Write short note on Environment and Sustainable Development.

Environment and Sustainable Development

Ancient man was living in jungles and was leading a harmonious life with the nature. But the modern man is living in the age of science and technology. Earlier, man was being controlled by the nature but now, man is controlling the natural environment. He has developed big cities, industries, agricultural lands, dams, means of transport, and communication etc. however this has caused depletion and degradation of natural environment because of the fact that he has utilized the various natural resources to a very large extent. Sustainable development means to maintain a balance between development and environment.

Following are some of the methods suggested for sustained development without depletion of natural resources and ecodegradation.
1 Reduction in man’s dependence on fossil fuels and development of alternate sources of energy like solar energy. Solar energy can be trapped by the development of photovoltaic cells, cooker, heaters etc.
2. Development of battery driven vehicles.
3. The use of biogas plants so that agricultural and animal wastes can be utilized for the production of energy.
4. The use of wind and tidal power should be explored more extensively.
5. Exploitation of sea and its resources.
6. Cultivation of more fuelwood trees and shrubs in the various areas of the land where they are not growing.
7.Recycling of Wastes.

Important principles of social responsibility

(i) To avoid misuse of national resources.
(ii) To avoid government regulation and control.
(iii) The iron law of responsibility.
(iv) To avoid class conflicts.

Social Environment : The social environment of business by certain factors like social behaviour, social interests, expectation level of education and understanding among people, social values and beliefs, social customs and traditions.  The business which neglects these factors will be subjected to criticism. A business cannot build up its image in the society without considering the social objects and values.

Cultural environment : The cultural environment is formed by the art, sahitya and life style of the people.  Arthur Millan in his Drama entitled “The Death of a Salesman” has stated that the pressure of competition influenced the thinking of a salesman in such a way that ultimately he committed suicide. The cultural values developing throughout the-world towards ‘Women’s liberation’, drug culture, youth-oriented society, etc. have influenced considerably the business policies.

The society and culture are the fundamental base of business. No business can overlook the country’s cultural heritage and values, if it wants to survive. Businessmen need to function on the basis of social expectations, desires, likes and preferences. They have to respect the human society, its cultural, values and traditions.

Describe the Tropical Cyclone and Local Storms.

Tropical Cyclones and Local Storms

Tropical cyclone representing closed low pressure system generally having a diameter of about 650 kilometres, is one of the most powerful, destructive, dangerous and deadly atmospheric storms on the planet earth. Tropical cyclones are variously called in different parts of the globe as HURRICANES in the North Atlantic Ocean (mainly in the Caribbean Sea and south eastern U.S.A.), TYPHOONS in the North Pacific Ocean (mainly in China Sea, eastern and southern coasts of China, Japan, Philippines and southeast Asia), CYCLONES in Bangladesh and eastern coastal areas of India and ‘WILLY WILLY’ in Australia.

Tropical cyclones become more disastrous natural hazards because of their high wind speed of 180 to 400 kilometres per hour, high tidal surges, high rainfall intensity (highest recorded rainfall value exceeded 2000 mm per day in Philippines) very low atmospheric pressures causing unusual rise in sea level, and their, persistence for several days or say about one week. The total cumulative effects of high velocities of wind, torrential rainfall and transgression of sea water on to the coastal land become so enormous that the cyclones cause havoc in the affected areas and thus tremendous loss of human lives and property is the ultimate result of such atmospheric deluge. The storm surge or tidal surge refers to unusual rise in sea level caused by very low atmospheric pressure and the stress of the strong gusty winds on the sea surface. These storm surges or tidal surges, when coincide with high tide, are further intensified and after intruding into the coastal land cause widespread inundation of coastal areas and great damage of human lives and property. The following case histories of a few most powerful and disastrous tropical cyclones may unravel the magnitude of destruction wrought by these natural atmospheric disturbances.

