Change in physical, chemical or biological characteristics of air, water and land that has the potentiality to harm human life, lives of other desirable species, industrial processes, living conditions, cultural assests and natural resources is called pollution.
Pollutant : Pollutant is a substance (e.g., fly ash), chemical (e.g., ozone, nitrogen oxides) or factor (e.g., radiation, noise, heat) which has the potentiality to harmfully affect human life, lives of other desirable species, industrial processes, cultural assets and natural resources. Pollutants are divisible into several categories. The important ones are as follows :
(1) Primary pollutant : Pollutant persisting in the environment in the form it is produced e.g., carbon monoxide.
(2) Secondary pollutant : Pollutant formed from a primary one through change or reaction. Nitrogen oxides and hydrocarbons react photochemically to produce peroxyacyl nitrates and ozone. The secondary pollutants may be more toxic than the primary ones. The phenomenon is called synergism.
(3) Qualitative pollutant : The pollutant is a harmful substance, chemical or factor that does not occur in nature but is added by human beings, e.g., insecticide, herbicide.
(4) Quantitative pollutant : It is a normal component of nature that becomes pollutant when its concentration becomes higher than the normal, e.g., nitrogen oxides, carbon monoxide.
(5) Degradable pollutant : The pollutant degrades after some time either automatically (e.g., heat) or through the agency of microorganisms (= biodegradable, e.g., sewage, livestock wastes, market garbage). Biodegradable pollutants are easily disposed off or degraded through natural processes or waste treatment plants. They can be turned into a resource, e.g., compost, manure.
(6) Non-Degradable pollutant : It is a pollutant which does not breakdown or get converted to harmless state by natural processes of dissipation, dispersal, oxidation or biological decomposition, e.g., DDT, glass, plastic. It is also known as conservative or persistent pollutant.
Types of pollution
(1) Natural pollution : It is pollution caused by natural sources, e.g., volcanic eruptions, release of methane by paddy fields and cattle, release of carbon monoxide by plants and animals, emission of natural gas, ozone, nitrogen oxides, soil erosion, dust storms, cosmic rays, ultra-violet rays, etc.
(2) Anthropogenic or Man-made pollution : It is pollution caused by human activities like noise, automobiles, industries, smoking, pesticides etc. Anthropogenic pollution is often quite small in quantity as compared to natural pollution. Example, 0.05% of atmospheric pollution is man-made while 99.95% is natural pollution.
On the basis of source of pollution, it can be :
(1) Air pollution : Air or atmospheric pollution is the addition of materials or chemicals into atmosphere in such concentration that they begin to exert adverse effect on human beings, other desirable species, human assets and resources. Total amount of air pollutants is estimated to be 1 × 1012 tonnes, out of which pollutants added by human activities are only 5 × 108 tonnes or 0.05%.
(i) Air Pollutants : The common air pollutants are : Dust, Smoke, Carbon monoxide (CO), Ammonia (NH3), Sulphur dioxide (SO2), Hydrogen sulphide (H2S), Nitrogen dioxide (NO2), Hydrogen cyanide, Hydrogen fluorides, Chlorines, Phosgenes, Arsines, Aldehydes, Ozone, Ionising and radiations. CO2 is not a normal air pollutant. There is 0.03% CO2 in the air its higher percentage is the cause of green house effect.
Types of air pollutants : It is of two types :
(a) Primary air pollutants : Air is polluted by poisonous gases and undesirable substances. They are released by burning fossil fuels. These substances are called primary air pollutants. The primary air pollutants are the following :
Soot released from unburned fuel.
Sulphur dioxide (SO2).
Benzopyrene (hydrocarbon) released from cigarette smoke.
Ammonia (NH3).
Oxides of nitrogen.
Carbon monoxide (CO).
Lead (Pb).
(b) Secondary air pollutants : Secondary air pollutants are poisonous substance formed from primary air pollutants. In bright sun light nitrogen, nitrogen oxides, hydrocarbons and O2 interact to produce more powerful photochemical oxidants like ozone (O3), peroxyacetyl nitrate (PAN), aldehydes, sulphuric acid, peroxides, etc. All these constitute photochemical smog, which retard photosynthesis in plants.
(ii) Causes of air pollution
(a) Agriculture : Hydrocarbons released by plants, pollen grains, insectisides etc. cause air pollution.
(b) Dust : Dust in the air is increased by dust storms wind, volcanoes, automobiles, etc.
(c) Industries : Combustion of fossil fuels like coal, petroleum, etc. Industrial smoke is the main source of pollution.
(d) Automobiles : The combustion of petrol and diesel in automobiles releases harmful gases into the air. They also produce dust.
(e) Ionising radiations : Ionizing radiations include alpha particles, beta particles and gamma rays. They are released into the air on testing atomic weapons.
(f) Freons : Use of freons and other chloro-fluoro-carbon compounds in refrigerants, coolants and as filling agents in aerosol also cause pollution.
(g) Aerosols : Aerosols are small particles of all sorts of solid or liquid substances suspended in the air. They block the stomata of plants and prevent the gaseous exchanges between plants and atmosphere. They may also change the climate of an area.
(iii) Biological Indicators : Some plants are sensitive to certain air pollutants. These plants are used to indicate the presence of these substances. These plants are called biological indicators. e.g.,
(a) The tissues present in the tip of dusheri mango turns black when they are exposed to sulphur dioxide (SO2) fumes.
(b) Pinto beans and Petunias are used to indicate the presence of peroxy acetyl nitrate (PAN).
(c) Tobacco and annual blue–grass plants are used to show the presence of ozone (O3). Lichens are biological indicaters of air pollution caused by SO2.
(iv) Ecological effects of air pollution
(a) Death : When air is polluted with poisonous gases, death comes as a result immediately. Bhopal episode is a good example. Bhopal episode – On 2nd December 1984 about 3000 human beings died, due to the leakage of methyl isocyanate (toxic gas) into the air from an insecticide plant managed by Union Carbide Corporation.
(b) Chlorosis : The disappearance of chlorophyll is called chlorosis. It is caused by SO2, nitrogen dioxide, ozone and fluorides.
(c) Necrosis : The breakdown of cells is called necrosis. It is caused by SO2, nitrogen dioxide, ozone and fluorides.
(d) Green house effect : CO2 is released into the air by the combustion of fuels. It is estimated that CO2 content of the air is increasing at the rate of 0.4% per annum. This will result in an appreciable warming up of the earth. This is called green house effect.
(e) Crop losses : Heavy loss of crop is caused by smog. Smog denotes a combination of smoke and fog. The important components of smog are ozone and PAN (peroxy acetyl nitrate). They damage leafy vegetables, cereals, textile crops, ornamental plants, fruits and forest trees.
(f) Respiratory disorders : Excessive ethylene accelerates respiration causing premature senescence (old age) and abscission (accumulation of yellow fluid (pus) in the body). Aldehydes irritate nasal and respiratory tracts. Chlorine and phosgenes (carbonyl chloride) cause pulmonary oedema. Bronchitis is another bad effect of air pollution.
(g) Nausea : H2S smells like rotten eggs and causes nausea.
(h) Vomiting :SO2 causes vomiting.
(i) Jaundice : Arsines induce RBC breakdown and jaundice.
(j) Oxygen carrying capacity : CO reduces O2 carrying capacity of RBC by its permanent combination with haemoglobin.
(k) Coughing : Coughing is induced by phosgenes (carbonyl chloride).
(l) Headache : SO2 causes headache.
(m) Cancer : Cancer is caused by air pollutants like ash, soot, smoke, chromium, nickel and radioactive elements.
(n) Mutation : Radioactive elements produce mutation. Ozone produces chromosomal aberrations.
(o) Cardiac diseases : Cadmium causes high blood pressure and heart diseases.
(p) Pneumonia : Pneumonia is caused by breathing in too much of manganese particles.
(q) Depletion of Ozone umbrella : In the atmosphere, about 30 km above the surface of the earth, the ozone molecules (O3) form an umbrella. It prevents the penetration of harmful ultra violet radiation from the sun and thus protects the life of the earth. It is now feared that there is danger of depletion of the ozone umbrella, which may occur by the use of freons and other CFC-compounds in refrigerants, coolants in domestric refrigenrators and cold storage facilities, and as filling agents in the form of plastics and in aerosol packages. On reaching the ozone umbrella, they destroy ozone molecules as a result of photochemical reactions. Over the past 16 years, the density of the ozone layer has been diminishing at an average rate of 3%. It is calculated that the depletion of ozone layer by 1% results in an increase in the incidence of skin cancer by 5% to 7%. A hole in O3 layer has been discovered in Antarctica.
(r) Acid rain : One of the major environmental issues facing human society at the national and international level is the problem of rain water having low pH. The rainwater is always slightly acidic as CO2 in the atmosphere gets dissolved in it. However during recent years, it has been noted a further lowering of pH of rain water often as low as 2.4. This lowering of pH is due to the dissolution of acids in the rain water. Precipitation of oxides of sulphur and nitrogen with rain is termed acid rain. Acid rain is caused by air pollution. When atmospheric air contains sulphur dioxide (SO2) and oxides of nitrogen such as nitrous oxide (N2O) and nitric oxide (NO), they dissolve in rain water forming sulphuric acid and nitric acid. The rain water falls as acid rain.
