Chapter 30 Environmental issues, Biodiversity and Conservation by TEACHING CARE online coaching classes Chapter 28 Organisms and Populations by TEACHING CARE online coaching classes

Chapter 30 Environmental issues, Biodiversity and Conservation by TEACHING CARE online coaching classes


  • Tropical deciduous forest extends in largest area in P.
  • In Detritus : ecosystem, producers are
  • Ecotone : The zone of transition between two nearby ecosystems is called an
  • Stability of an ecosystem depends upon Croplands are mostly monocultures and lack diversity.
  • The scientific study of lakes is known as
  • Ecotone is the transitional zone between two vegetation
  • There is the highest species diversity in tropical rain forest
  • Forest occupy 40% of land is In India forests occupy only 22.8% of land area.
  • Energy content are determined by igniting the plant contents in O2 bomb
  • Lindemann gave the low of 10% for energy flow (10% energy transfer law).
  • The species which are restricted to small areas are called


 Environmental pollution.

According to Odum pollution is an undesirable change in the physical, chemical or biological characteristics of our air, land and water that will harmfully affect the human life and the desirable species so that may waste or deteriorate our raw material resources. Pollution is the deliberate or accidental contamination of the environment with man’s waste. Pollution is defined as matter in the wrong place. Pollution produces bad effects on ecological (environmental) balance substances which cause pollution are called pollutants there are two categories :

  • Biodegrodable Pollutant : These pollutant can be decompose by micro–organisms. However if they are released in large amount then they begin to accumulate in environment. When their concentration crosses a critical limit then they become toxic and start acting as
  • Non–biodegradable pollutant : These pollutant can not be decomposed by micro–organism. e.g., DDT, BHC, Aldrin, Plastics, Hg, Salfs These pollutants are continiously accumulating in our environment.

Types of pollution : Pollution is classified into the following types :

(1) Air pollution  (2) Water pollution    (3) Land pollution  (4) Noise pollution   (5) Thermal pollution.

  • Air Pollution : Air pollution refers to the undesirable change occurring in air causing harmful effects on man and domesticated
    • 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 There is 0.03% CO2 in the air its higher percentage is the cause of green house effect.

Types of air pollutants : It is two types :

  • Primary air pollutants : Air is polluted by poisonous gases and undesirable substances. They are released by burning fossil These substances are called primary air pollutants. The primary air pollutants are the following :
  • Soot released from unburned
  • Sulphur dioxide (SO2).
  • Benzopyrene (hydrocarbon) released from cigarette
  • Ammonia (NH3).
  • Oxides of




  • Carbon monoxide (CO).
  • Lead (Pb).
  • Secondary air pollutants : Secondary air pollutants are poisonous substance formed from primary air 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.
    • Causes of air pollution
  • Agriculture : Hydrocarbons released by plants, pollen grains, insectisides cause air pollution.
  • Dust : Dust in the air is increased by dust storms wind, volcanoes, automobiles,
  • Industries : Combustion of fossil fuels like coal, petroleum, Industrial smoke is the main source of pollution.
  • Automobiles : The combustion of petrol and diesel in automobiles releases harmful gases into the They also produce dust.
  • Ionising radiations : Ionizing radiations include alpha particles, beta particles and gamma rays. They are released into the air on testing atomic
  • Freons : Use of freons and other chloro-fluoro-carbon compounds in refrigerants, coolants and as filling agents in aerosol also cause
  • 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 They may also change the climate of an area.