1. CYCLONIC hazards very often visit the eastern coastal areas of India and the southern coastal areas of Bangladesh. The disaster of the deadliest storm in the recorded history occurred on November 12,. 1970 in the coastal lowland of Bangladesh. This Bay of Bengal disastrous cyclone tells the magnitude of environmental hazards in respect of its killer impact on the affected people as it caused as many as 3,00,000 deaths (some sources put the figure between 300,00 and 1,000,000 deaths in Bangladesh and West Bengal of India) wherein most of the death were caused by drawing in the storm surge of oceanic water (20 feet) on the land. The official record of Bangladesh presented the total loss as death of people-200,000 missing persons-50,000 to 100,000 rendered homeless. The standing kharif crops over 1.75 million hectares were destroyed. The loss of property mounted to about 10,000 crore rupees (1000 billion rupees). The severe super cyclonic storm resulted the disruption of the supply of water and electricity. The communication system was thrown out of gear. Destruction and obstruction of roads and rails brought a grinding halt to rail and road transport which continued for weeks. Thousands of families suffered from mental agony due to separation of their kith and kins. Paradeep Port was so greatly damaged that it became unoperational for weeks. Most of the trees were uprooted. Surface and ground water was so greatly polluted due to dead bodies (both human and animal) that it became unsuitable for domestic uses and birth to the outbreak of epidemic. Though the cyclone vanished by October 31 but it left behind ugly scene of destruction and tragedy of epidemic hunger and pollution which broke the backbone of already poor inhabitants.


The northern part of the Bay of Bengal mostly the Ganga Delta Plains of West Bengal. India and Bangladesh very often suffer from frequent severe cyclonic storms and resultant storm surges (tidal waves) because of a combination of several natural conditions and phenomena such as large astronomical tides. Funneling coast configuration (spread of land from three side in arcade shape, forming the head of Bay of Bengal), low and flat terrains of coastal area and frequent occurrence of severe cyclonic storms. About 12 to 13 tropical cyclones with wind speed below 63 kilometres per hour occur every year in the northern Bay of Bengal. About 5 of these tropical cyclones become strong and severe with average wind speed of more than 63 kilometres per hour. The recurrence interval of disastrous cyclone is every five years.

2. HURRICANES very often strike the southern and the south-eastern coasts of the USA. Gulf coasts of Louisiana, Taxas, Alabama and Fonda are worst affected areas. The Galveston, Taxas (USA) disaster of September 8, 1900 tells the story of devastation caused by hurricanes in the Gulf coastal regions of the U.S.A. The terrible hurricane generated a strong storm surge (tidal wave) which raced inland and killed 6000 people mostly through drowning caused by inhumation under 10 to 15 feet (3 to 4.5m) deep water and destroyed 3000 houses. Flying planks and timbers under the force of strong gale winds also caused several deaths and damage to human structures.

It may be pointed out that Mississippi Delta Plans of the State of Louisiana (U.SA.) have the equivalence of Ganga Delta Plains of India and Bangladesh as regards the frequency and intensity of tropical cyclones but the damages mainly in the form of human causalities are far less in the former than in the latter because of more advanced and better warning systems. The Audrey Hurricane of June. 1957 struck the Louisiana Coast between New Orleans and Galveston. Though the storm was very severe as it smashed houses and floated them away, uprooted sealed concrete tombs and floated them 32 kilometres away from their resting places, but only 550 human death could be caused because of better warning systems and spontaneous response of people to the warning and predictions. In fact the water level used to rise at the rate of 1.5 feet per hour. Thus most of the people had ample time to evacuate them to safer places before the water level forced by strong storm surge could reach its peak of 8 to 12 feet (2.4 to 3.6m) above high tide water.

3. TRACY CYCLONE struck Darwin city of Australia (a coastal city of the Northern Territory) on the Christmas Day of 1974 and caused deaths of 49 persons and left 16 people missing. Thought the Tracy storm was small as the diameter of the area of gale force winds (above 63 kilometres per hour) was only about 100 kilometres but it was certainly an intense Storm as its destructive intensity was concerned. The destructiveness of the storm surge caused by this cyclone was minimized because of the fact that it occurred during a period of neap tides inspite of reduction in the intensity the Tracy cyclone damaged 80 per cent of the buildings of Darwin city having a population of 45000 people at that time (1974), caused total distuption of power supply thus plunging the entire city into darkness, put all the services of water and power supply, sanitation, transport and communication out of gear. There is little doubt that the relatively very small loss of life in Darwin (city) can be attributed to the fact that the cyclone was accompanied by a restricted storm surge effect; major damage was produced by high winds and torrential rain. Nevertheless, the problems encountered in Darwin, serve to highlight the magnitude of the tropical cyclone danger in much more densely populated areas of developing rather than developed countries (i.E. Hobbs, 1980).

