, dysentry, poliomyelites and so on.
6. Pesticides, fertilizers and industiral products pollute rivers and seas. They enter into aquatic life and become septic for them and even kill them.
7. Mercury, lead, cadmium and copper are the important metals of concern. They enter into fish and other edible marine animals. They make sea-food unsafe for human consumption.
Ways of Controlling Water Pollution
1. The use of herbicides and pesticides should be limited.
2. Proper drainage for industrial wastes, human and animal wastes, and other wastes, should be provided.
3. Too much chemical should not be used for water purification.
4. Proper large scale water purification methods have to be adopted.
5. Sewage disposal system and recycling of waste should be insisted upon.
6. The effluents from industries should not be allowed to go into fields.
7. To avoid pollution, large scale filtering mechanism should be implemented.
8. Special instructions or directions should be given to industries to adopt re-cycling wastes.
Noise Pollution
The term noise is derived from the Latin word Nausea which means a feeling of sickness in the stomach with an urge to vomit. Any unpleasant or undesirable sound is called noise. It is one form of pollution. Hence noise pollution may be defined as unwanted noise dumped into the atmosphere. This is responsible for adverse effects on man. The damage caused by noise pollution is unbearable and irreversible.
Effects of Noise Pollution
1. People, who are exposed to continuous or excessive noise at their work spot, are likely to suffer from temporary impairment of hearing.
2. The prolonged exposure of a person to sound may change his behaviour due to annoyance from unhealthy sound.
3. The noise pollution may cause cardio-vascular problems among some people.
4. The noise pollution may also cause peptic ulcer and asthma.
5. The central nervous system may be affected by noise pollution.
6. People may get physiological tension, nervousness and irritability due to much exposure to unwanted sound.
Control of Noise Pollution : The following measures could be adopted to control the noise pollution.
1. The industries should be shifted to non-residential areas.
2. Periodical overhauling of machines should be done.
3. Replace the old machines.
4. Newly designed noise-free machines are to be preferred.
5. People working in the industries should be given ear muffs.
6. Cultivate green plants around the industries, this would ensure not only reduction of noise pollution but also render fresh air.
7. The workers of the industries should be given sufficient medical facilities.
Soil Pollution : It is usually a direct effect of dumping and disposal of agricultural chemicals, human and livestock excreta.
Biodegradable Wastes : The waste materials which can be broken down into non-piosonous substances by the action of micro-organisms are called biodegradable wastes.
For example, paper, wheat, cattle-dung, biogas, gobar gas, biological wastes, dead plants and animals, animal bones, animal excreta.
Non-biodegradable Wastes : The waste materials which cannot be broken down into non-poisonous substances are called non-biodegradable wastes. The rate of decomposition of these wastes is very slow, and so they continue to accumulate and become serious pollutants.
For example, plastics, metallic containers (like aluminium cans), D.D.T., radioactive wastes, rubber, polythene bags, glass bottle.
Biochemical Oxygen Demand (B.O.D.) : The polluting strength is characterized by biochemical demand. The quality of waste water is measured in terms of its biochemical or biological oxygen demand. It represents the amount of dissolved oxygen which is required for bacteria in decomposing the wastes. The BOD test helps to predict a drop in dissolved oxygen levels in nature.
Thermal Pollution : When human activity brings about an increase in temperature upsetting the natural balance in communities, it is considered as thermal pollution. Water which is used to cool machinary of electric power stations is released into the rivers, raising the water temperature to such an extent that only a few thermophilic bacteria survive. Accelerated microbial activity leads to death of fishes. On account of increase in water temperature the solubility of water is reduced, causing deoxygenation. Anaerobic decomposition causes development of offensive odours.
Radioactive Waste Disposal : One of the major problem of using radioactive materials is how to dispose of the wastes. It is observed that even if radioactive wastes are for hundreds of years, they retain their damaging property. Thus radioactive wastes only with sufficiently low radiation can be discharged into sewage.
Nuclear Fallout : The undesirable additions to environment as a result of nuclear explosion are termed as nuclear fallout.
Products of Nuclear Fallout
1. Iodine—131, 2. Strontium—90, 3. Phosphorus—32, 4. Zinc—65, 5. Cobalt 60 and 50.
Oil slick : When oil (petroleum) flows into sea or lake, it forms a thin layer on the surface of water. This thin film of oil on the surface of water is called oil slick. Oil slick pollutes the water. It cuts off the supply of oxygen to the aquatic plants and animals, and thus kills marine life. It makes the water unfit for drinking and other uses.
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