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.,

  • The tissues present in the tip of dusheri mango turns black when they are exposed to sulphur dioxide (SO2)
  • Pinto beans and Petunias are used to indicate the presence of peroxy acetyl nitrate (PAN).
  • 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.
    • Ecological effects of air pollution
  • Death : When air is polluted with poisonous gases, death comes as a result Bhopal episode is a good example. Bhopal episode – On 2nd December 1984 about 3000 human beings died, about 5000 paralysed and thousands of cattles, birds, dogs and cats died in one night at Bhopal. This mass death is due to the leakage of methyl isocyanate (toxic gas) into the air from an insecticide plant managed by Union Carbide Corporation.
  • Chlorosis : The disappearance of chlorophyll is called It is caused by SO2, nitrogen dioxide, ozone and fluorides.
  • Necrosis : The breakdown of cells is called It is caused by SO2, nitrogen dioxide, ozone and fluorides.
  • Green house effect : CO2 is released into the air by the combustion of 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. It is very likely that 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.




  • Not only CO2 but CFC and to some extent methane and oxides of nitrogen disturb the temperature of earth hence they all are described as green houses
  • 0 pH has been recorded in acid rain.
  • 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
  • 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
  • Nausea : H2S smells like rotten eggs and causes
  • Vomiting : SO2 causes
  • Jaundice : Arsines induce RBC breakdown and
  • Oxygen carrying capacity : CO reduces O2 carrying capacity of RBC by its permanent combination with
  • Coughing : Coughing is induced by phosgenes (carbonyl chloride).
  • Headache : SO2 causes
  • Cancer : Cancer is caused by air pollutants like ash, soot, smoke, chromium, nickel and readioactive
  • Mutation : Radioactive elements produce Ozone produces chromosomal aberrations.
  • Cardiac diseases : Cadmium causes high blood pressure and heart
  • Pneumonia : Pneumonia is caused by breathing in too much of manganese
  • Depletion of Ozone umbrella : In the atmosphere, about 30 km above the surface of the earth, the ozone molecules (O3) form an 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.
  • 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 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. The main source of releasing




oxides of sulphur and nitrogen are the power plants based on coal and oil. They contribute more than 60% of all sulphur oxides and 25 to 30% of nitrogen oxides in the atmosphere. Automobiles make a substantial contribution in large cities. Ozone is now recognised as a major factor in the formation of 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. The concentration of SO3 in atmosphere is around 0.01 ppm.

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.

  • Control of air pollution
  • The emission of exhaust from automobiles can be reduced by devices such as positive crankcase ventilation valve and catalytic
  • Electrostatic precipitators can reduce smoke and dust from
  • Gaseous pollutants arising from industries can be removed by differential solubility of gases in
  • A finepray of water in the device called scrubber can separate many gases like NH3, SO2, etc. from the emitted
  • Certain gases can be removed by filtration or absorption through activated
  • Certain gases can be made chemically intert by chemical
  • At the Government level pollution can be controlled by framing
  • Vehicles based on compressed natural gas (CNG) should be
  • Water Pollution : Water pollution refers to the undesirable change occurring in water which harmfully affect the life activities of man and domesticated
    • 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
    • Causes of water pollution
  • Domestic sewage : Domestic sewage consists of human faces, urine, and the dirty used–up water in 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.
  • 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 The industrial wastes include heavy metals (Hg, Cu, lead, zinc etc), Detergents, Petroleum, Acids, Alkalies, Phenols, Carbonates, Alcoholcyanides, Arsenic, Chlorine, etc.
  • Thermal pollution : Many industries use water for cooling. The resultant warm water is discharged into This brings about thermal pollution.
  • Agricultural pollution : The fertilizers used for crops are washed into ponds and