4. LOCAL STORMS The severe local storms of hazardous nature include TORNADOES (which affect the southern and the eastern USA) and thunderstorms. Tornadoes, though smallest in area of all the hazardous atmospheric storm, are very deadly to human lives and property. On an average the annual toll caused by tomatoes in the U.S.A. includes damage to property worth, 100,000,000 dollars and 150 human deaths. The deadliest part of the tornandoes is the TORNADO MISSLILES (consisting of uprooted trees, their branches, roofs of buildings etc. which are carried away by dynamic force of winds) which inflict great damage to buildings, other human structures and human lives. A tornado for example at Lubbock (Texas. U.S.A.) in 1970 moved a long cylindrical fertilizer tank (3.35 m x 12.5 mm size with a weight of 11 tons) for a distance of 1.21 km. from its original place.

Two great seasons of tornado outbreak in the U.S.A. tell the awful story of ravages caused by deadly tornadoes. The occurrence of tornadoes in groups hazardous but when very hot and dry days prevail for a few weeks in continuation, environmental hazard in the form of heat waves occurs which affect the environment and human lives, plants and animals. The persistence of exceptionally cold conditions for several days causes severe snowfall. A dry season a year may not be as much disastrous as continued dry seasons for several years. The perception and concept of drought vary from place to place and from one group of people to other group based on profession and occupation. In fact, drought occurs when there is appreciable decrease in rainfall from the average normal rainfall. Floods are still very severe environmental hazards which are related to atmospheric processes. Mississippi flood plains (U.S.A.) and the Ganga Plains (India) are frequented by severe flood hazards. It may be pointed out that floods are not always hazards rather these are also boom because these bring rich fertile alluvial soils each time and thus increase agricultural productivity.

What are Earthquake Hazards (Disasters).

Earthquake Hazards / Disasters

An earthquake is a major demonstration of the power of the tectonic forces caused by end genetic thermal conditions of the interior of the earth. An earthquake is motion of the ground surface, ranging from a faint tremor to a wild motion capable of shaking building apart and causing gaping fissures to open in the ground. The earthquake is a form of energy of wave motion transmitted through the surface layer of the earth in widening circles from a points of sudden energy release the focus.

The magnitude or intensity of energy released by an earthquake is measured by the RICHTER SCALE devised by Charles F Richter in 1935. The number indicating magnitude or intensity (M) on Richter scale ranges between 0 and 9 but in fact the scale has no upper limit of number because it is a logarithmic scale. It is estimated that total annual energy released by all earthquakes is about 10 25 ergs, and most of this is from a small number of earthquakes of magnitude over 7’ (A.N.Strahler and A.H. Strahler, 1976). The 1934 Bthar earthquake (India) measuring 8.4 magnitude on Richter Scale and Good Friday Earthquake of March 27, 1964. in Alaska, U.S.A. measuring 8.4 to 8.6 on Richter Scale may help in assessing the devastation caused by the energy release during earthquakes of varying magnitudes. The World’s largest and most intensive recorded earthquake was of the magnitude of 8.9 and the number of recorded earthquakes increase 10 times as magnitude decreases by one.


The quakes of magnitude 5.0 equal in energy to ordinary atomic
bomb. The atomic bomb hurled over Hiroshima (Japan) during
Second World War equaled the magnitude of 5.7 on Richter
Scale. The energy released from such earthquakes equals 8 x
1020 ergs.

Another scale of the measurement of the degree of destructiveness or intensity of earthquakes is MERCALLI SCALE. The degree of destructiveness on intensity of an earthquake depends on a variety of factors e.g. magnitude, distance from epicenter, acceleration, duration amplitude of waves, type of ground, water table, nature of geometries of the region concerned and the nature and type of constructions (such as building made of wood or bricks, earthen buildings made of muds, tin shades, huts etc.) affected by an earthquake.

