Pollution and its Factors

 Chapter 5

Pollution and its Factors

INTRODUCTION

Pollution may be defined as an undesirable change in the physical, chemical or biological characteristics of air, water and land that may be harmful to human life and other animals, living conditions, industrial processes and cultural assets. Pollution can be natural, or manmade. The agents that pollute are called pollutants.

Pollutants 

Pollutants are by-products of man’s action. The important pollutants are summarized below:

• Deposited matter—Soot, smoke, tar or dust and domestic wastes. 
• Gases—CO, nitrogen oxides, sulphur oxides, halogens (chlorine, bromine and iodine). 
• Metals—Lead, zinc, iron and chromium. 
• Industrial pollutants—Benzene, ether, acetic acid etc., and cyanide compounds. 
• Agriculture pollutants—Pesticides, herbicides, fungicides and fertilizers. 
• Photochemical pollutants—Ozone, oxides of nitrogen, aldehydes, ethylene, photochemical smog and proxy acetyl nitrate. 
• Radiation pollutants—Radioactive substances and radioactive fall-outs of the nuclear test.

Classification of Pollutants

On the basis of natural disposal, pollutants are of two types:

Non-degradable pollutants: These are the pollutants, which degrade at a very slow pace by the natural biological processes. These are inorganic compounds such as salts (chlorides), metallic oxides waste producing materials and materials like, aluminum cans, mercuric salts and even DDT. These continue to accumulate in the environment.

Biodegradable pollutants: These include domestic sewage that easily decomposes under natural processes and can be rapidly decomposed by natural/ artificial methods. These cause serious problems when accumulated in large amounts as the pace of deposition exceeds the pace of decomposition of disposal.

Secondary pollutants. The secondary pollutants are produced by the combination of primary emitted pollutants. in the atmosphere. In bright sunlight, a photochemical reaction occurs between nitrogen oxides; oxygen and waste hydrocarbons from gasoline that forms peroxyacetyl nitrate (PAN) and ozone (O3), Both of them are toxic components of smog and cause smarting eyes and lung damage.

AIR POLLUTION

The WHO defines air pollution as the presence of materials in the air in such concentration which are harmful to man and his environment. A number of ingredients find their way in the air and these are mostly gases, which rapidly spread over wide areas.

SOURCES OF AIR POLLUTION

Various sources of air pollution are fossil fuels, industries, agricultural activities, wars, natural causes arid emissions from vehicles.

• Burning Fossil Fuels: Burning of wood, charcoal and other fossil fuels causes air pollution by the release of carbon dioxide (CO2), carbon sulphur dioxide etc. Petroleum consists mainly of hydrocarbons, sulphur and nitrogen.

• Emissions from Automobiles: Vehicles are mainly responsible for more than 80% of total air pollution. The major pollutants released from automobiles, locomotives, aircraft etc., include CO, unburnt hydrocarbons and nitrogen oxide.

•  Industries: Paper and pulp factories, petroleum refineries, fertilizer plants, and steel industries, thermal power plants are the main sources of air pollution. They add various harmful gases like CO, SO3, NO, Hydrocarbons etc., to the atmosphere. Textile factories release cotton dust into the air. Cities experiencing this type of pollution are Kanpur, Surat and Ahmedabad. The pesticide and insecticide industries are posing serious threat to the environment. Food processing industries and tanneries emit offensive odors. Release of poisonous gases from accidents also poses serious threats. e.g. Bhopal Gas Tragedy in which methyl isocynate (MIC) gas leakage killed several people. In Tokyo, about 34 tons of carbon particles mixed with other suspended particles settle per square kilometer every day

• Agricultural Activities: Spraying of insecticides and weedicides also cause air pollution. These, when inhaled create severe problems to both animals and man.

• Wars Various forms of explosives used in war pollute the air by releasing poisonous gases. This greatly disturbs the ecology of the area. Nuclear explosions pollute air by radioactive rays. The effects of nuclear explosions on Hiroshima and Nagasaki are well-known examples

• Natural: Causes Gas emissions from active volcanoes, marsh gas, spores of fungi and pollens are the natural causes of air pollution.

COMMON AIR POLLUTANTS

ir pollutants are of two main types ~gaseous and particulate. Oxides of carbon. Nitrogen and sulphur are gaseous pollutants. Particulate pollutants may be solid or liquid particles, larger particles settle down quickly viz., sand and water droplets whereas small dust particles remain suspended in air for a long time. These are added into the atmosphere by the processes of blasting, drilling, crushing, grinding and mixing.

• Carbon Dioxide CO2 content of air has increased by 20% during the last century. CO2 causes nausea and headache. It’s increase in the air may cause greenhouse effect, rise in the atmospheric temperature. This may melt the polar ice resulting in rise in level of oceans and flooding of coastal regions

• Carbon Monoxide It is a very poisonous gas and is produced by incomplete combustion of fuel. If inhaled. it combines with hemoglobin and reduces its oxygen-carrying capacity. This leads to laziness, reduced vision and death.

• Oxides of Nitrogen These include NO and NO2, which are released by automobiles and chemical industries as waste gases and also by burning of materials. These are harmful and lower the oxygen carrying capacity of blood.