  • Pesticides : Pesticides are used to control pests in fields and houses. They include DDT, BHC, endrin
  • Radioactive wastes : Liquid radioactive wastes are released into the sea around nuclear The oceanic currents carry the radioactive contaminants every where.
  • 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 after 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
  • Eutrophication : Rich growth of micro-organisms consumes most of the dissolved oxygen, so as to depreve other 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.
    • Control of water pollution : Pollution control by sewage treatment includes the following steps :
  • Sedimentation : When sewage is allowed to stand, the suspended particles settle to the bottom. So by sedimentation the suspended particles are removed from
  • Dilution : The sewage can be diluted with water. This increases the O2 contents and reduces BOD and CO2.
  • Storage : The diluted sewage is stored in a This facilitates the growth of micro-organisms. This renders further oxidation of sewage.
    • Waste stabilization pond or Oxidation pond : The National Environmental Engineering Research Institute (NEERI) at Nagpur has devised a very economical method for the treatment of industrial and domestic 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–oranisms 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.
    • Recycling : Pollution can be prevented to a certain extent by reutilizing the wastes. This is called 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 Certain pollutants from industrial effluents can be removed by filtrationand selective absorption. Excessive use of pesticides and herbicides should be avoided. At the Government level, legislations should be framed to control water pollution.
  • Land pollution : The undesirable change in the land that harmfully affect the life activities is called land
    • 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 The main sources of land pollution are pesticides, radioactive elements and fertilisers.
    • Pesticides : Pesticides are chemicals used to kill pests like insects, rats, snails, fungi, herbs, etc. They are collectively called biocides because they kill They are of the following types :
  • Insecticides : There are chemicals used to kill insect
  • Rodenticides : These kill




  • Fungicides : These kill
  • Herbicides : These kill
  • Helminthicides : These kill helminth
  • Chemistry of pesticide : Based on chemical composition, pesticides are divided into following main They are :
  • Chlorinated hydrocarbons : DDT (Dichloro diphenyl trichloroethane), aldrin, dieldrin, endrin, benzene hexa chlorids (BHC) and their close relatives form chlorinated hydrocarbon. They are very poisonous, very persistent, highly mobile and highly capable of dissolving in As they have higher affinity for fat, they tend to move out of the physical environment and enter the living organisms. They are non–degradable pollutants.
  • Organic phosphorus pesticides : These include arsenic and sulphur These are much less in use.
  • Ecological effects of pesticides
  • Mutation : Insecticides induce gene mutation in human beings (Wurster, 1974).
  • Cancer : DDT produces cancer in human
  • Congenital birth defects : Certain herbicides like diozan increase birth defects in both people and
  • Sex hormones : DDT affects sex hormones in mammals and
  • Decline of reproduction : In Bermuda petral, a sea bird, the rate of hatching of eggs is much reduced because of the accumulation of 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
  • Biomagnification : The pesticides are non–degradable. They have much affinity towards fat. Hence they tend to move into the living 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.
  • Control of pesticide pollution
  • Minimum use : Pesticides should be used at minimum rates and that to only when
  • Biological control : Pests should killed either by rearing predators or
  • Sterilization : Juvenile hormones prevent metamorphosis and maturation in
  • Decoy plants : Pests can be minimised in high value crops by cultivating low value
  • Rotation of crops : Different types of crops should be cultivated in different
  • Radioactive pollution : This pollution occurs through Radiations are of two types.
  • Non ionising radiations : UV rays, IR rays, UV rays cause skin burning, IR rays increases atmospheric temperature and leads to the green house effect.



  • Ionising radiation : X rays, b -rays, g -rays, x – rays cause genetic injury on

Certain elements continuously disintegrate by emitting ionizing radiations. These elements are called radioactive isotopes. Ecologically important radioactive elements are Strontium-90, Argon-41, Iodin-131, Cobalt- 60, Cesium – 137, Plutonium – 238, etc. Among these Sr-90′ is the most dangerous radioactive pollutant.

  • 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 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
  • Gamma rays : These are short wavelength rays emitted by radioactive 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.
  • Internal emitters : The alpha and beta particles have low penetrating power. Hence they produce their effect in organisms only when they are ingested into the Hence these are called internal emitters.
  • External emitters : The radiations with short wave length like gamma rays have high penetrating They can affect the internal tissues even when they remain outside by virtue of their high penetrating power. Hence they are called external emitters.
    • Fall outs : Atomic blasts and nuclear explosion release radioactive isotopes into the atmosphere. These radioactive isotopes fall over the earth from the atmosphere continuously for a long time. Hence they are called fall- outs or nuclear fall-outs or radioactive fall-outs. These fall-outs contaminate the air, soil, water, vegetation and The contaminants persist for several years.
    • Ecological effects of radioactivity : Radioactivity causes the following effects : Cancer, Leukaemia, Mental retardation, Congenital malformations, Retarded growth, Deleterious mutations, Infant mortality.