Acid rain affects both materials and organisms. It attacks building materials principally sandstone, limestone, marble, steel and nickel. In plants, it leads to chlorosis (gradual yellowing in which the chlorophyll making mechanism is impeded) or depigmentation of leaves.
Acid rain increases the acidity of lakes and rivers. Vast tracts of forests and lakes in Europe and North America have been destroyed by acid rain. Acidity kills fish, bacteria and algae and the aquatic ecosystem collapses into sterility leaving a crystal clear but ultimately a dead lake.
(v) Control of air pollution
(a) The emission of exhaust from automobiles can be reduced by devices such as positive crankcase ventilation valve and catalytic converter.
(b) Electrostatic precipitators can reduce smoke and dust from industries.
(c) Gaseous pollutants arising from industries can be removed by differential solubility of gases in water.
(d) A finepray of water is the device called scrubber can separate many gases like NH3, SO2, etc. from the emitted exhaust.
(e) Vehicles based on compressed natural gas (CNG) should be introduced.
(2) Water pollution : Water pollution is degradation of quality of water due to addition of substances (e.g., silt), chemicals (e.g., metals, inorganic and organic chemicals) or factors (e.g., heat) and deprivation that makes it a health hazard, unfit for human use, use by animals and industries as well as growth of aquatic biota. Water pollutants belong to three categories – biological, chemical and physical.
(ii) Chemical : Organic wastes, organic biocides (e.g., DDT, BHC) and polychlorinated biphenyls (PCBs), inorganic chemicals like As, Pb, Cd, Ni, Hg, phosphates, nitrates, fluoride, etc.
(iii) Physical : Hot water, oil spills.
Water pollution is of both types natural and anthropogenic.
Natural water pollution : It is water pollution caused by natural processes of soil erosion and addition of clay or silt, run off and leaching.
Anthropogenic or Man-made pollution : It is water pollution caused by human activities like industrial effluents, domestic sewage, waste from animal sheds and slaughter houses, detergents, pesticides and fertilizers, oil spills, etc.
(i) Water pollutants : The common water pollutants are : Domestic sewage, Industrial effluents, Pesticides, Herbicides, Fertilizers, Bacteria and Viruses, Plankton blooms and Heavy metals like Mercury, Temperature, Silt, Radioactivity, Oils etc.
(ii) Causes of water pollution
(a) Domestic sewage : Domestic sewage consists of human faces, urine, and the dirty used–up water in houses. It contains a large number of bacteria and virus. The sewage is released into the rivers on the banks of which most of the cities are situated.
(b) Industrial effluents : All industrial plants produce some organic and inorganic chemical wastes. Those nonusable chemical are dumped in water as a means of getting rid of them. The industrial wastes include heavy metals (Hg, Cu, lead, zinc etc), Detergents, Petroleum, Acids, Alkalies, Phenols, Carbonates, Alcoholcyanides, Arsenic, Chlorine, etc.
(c) Thermal pollution : Hot effluents and hot water (e.g., thermal plants/atomic reactors) bring about rise in water temperature. Warm water contains less oxygen, has lower rate of putrescibility resulting in increased organic loading, replacement of green algae by blue-green ones. Many animals fail to reproduce e.g., Trout, Salmon.
(d) Run off from Agricultural fields : It is of three types – animal wastes, fertilizers and pesticides.
(e) Radioactive wastes : Liquid radioactive wastes are released into the sea around nuclear installations. The oceanic currents carry the radioactive contaminants every where.
(f) Oil pollution : Oil is a source of pollution in sea-water. Oil pollution is due to ship accidents, loading and discharging of oil at the harbour, oil refineries and off-shore oil production. Degree of impurity of water due to organic matter is measured in terms of BOD (Biochemical Oxygen Demand). It is the demand for O2 to decompose organic wastes in liter of water.
(g) Eutrophication : Rich growth of micro-organisms consumes most of the dissolved oxygen, so as to depreve other organisms. It generally occurs at the bottom layers of deep lakes. Addition of excessive plant nutrients intensifies eutrophication. It harmful to fish and other aquatic life.
(h) Ground water : Though a lot of filtration occurs before water reaches the underground water table, ground water does become polluted due to following reasons :
Underground sewage disposal pits.
Septic tanks.
Refuse dumps.
Industrial effluent dumps.
Leaching of pesticides and fertilizers.
(iii) Effect of water pollution
(a) Chemical pollutants
Many chemicals present in industrial effluents are poisonous causing various types of deformities, g., mercury (minamata disease), lead (plumbism), cadmium (itai-itai), nickel, arsenic, chromium, etc.
Some chemicals like acids contained in industrial effluents are corrosive. They damage water treatment plants.
Persistent pesticides enter food chains, undergo biomagnification and harm the aquatic life as well as land animals dependent on it.
Organic sulphur inhibits nitrification.
(b) Odour : Free chlorine, ammonia, hydrogen sulphide, phenols, growth of algae and microorganisms produce unpleasant odour.
(c) Turbidity : Water becomes muddy or turbid due to suspension of mineral dust, silt and related colloidal particles. Turbidity hinders penetration of light. It causes clogging of gills in fishes. Therefore, both plant and animal life is destroyed. Turbid water is also not suitable for drinking or industrial use.
(d) Colour : Dyes, iron and chromium compounds and anaerobic decomposition cause colouration of water. the coloured water is not suitable for recreational, drinking and industrial uses.
(e) Taste : It is impaired due to occurrence of pollutants like free chlorine, phenol, iron, manganese, detergents, hydrocarbons, oils and decomposition products.
(f) Foam : It develops over the surface of water due to mixing of detergents, soaps and alkalies. Foam makes the water unfit for various human uses.
(g) Oil pollution : It comes from spills of oil refineries, oil wells and washing of oil tankers. Oil spreads over water, kills plankton, neuston, necton, water birds and other organisms. Oil may also catch fire.
(h) Scum and Sludge : They are produce by organic wastes especially H2S produced by them. The sulphide combines with metallic ions and form brownish or blackish substance that float over ad inside water.
(iv) Control of water pollution : Pollution control by sewage treatment includes the following steps :
(a) Sedimentation : When sewage is allowed to stand, the suspended particles settle to the bottom. So by sedimentation the suspended particles are removed from sewage.
(b) Dilution : The sewage can be diluted with water. This increases the O2 contents and reduces BOD and CO2.
(c) Storage : The diluted sewage is stored in a pond. This facilitates the growth of micro-organisms. This renders further oxidation of sewage.
(d) Waste stabilization pond or Oxidation pond : Domestic and industrial wastes are stored in a dilute condition in shallow ponds called oxidation or stabilization ponds. After a few days micro-organisms and algae flourish. The micro–organisms decompose the organic wastes by oxidation, and the water is purified. This water is rich in nitrogen, phosphorus, potassium and other nutrients. This water can be used for fish culture, agriculture etc.
(e) Recycling : Pollution can be prevented to a certain extent by reutilizing the wastes. This is called recycling. e.g., :
The dung of cows and buffalo can be used for the production of energy (gobar gas).
Sewage can be used for irrigation and fish culture after treatment in oxidation pond. Certain pollutants from industrial effluents can be removed by filtration and selective absorption.
(3) Soil pollution or Land pollution : It is alteration in soil caused by removal or addition of substances and factors which decreases its productivity, quality of plants and ground water. It is of four types – negative pollution, positive pollution, third pollution and third poison.
Soil pollution is direct if the pollutants are passed over it directly e.g., industrial effluents, fertilizers. It is indirect if the pollutants reach soil from other resources like air and water, e.g., acid rain.
(i) Land pollutants : Manure, crop–residues, ashes, cinders (pieces of coal), garbage (waste food), paper, card board and plastics. Plastics are the most important land pollutants. Rubber, leather, cloth, rubbish, bricks, sand, metal, broken glasses, demolished building, dead animals, discarded furniture, automobiles, insecticides, herbicides and other biocides and radioactive elements are some of the important land pollutants. The main sources of land pollution are pesticides, radioactive elements and fertilizers.
(a) Pesticides : Pesticides are chemicals used to kill pests like insects, rats, snails, fungi, herbs, etc. They are collectively called biocides because they kill life.
Ecological effects of pesticides
Mutation : Insecticides induce gene mutation in human beings (Wurster, 1974).
Cancer : DDT produces cancer in human tissues.
Congenital birth defects : Certain herbicides like diozan increase birth defects in both people and livestock.
Sex hormones : DDT affects sex hormones in mammals and birds.
Decline of reproduction : In Bermuda petral, a sea bird, the rate of hatching of eggs is much reduced because of the accumulation of DDT. If the accumulation increases further, there will be failure of reproduction in this species in future.
Calcium metabolism : DDT interferes with calcium metabolism resulting in calcium deficiency. DDT causes hormonal disturbance resulting in delayed ovulation and inhibition of gonad development.
Biomagnification : The pesticides are non–degradable. They have much affinity towards fat. Hence they tend to move into the living organisms. They are concentrated as they pass up the food chains. For example, at each trophic level, the accumulation of insecticides increases by 10 times. For example if the goat gets one part per million (PPM) of DDT from the grasses, it will have 10 ppm in its tissues. The man, eating the goat will have 100 ppm. The man-eating tiger will have 1000 ppm. If the food chain is still greater, the accumulation will still be higher. This increasing accumulations of insecticides in higher organisms is called biomagnification or biological amplification. DDT causes the pollution of air, water and soil.