The place of the origin of an earthquake is called FOCUS which is always hidden inside the earth but the depth of which varies from place to place. The deepest earthquake may have its focus at a depth of even 700 km. below the ground surface but some the major Himalayan earthquakes, such as the Bihar-Nepal earthquake of August 21,1988, had their focus around 20-30 km. deep. The place on the ground surface, which is perpendicular to the buried focus’ or hypocenter’ recording the seismic waves for the first time is called EPICENTRE. The seismic waves move away from the source of the earthquake (focus or hypocenter) in the form-of (1) primary or Pressure waves (P waves), (2) Secondary, Shear or Transverse waves (S waves) and (3) Long waves or surface waves (L waves). These seismic waves are recorded with the help of an instrument called SEIMOGRAPH or SEISMOMETER at the epicenter. The patterns of recorded seismic waves are studied and various definite information about the centre of the origin of the earthquake (focus or hypocenter), magnitude and destructive power of the earthquake etc. are received.

Magnitude and energy released during an earthquake is generally related to the effects of the earthquake in terms of human beings and his habitats. It is apparent from table that most of the earthquakes occurring on the earth are small. On an average about 80,000 earth tremors are recorded by seismographs each year but most of them are not felt by human beings. Beno Guttenburg and Charles F.Richter have stated that the size (magnitude M) and the logarithm of frequency (number of earthquakes N) of earthquakes in a given area of observation are linearly related. On the basis of this analysis one can calculate the probable return periods of earthquakes, or different magnitudes. Great earthquake, with magnitudes over 8, generally occur about once every 5 to 10 years. Earthquake of magnitude 8 or more has a probable return period of 50 years in North-East India. Real damages caused by earthquakes begin at magnitude 5 and continue to increase to nearly total destruction in the neighbouring settlements by the earthquakes with more than 8 magnitude. Maximum recorded magnitude is 8.9.

What are the main causes of Land Slide?

Main causes of Land Slide

Land slide is a natural problem. In high rain when areas when the big rocks come down with water we call it, land-slide. There are many. reasons of land slide:

(1) In hill area due to undeveloped of trees comes this situation.

(2) If we don’t dig the mines in proper way, this situation will come.

(3) Due to earth quake, spoil the balance of land, cutting of trees, this situation comes.

(4) Due to earthquake and volcano and the land slide happens.

(5) Sometime human activities are responsible for land-slide as mining,
tree cutting etc.

 Write an essay on Green House Effect?

A glass house used for raising delicate plants is called Green House. A green house has higher temperature inside than outside though the interior receives less radiations. It is called Green House Effect. The factors which contribute to this effect are (i) glass walls (ii) high carbon dioxide content and (iii) high water vapour content of the air in the Green House. They let the short wave radiations (wave length 0.15-4.0 pm) pass through them but prevent the passage of long wave (infra red) radiations emitted by the earth’s surface. This makes inside of the Green House warmer than outside.

In the context of environment, Green House effect refers to ‘selective energy absorption by some atmospheric gases, which allow short wave length energy to pass through but absorbs longer wave lengths and reflect heat back to earth’. The atmospheric gases which are permeable to short wave solar radiations, but are strong absorber of long wave radiations emitted from the surface of earth are called Green House gases. These include carbon dioxide, nitrous oxide, methane, chlorofluorocarbons, ozone and water vapour. Though carbon dioxide contributes maximum to the Green House effect on the earth, methane (CH) and chlorofluoro carbons (CJ Cs) are potent Green House gases even though their contributions in the atmosphere are much less than that of carbon dioxide. Carbon dioxide is chiefly produced by the burning of fuels. It is also released by plants and animals during the process of respiration. Methane is the primary component of natural gas and it emanates from garbage dumps, swamps and rice fields. Chlorofluorocarbons are used around the world as refrigerants, aerosol propellants, in isulators and fire extinguishers. These gases are responsible for about 15 per cent of the green House Effect.

Nitrous oxide (N2O) is produced during the process of destruction of ozone layer in the stratosphere. The ozone in the stratosphere acts as a protective layer, because it absorbs much of the ultra violet radiation from the sun. however, its higher Concentration in troposphere acts as a Green House gas. It is responsible for about 10-20 percent of the Green House effect.

Write an essay on solid waste management ?