• Oxides of Sulphur SO2 and SO3 are produced by burning of coal and petroleum and are harmful to buildings, clothing, plants and animals. High concentration of SO2 causes chlorosis (yellowing of leaves), plasmolysis, damage to mucous membrane and metabolic inhibition. SO2 and SO3 react with water to form Sulphury and sulphureous acids. These may precipitate as rain or snow producing acid rain or acid precipitation.

• Photochemical Oxidants Formed by the photochemical reactions between primary pollutants, viz. oxides of nitrogen and hydrocarbons. Nitrogen oxides in the presence of sunlight react with unburnt hydrocarbons to form peroxyacyl nitrate (PAN), Ozone, aldehydes and some other complex organic compounds in the air.

• Hydrocarbons These are unburnt discharges from incomplete combustion of fuel in automobiles. These form PAN with nitrogen oxides, which is highly toxic

• Particulate Matter Industries and automobiles release fine solid and liquid particles into the air. Fly ash and soot from burning of coal, metal dust containing lead, chromium, nickel, cadmium, zinc and mercury from metallurgical processes; cotton dust from textile mills; and pesticides sprayed on crops are examples of particulate pollutants in the air. These are injurious to respiratory tract.

• Aerosols: Aerosols are chemicals released in the air in vapour form. These include fluorocarbon (carbon compound having fluorine) present in emissions from the Jet aero planes. Aerosols deplete the ozone layer. Thinning of ozone layer results in more harmful ultraviolet rays reaching the earth, which are harmful to skin, and can lead to skin cancer also.

POLLUTION IN INDIA

India supports a large network of factories and industries. These factories are generally localized in eight or ten large industrial centers. These are also a great source of air as well water pollution. To be on a safer side delocalization of industries is the need of the time. This would lead to an even distribution of pollutants and faster degeneration of pollutants. The major pollutants coming out from these industries are - 

• Industrial Pollutants. The common air pollutants from industries are SO2, CO, CO2, H2S and hydrocarbons together with dust, smoke and grit. These are produced by the burning of coal and petroleum and by the combustion of lignite at thermal power stations. The chemical industries release HCl, chlorine, nitrogen oxide and oxides of copper, zinc, lead and arsenic. The fertilizer factories at Gorakhpur and Ahmedabad; the steel industries at Bhilai, Rourkela, Jamshedpur and Durgapur pollute the air with above-said gases. 

• Automobile Exhausts. Automobiles run by petrol and diesel produce CO, nitrogen oxides and hydrocarbons. Hundreds and thousands of tons of hydrocarbons and CO are emitted into air daily. Metropolitan cities harbour lakhs and crores of automobiles. Every gallon of petrol consumed by automobiles produces 3 pounds of carbon monoxide and 15 pounds. of nitrogen oxide. 

• Ionizing Radiations from Radioactive Substances. Ionizing radiations include alpha, beta particles and the gamma rays etc. These are produced by atomic explosions and testing of atomic weapons.

Effects of Air Pollution

Effect on Plants:

• SO2 causes chlorosis and also results in the death of cells and tissues. 
• luorides and PAN damage leafy vegetables such as lettuce and spinach. 
• Oxides of nitrogen and fluorides reduce crop yield. 
• Smog bleaches and blaze foliage of important leafy plants. 
• Hydrocarbons cause premature yellowing, fall of leave and flower buds, discoloration and curling of sepals and petals. 
• Smoke and dust cover the leaf surface and reduce photosynthetic capacity of plants. (vii) Ozone damages cereals, fruits, and cotton crop

Effect on Man

The effect of pollutants on animals and man are as follows-

• Ozone causes dryness of mucous membranes, changes eye vision, causes headache, pulmonary congestion and oedema. 
• Ozone has been reported to produce chromosomal aberrations. 
• SO2 causes drying of mouth, scratchy throat, smarting eyes and disorders of respiratory tract. 
• SO3, CO and NO2 diffuse into blood stream and reduce oxygen transport. CO damages cardiovascular system. Hydrocarbons and other pollutants act, as carcinogens and lead to different cancers. 
• Cotton dust leads to respiratory disorders e.g. bronchitis and asthma.
• Smoking of tobacco causes cancerous growth in lungs

Change in Climate

• CO2 content of air is increasing due to deforestation and combustion of fuel. This increase is affecting the composition and balance of gases in the atmosphere. Increase in CO2 concentration may increase the atmospheric temperature, producing greenhouse effect A rise of global temperature by more than 2-3 degrees may melt glaciers and polar ice. This would lead to a rise in ocean level and consequent flooding and submergence of coastal areas. Rainfall pattern may also change, affecting agricultural output in various regions of’ the world. Aerosols deplete the ozone layer in the stratosphere. Thinning of ozone layer would permit more of the harmful ultraviolet rays to reach the earth. This may cause, sunburn, blindness and inactivation of proteins, RNA, DNA and plant pigments.

Aesthetic Loss

• Dust and smoke spoils the beauty of nature. Especially the mountain environments, which serve as a great attraction for tourists. Foul odours emitted by industries, automobiles, dirty drains and garbage heaps in cities are a great nuisance.