(b) Fertilizers : Excessive use causes soil deterioration through decrease of natural microflora. Leaching down causes pollution of underground water (third poison). Salts entering crop plants in excess may prove harmful.
It reduces soil microflora so that biogeochemical cycling and decomposition processes are disturbed.
It destroys crumb structure of soil.
It increases salt loading of soil causing salination.
A part of the fertilizer supply leaches downwardly into ground water.
Extra minerals bring about mineral enrichment of foliage crops. Extra nitrate is known to harm respiratory system because of the production of methaemoglobin which is unable to carry oxygen.
(c) Industrial wastes and chemicals : Industrial wastes and effluents are often dumped over soil. They contain several heavy metals like nickel, chromium, aluminium, tin, copper, zinc, cadmium, toxic chemicals like cyanides, acids and alkalies, dyes, organic solvents, etc. The chemicals become part of soil. They harmfully affect plant growth and soil biota. Both ground water and nearby water bodies are polluted through leaching and run-off.
(d) Mining wastes : They include mine dust, rock tailings, slack and slag. Open cast mining (surface dug out to bring out mineral deposit) completely spoil the surrounding soil. Toxic metals and chemicals present in the mining wastes destroys vegetation and produce many deformities in animals and human beings.
(e) Radionuclides : They are present in ores, coal, waste of mineral purification and uranium mines, etc. A lot of radio-isotopes are also used in research and medicine. Despite best precautions some radionuclides constantly enter soil and are transferred to food chain.
(f) Manures : They are prepared from garbage, sewage sludge and excreta of livestock. The manures carry a lot of pathogens. They contaminate soil and crops. From crops, the pathogens are transferred to domesticated animals and human beings.
(g) Discarded materials : Waste food, garbage, rubbish, glass, plastic and metallic waste articles are dumped over the soil, generally on the outskirts of urban areas. The soil gets polluted, contaminated and becomes breeding place of several pathogens.
(ii) Control of soil pollution
Soil pollution caused by solid wastes can be corrected by the following methods.
(a) Salvage : Articles which can be recycled should be removed from garbage, e.g., metals, glass, polythene, paper, rags, etc. It provides employment to rag pickers and helps in recycling of wastes.
(b) Construction material : Flyash is being converted into bricks for construction work. Flyash, industrial effluents containing toxic chemicals and hazardous metals can be used as bedding material for road construction.
(c) Dumping (Landfilling) : Dumping is piling of waste on selected low lying land. It is of two types, open and sanitary.
(d) Pyrolysis : The waste is heated anaerobically at a temperature of 1650°C. It yields industrial gas, alcohols and a number of other chemicals. The bulk of the waste is reduced. Residue is disposed off in land-fill.
(e) Burning : This is a common method for reducing bulk of wastes. Rubbish and garbage are commonly burnt in open spaces. It, however, releases offensive odour and smoke.
(f) Incineration : Waste is burnt aerobically at 900-1000°C. The hot gases and smoke are further passed into a chamber where the temperature is 1300°C. It burns the smoke particles. The gases released from the second chamber are taken to wet scrubber for removing suspended particles and soluble gases. Ash formed in incinerator is collected and disposed off in land filling.
(g) Recycling of wastes : Paper, glass, polythene and metals can be recycled. Though paper recycling is a bit costlier, it saves a lot of wood. For example one tonne of recycled paper saves 17 medium sized trees from felling. Recycling of metals not only saves the scarce resource but is also cheaper and less polluting.
(h) Agricultural wastes : Instead of burning or manuring them, they can used for preparation of industrial paper, cardboard, hardboard, poultry feeds, etc.
(i) Pesticides and Fertilizers : Their use should be reduced by resorting to biological control (for pests) and organic farming.
(j) Biogas plants : Cow dung, human excreta and putrescible garbage can be mixed and used for generation of biogas. Manure is produced as a by-product.
(k) Sludge : Sludge obtained from sewage treatment plants can be used in thermal power plants along with coal.
(4) Radioactive pollution : It is degradation of environment due to release of radioactivity (emission of a-particles, b-particles and gamma rays) by changes in nuclides of unstable/radioactive elements causing short-range and long range harmful effects on living beings including humans. Radioactivity is measured in units called roentgens or r.
(i) Types of radiations
(a) Background radiation : It is radiation level found naturally in biosphere due to cosmic rays reaching earth and radio-nuclides found in earth’s crust. Maximum background radiation is found in Kerala beach where 75% of thorium deposits of the world are found.
(b) Man-made radiations : They are due to mining and refining of radioactive elements like Plutonium, Uranium and Thorium, nuclear power plants and fuels, preparation of radio-active isotopes, production and explosion of nuclear weapons.
Nuclear weapons : Radiations are released during atmospheric testing of nuclear weapons and their actual use. Atmospheric testing of nuclear weapons has been banned because of release of destructive radiations. Nuclear weapons use uranium-235 and plutonium-239 for fission (atom bomb) and additional hydrogen or lithium for fusion (hydrogen bomb). A nuclear explosion gives rise to –
Radioactive gaseous matter rising up as a mushroom like cloud that disperses later on to spread radioactivity far and wide, polluting air, water and soil of all the places. Radioactivity passes into food chains and affects the whole biota.
Atomic reactors : They employ controlled radioactive fission fusion for liberation of energy.
The coolant water causes thermal pollution.
Small amount of radioactivity enters coolant water which undergoes biomagnification to some 75000 times in birds.
(vii) Mishaps do occur in nuclear reactors. One of the causes is core melting, g., Chernobyl in Ukraine (1986).
Radio-Isotopes : They are used in research (e.g., metabolic pathways, induction of mutations in plants and microorganisms, radiotherapy, etc.) e.g., Co-60, P-32, C-14, I-125.
X-rays : They are employed for detecting diseases of lungs, heart, kidneys, joints and fractures. Repeated exposure to X-rays is harmful. Radiologists are prone to radiation disorders.
Other exposures : Workers engaged in radioactive mineral extraction, fuel processing, nuclear power plants, irradiation plants, etc. are always at risk of exposure to radiations.
This pollution occurs through radiations. Radiations are of two types.
Non ionising radiations : UV rays, IR rays, etc. UV rays cause skin burning, IR rays increases atmospheric temperature and leads to the green house effect.
Ionising radiation : X – rays, -rays, -rays, rays cause genetic injury on mutation.
Types of ionizing radiations : Radioactive isotopes release three types of radiations :
Alpha particles : These are large particles emitted by radioactive isotopes (as U238). They travel only short distances. They cannot penetrate the organisms. They cause ionization.
Beta particles : These are small particles emitted by radioactive isotopes. They can travel long distances. They can easily penetrate the body tissues and cause ionization.
Gamma rays : These are short wavelength rays emitted by radioactive isotopes. They can travel long distances. They can easily penetrate the body tissues and cause ionization. On the basis of the biological effects produced, the radioactive radiations can be grouped into two types, namely internal emitters and external emitters.
(ii) Harmful effects : They were first recorded in 1909 in uranium miners as skin burns and cancers. Many plants are killed even at low level of radioactivity. Young and recently divided cells are more easily damaged.
(a) Short range effects : Loss of nails and hair, subcutaneous bleeding, changed proportion of blood cells, changed metabolism, damaged to all organs death in high dose.
(b) Long Range/Delayed Effects : Tumours, cancers, mutations, genetic deformities, shorter life span.
(iii) Control of radiation pollution : There is no cure for radiation damage. Therefore, the only solution is prevention of radioactive pollution. The various methods are as follows :
(a) Leakages : Strict safety measures should be enforced to check leakage of radioactivity from reactors, reactor fuel during its handling and transport, radio-isotopes and radioactive wastes.
(b) Monitoring : A regular monitoring of radioactivity should be carried out in all risk areas.
(c) Accidents : All measures required to prevent occurrence of accidents should be followed.
(d) Waste disposal
Substances with very low radiation level can be discharged into municipal sewers.
Low activity wastes should be stored for some time as to reduce their activity further before final disposal.
Radionuclides should be separated through precipitation, coagulation or concentration. The concentrated wastes are then changed into glass, ceramic or concrete. This transforms the radioactive waste into non-absorbable and unleachable form. The locked waste is the put in concrete filled drums which are sealed and buried in sea at least 1000 fathoms deep.
(e) Safety norms : All safety norms should be strictly followed in copy book style by all workers. This includes wearing of protective dresses.
(5) Noise pollution : Noise is unwanted annoying sound of generally 80 dB and above. It is a physical non-persistent pollution which affects the receiver directly. Upto a certain limit, the effect depends upon the mood and upbringing of the person.
(i) Frequency : Frequency of sound is measured in cycles per second called Hertz or Hz. Human hearing lies within the frequency of 50–15,000 Hz. Below 50 Hz is infra sound while above 15,000 Hz is ultrasound. Infrasonic sound or infrasound waves cannot be listened but certain body parts resonate at this frequency. Therefore, they can be felt. Infrasound can damage the body parts. Ultrasonic vibrations or ultra sound waves are employed in imaging, cleaning, drilling, cutting, welding and sealing packages.
(ii) Loudness : Loudness or sound intensity is measured in decibels or dB.