 Biogeochemical cycle.

Organisms are built up on chemical substances. They require certain chemicals like N2, O2, H2, P, C, etc. continuously for their survival. These chemicals enter the organisms from the environment and come out after undergoing changes or without changes. Thus these elements tend to circulate in a characteristic path from the environment to the organism and back to the environment. This cyclical path of the elements from the abiotic system to the biotic system and back is called biogeochemical cycles (Bio = living organism; Geo = water, air, earth). As these chemicals form the components of food, these cycles are also called nutrient cycles.

  • Phases of biogeochemical cycles : Each biogeochemical cycle has two phases, namely the biotic phase (organic phase) and the abiotic
  • Biotic phase : It refers to the flow of chemicals in the living organisms through food
  • Abiotic phase : It refers to the distribution and flow of chemicals in the non-living
    • Types of biogeochemical cycles : The biogeochemical cycles are classified into two types, namely gaseous cycles and sedimentary




  • Gaseous cycles : In gaseous cycles the main reservoirs of chemicals are the atmosphere and ocean. e.g. Carbon cycle, N2 cycle, O2 cycle
  • Sedimentary cycle : In sedimentary cycles the main reservoirs are soil and e.g., Sulphur cycle, phosphorus cycle, etc.
    • Important biogeochemical cycles
      • Carbon cycle (ii) Nitrogen cycle  (iii) Oxygen cycle      (iv) Phosphorus cycle (v) Sulphur cycle
    • Carbon Cycle : The cycling of carbon between biotic and abiotic systems is called carbon It is a gaseous cycle. The main source of carbon is the carbon dioxide (CO2). CO2 is present in the air and water. Air is the main reservoir. CO2 content of air is 0.03%. Its amount remains


  • Flow of Carbon into the biotic system : Carbon flows into the biotic system in two ways :
  • Photosynthesis : Carbon enters the biotic system through photosynthesis. In photosynthesis green plants utilize CO2 and incorporate the carbon of CO2 in glucose. Glucose is used for the synthesis of other types of carbohydrates, proteins and These compounds, containing carbon, are stored up in the plant


tissues. When plants are eaten up by herbivores, the carbon flows into the body of herbivorous animals through food chain. When

herbivores are eaten by carnivores, the carbon enters the body of carnivorus animals.

6CO2 + 6H2O ® C6H12O6 + 6O2.


Fig: Carbon cycle


  • Formation of shell : The CO2 dissolved in sea water is utillized by the marine animals like protozoans, corals, molluscs, algae, etc., for the construction of shell. In these animals CO2 is converted into calcium carbonate (CaCO3) which is used for the construction of

CO2 + H2O ® H2CO3 (Carbonic acid)

H2CO3 ® H+ + HCO3 (Bicarbonate)

HCO3 + Ca+ ® H+ + CaCO3 (Calcium carbonate)

  • Flow of Carbon into the abiotic system : The carbon of the biotic system flows into the abiotic system in five ways :
  • Respiration : Plants and animals release CO2 by respiration (biological oxidation).

C6H12O6 ® CO2 + H2O + Energy

  • Decomposition : When plants and animals die, the dead bodies are decomposed into CO2 by decomposers like bacteria, algae,
  • Shells : After the death of marine animals, CaCO3 stored in the shells is either deposited as sedimentary rocks or dissolved in water to release CO2 by the reversion of the above said reactions.
  • Coal : A certain proportion of carbon from plants is deposited as Carbon from coal returns to air in the form of CO2 through combustion and weathering.