Control of Air Pollution

Following measures have been suggested to control air pollution-

• Some gases, which are more soluble in a particular liquid than air, for example, ammonia in water, can be separated by dissolving in it.
• Particles larger than 50 mm are separated in gravity settling tanks. Using cyclone collectors or electrostatic precipitators separates fine particles. 
• The height of chimneys should .be increased to the highest possible level to reduce pollution at the ground level. 
• SO2 pollution can be controlled by extracting sulphur from the fuel before use. 
• Pollution control laws should be enforced strictly. 
• Trees should be planted on the roadside, riverbanks, parks and’ open places as they keep the environment fresh.
• Population growth, which is the main cause of pollution should be checked. 
• Nuclear explosions should be restricted.

Water Pollution

• Water is extremely essential for life; this common fact is known to all. It is required to meet our basic needs in day-to-day life viz., cooking, drinking, bathing, disposal of sewage, irrigation, generating electricity in power plants, cooling and manufacturing different products in industries and the disposal of industrial wastes. During all these processes the undesirable substances are added to the water resources to a great extent. This alters the basic chemistry of water in rivers and streams.

Sources of Water Pollution

• Domestic sewage This includes household’s wastes like food wastes, synthetic detergents used for washing clothes and cleaning bathrooms and latrines and water-based paints.

• Industrial effluents: The industrial wastes are discharged in the adjoining rivers and streams through flush lines of factories. The textiles, sugar and fertilizers factories, oil refineries, drugs manufacture, rubber, and rayon fibers, the paper industries and the chemical factories all produce Chemical pollution

• Agricultural source Increased use of fertilizers has become essential for high yielding crop plants. Excess of nitrates used as fertilizers seep into ground water is carried into lakes and pond. On entering the drinking water supply system these create several health problems.

Effect of Water Pollutants

The main effects of water pollutants are:

• Compounds of mercury, arsenic and lead are poisonous and chemically harmful as they even affect water treatment plants e.g., organic sulphur compounds interfere with nitrification.
• Mercury when dissolved in water is absorbed by aquatic plants and enters the food chain. Lead impairs metabolism and brings about congenital deformities, anaemia etc.
• Cadmium damages kidneys and liver.
• Inorganic nitrates and phosphates promote growth of oxygen-consuming algae, which result in the death of fishes and other aquatic animals.
• Presence of dyes and compounds in the discharged water changes the colour of water

CONTROL OF WATER POLLUTION

• Separate ponds and tanks to be used for cattle and animals.
• Use of pesticides, insecticides and fertilizers should be done judiciously. Rapid biodegradable substitutes for pesticides should be employed. 
• In towns where sewage facilities are not available, septic tanks should be made in the houses.  
• Rivers and lakes should not be used for bathing or washing as it contaminates water. . 
• Domestic sewage and industrial wastes should be treated before discharging them into drains

Treatment of wastewater

Domestic sewage and industrial wastes should be properly treated before these are drained in the mainstream water. Treatment involves the following two steps:

• Primary treatment. It involves physical processing of sedimentation, flotation and filtration where sewage water is passed through screens to remove larger particles and then through grinding mechanism to reduce the larger particles to smaller size. The sewage is finally passed through settling tanks to remove suspended impurities.

• Secondary treatment. Sewage obtained after primary treatment is sent to aeration tank where it is mixed with air and sludge laden with bacteria and algae. The algae provide oxygen to the bacteria and decompose organic matter into simple compounds. Chlorination is finally done to remove bacteria.

• Treatment of industrial effluents involves neutralization of acids and bases, removal of toxic compounds, coagulation of colloidal impurities, precipitation of metallic compounds and reducing the temperature of effluents to decrease thermal pollution.

SOIL POLLUTION

• Like water and air, soil is also equally important for living organisms. It supports plants on which. all other living organisms depend. The process of soil formation is so slow that the soil may be regarded as a non-renewable source. Therefore, the study and control of soil pollution is important. Any substance that reduces soil productivity is called soil pollutant.

ources of Soil Pollution

here are several materials, which adversely affect physical, chemical and biological properties of the soil and thus reduce its productivity. These are:

1. Chemicals present in industrial waste.
2. Pesticides and insecticides that are sprayed on crops. 
3. Fertilizers and manures that are added to the soil to increase the crop yield

Effect of Soil Pollutants

• Chemicals and pesticides affect the structure and fertility of soil by killing the soil microorganisms. Pesticides are absorbed by the plants and then transferred to other organism. Hence, they affected food chains and food webs. Excretory products of livestock and human beings used as manure pollute the soil besides giving high yield. The faulty sanitation and unhygienic practices of the people add to the soil pollution. Pathogens present in the wastes and excreta contaminate the soil and vegetable crops causing diseases in man and domesticated animals.

Types of Soil Pollution

Positive soil pollution Reduction in the productivity of soil due to the addition of undesirable substances like pesticides, herbicides, fertilizers, etc. is called positive pollution. These pollutants have cumulative effect and kill the soil organisms

Negative soil pollution It is caused by the removal 01 useful components from soil by erosion, deforestation and improper methods of agriculture.

Salination of Soil

• Increase in the concentration of soluble salts is called salination. This adversely affects the quality and productivity of soil. It takes place in two ways: accumulation of salts dissolved in irrigation water on the soil surface due to intensive farming and poor drainage, and deposition of salts as white crust during summer months drawn by capillary action from the lower surface to the top surface.

Control of Soil Pollution

• Transfer stations for bulk shifting of refuse should be constructed in cities and big towns. 