(iii) Some boom : It is a series of shock waves left behind by a supersonic jet flying at a speed of more than one Mach (speed of sound). It produces sudden rattling of windows and doors. Buildings may develop cracks. Startle reaction may appear in human beings and animals.
(iv) Sources of noise pollution : Natural sources of noise pollution are rare (e.g., thunder of clouds). Man-made noise pollution is also a recent phenomenon. The important sources are as follows :
(a) Loud speakers
(b) Commercial establishments
(c) Builders
(d) Defence equipment
(e) Agricultural machines
(f) Industries
(g) Functions
(h) Crackers
(i) Transport vehicles
(j) Domestic gadgets
(v) Effects : Noise brings about :
(a) Damage to ear drum and impairment of hearing (a ten year exposure to 80 dB impairs hearing by 15 dB).
(b) Interference in conversation and hearing.
(c) Emotional disturbance, development of anxiety and stress (first effect).
(d) Damage to eye sight, colour perception, night vision, etc.
(e) Hypertension, changes in peripheral circulation and breathing pattern, decreased heart output and gastric problems.
(f) Startle reaction.
(g) Headache, sleeplessness, annoyance and irritability.
(h) Reduced productive performance.
(vi) Control of noise pollution : Noise pollution can be controlled through three methods :
(a) Reduction at source.
(b) Protection of receiver.
(c) Interruption in transmission.
The various methods of controlling noise pollution are as follows :
Sound absorption : The sound entering residential areas and dwelling units should be reduced. Acoustic furnishing should be undertaken to absorb sound and reduce noise pollution.
Sound diversion : High intensity sound should be deflected away from residential areas.
Quieter machines : Efforts should be made to develop quieter machines.
Loud speakers : Their use should be restricted. Under no condition the sound level be raised above 90 dB during the day and 60 dB during the night.
Occupational exposures : In case a person works in industry producing high intensity sound, ear plugs and ear muffs should be used for protection of ears.
Traffic : Highway traffic is not allowed to pass through towns and cities. It is diverted through by passes and over-bridges. Pressure horns are not allowed inside towns and cities.
Green muffler : 4 – 5 rows of trees and shrubs are grown along roads, rails, around industrial area and residential complexes in order to decrease the intensity of sound.
Noisy machines : They are isolated or kept inside sound proof chambers.
Maintenance of machines : Regular maintenance and lubrication of machines keeps the sound level low.
? Maize is the sensitive indicator of fluoride pollution.
? The quantity of loss of top soil is maximum in India and is about 18.5% of the total global loss.
? Solonetz : Black alkaline soil.
? Solonchak : White alkaline soil.
? Maximum background radiations are found in kerala beach, where 75% of thorium deposits of the world are found.
? Love canal incidence is associated with dumping of toxic wastes.
? Noise is called a slow killer.
? Mumbai is considered to be the third noisest city in the world.
? Noise pollution has been declared as an offence.
? Silent spring : Novel written by Rachel Carson (1962) mentioning the effect of DDT on birds. DDT use has been banned in USA since then.
? Gulf War (1990) : Fire from oil wells changed the colour of clouds and rain in north India.
? Prevention and control of pollution Act. 1974.
? National Environment Policy Act. 1969
? Ganga Action Plan : For controlling pollution in Ganges; started 1985.
? Ecotoxicology : Study of passage of toxic materials in the ecosystems, their transformation, degradation and persistence in various trophic levels.
? Sr-90′ is the most dangerous radioactive pollutant.
Pollution
Global climate is threatened by increase in concentration of
(a) Oxygen (b) Nitrogen
(c)Water vapours(d) Green house gases
Accumulation of fluoride in plant leaves causes
(a) Chlorosis (b) Stem rot
(c) Tip burn (d) None of the above
Excessive inhalation of manganese causes
(a) Pneumonia (b) Gout
(c) Anaemia (d) Diptheria
Which of the following statement is incorrect
(a) Carbon monoxide is the major environment pollutant
(b) All pollutants are not waste
(c) Nitrogen and Mg can pollute water
(d) Lichens are affected by sulphur dioxide
A pollutant is any substance chemical or other factor that changes
(a) Natural geochemical cycles
(b) Natural balance of our environment
(c) Natural flora of a place
(d) The natural wild life of a region
Which of the following gas causes pollution
(a) CO (b) SO2
(c) Both (a) and (b) (d) None of the above
Cyanosis is caused by
(a) CO2 (b) Nitrate concentration
(c) Copper (d) Chromium
Carrier of fluorosis is
(a) CO2 (b) Chlorine
(c) Nitrogen (d) Water
Gastro–intestinal disturbances is caused by
(a) Chromium (b) Cadmium
(c) Sodium (d) Selenium
Decrease in rate of mitosis in root tips is caused by
(a) SO2 (b) CO2
(c) Copper (d) Lead
O.D. test or biological oxygen demand test is made for measuring
(a) Air pollution (b) Water pollution
(c) Noise pollution (d) Soil pollution
In B.O.D. test, oxygen plays an important role to
(a) Destroy inorganic matter
(b) Destroy pollution
(c) Destroy waste organic matter
(d) None of these
Water pollution can be stopped best by
(a) Treating effluents to remove injurious chemicals
(b) Rearing more fishes
(c) Cultivating useful water plants
(d) Spraying with DDT
When solid particles of the sizes less than 1.0 pm are suspended in air, it is called
(a) Dust (b) Smoke
(c) Fume (d) Fly ash
U238 emits [BHU 1982; BVP 2003]
(a) gamma–rays (b) beta–rays
(c) alpha–rays (d) None of these
Which of the following does not cause pollution
[MP PMT 1988; CPMT 1993, 2002]
(a) Hydroelectric schemes (b) Automobiles
(c) Nuclear energy project (d) Thermal power project
Which of the following damages WBC, bone–marrows and lymph nodes [CPMT 1989]
(a) I131 (b) Ca40
(c) Caesium (d) Sr90
Major aerosol pollutant present in the jet plane emission is
[CBSE PMT 1990]
(a) Sulphur dioxide (b) Fluorocarbon
(c) Carbon tetrachloride (d) Carbon monoxide
Metal generally present in polluted air is [MP PMT 1991]
(a) Cadmium (b) Lead
(c) Mercury (d) Zinc
Most important causative pollutant of soil may be
[MP PMT 1994]
(a) Plastics (b) Iron junks
(c) Detergents (d) Glass junks
O.D. is connected with [MP PMT 2002]
(a) Organic matter (b) Microbes
(c) Both (a) and (b) (d) None of these
In acid rain accounts for [Orissa JEE 2005]
(a) 70%(b) 100%
(c) 50%(d) 30%
1
c
2
c
3
a
4
a
5
b
6
b
7
a
8
c
9
a
(a) Automobiles and thermal power plants cause air pollution. Radioactive power plants are the source of radioactive pollution and thermal pollution.
(a) I131 enter in human body through H2O or food chain and damage WBC, can cause tumour formation, skin cancer and sterility.
(a) Because they can not be recycled.
(c) Biological oxygen demand is related with organic matter and microbes. It is indicate to water pollution. As such as BOD increased then it indicates that water pollution is also increased.
***
Where did the epidemic bone softening disease ‘Itai –Itai’ occurred first
(a) Burma (b) Japan
(c) South Korea (d) USA
What was the cause of ‘‘Yusho’’ disease which occurred in 1968 from a leak in canning factory
(a) DBCP (b) PCB
(c) Formaldehyde (d) Mercury
Which of the following would be a natural pollution
(a) Forest fires
(b) Eutrophication
(c) Occurrence of smog
(d) Occurrence of NO2 in atmosphere
Which of the following atmospheric pollutants cause general chlorosise. destruction of chlorophyll
(a) CO (b) CO2
(c) SO2 (d) Hydrocarbons
Which component of a living cell is affected by the pollutant SO2
(a) Nucleus (b) Membrane system
(c) Cell wall (d) Plasmodesmata
The major cause (80%) of air pollution in big cities is due to
(a) Transportation by automobiles
(b) Industrial activities
(c) Use of insecticides
(d) Radioactive fallouts
In metropolitan cities like Mumbai and Calcutta, the major atmospheric pollutants are
(a) Carbon monoxide and oxides of sulphur
(b) Hydrocarbons and hot air
(c) Pollens and marsh gas
(d) Ozone
Which of the following is a secondary pollutant
(a) SO2 (b) CO
(c) O3 (d) NO2
The common refrigerant chlorofluoro–methane (freon) and NO2 is a serious pollutant because
(a) It lowers atmospheric temperature
(b) It prevents cloud condensation
(c) It destroys haemoglobin
(d) It disrupts O3 layer
Pollutant from motor–car exhaust which causes a mental disease is
(a) NO2 (b) SO2
(c) Pb (d) Hg
Photochemical transformation of the automobile exhaust emission in UV wavelength of sunlight results into
(a) CO and CO2 (b) SO2 and NO2
(c) O3 and PAN (d) CH4 and C6 H6
Which of the following is a main factor of water pollution
(a) Commercial production (b) Windmill
(c) Smoke and ammonia (d) Detergents
Eutrophication is caused by
(a) Mine effluents
(b) Sewage and detergents
(c) Petrochemical and fertilizer plant effluents
(d) NO3– and SO4– present in acid rains
By which method the quantity of organic pollutants in water can be determined
(a) By pH measurement
(b) By transparency measurement
(c) By measuring the change of colour
(d) By measuring BOD
High coliform count in water is an indicator of
(a) Industrial pollution (b) Sewage contamination
(c) Hardness of water (d) Oil pollution
Which of the following causes outbreak of jaundice
(a) Air pollution (b) Water pollution
(c) Thermal pollution (d) Soil pollution
Brewery and sugar factory waste alters the quality of a water body by increasing
(a) Temperature (b) Turbidity
(c) pH (d) COD and BOD
Which of the following pollutants are inevitably associated with the existence of man
(a) Sewage
(b) Industrial waste
(c) Exhaust emissions
(d) Pesticides and insecticides
What is EIA
(a) Ecology in America
(b) Ecological investment and accounts
(c) Ecological impact analysis
(d) Environmental impact assessment
Non-ionising radiations damaging to DNA are
(a) X-rays (b) UV rays
(c) Gamma rays (d) Beta rays
Which of the following is a weightless pollutant
(a) Sewage and exhaust emissions
(b) SO2 and NO2
(c) Photochemical smog
(d) Heat, sound and radioactive waste
3, 4–benzopyrene causes
(a) Leukaemia (b) Cytosilicosis
(c) Lung cancer (d) Tuberculosis
Leukaemia is caused by
(a) Ca–40 (b) Sr–90
(c) Caesium (d) Iodine
Problem associated with nuclear power plants is
(a) Thermal pollution
(b) Emission of hazardous radio–nuclides
(c) Disposal of radioactive waste
(d) All the above
Which of the following intensity of sound becomes a pollutant
(a) 40 db (b) 70 db
(c) 100 db (d) 200 db
The greatest air pollution disaster of last decade was observed in
(a) Calcutta (Bengal) (b) Bhopal (M.P.)