Solid waste, often called the third pollution after air and water pollution, as that material which arises from various human activities and which is normally discarded as useless or unwanted. It consists of the highly
heterogeneous mass of discarded materials from the urban community as well as the more homogeneous accumulation of agricultural, industrial and mining wastes.

Solid wastes may be classified based partly on content and partly on value. A typical classification is as follows :

(a) Garbage : Refers to non-putrescible solid waste constituents produced during the preparation or storage of meat, fruit, vegetables, etc. These wastes have a moisture content of about 70% .

(b) Rubbish: Refers to non-putrescible solid waste constituents either
combustible or non-combustible. Combustible waste would include paper,
wood, scrap, rubber, leather etc. Non-combustible wastes are metals, glass , ceramics etc. These wastes contain a moisture content of about 25% and the heating value of the waste is around 15 x 106 J/kg.

(c) Pathological Wastes: Dead animals, human waste, etc. The moisture content is 85% and there are 5% non-combustible solids.

(d) Industrial wastes: Chemicals, paints, sand, fly ash etc.

(e) Agricultural wastes:  Farm animal manure, crop residues, etc.

In India authentic information regarding the composition of the urban wastes is not generally available as regular analysis of the refuse is not carried out by the municipalities. In fact, refuse is very heterogeneous in composition and the geographical, temporal and seasonal variations in its composition make it difficult to define a “typical refuse”. The solid refuse generated in urban areas contains articles of various sizes and types and consists of dust, vegetable leaves, waste paper, large paper-board cartons, glass bottles, worn out tyres, carcasses of animals and night soil.

Potential Methods of Disposal

In recent years new and better methods for solid waste management have been suggested and / or developed. Some of the ideas are discussed in this section.

(a) Utilization: Many solid wastes generated by industry can be utilized directly. Fly and bottom ash from power plants can be used commercially, largely as cement substitute. New uses are being developed for fly ash, e.g.,. to make bricks, do dewater industrial wastewater sludge, as a land cover etc. India produces about 6 x 10 tones of bagasse from sugar cane annually. This bagasse can be utilized for the manufacture of paper pulp which can displace hardwood pulp of similar quality and cost. There are some novel uses of sugar cane bagasse. One sugar cane company in South Africa has integrated its operation with the production of eggs and dairy products.

(b) Recovery and Recycling : Solid wastes contain significant amounts of valuable materials like steel, aluminum, copper and other metals which, if they are recovered and reused, would reduce the volume of the wastes to be collected and at the same time would yield significant salvage and resale income. In addition, better reclamation techniques will help to save valuable natural resources and turn wastes, which could be dangerous, into useful products. Some important solid wastes that have been successfully reclaimed  are paper, glass, metals and plastics.

Write short note on Thermal pollution.

Thermal Pollution

Radioactivity is not the only waste that nuclear power plants produce. There is another unseen Waste. For cooling purposes nuclear reactors, thermal power station and various industries use large quantities of water. Many times it is easier to take water from the source of lower temperature and let off the hot water into river causing rise in temperature.

Effect of thermal pollution

Change in temperature has a disastrous effect on aquatic plants and animals. It is estimated that a rise of 3.6 C in the earth temperature would make ice caps to melt in the Antarctic and Arctics. As a result of melting and expansion of water, the level of oceans would go up to 100 meter. Scientists believe that this condition may come in 108 years at the present rate of expansion. Cooling brought by increased dust particles would bring an ice age. This requires only a fall of 4°C in temperature.

Control of thermal pollution

For controlling the thermal pollution factories and power houses should make their cooling towers and spray ponds. This way the water can be used• again and again and the thermal pollution can be eliminated.

Write an essay on Soil Pollution ?

Soil constitutes the upper crust of the earth which support land plants and animals. Like air and water, soil also gets polluted. Soil pollution can be defined ‘the addition of substances to the soil, which adversely affect physical, chemical and biological properties of soil and reduces its productivity. The process of soil formation is very slow, therefore the soil may be considered as non-renewable resource. This makes the problem of soil pollution more acute.