• Pneumatic pipes should be laid for collecting and disposing wastes. 

• Materials like paper, glass and plastics can be recycled. 

• Metals should be recovered from scrap and disposed materials. 

• Use of chemical fertilizers should be reduced by the use of bio fertilizers and manures. 

• Use of pesticides can be reduced by adopting biological control of pests. 

• Use of cattle dung and agricultural wastes in biogas plants should be encouraged. 

• Deforestation can check soil erosion to a great extent

Land Degradation

• Besides pollution, land and soil face several other problems. Removal of topsoil is called soil erosion. Soil erosion factors are water, wind, ocean, waves and glaciers, felling of trees, overgrazing by cattle, over-cropping etc. Erosion occurs both in wet and dry regions. It leads to floods.

Sources of Radiations

• The radiations are produced from the radioactive elements, which are known as radionuclides or radioactive isotopes, e.g. Uranium. Radium, Thorium, and Carbon-14. These contribute to background radiation. But isotopes of certain metabolically important elements like Carbon-14, Cobalt-60, Calcium 45, Iodine-131, Phosphorus-32, etc. are not ecologically harmful but are used as tracers. The third category of radionuclides comprises of fission products of uranium and certain other elements. These are cesium, strontium, and plutonium etc.

Biological Effects of Radiation

• The effects of radiation have revealed that acute doses are found to be deleterious and may kill the organisms, whereas the increase in radiation in biological environment leads to different kinds of mutations. The effects of Cobalt-60 or Cesium-137 gamma radiations have now been studied on communities and on ecosystems at different places. The research concludes that Irradiations eliminate varieties in species. The sensitivity of cells, tissues and organisms to radiation varies. The cells with larger chromosomes are more sensitive. Herbaceous communities and early stages of succession are resistant than the mature forest.

Nuclear Fall Outs or Radioactive Fall Outs

• The atomic blasts not only produce the local ionizing radiations at that time but the radioisotopes produced as a result of explosion enter the atmosphere and continue to fallout gradually over broad geographic areas for a very long time. These are known as nuclear fallout or radioactive fallout. These are dangerous for life as they also produce ionizing radiations.

Biological Effects of Fall outs

• The fallout of radionuclides combines with various metals and dust and from colloidal suspension combines with organic compounds to form complexes. The smaller particles of radionuclides adhere tightly to the leaves of plants and produce radiation damage to leaf tissue besides entering the tissues also. Through grazing animals these enter the food chain directly at the primary consumers level. Radionuclides, which combine with organic substances, enter the food chain through producer tropic level. Therefore, the radionuclides fall out manages to enter the body of all living organisms. Radioactive Strontium-90 poses a health hazard in human beings and other higher vertebrates. It continues to deposit in the bones and causes bone cancer and leukemia. Radioactive Cesium-137 is known to cause irreversible genetic changes in different organisms. The fallout radiations do cause changes in the genetic constitution of organisms, resulting in gene mutations and chromosomal aberrations. Their considerable, doses may kill, cripple and alter the animals and plants in the areas.

Control of Radiation Pollution

• Workers in nuclear plants should be provided with nuclear gadgets and safety measures against accidents. 
• Leakage of radioactive elements from nuclear reactors, laboratories, transport, careless handling and use of radioactive fuels should be checked. 
• Level of radiation pollution should be monitored regularly in risk areas. 
• Disposal of radioactive wastes deserves special attention

Case studies

• The tale of Hiroshima and Nagasaki is a painful experience. It is for the first time that an atomic bomb has been exploded over human population. The incident took place on August 6,1945 at 8:15 a.m. The bomb with an approximate temperature of around 100 million 0°C was exploded on a fine morning in Hiroshima (Japan). The temperature of the city hiked like anything, almost like an oven. After three days, Nagasaki too suffered the ravages of a nuclear attack. More than 1,00,000 people were reported to die just after the event took place. Since radiations from nuclear elements remain active even after, the generations to follow up also suffered from various diseases. Even the babies in the mother’s womb were affected and a few perished. Blindness, deafness, skin diseases and cancers, distortion of bones and other parts became the fortune of human civilization.

Chernobyl Accident

• This incident took place in Ukraine on April 26, 1986. There was a Chernobyl nuclear power plant in Ukraine after which the event has been named. Approximately four million people had been reported to suffer from the accident. The accident contaminated neighboring environment up to several kilometers. The sites were evacuated and resettlement was done for the affected people. The radiations released affected ground water and surface waters, affecting large areas of Europe. 131 Iodine and 137 Cesium are the most dangerous amongst the 20-odd radioactive elements released during Chernobyl disaster. As per the Soviet Health Ministry, 31-persons died shortly after the disaster. Of the 276,614 people who worked for rehabilitation and cleaning operations, a total of 1065 died by the end of 1990.

Marine Pollution

• All river drainages end up in the seas. On the way to sea, rivers carry large amounts of sewage, garbage, and agricultural discharge, biocides, including heavy metals. Besides this discharge of oils and petroleum products and dumping of radionuclides waste into sea also cause marine pollution. Huge quantity of plastic is being added to sea and oceans. Over 50 million lb plastic packing material is being dumped in sea of commercial fleets. Many marine birds ingest plastic that causes gastro-intestinal disorders. The chemical principle in CBs causes more damage as thinning of eggshell and tissue damage of egg. Radionuclide waste in sea includes Sr-90, Cs-137, Pu-239, and And Pu-240.