(c) Ahmedabad (Gujrat) (d) Agra (U.P.)
The reason of pollution is
(a) Population explosion (b) Urbanisation
(c) Industrialisation (d) All the above
Which is the most SO2 polluted city
(a) Madras (b) Calcutta
(c) Delhi (d) Bombay
It is said, the Tajmahal may be destroyed due to
[BHU 1980; CPMT 2004]
(a) Flood in Yamuna river
(b) Decomposition of marble as a result of high temperature
(c) Air pollutants released from oil refinery of Mathura
(d) All the above
Which of the following is a water polluting factor
[CPMT 1980; MP PMT 1986, 2000; BHU 1991]
(a) Smoke (b) Industrial waste
(c) Detergent (d) Ammonia
Which of the following is normally not an atmospheric pollutant
Some effects of sulphur dioxide and its transformation products on plants include
[JIPMER 1983; MP PMT 1998; BHU 1999, 2004]
(a) Chlorophyll destruction (b) Plasmolysis
(c) Golgi body destruction (d) None of the above
In a polluted lake, the index of pollution is [DPMT 1983]
(a) Daphnia (b) Artemia
(c) Frog (d) None of the above
Indicator plants which can be used to indicate atmospheric pollution by SO2 are [NCERT 1983; CPMT 1989, 94]
(a) Lichens like Usnea
(b) Grassland like Deschampsia
(c) Moss like Sphagnum
(d) Climbers like Cucurbita
BOD stands for [AIIMS 1984; Kerala PMT 2004]
(a) Biological organism death
(b) Biochemical organic matter decay
(c) Biotic oxidation demand
(d) Biochemical oxygen demand
Radioactive strontium as a result of radioactive fall out, is
[BHU 1984]
(a) Sr80 (b) Sr90
(c) Sr85 (d) Sr95
Spraying of D.D.T. on crops produces pollution of
[CPMT 1984, 90; MP PMT 1995, 98]
(a) Air only (b) Air and soil only
(c) Air, soil and water (d) Air and water only
Lichens do not like to grow in cities
[DPMT 1985; AFMC 2004]
(a) Because of absence of the right type of algae and fungi
(b) Because of lack of moisture
(c) Because of SO2 pollution
(d) Because natural habitat is missin
Thermal pollution of water bodies is due to [DPMT 1986]
(a) Discharge of heat (hot water) from power plants
(b) Discharge of chemicals from industries
(c) Discharge of waste from mining
(d) Discharges of agricultural run off
Biological treatment of water pollution is done with the help of
[CPMT 1986]
(a) Phytoplankton (b) Lichens
(c) Fungi (d) None of the above
Major pollution causing agent is [CPMT 1986]
(a) Man (b) Animals
(c) Hydrocarbon gases (d) None of the above
Effect of pollution is first and most marked on [CPMT 1988]
(a) Natural flora of a place
(b) Natural geochemical cycle
(c) Natural gaseous cycle
(d) Natural balance of our environment
Green house effect is due to the presence of
[CBSE PMT 1989, 91; CPMT 1998, 99; AIIMS 2000]
(a) Ozone layer in the atmosphere
(b) Infrared light reaching the earth
(c) Moisture layer in the atmosphere
(d) CO2 layer in the atmosphere
A pollutant is an agent which causes change in [CPMT 1989]
(a) Balance of nature (b) Local flora
(c) Geochemical cycles (d) Local fauna
Polluted water can be purified by using [CBSE PMT 1990]
(a) Micro-organisms (b) Algae
(c) Pesticides (d) Fishes
Sewage water can be purified for recycling with the action of
[CBSE PMT 1990]
(a) Aquatic plants (b) Penicillin
(c) Micro-organisms (d) Fishes
One of the most dangerous radioactive pollutant to Homo sapiens is [MP PMT 1990; CPMT 1990; CBSE PMT 1995]
(a) Strontium – 90 (b) Phosphorus – 32
(c) Sulphur – 35 (d) None of the above
Which of the following disease is caused or aggravated by pollution [MP PMT 1990]
(a) Bronchitis (b) Rheumatism
(c) Scurvy (d) Haemophilia
Generally speaking, the atmosphere in big cities is polluted most by [BHU 1990; AMU 1991]
(a) Radioactive fall out
(b) Household waste
(c) Automobile exhaust
(d) Pesticide residues
The excessive discharge of fertilizers into water bodies results in
[MP PMT 1990]
(a) Growth of fish (b) Death of hydrophytes
(c) Eutrophication (d) Silt
Ozone layer in upper atmosphere (stratosphere) is destroyed by or which one of the chemicals is responsible for the reduction of ozone content of atmosphere
[MP PMT 1990, 2002, 04; BHU 1989, 90; CPMT 1993;
KCET 2000; Pb. PMT 2000]
(a) Hydrochloric acid
(b) Photochemical smog
(c) Chlorofluoro carbon (CFC)
(d) Sulphur dioxide
What are the chief pollutants of the atmosphere which are most likely to deplete the ozone layer
[CPMT 1990; 1995; CPMT 1998]
(a) Sulphur dioxide
(b) Nitrogen oxide and fluorocarbons
(c) Carbon dioxide
(d) Carbon monoxide
The pollutants emitted by jet aeroplanes in outer atmosphere flourocarbons are known as
Acid rain is caused due to increase in concentration of (in atmosphere)
[CPMT 1991, 98; MP PMT 2002; J & K CET 2005]
(a) SO2 and NO2 (b) CO and CO2
(c) CO and SO3 (d) O3 and dust
Today the concentration of green house gases is very high because of [CPMT 1991]
(a) Use of refrigerator
(b) Increased combustion of oils and coal
(c) Deforestation
(d) All of the above
Increase in the percentage of fauna and decrease in flora may be dangerous because it enhances [CPMT 1991]
(a) Percentage of CO2
(b) Percentage of radioactive fall out
(c) Percentage of O2
(d) Persentage of diseases
The pollution in city like Delhi may be controlled to great extent [CPMT 1991]
(a) By proper sewage and proper exit of chemicals from factories
(b) By wide roads and factories away from the city
(c) By cleaning city and scanty use of pesticides
(d) All of the above
Domestic waste contains [CBSE PMT 1991]
(a) Non-biodegradable pollutants
(b) Biodegradable pollutants
(c) Hydrocarbons
(d) None of the above
Foul smell in the water of tanks, ponds etc. is due to
[MP PMT 1994]
(a) Anaerobiosis (b) Aerobiosis
(c) Biological magnification (d) Psammophytes
Measurement of the rate of O2 consumption in unit volume of water over a period of time is done to find out
[MP PMT 1996]
(a) Biogas generation
(b) Biological oxygen demand
(c) Biosynthetic pathways
(d) Fermentation
Formation of ozone hole is maximum over [CBSE PMT 1997]
(a) India (b) Antarctica
(c) Europe (d) Africa
Which one of the following organisms is used as indicator of water quality [CBSE PMT 1998, 2004; BVP 2001]
(a) Biggiata (b) Chlorella
(c) Azospirillum (d) Escherichia
Which of the following serves as an indicator of atmospheric pollution [CBSE PMT 1992]
(a) Ferns (b) Liverworts
(c) Hornworts (d) Epiphytic lichens
Lead (Pb) causes [CPMT 1992; MP PMT 2000]
(a) Soil pollution (b) Air pollution
(c) Radioactive pollution (d) All the above
The stratospheric ozone depletion leads to : [AIIMS 1994]
(a) Global warming
(b) Increase in the incidence of skin cancers
(c) Forest fires
(d) All the above
Which causes water pollution [MP PMT 1993]
(a) 2, 4–D and pesticides (b) Smoke
(c) Automobile exhaust (d) Aeroplanes
Pollution can be controlled by [MP PMT 1993]
(a) Sewage treatment
(b) Manufacturing electrically operated vehicles
(c) By checking atomic blasts
(d) All of the above
Checking of reradiating heat by atmospheric dust, water vapour, ozone, CO2 is known as [MP PMT 1994]
(a) Green house effect
(b) Radioactive effect
(c) Ozone layer effect
(d) Solar effect
Photochemical smog is related to the pollution of
[MP PMT 1994]
(a) Soil (b) Water
(c) Noise (d) Air
Eutrophication results in the reduction of
[KCET 1994; CPMT 2000]