Soil pollution is an extremely complicated process. It may occur directly by dumping, and disposal of wastes, application of agro-chemicals or the indirect result of air pollution such; as acid rains. The main soil pollutants are : (i) industrial wastes (ii) pesticides (iii) fertilizers and manures (iv) discarded wastes (v) radioactive (vi) other pollutants.

(i) Industrial wastes : Both solid and liquid wastes of industries are dumped over the soil. The wastes contain a number of toxic chemicals such as mercury, lead, copper, zinc, cadmium, cyanides, thiocynates, chromates, acids, alkalies, organic substances etc. Some toxic chemicals reach by mining operations also.

(ii) Pesticides:  Now-a-days a number of chemicals are used to kill insects (insecticides), fungi (fungicides), algal bloom (algacides), rodents
(rodenticides), weeds (weedicides or herbicides) in order to improve agriculture, forestry and horticulture. They are sprayed on plants in the form of fine mist or powder. Most of the pesticides are broad spectrum and effect all types of life. They are, therefore, also called “biocides”. Pesticides reduce the population and number of species of living organisms including micro organisms, thus effect the structure and fertility of soil. Several pesticides or their degradation products are absorbed by plants which in turn may affect the entire food chains and food webs.

(iii) Fertilizers and manures: Chemical fertilizers are added to the soil for increasing the crop yield.  The excretory products of people and livestock and digested sewage singe used as manure pollute the soil. The innumerable pathogens contained in these wastes contaminate the soils and vegetable crops and cause serious health hazards for man and domesticated animals. However, biological sources are the minor factors in altering soil composition.

(iv) Discarded materials: A large number of discarded materials are dumped on the soil by man. These include concrete, asphalt, rugs, leather, cans, plastics, glass, discarded food, paper and carcasses. The addition of solid wastes is sometimes called the third pollution.

(v) Radioactive wastes : Radioactive elements from mining and nuclear power plants, find their way into water and then into the soil.

(vi) Other pollutants : Many air pollutants (acid rain) and water pollutants ultimately become part of the soil. The soil also receives some toxic chemicals during weathering of certain rocks.


Write an essay on Radio Active Pollution ?

Radiation is a special type of physical phenomenon in which energy travels through space. That radiations have a direct impact on the living systems was first shown by Roentgen. He interposed his wife’s hand between a vacuum tube and a fluorescent screen and saw the bones. Later on, Becquerel burnt himself with a natural radioactive substance -. radium. Subsequently P.Curie and M.Curie (husband and wife) succeeded in extracting and purifying radium and they also showed its biological implications.

Sun is the main source of radiations such as infra-red, UV-rays Xrays, cosmic rays etc. thus environmental radiations are of two types; (1) natural and (2) man-made.

Radiations can also be broadly categorized into two groups: (i) non ionizing such as UV-rays that do not penetrate deep into the body tissues; and (ii) ionizing such as X-rays, a-rays, B-rays, protons, neutrons etc. that penetrate deep into the body tissues.

Man-made Sources of Radio Active Pollution

Man-made Sources. They include mining and refining of plutonium and thorium and explosion of nuclear weapons, nuclear power plants and fuels and preparation of radio-active isotopes.
(i) Atomic explosion (Nuclear fall out) : Atomic explosions are performed to test the nuclear arms. The nuclear arms use uraniurn-235 and plutonium-239 for fission and hydrogen of lithium as fusion material. Atomic explosions produce radioactive particles that are thrown high up into the air as huge clouds. These particles are carried to long distances by wind and gradually settle over the earth as fall out or are brought down by rain. The fall out contains radioactive substances such as strontium-90, cesium-137, iodine -131 and some others. From the soil, these materials are absorbed by plants and reach animals and man through food chains. From [and radioactive materials are wasted to water sources.
The explosion of first atomic bomb was done in Nagasaki and second in the Hiroshima in Japan in 1945, which caused large scale destruction of human, animal and plant life. In spite of this great tragedy, the big powers are still engaged in the race for nuclear arms. The present stock pile c weapons is enough to destroy the earth completely.