• The pollutants in sea may become dispersed by turbulence and ocean currents and finally becomes a part of food chain. Bioaccumulation in food chain may result into loss of species diversity. The pollution in Baltic Sea along the coast of Finland, took place largely from sewage and effluents from wood industries. This pollution effect brought changes. in species diversity in the bottom fauna. In less polluted water there was rich species diversity, which tended to decrease with increasing pollution load. In heavily polluted areas, macroscopic benthic animals were absent, but chirognomy larvae occurred at the bottom. In marine water the most serious pollutant is oil. Spill of oil or petroleum products due to accidents/ deliberate discharge of oil polluted waste brings about pollution. About 285 million gallons of oil are spilled each year into ocean, mostly from transport tankers. Oil pollution causes damage to marine fauna and flora including algae, fish, birds, and invertebrates. About 50,000 to 2,50,000 birds are killed every year by oil. The oil is soaked in feathers, displacing the air and thus interferes with buoyancy and maintenance of body temperature. Hydrocarbons and benzpyrene accumulate in food chain and consumption of fish by man may cause cancer. Detergents used to clean up the spill are also harmful to marine life.

 Thermal Pollution

• The increase in water temperature by industrial units such as steel and iron factories, electric powerhouses and atomic power plants may be called as thermal pollution. Some of the industries generate their own power supply where water is used to cool the generators. This hot water is released into the main stream, causing a warming trend of surface waters. If the drainage is poorly flushed, a permanent increase in the temperature may result.

• Many organisms are killed instantly by the hot water resulting into a high mortality. It may bring other disturbance in the ecosystem. The eggs of fish may hatch early or fail to hatch at all. It may change the diurnal and seasonal behaviour and metabolic responses of organisms” It may lead to unplanned migration of aquatic animals. Macrophysics population may also be changed. As temperature is an important limiting factor, serious changes may be brought about even by a slight increase in temperature in a population. Heat stress (5-1 one above the normal growing temperature of organism) induces expression of specific gene families called heat shock genes, which lead to the synthesis of a new set of proteins called heat shock proteins. Heat shock proteins have been found in every organism from unicellular prokaryotes to multicultural organisms including Homo sapiens. Heat Shock Proteins synthesis lead to acquired thermo tolerance, i.e. the ability of an organism to withstand a normally lethal temperature. Thermo tolerant genotypes show adaptations at various levels of organization besides showing qualitative and quantitative differences in heat shock proteins as compared to the thermo sensitive genotypes.

Solid Waste Management

• Environmental problems also include solid waste disposal. At all levels of development human beings produce domestic wastes. These comprises of kitchen wastes, ashes from fires, broken utensils and worn-out clothing. The industrial revolution leads to the concentration of people in urban areas with very high population density. This resulted in addition of new sources of wastes from shops, institutions and factories. In developed countries services for the regular removal of domestic and trade wastes have been in operation for last many years.

• Many changes have taken place in our society. The character of the wastes has altered with rising living standards, changes in retail distribution methods and fuel technology. Grave environmental concerns have come up with rise in construction of new buildings, supermarkets, and industrial wastes of many kinds. In the industrialized countries, therefore, basic health and environmental problems have been solved in the storage and collection of solid wastes, although major problems remain in regard to resource recovery and disposal. The technology of wastes handling is now highly developed. The substantial sectors of industry are engaged in the production of equipment with regard to removal of wastes. Many institutions give technical training and support. However developing nations like India are facing the problems of urbanization with high population densities. The developing countries are aware of the importance of avoiding the environmental pollution. The quality of urban environment is a matter of growing concern, and the importance of solid wastes management is increasingly being recognized. 

Sources and Characteristics

• The main constituents of solid wastes are similar throughout the world, but the proportions vary widely. As personal income rises, paper increases, kitchen wastes decline, metals and glass increase, total weight generated rises and the density of the waste's declines. Clearly, the amount of work involved in refuse collection depends upon the weight and volume of wastes generated and the number of collection points from which the wastes have to be removed.

Health and environmental implications

• Improper handling of solid wastes results in increased potential risks to health and to the environment both. Direct health risks concern mainly the workers in this field, who need to be protected, as far as possible, from skin contact with wastes. For the general public, the main risks to health are indirect and arise from the breeding of disease vectors, primarily flies and rats. More serious, however, and often unrecognized, is the transfer of pollution to water, which occurs when the leach ate from a refuse dump enters surface water or wastes, either in the open air, or in plants that lack effective treatment facilities for the gaseous effluents. Traffic accidents can result from wastes accumulated and dispersed on to streets and roads. They have caused death and injury to people in the surrounding areas. There also persists the specific danger of the concentration of heavy metals in the food chain. These metals can be taken up by the plants growing on land on which sludge has been deposited, creating risks to the animals which graze and the humans who consume these animals.

Economic implications

• Labour and transport absorb a major part of the operating cost of solid wastes management services. The level of mechanization that should be adopted for solid wastes management systems relates directly to the cost of labour, as compared to that of plant and energy. There is not much variation, worldwide, in energy or mechanical plant costs, but there is wide variation in the range of labour costs. Thus, there are no universally applicable solid wastes management systems. Every country must evolve indigenous technology based on the quantity and character of the wastes, the level of national wealth, wage rates, equipment, manufacturing capacity, energy costs etc. It is necessary to deploy a complete set of technical skills, which derive from several professional disciplines. These include civil and mechanical engineering, chemical engineering, transport organization, land use planning and economics.