(a) Dissolved hydrogen (b) Dissolved oxygen
(c) Mineral salts (d) None of these
The toxic effect of carbon monoxide is due to its greater affinity for haemoglobin as compared to oxygen by (approx.) [CBSE PMT 1995]
(a) 200 times (b) 2 times
(c) 1000 times (d) 20 times
Taj Mahal is threatened due to the effect of
[CBSE PMT 1995; BHU 1999; CPMT 2002]
(a) Chlorine (b) Sulphur dioxide
(c) Oxygen (d) Hydrogen
When huge amount of sewage is dumped into a river, the BOD will [CBSE PMT 1995]
(a) Increase (b) Remain unchanged
(c) Slightly decrease (d) Decrease
A dental disease characterised by mottling of teeth is due to presence of a certain chemical element in drinking water. Which is that element [CBSE PMT 1995]
(a) Boron (b) Chlorine
(c) Fluorine (d) Mercury
Most harmful pollutant is [Bihar MDAT 1995]
(a) CO2 (b) SO3
(c) NO2 (d) CH4
(e) SO2
Biodegradable pollutant is [EAMCET 1995; Pb. PMT 2000]
(a) Plastic (b) Asbestos
(c) Sewage (d) All of these
‘Heat islands’ are produced due to [EAMCET 1995]
(a) Air pollution (b) Water pollution
(c) Land pollution (d) All the above
In big cities, air pollution is due to [CPMT 1995]
(a) Burning of fossil fuels (b) Thermal power plant
(c) Sewage (d) H2S
In the last decades, most serious nuclear reactor accident created MIC gas tragedy in [CBSE PMT 1996; BHU 2000]
(a) Russia (1990) and Bhopal (1996)
(b) Ucraine (1986) and Bhopal (1984)
(c) Bhopal (1994) and Russia (1990)
(d) Ucraine and USA (1984)
Which of the following country is responsible for releasing largest amount of green–house gases
[CBSE PMT 1996, 2002; BVP 2002]
(a) Russia (b) Germany
(c) Brazil (d) America (USA)
Fishes die by sewage because [CBSE PMT 1996]
(a) Of its bad smell
(b) It replaces food material of fishes
(c) It increases oxygen competition among fishes
(d) CO2 is mixed in large amount in water
Acid rain is due to [MP PMT 1996; Wardha 2005]
(a) Sulphur dioxide pollution
(b) Carbon monoxide pollution
(c) Pesticide pollution
(d) Dust particles
Carbon monoxide is a major pollutant of [MP PMT 1996]
(a) Water (b) Air
(c) Noise (d) Soil
Air pollution effects are usually found on [MP PMT 1997]
(a) Leaves (b) Flowers
(c) Stems (d) Roots
Water pollution [MP PMT 1997; BHU 2002]
(a) Increases oxygenation
(b) Decreases turbidity
(c) Increases turbidity and deoxygenation
(d) Increases photosynthesis
The river ‘Sone’ receives wastes from [MP PMT 1997]
(a) Refinery (b) Distillery
(c) Textile mill (d) Paper mill
Oxides of sulphur and nitrogen are important pollutants of
[MP PMT 1997]
(a) Air and water (b) Air
(c) Water (d) Soil
Leaf curling is caused by [MP PMT 1997]
(a) SO2 (b) O3
(c) H2S (d) CO
In coming years, skin related disorders will be more common due to [CBSE PMT 1997]
(a) Pollutants in air (b) Use of detergents
(c) Water pollution (d) Depletion of ozone layer
Phosphate pollution is caused by [CBSE PMT 1997]
(a) Phosphate rock only
(b) Agricultural fertilizers only
(c) Sewage and phosphate rock
(d) Sewage and agricultural fertilizers
Most hazardous metal pollutant of automobile exhaust is
[KCET 1998, 2000; MP PMT 2002; Pb. PMT 2000]
(a) Mercury (b) Lead
(c) Cadmium (d) Copper
Photochemical smog always contains [CPMT 1998]
(a) O3 (b) CH4
(c) CO (d) None of these
Which important green-house gas, other than methane, is being produced from the agricultural fields
[CBSE PMT 1998]
(a) Arsine (b) Sulphur dioxide
(c) Ammonia (d) Nitrous oxide
Carbon monoxide is a pollutant because [CBSE PMT 1998]
(a) It reacts with O2
(b) It inhibits glycolysis
(c) Reacts with haemoglobin
(d) Makes nervous system inactive
Noise pollution is created if noise is in excess to
[Pb. PMT 1999]
(a) 70-75 dB (b) 50-60 dB
(c) 80-99 dB (d) 40-65 dB
PAN (Peroxyacetyl nitrate) is an important constituent of photochemical smog. It is a [CBSE PMT 1999; BHU 2005]
(a) Primary pollutant (b) Secondary pollutant
(c) Natural pollutant (d) Corrollary pollutant
Secondary pollutant which stops Hill reaction is
[CBSE PMT 1999; Kerala CET 2002]
(a) Sulphuric acid
(b) Nitric acid
(c) Peroxyacetyl nitrate (PAN)
(d) Aldehydes
Which of the following is the use of lichens in case of pollution [CBSE PMT 1999; Kerala PMT 2004]
(a) They treat the polluted water
(b) They act as bioindicators of pollutions
(c) They promote pollution
(d) Lichens are not related with pollution
In 1984, Bhopal gas tragedy was caused due to leakage of
In Minamata Bay, Japan, which of the following animals remained free from Minamata disease [CBSE PMT 1995]
(a) Cats (b) Rabbits
(c) Dogs (d) Pigs
How carbon monoxide, emitted by automobiles, prevents transport of oxygen in the body tissues [CBSE PMT 1998]
(a) By chaning oxygen into carbon dioxide
(b) By destroying the haemoglobin
(c) By forming a stable compound with haemoglobin
(d) By obstructing the reaction of oxygen with haemoglobin
Photochemical smog formed in congested metropolitan cities mainly consists of [AIIMS 2003]
(a) Ozone, peroxyacetyl nitrate and
(b) Smoke, peroxyacetyl nitrate and
(c) Hydrocarbons, and
(d) Hydrocarbons, ozone and
The phenomenon in which nutrient enrichment of a water body supports a dense growth of one or may organisms but decreases the species diversity is called [AMU 2005]
(a) Biological magnification(b) Species promotion
(c) Eutrophication (d) None of the above
Read the assertion and reason carefully to mark the correct option out of the options given below :
(a) If both the assertion and the reason are true and the reason is a correct explanation of the assertion
(b) If both the assertion and reason are true but the reason is not a correct explanation of the assertion
(c) If the assertion is true but the reason is false
(d) If both the assertion and reason are false
(e) If the assertion is false but reason is true
Assertion : Inhabitants close to very busy airports are likely to experience health hazards.
Reason : Sound level of jet aeroplanes usually exceeds 160 dB. [AIIMS 2003]
Assertion : There is an adverse effect of pollutants on Taj Mahal.
Reason : Discolouring of Taj Mahal is due to nitrogen oxides.
Assertion : The main cause of Bhopal gas tragedy was phosgene.
Reason : Phosgene is a volatile liquid.
Assertion : causes green house effect.
Reason : Other gases do not show such effect.
Assertion : and rays emit by disintegration of atomic nuclei of radioactive elements.
Reason : Nuclear fall out is shown by radioactive elements.
Assertion : Methylmercury is a highly persistent kind of pollutant that accumulates in food chains.
Reason : Mercury pollution is responsible for Minamata disease.
Assertion : Water pollutants are measured by BOD.
Reason : If BOD is more, the water is polluted.
Assertion : Eutrophication shows increase in productivity in water.
Reason : With increasing eutrophication, the diversity of the phytoplankton increases.
Assertion : Presently, the global atmosphere is warming up.
Reason : The depletion of stratospheric ozone layer has resulted in increase in ultraviolet radiations reaching the earth. [AIIMS 2005]
Assertion : Suspended particulate matter (SPM) is an important pollutant released by diesel vehicles.
Reason : Catalytic converters greatly reduce pollution caused by automobiles.