  • Forest fire : Combustion of wood in the forest, releases carbon from plants in the form of CO2.
  • Nitrogen cycle : The cycling of nitrogen between abiotic and biotic systems is called nitrogen It is a gaseous cycle. The main source of N2 is air which contains 79% N2.
  • Flow of Nitrogen into the biotic system : Nitrogen is an important nutrient of But plants cannot utilize free N2 of air. They obtain N2 from ammonium salts, nitrites and nitrates. These compounds are formed from atmospheric N2 by a process called nitrogen fixation.

Nitrogen fixation is a process by which atmospheric free N2 is converted into soluble salts like nitrites and nitrates. It occurs in two ways namely electrochemical fixation and


biological fixation.

  • Electrochemical fixation : A certain amount of

Fig : Nitrogen cycle


free N2 is fixed by the action of lightning. The amount of nitrate formed by this method is about 35 mg/m2/year.

  • Biological fixation : It refers to the conversion of free N2 into soluble salts by the activity of certain These organisms are called N2 fixing organisms. The amount of nitrate formed by this method is about 140 to 700mg/m2/year, and in a fertile area it exceeds 20000 mg/m. The N2 fixing organisms are bacteria, blue green algae, fungi and other micro-organisms. e.g. Rhizobium, Azotobacter, Closteridium, Bacillus, Nitrosomonas, Nitrococcus, Nitrobacter, Anabena, Nostoc, etc.

The fixed N2 is absorbed by plants through the root system and is incorporated into the proteins. When herbivores feed on these plants, the N2 flows on the carnivores through food chain.

  • Flow of Nitrogen into the abiotic system : The nitrogen of the biotic system flows into the abiotic system by four methods, namely decomposition, excretion, denitirfication and
  • Decomposition : Plants and animals contain nitrogen in their body protein. After death, the proteins of dead bodies are decomposed by decomposers into amino acids and ammonia. The convertion of protein from dead bodies into ammonia by decomposition is called ammonification. This ammonia may be converted into nitrates or free



Protein in dead bodies

¾¾Am¾mo¾ni ®







  • Excretion : Animals excrete nitrogenous waste products in the form of ammonia, urea and uric acid. These compounds are decomposed to release N2.





  • Denitrification : The conversion of nitrate into ammonia or free nitrogen is called denitrification. This is done by denitrifying e.g., Pseudomonas.These bacteria utilize the O2 present in the nitrate for the oxidation of carbohydrate.
  • Sedimentation : Some amount of nitrate is lost from the ecosystem by



  • Oxygen cycle : The cycling of O2 between biotic and abiotic systems is called O2 It is a gaseous cycle. Air is the reservoir for O2. O2 enters the biosphere through respiration. The O2 taken into the body is used for oxidation of carbohydrates, proteins and fats. Certain amount of O2 in atmospheric air is converted into ozone (O3) the ozone forms an umbrella-like layer in the outer atmosphere. This layer prevents the ultraviolet radiations from reaching the earth’s surface.


C6 H12 O

® 6CO2 + 6H 2O +



O2 + O ® O3

Carbon monoxide is released from volcanoes. This CO is unstable. It combines with O2 to form CO2.

O2 combines with a variety of elements to form compounds. For example, it forms CO2 with carbon, water with hydrogen, nitrates with N2 ferric axide with iron etc. O2 returns to air by two main methods, namely photosynthesis and photodissociation.