Sanitary Landfill Disposal

• Land disposal (burying of wastes) is the only approved method of disposal, which is performed at a single site. Incineration, composting, and salvage are either a form of refuse handling or processing. They are not complete methods of disposal, and they require disposal of residue. Sanitary landfill can be defined as the use of solid wastes for land-reclamation, a typical example being the restoration, by filling to the original level of man made surface dereliction such as a disused surface, mineral excavation. Solid wastes may also be used to improve natural features by raising the level of low-lying land to enable it to be used or cultivation or industrial development. Thus, sanitary land filling has two essential features, which differentiate it from crude dumping:

Control of Hazards

• Control over pathogens is dependent upon a rigorous policy of covering the wastes soon after deposit. This serves both to isolate the wastes and to retain the heat, which is quickly generated during aerobic decomposition. 

• The main source of insects will be the eggs of flies. Which have been deposited in the wastes before they arrive at the site. Most of these will be buried deep in the wastes and will succumb to the temperature increase. 

• Fire at a sanitary landfill can arise from innumerable causes, hot ashes in a vehicle delivering wastes: a cigarette thrown by a worker; the sun’s ray though a fragment of glass on the surface. With some kinds of wastes the consequence of fire may be very serious and underground fires have been known that ultimately caused the collapse of the surface into voids caused by the fire. 

• The pollution of static water, ditches, river or the sea occurs when a sanitary landfill adjoins a body of water. The normal source of the leach ate causing this pollution is rain falling on the surface.

Incineration

• Open burning, barrel burning, and other related uncontrolled forms of burning have a long history of use. Many liquid wastes and pathological wastes are best disposed of by incineration. Originally, solid waste incineration was practiced reducing the quantity of refuse or disposal. After it was proven that heat could destroy most pathogens, incinerators were used in hospitals for destruction of pathological wastes. With few exceptions, incinerators are not “good neighbors,” and the environmental nuisances of dust. Noise and air pollution have provoked communities to an anti-incinerator philosophy. To overcome this negative community feeling is going to require that incineration prove its worth and that imagination be used in the design of future units. Incineration of solid wastes yields the highest percent of volume reduction except for Pyrolysis. Unlike a sanitary landfill, incineration of solid wastes can be performed on the premises of apartments, supermarkets, departments’ stores, and similar establishments.

Role of an Individual in Prevention of Pollution

• Which are the most viable, efficient and economical ways to eliminate pollution problems? We very often see people blaming public and government sectors to control pollution through controlling market mechanisms and government blaming people to avoid and check pollution. Who would control whom? Many ecologists and environmental scientists believe in that pollution problems can be overcome by using market mechanisms to reduce pollution rather than rigid rules and regulations. However, on the other hand man should identify and gear up his own potential to curb down pollution. Man could achieve this by identifying his own role at individual level in prevention of pollution. This is possible through environmental awareness, education and enlightenment.

Ways and means by which pollution problems can be greatly reduced at individual level are:

• Masses at personal level should determine to consume optimum level of resources, which would lead a comfortable life. Because excessive resource consumption is in some way related to pollution problems and hazards (natural and anthropogenic both). 

• Waste disposal at personal level should be optimally reduced as waste destruction by any means causes pollution. 

• Maintenance of vehicles should remain proper as to avoid introduction of harmful gases and other pollutants into the atmosphere. 

• Generators and other household gadgets that add to pollution of environment should be kept well maintained.  

• Use of chemical fertilizers should be limited as to avoid water pollution e.g. DDT 

• Timely disposal of waste to prevent decomposition of household refuge as to check foul odours and spread of disease by insects, flies and other pathogenic bacteria. 

• Industrialists should check for proper disposal of treated water from factory units as to avoid thermal pollution of water bodies. They should also deploy a water treatment plant to prevent the flow of hazardous material. 

• Service centres of vehicles should minimize the disposal of organic solvents into the main drains.  Music lovers should listen and operate their music systems at optimum levels as to avoid noise pollution. 

Disaster Management

• Loss of life and property due to natural disasters like tropical cyclones, floods, droughts, tornadoes, earthquakes, volcanic eruptions etc, is very large. Fortunately warning facilities are available today and by mitigation measures, loss of lives and properties can be minimized. National Meteorological Services of the world to provide warnings to the public for some of the weather-related natural disasters. It is not possible to forecast a long period ahead precisely when and where a dangerous natural phenomenon will take place. While natural disasters cannot be prevented, taking proper long-term and short-term disaster mitigation measures can minimize the loss of life and property.

Floods

• Floods are defined as a relatively high flow of water discharged from river and stream network, which sets the riverbank margins to overflow and lead to the inundation of low land areas surrounding the riverbed. It is essentially a physical phenomenon. Floods arise from abnormally heavy rains, dam failures, snow melts, river blockages. Flood disasters rank second only to droughts in the total number of people affected worldwide.