[AIIMS 2005]
Pollution
1
d
2
c
3
a
4
b
5
b
6
c
7
b
8
d
9
d
10
d
11
b
12
c
13
a
14
b
15
b
16
a
17
c
18
b
19
a
20
a
21
c
22
d
23
c
24
c
25
d
26
b
27
d
28
b
29
b
30
d
31
a
32
d
33
b
34
d
35
c
36
b
37
b
38
c
39
b
40
d
41
b
42
c
43
b
44
b
45
b
46
c
47
a
48
d
49
d
50
c
51
a
52
a
53
a
54
a
55
d
56
b
57
c
58
c
59
a
60
a
61
a
62
a
63
d
64
c
65
a
66
c
67
a
68
a
69
c
70
c
71
c
72
b
73
c
74
a
75
d
76
a
77
d
78
b
79
a
80
b
81
b
82
d
83
d
84
b
85
d
86
a
87
d
88
a
89
d
90
b
91
a
92
b
93
a
94
c
95
e
96
c
97
b
98
a
99
b
100
d
101
c
102
a
103
b
104
a
105
c
106
d
107
b
108
d
109
d
110
d
111
b
112
a
113
d
114
c
115
c
116
b
117
c
118
b
119
d
120
d
121
c
122
c
123
d
124
d
125
c
126
d
127
d
128
c
129
a
130
b
131
d
132
b
133
a
134
c
135
c
136
b
137
a
138
b
139
d
140
d
141
c
142
c
143
c
144
b
145
b
146
c
147
d
148
a
149
a
150
b
151
a
152
d
153
b
154
a
155
d
156
b
157
b
158
b
159
a
160
b
161
a
162
c
163
a
164
c
165
b
166
d
167
b
168
d
169
d
170
b
171
b
172
d
173
b
174
b
175
b
176
c
177
b
178
b
179
c
180
c
181
d
182
a
183
a
Critical Thinking Questions
1
d
2
c
3
c
4
c
5
c
6
b
7
b
8
b
9
c
10
c
11
b
12
c
13
b
14
c
Assertion and Reason
1
a
2
c
3
e
4
c
5
b
6
b
7
a
8
b
9
b
10
b
Pollution
(d) Because this will cause the melting of polar ice caps resulting in a rise of nearly 60 feet on the sea level. Coastal regions and low lying areas all over the world will be go under water.
(c) Important air (gaseous) pollutants are CO, SO2, NOX (Oxides of nitrogen), etc.
(b) Strength of sewage or degree of water pollution is measured in terms of BOD (Biochemical oxygen demand) value.
(c) BOD means number of miligrams of O2 required for decomposition of one litre of waste or waste by decomposing microorganisms (bacteria).
(a) For control of water pollution, sewage oxidation ponds or filter beds or septic tanks or decomposition ponds have been developed. These oxidation ponds have luxuriant growth of algae and bacteria. Algae release O2 and anerobic bacteria break down sewage using this O2.
(c) SO2 causes bleaching of leaf pigment (Chlorophyll) or causes chlorosis and necrosis of vegetation and destroy all membrane activity and convert chl. a to phaeophytin a.
(a) Automobiles are the greatest pollutor of the atmosphere and are responsible for 80% of air pollution of big cities.
(c) Ozone (O3) is secondary pollutants which is formed by the interaction of primary air pollutants.
(c) Lead (Pb) is released by combustion of petrol as tetra ethyl lead is used as antiknock in petrol. This lead is very harmful and causes plumbism or lead poisoning, which disturbs nervous system, liver, kidney’s in adults and also causes brain damage in children.
(c) In the presence of sunlight the hydrocarbons and oxides of N2 react to form O3 and PAN (Peroxy acetyl nitrate) and aldehyde and other organic substance.
(c) 3,4 benzopyrene released mainly in idling of automobiles causes lung cancer.
(b) Most important long lived radioactive substance released in nuclear explosion is Sr90 which accumulate in bone-marrow and cause cancer (leukemia or blood cancer).
(c) Generally sound above 80 dB is termed as noise.
(c) Yellowing and blackening of Taj Mahal at Agra is due to SO2 and other pollutants released by Mathura refinery.
(b) Water pollution is mainly caused by industrial wastes, sewage, insecticide, herbicides, etc.
(b) Because carbon dioxide is necessary for photosynthesis in plants and non-harmful for human beings.
(d) CO is highly toxic and impairs respiration. CO combine with haemoglobin of blood and reduces its O2 carry capacity.
(a) DDT is a non-biodegradable pollutant. These are persistent pollutants and are not decomposed naturally or by activity of micro organisms and thus are not recycled back into the atmosphere.
(a) Plants are more sensitive to SO2 than animals and man. In most plants chlorophyll pigment destroyed under intense exposure to SO2 due to conversion of chlorophyll a to phaeophytin a.
(a) Some organism like Daphnia, Trout and fishes are sensitive to water pollution and they are indicators of water pollution.
(d) BOD µ Water pollution.
(c) Because they are very sensitive to sulphur dioxide and in cities the amount of SO2 is high so lichen do not grow in cities.
(a) Due to nuclear and other conventional sources, temperature of water bodies and atmosphere increases, which has adverse effect on different organisms.
(a) Because he made factories, automobiles etc. which is most polluting.
(d) About 50% of increase in earth’s temperature is due to CO2; 20% due to chlorofluorocarbons.
(a) Because in the presence of oxygen micro-organisms (Bacteria)oxidise the complex organic components to inorganic forms.
(c) Because micro-organisms can decompose complex organic compounds into simple organic compound.
(c) Because the number of automobiles in big cities is very high and automobile exhaust have many atmospheric pollutants like CO, SO2 and oxides of lead etc.
(c) CFC is strong enemy of ozone and causes depletion of ozone layer.
(c) Chemicals released in the atmosphere with force in the form of mist or vapours are called aerosols. Jet aeroplanes release aerosols which contain CFC.
(a) The main precursors of acid rain are SO2 and NO2 in atmosphere which form H2SO4 (Sulphuric acid) and HNO3 (nitric acid) with H2O and these come down with rain. Such rains are called acid rains.
(a) Because increase in percentage of fauna (animals) will increase the amount CO2 in atmosphere and the decrease in flora (plants) will decrease the utilization of CO2 via photosynthesis thereby increasing the percentage of CO2 in atmosphere.
(d) The presence of E.coli in the water indicates faecal pollution.
(d) Because lichens are very sensitive to atmospheric pollution (specially SO2 pollution).
(a) Herbicides (e.g., 2, 4-D, 2, 4, 5-T), insecticides (e.g. DDT, aldrin, BHC) and rodenticides causes water pollution.
(b) SO2 combines with atmospheric water vapours to produce acid rains which imparts yellow colour to the white marble.
(a) The degree of pollution is directly proportional to BOD, therefore more the organic pollution (Specially sewage), the more would be BOD of water.
(c) The excess of fluorine in water causes flourosis. The symptoms of fluorosis are mottling of teeth (yellowish streaks) and abnormal bones liable to fracture etc. It is an example of endemic disease.
(b) Bhopal gas tragedy occured on 3rd Dec. 1984 due to leakage of methyl isocyanate creating air pollution and causing death of about 2500 persons. Chernobyl disastrous tragedy occured on April 26, 1986 due to explosion at chernobyl nuclear power station resulting huge amount of radioactive clouds in the Ucraine atmosphere.
(d) Because USA is the largest consumer of fuel energy.
(a) Sulphur dioxide forms sulphuric acid by reacting with atmospheric moisture (H2O) and causes acid rain.
(b) CO is major pollutant in air exhausted by various automobiles.
(d) In coming years, when the ozone layer becomes thinner or has hole, ultraviolet radiations come directly that causes cancer especially relating to skin like melanoma.
(d) Man has been releasing large quantities of phosphorous into the biosphere in the form of agricultural fertilizers (Superphosphates) and synthetic detergents.
(a) Photochemical smog is formed due to photochemical oxidation (due to action of sunlight) of hydrocarbons and nitrogen oxides. UV light is absorbed by NO2. This highly energised molecule (NO2) decomposes into nitric oxide and atomic oxygen. Atomic oxygen reacts quickly with oxygen to form ozone.
(d) In addition to CO2, some other gases also contribute to green house effect. These include ozone, CFCs, nitrous oxids and even methane. Nitrous oxide is produced by denitrifying bacteria acting on artificial fertilizers applied to poorly aerated soils.
(c) Carbon monoxide is the main air pollutant. It first reduces the oxygen carrying capacity of haemoglobin and then causes asphyxiation.
(b) Pollutant formed by chemical interaction of primary pollutants with atmospheric gas and moisture, often catalysed by sunlight are called secondary pollutants. PAN is one such substance.
(c) PAN prevents photolysis of water in photosynthesis or hill reaction.
(d) Increase in CO2, CFC, SO2 and other substances has disturbed the balance between the amount of energy received and that reflected back into the space. This leads to rise in global temperature.
(c) Silicosis is caused by inhalation of dust containing free silica or silicon dioxide especially by workers engaged in mining, pottery, ceremic industry, sand blasting, building and construction industries.
(d) Reflection of light and heat takes place from plant community and soil. The reflected heat absorb by and produces heating in atmosphere. It is known as green house effect.
(c) DDT is a non-biodegradable pollutant. This often biologically magnified with their subsequent movement in food chain. Its concentration in ‘sea gull’ will be highest.
(d) Aerosol is produced by jets, aeroplanes, trucks and other vehicles. It can decrease the growth and productivity of plant and also cause abscission of leaves.
(a) Radioactive pollution causes gene mutation. It can change the base sequence of DNA
(b) Ozone layer present in stratosphere region. This layer is good ultraviolet radiation absorbent. Due to this property it protects earth from harmful U.V. rays.
(a) In human beings (carbon mono oxide) causes headache and difficulty in breathing. The haemoglobin has greater affinity to CO than oxygen. The Hb.CO reduces the oxygen carrying capacity of haemoglobin.