(ii) Reactors and nuclear fuels : Radioactive isotopes such as uranium- 235 are used as fuel to bring about disintegration of other atoms. The process releases large amount of energy as heat, which is used to produce steam for turning large turbines to produce electricity. Both the fuel elements and coolants contribute to radiation pollution. The biggest problem is the disposal of radioactive wastes, which contain excess of fission and activation products. The radioactive wastes are dumped in underground tanks for natural decay. If they escape, they pose grave public health hazards. Inert gases and halogens escape as vàpours and become potential pollutants of the environment by settling on ground or reaching surface waters by rain. People working nuclear reactors, fuel processors, power plants or living nearby are vulnerable to radiation exposure.

(iii) Radioactive isotopes : A large number of radioactive isotopes such as 14C, 125I 32P and their compounds are used in scientific research. These radioactive materials reach water sources with waste water from laboratories. Some of these isotopes such as radioactive iodine and phosphorus enter human body through food chains.

(iv) Radiation therapy: Human being voluntarily receive radiations from diagnostic X-rays and radiation therapy for cancers.

Effects of Radiations of Living Systems

1. Non-ionising radiations may be lethal to micro-organisms but are capable of injuring only the superficial tissues of higher plants and animals.

2. Radiations induce mutations and break in chromosomes particularly at the time of cell division.

3. Radiations damage various tissues of the animal body like epithelial linings of skin and intestine, blood forming cells in the bone marrow, reproductive cells etc. Immediate effects of radiations are nausea, vomiting, diarrhea, eventually loss of appetite and weight. Higher doses of radiations may cause ulceration of intestine, anaemia, leucopenia and sterility. Excessive use of X-rays causes death of the tissues. Young and growing tissues are more susceptible to radiations

4. In plants, chromosomal aberrations are induced by mutations This not only brings about morphological deformities but also reproductive malfunctioning leading to sterility. Different doses of radiations have different effects on different plants. For example; come plants can tolerate a dose of 3,000 rads but show reduced yield; young pine trees are destroyed with a dosage of 500 rads; onion plants can resist up to 25,000 rads. In general, seeds are more resistant to radiations.

5. The atomic explosion by the Allied Forces of U.S.A. on the two cities of Japan-Hiroshima and Nagasaki in 1945 during World War II had caused havoc and ruined these cities. This explosion killed all the innocent people, plants and animals. The radiations were so enormous that even after many years, the newborn babies were abnormal around these two cities.

Write an essay on Water Pollution ?

The contamination of water with harmful chemicals and radiations is called water pollution. There are various causes of water pollution including:
(i) Many industries and factories are built near the banks of rivers, lakes etc. as such water gets polluted.
(ii) The atomic explosions in seas spread radio active waste which pollute the water.
(iii) In some cities, sewer lines pour human and animals waste and garbage from the city into nearby river or other water body so water gets polluted.
(iv) In villages people wash their dirty clothes, take bath and clean their utensils in the pond, lake, or near open wells. So water gets polluted.
(v) Nuclear power reactors discharge radio active wastes and hot water in rivers. So water gets polluted.

Control of Water Pollution
Water pollution can be checked or at least minimized by the following measures:

1. The sewage should be suitably treated before releasing it into water. It is one of the most important means to recover usable water from the sewage. It involves three steps:
(a) In the first step primary treatment stage, the larger and suspended particles are removed by simple physical methods such as sedimentation and filtration.
(b) In the second step ox secondary treatment stage, air is supplied to promote bacterial decomposition of the organic matter followed by chiorintion to kill’the germs.
(c) In the third step or tertiary treatment stage, the salts like nitrates and phosphates are removed by precipitation technique. Many developing countries follow only the first two steps as the third step is quite expensive.

Three stages of sewage treatment: The primary stage removes solid material. In the second stage, organic wastes are decomposed by micro organisms. Tertiary treatment removes minerals that may case cutrophication.

2. The industrial effluents should be suitably treated before releasing pollutants. For example, the acids and alkalies can be neutralized, the colloidal materials can be coagulated, while the metallic salts can be precipitated.

3. Hot water should be cooled before release from the power plants.

4. Washing clothes and taking bath directly in tanks, streams and rivers, which supply drinking water, should be prohibited.

5. Excessive use of fertilizers and pesticides should be avoided and as far as possible less stable pesticides should be used.

6. Water hyacinth (an aquatic weed) can purify water by taking some toxic materials and a number of heavy metals from water.