Types of Floods

• River floods Rivers get charged due to heavy rains over large catchments areas or by melting of snow or sometimes both especially in the mountainous tracts. The floods take place in river systems with tributaries that may drain into large geographic areas and encompass many independent river basins. Amount of flooding depends on moisture in the soil, vegetation cover, and depth of snow and size of catchments basin.

• These floods occur within six’ hours of the beginning of rainfall and; are characterized with rising clouds, thunderstorms and tropical cyclones. These result from runoff from a torrential downpour, particularly if the catchments slope is unable to absorb and hold a significant part of water. Other causes of flash floods include dam failure, sudden break up of glaciers etc. These offer potential threats in the areas where the terrain is steep, surface runoff is high, water flows through canyons and where severe rainstorms are likely.

General Characteristics of Floods

• Man made structures and forest vegetation exhibits different levels of tolerance towards effects of floods.
• Intensity of damage is governed by the time interval of standing floodwaters. 
• High velocity of running water may uproot or weaken foundations of buildings. 
• Rate of rise and discharge of a river is important as a basis for flood control. 
• Frequency of occurrence estimated over a length of period would determine the kind of activities the flood plain should be put to. 
• Generally the rainy season is characterized by the floods during which agricultural economy suffers a huge loss 

Effects of Floods

• Rising water, erosion and the force damages the residential and commercial building. They are dangerous for villages lying in the coastal areas as it sweeps away everything, which comes into its path. In mountainous areas it is the chief cause of landslides. 
• Fisherman, local people, cattle, animals and vegetation suffer a great loss of life and property. Most of the deaths are reported to be from drowning. 
• Fresh water supplies by all sources are nearly destroyed and contaminated hence the areas falling under its impact bear a great risk of suffering from water borne diseases. 
• The destruction of food and fodder crops result in acute food shortage. 
• Floods also make soil infertile, as the topsoil is lost due to erosional activity.
• Floods are also known to preserve, wetlands and recharge ground water.

Earthquakes and Seismology

• An earthquake is a major demonstration of the power of the tectonic forces caused by endogenetic thermal conditions of the interior of the earth. An earthquake is a motion of the ground surface, ranging from a faint tremor to a wild motion capable of shaking buildings apart and causing gaping fissures to open in the ground. The Richter scale devised by Charles F. Richter in 1935 measures the magnitude or intensity of energy released by an earthquake. Good Friday Earthquake of March 27, 1964 in Alaska (USA) measuring 8.4 to 8.6 on Richter scale is among the greatest earthquakes of the world ever recorded.

• The science that studies the behaviour and patterns of seismic waves is called seismology. The place of origin of an earthquake is called focus, which is always hidden inside the earth, but its depth varies from place to place. The place of the origin of an earthquake is called ‘focus’ which is always hidden inside the earth. The deepest earthquake may have its focus at a depth of even 700 km below the ground surface. Major Himalayan earthquakes, such as the Bihar-Nepal earth quake of August 2, 1988, have 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 ‘epicenter’. The waves generated by an earthquake are called ‘seismic waves’ which are recorded by an instrument called seismograph. The lines joining the places of equal intensity of seismic waves on the maps are called is oseismallines

Causes of Earthquakes

• Earthquakes are caused mainly due to disequilibria in any part of the crust of the earth. A number of causes have been assigned to cause disequilibria in the earth’s crust such as volcanic eruptions, faulting and folding, gaseous expansion and contraction inside the earth, hydrostatic pressure of man-made water bodies like reservoirs and lakes, and plate movements.

• Vulcan City Volcanic activity is considered to be one of the major causes of earthquakes. Vulcan city and seismic events are so intimately related to each other that they become cause and effect for each other. Earthquakes follow each volcanic eruption and many of the severe earthquakes cause volcanic eruptions. The explosive violent gases during the process of Vulcan city try to escape upward and hence they push the crystal surface from below with great force and thus is’ caused severe earth tremors of high magnitude.
• Faulting and Elastic: Rebound Theory The horizontal and vertical movements caused by end genetic forces result in the formation of faults and folds which in turn cause isocratic disequilibria in the crystal rocks which ultimately causes earthquakes of varying magnitudes depending on the nature and magnitude of dislocation of rock blocks caused by faulting and folding. The 1950 earthquake of Assam was believed to have been caused due to disequilibria in crystal rocks;

CLASSIFICATION OF EARTHQUAKES

• Each earthquake differs from the other and thus it becomes difficult to classify all the earthquakes into certain categories.

World Distribution of Earthquakes

• Earthquakes are, in fact associated with the weaker and are statically distributed areas of the world. Most of the world earthquakes occur in the zones of young folded mountains, the zones of faulting and fracturing, the junction of continental and oceanic margins, the zones of active volcanoes and along the different plate boundaries. The world map of the distribution of earthquakes prepared by seismologists show the occurrence of earthquakes along the following belts.

Effects of Earthquake hazardous

• Earthquakes and their hazards are determined on the basis of the magnitude of seismic intensity as determined by Richter scale but are decided in the basis of quantum of damages done by a specific earthquake to human lives and property

• Structures such as buildings, roads, rails, factories, dams, bridges suffer a huge damage thus causing a heavy loss of human life and property both. The vibrations of earthquakes last longer and the amplitudes of seismic waves are greater artificially in filled and leveled depressions, swamp deposits etc. than in the structures of consolidated materials and bedrocks. Two major earthquakes of Bihar-Nepal border in 1934 and 1988 explain the impact of earthquake disasters on human structures and human lives. The damage caused by the Bihar earthquake of 15 January 1934, measuring 8.4 on Richter scale, include 10,700 human deaths, landslides and slumping in an area of 250 km length and 60 km width, ruptures and faults in the ground surface etc.