(c) Domestic wastage are mainly made up of degradable organic compounds.
(d) Large green plants are planted in high noise pollution zone because they have capacity to absorb sound waves and these green plants for checking noise pollution are known as green mufler.
(c) CO is more toxic than CO2 because it bounds with haemoglobin resultant is less amount of haemoglobin to carry oxygenated blood.
(c) Acid rain is the secondary effect of air pollution. The gases like SO2 and NO2 concentration is more in the air then these gases mix with the air moisture in clouds and form H2SO4 or NHO3 acids which come down to the earth in the form of acid rain causing much damage to the living organism (plants, animals).
(b) Ecological balance is the maintenance of an equilibrium between living components of an ecosystem. So the pollution disturbs the ecological balance.
(d) These gases causes global warming of atmosphere which is called ‘green house effect’ and these gases are called green house gases.
(a) A range of sound 70-90 decibles is very loud which is generally occurring during heavy traffic on high ways.
(b) CFCs reacts with ozone and cause its depletion. That is why CFCs are not recommended to be used in refrigerators.
(d) Cadmium accumulation in liver, kidneys and thyroid causes itai-itai (ouch-ouch) disease.
(b) On 26 April, 1986 at the chernobyl power station released a huge amount of radioactive cloud into the atmosphere in which tragedy many peoples were killed.
(b) Hydrogen is not a pollutant where as sulphur dioxide and carbon monoxide are the main constituents of atmosphere pollution. is not a pollutant at normal concentration but higher concentration of cause green house effect.
(a) Aldrin is a organochlorine (Chlorinated hydrocarbon) which is added in building foundations to prevent attack of termites.
(b) In polluted water nitrogen and phosphorous (from sewage) are accumulated which results in excessive growth of algae on water surface. Excessive growth of algae called water bloom. Due to death and decomposition of organic matter O2 not available to aquatic animals.
(a) CO is released in incomplete combustion of petroleum products and automobiles are responsible for production of 74% of total man made CO in atmosphere.
(b) Mercury is very persistent effluent. Higher concentration of Hg causes a serious disease called Minamata disease.
(b) Methane (hydrocarbons), aerosols, freon gas and nitrogen oxides destroy ozone layer in upper atmosphere (stratosphere).
(d) Acid rain is a water pollutant whereas SO2, CO and CO2 are air pollutants.
(b) During waste water treatment
Primary treatment involves physical process of removing the suspended matters.
Tertiary treatment involves the removal of phosphate, nitrate and sulphate.
(d) Eichhornia, Azolla, Lemna, Salvinia, etc. have potential of environmental clean up because they can tolerate, uptake and even accumulate heavy metals and other toxicants in their cells.
(b) Due to addition of domestic sewage, phosphates, nitrates etc. in water body, the water body become rich in nutrients especially phosphates and nitrates ions, as a result of nutrient enrichment water bodies become highly productive or eutrophic and this phenomena is called eutrophication.
(c) Solar energy is not responsible for green house effect instead it is a source of energy for the plants and animals.
Critical Thinking Questions
(d) Lichens (Usnea) are extremely sensitive to SO2 and could be regarded as indicators of SO2 pollution (indicators of pollutants. Lichens have given Indices of Atmospheric Purity (IAP)
(c) CO2 concentration is increasing day by day in the atmosphere. CO2 has capacity of absorbing heat radiation and thus increases global temperature (global warming).
(b) When SO2 pollution in air is much higher. Sometimes, SO2 mixes in the air with small particles of metals near the factories and gets oxidised into sulphur trioxide SO3. These gases are harmful and they react with water to form sulphuric acid (H2SO4) or sulphurous acid (H2SO3) and come down to earth with rain water; it is called acid rain or acid precipitation.
(c) Carbon monoxide when inhaled combines with haemoglobin more rapidly than oxygen. It blocks the oxygen transport by forming stable compound carboxyhaemoglobin. Its prolonged inhalation may lead to death.
Assertion and Reason
(a) Noise level upto 64 dB (decibel) is well tolerated. Prolonged exposure to noise level to 80 dB or more leads to loss of hearing ability, fatigue, nervousness, fever, hypertension, gastric disorder, increase in cholesterol level and dilation of pupil of the eye. As the jet aeroplanes have the noise upto 150-160 dB, the inhabitants in the vicinity of busy airports are likely to experience above health hazards. Maximum noise level is recorded in rockets, e., 180 dB.
(c) The refinery in Mathura has adversely affected Taj Mahal. It is due to and other emissions from refineries, which adversely affected the marble and red sandstone of the building. The crude oil intended to be processed in the Mathura refinery is estimated to contain up to about 2% sulphur. This oxidized to and will be emitted from the chimney of the refinery. Thereafter in the moist atmosphere it is converted to dilute acid which causes decay of stone and marble. also causes discolouring, disfigurement and deterioration of Taj Mahal.
(e) Phosgene is a poisonous and suffocating volatile liquid. Release of phosgene and methyl isocyanate in industrial accident of Bhopal killed over 2500 persons.
(c) Green house effect is due to the occurrence of high carbon dioxide content, high vapour content and glass walls. Gases like are called green house gases because they are transparent to solar radiations (wavelength 0.15 – 4.00 µm) but are strong absorbers of long wave or infra red radiations emitted by the surface of the earth.
(b) The elements that give radiation are called radioactive elements. The radioactive materials are transformed into gases and fine particles which are carried to distant places by wind. When rain drops, the radioactive particles fall on the ground, it is called nuclear fall – out.
(b) Mercury pollution has been responsible for several deaths in Sweden and Japan and has caused the Minamata disease in Japan, chlor-alkali plants seem to be chief sources of mercury containing effluents. Mercury is persistent in water it gets changed into water soluble dimethyl form and enters the food chain accompanied by biological or ecological amplification.
(a) Water pollutants are commonly measured by their main common denominator, called BOD (Biochemical Oxygen Demand), e., the amount of free oxygen absorbed by extraneous substances from water. If water is polluted, it will consume more oxygen, thereby enhancing the BOD of water.
(b) Eutrophication is a natural process which literally means well nourished or enriched. It is a natural state in many lakes and ponds which have a rich supply of nutrients. Eutrophication become excessive, however when abnormally high amount of nutrient from sewage, fertilizers, animal wastage and detergent, enter streams and lakes causing excessive growth or blooms of microorganisms. With increasing eutrophication, the diversity of the phytoplankton community of a lake increases and the lake finally becomes dominated by blue – green algae.
(b) The warming up of global atmosphere present day is due to the increase in green house effect.
Green house effect (GHE) describe the roles of water vapour, CO2 and other trace gases in keeping the Earth’s surface warmer than it would be otherwise. These radiatively active gases are relatively transparent to incoming shortwave radiation (visible spectrum), but are relatively opaque to outgoing reradiating (infrared rays) longwave radiation. The latter radiation, which would otherwise escape to space, is trapped by these gases within the lower levels of the atmosphere. The subsequent reradiation of some of the energy back to the surface maintains surface temperature higher than they would be if the gases were absent (without the green house effect the Earth’s average global temperature would be –18 degree celsius rather than the present 15 degree celsius).There is concern that increasing concentration of the green house gases including CO2, CH4, and man made chlorofluorocarbons (CFCS), may enhance the green house effect and cause global warming.
Ozone layer present in the stratosphere is depleted by the aerosols and chloroflurocarbons. Ozone protects the earth from high energy ultra violet radiation.
(b) SPM (Suspended Particulate Matter) is defined as particles floating in the air with a diameter is below 10 mm. Studies have shown that high SPM concentrations in the air can have a detrimental impact on respiratory organs. SPM is generation from natural sources (e.g., volcanoes or dust storms) and human activities (vehicles, incinerators and industrial plants).
SPM
Other aerosols
Less than 10 mm
Tend to float longer in air due to small size
Less than 100mm
Tend to settle fairly quickly due to comparative heaviness
Catalytic converters is a devices designed to reduce the amount of emissions from automobiles. The current (so-called three-way) systems use a heated metal catalyst to reduce the emissions of carbon monoxide (CO), hydrocarbons, and nitric oxide (NO), all of which contribute to the formation of photochemical smog. In an automobile’s exhaust system, a catalytic converter provides an environment for a chemical reaction where unburnt hydrocarbons completely combust. Hence the combustion process continues but outside the engine combustion chamber where no useful energy is extracted. Toxic car gases such as unburned hydrocarbon (UHC) and carbon monoxide (CO) would not exist if the fuel to energy conversion in the engine were perfect.
(a) Aseptate and multinucleate (b) Septate and multinucleate (c) Aseptate and uninucleate (d) Septate and uninucleate Answer. (b) The mycelium of Aspergillus consist of branch septate hyphae. Cells of hyphae are multinucleate. (184)
(a) Parenchyma (b) Chlorenchyma (c) Plectenchyma (d) Collenchyma Answer. (c) Plectenchyma (Pseudoparenchyma) is nothing but the interwoven mass of fungal mycelium which in cross-section look like parenchyma. (104)
(a) Colletotrichum falcatum (b) Phytophthora infestans (c) Potato mosiac virus (d) Alternaria solani Answer. (b) Late blight of potato is a seed born disease which is caused by Phytophthora infestans. The disease is characterised by brownish to blackish dead areas …