• Cities and towns are worst affected due to large concentration of human population, commercial complexes and residential areas. Due to collapse of large buildings there is greater loss of life and property. Due to collapse of buildings ground water pipes are bent and damaged thus water supply is disrupted, electric and telephone poles are uprooted and there is total disruption of power and communication. Other side effects are collapsed sewer system causing epidemics, roadblocks etc.

• Earthquakes strongly shake the buildings and thus strong oscillations cause severe fires in houses, mines and factories because of overturning of cooking gas cylinders, contact of live electric wires, churning of blast furnaces, displacement of other electric and firerelated appliances.

A CASE STUDY

• A severe earthquake occurred in Garhwal region of Uttar Pradesh on 20th Oct. 1991. Intensive tremors were felt at 2.53 a.m., which lasted for about 45 seconds. The magnitude of earthquake was measured 6.6 on Richter scale and its epicenter was at Angola, a place near Uttarkashi, Mild tremors are a regular feature of the area. The worst affected areas have been in the district of Uttarkashi, Tehri Garhwal and Chamoli while it also caused sizeable damage in the districts of Dehradun, Pauri Garhwal and Nainital. The roads and bridges are the chief means of communication in hill region, which underwent heavy damage. The economy of such places is based on tourism to a great extent, which suffered a great set back. The overhead drinking tanks and pipelines had developed cracks. Sources of drinking water had been damaged. The earthquake caused intensive damage to the building of various government departments, Forest, Home, Finance and Rural Development.

Cyclones

• Cyclones are the centers of low pressure surrounded by closed isobars having increasing pressure outward and closed air circulation from outside towards the central low pressure in such a way that air blows inward in anticlockwise on northern hemisphere and clockwise in southern hemisphere. They range in shape from circular, elliptical to V shape. From locational viewpoint cyclones are classified into two principal types e.g. i) extra-tropical cyclones/temperate cyclones ii) tropical cyclones.

Temperate Cyclones

• Temperate cyclones are atmospheric disturbances having low pressure in the centers produced in the middle latitudes characterized by converging and rising air, cloudiness and precipitation. They are formed in the regions extending between 350- 65" latitudes in both hemispheres due to convergence of two contrasting air masses e.g. After their formation temperate cyclones move in easterly direction under the influence of westerly winds and control the weather conditions in the middle latitudes.

• Temperate cyclones are of different shapes e.g., circular, semi-circular, elliptical, elongated or V, but all of them are characterized by low pressure in their centres and closed isobars. The pressure difference between the centre and periphery is about 10-35 mb. It means that pressure increases from the centre towards outer margin. Average large diameter of an ideal cyclone is about t 900 km while short diameter measures t 000 km. The temperate cyclones move eastward under the influence of westerly winds with average velocity of 32 km per hour in summer and 48 km per hour in winters

ANTICYCLONES

General Characteristics

• Surrounded by circular isobars anticyclone is such a wind system which has highest air pressure at the centre and lowest at the outer margin and winds blow from the centre outward in clockwise direction in the northern hemisphere and anticlockwise in the southern hemisphere fig.13. Thus, anticyclones are high-pressure systems and more common in the subtropical high-pressure belts but are practically absent in the equatorial regions. Anticyclones were classified.

• Wind system is not fully developed in anticyclones because of weak pressure gradient. On an average, wind circulation is of divergent system wherein winds spread in all directions from high-pressure centre to low-pressure periphery. The winds are very much sluggish in the rear portion in comparison to the front portion. The centre is characterized by light breeze.

• These arise due to the descent of either polar cold air mass or warm tropical air mass. Cold anticyclones are associated with extremely low temperature, and they cause cold waves during winter season but when they come in summer season, weather becomes pleasant.

• Anticyclones are generally of circular shape but are very large in size. They become so large in size that their diameters become 9,000 km.

• Generally, anticyclones are rainless and sky is free of clouds because of the fact that descending air in the centre of anticyclone is warmed up at dry adiabatic rate due to subsidence. This causes rise in temperature, which reduces normal lapse rate of temperature, with the result the stability of air increases resulting into marked increase in the aridity of air. This is why anticyclones are indicative of dry weather. 

Suggestions

• Various studies indicate that for each linear kilometer of mountain road, 10 small to medium landslides occur. Prior to the 1962 border war with China, the Himalayan section in India was in most parts accessible only on foot. The shock of the Chinese military presence, the three India-Pakistan wars of 1947, 1965, and 1971, the continued border tensions (especially along the Kashmir ceasefire line), and several other problems led to accelerated construction of up to 10,000 km of highways and connecting roads. The poor alignment and ill-considered design are causing a total soil loss of 0.199 t of sediment per linear meter of road per annum. Valdiya (1973) indicated that during the construction phase an average kilometer of road requires the removal of 40,000-80,000 m3 of debris. These enormous volumes are dumped on the roadsides and damage ecologically fragile slopes by depriving them of natural vegetation and at times destroy the terraces