O2 + C ® CO2

O2 + 2H 2  ® 2H 2 O

O2 + N 2  ® NO3

  • Photosynthesis : Green plants synthesize carbohydrate by photosynthesis. During photosynthesis water molecules break up into hydrogen and oxygen. O2 is released into the atmosphere and H2 is trapped and turned into

12H 2 O + 6CO2 ® C6 H12 O6  + 6H 2 O + 6O2

  • Photodissociation : Water vapour is dissociated to release H2 and O2, in presence of
  • Phosphorus cycle : The cycling of phosphorus between biotic and abiotic system is called phosphorus It is a sedimentary cycle. Phosphorus is an
Phosphate in soil

important mineral nutrient. The main source of phosphorus is rocks. Through erosion and weathering phosphorus is made available in the soil. Plants absorb ionic phosphate through roots. In plants it is incorporated into the protoplasmic components like DNA, RNA, AMP, ADP, ATP, GDP, GTP, NADP, phospholipids etc. from plants, it passes into herbivores and animals, the organic

molecules containing phosphate are decomposed and

Fig : Phosphorus cycle




phosphate is liberated as inorganic ion phosphate. It is again used by plants.

The excess of phosphate in the bodies of animals is excreted out through faces. The bird guano (excreta) contains a large amount of phosphate. Phosphate is also released to the soil through the combustion of forest trees and grasses. A large amount of phosphate is lost in the sea by sedimentation. A certain amount of phosphorus gets locked in bones and teeth.

  • Sulphur cycle : The cycling of sulphur between biotic and abiotic systems is called sulphur It is a sedimentary cycle. Sulphur is an important component of proteins and amino acids.

Sulphur exists in a number of states. Of these, three are important. They are elemental sulphur, sulphides and sulphates. Sulphur is present in is made available for plants in the form of inorganic sulphate by weathering and erosion. Sulphur passes into the animals through food chain. By the death of plants and animals, the decomposers again bring the sulphur to the soil for the use of plants.

Some sulphur in dead bodies is released into the air as hydrogne sulphide (H2S) by the bacteria called Escherichia coli under anaerobic combustion. Similarly incomplete combustion of fossil fuel releases sulphur dioxide (SO2) into the air.

Certain bacteria (green and purple photosynthetic bacteria) oxidise H2S of air to sulphate which can be used by plants.

H2S + 2O2 ® SO4 + 2H+

Certain amount of sulphur is lost in the sediments. If iron is present in the sediments, sulphur combines with it to form iron sulphide.

Fe + S ® FeS

Important Tips

  • CO2 is not a normal air
  • There is 0.03 % CO2 in earth’s atmosphere. Rise in the amount of CO2 causes green-house effect.
  • Primary air pollutants : These are CO, SO2, NH3,
  • Secondary air pollutants : These are poisonous substance formed from primary air (1) Nitrogen oxide (2) O3 (3) Sulphuric acid.
  • Methyl isocynate was responsible for Bhopal tragedy on December, 1984 which was used in production of savin insecticide in union
  • Hg is known to cause nervousness (reduces the nerve impulse).
  • Drinking water rich in nitrates cause methane globenemia (circulatory and respiratory system are affected).
  • Ozone day : September 16th.
  • Lichen and mosses are the first plants to die in SO2 polluted environment and hence act as indicators of air pollution (especially SO2 pollution). These are thus called indices of atmospheric purity (IAP).
  • coli, Wolffia, Chara and Utricularia are indicators of water pollution.
  • Gombusia (fish) was introduced in to several tropical regions to control

Anything which is useful to man or can be transformed into a useful product or can be used to produce a useful thing can be referred to as a resource. A natural resource is the resource obtained from nature. It is these natural resources which form the very basis of entire life on this planet. A natural resource can be of the following two types : living (biotic) or non-living (abiotic).




  • Biotic resources : A resource is directly or indirectly derived from photosynthetic activity of green plants. Food, fruits, wood, fibre, milk, milk products, fish, meat and leather are termed as biotic Coal, oil and natural gas are also biotic resources as they were produced by photosynthetic activity of plants which occurred millions of years ago.
  • Abiotic resources : Mineral material, fresh water, rocks, salts and chemicals etc. are termed as abiotic resources as biological activity is not involved in their
    • Types of natural resources : The natural resources can be classified into three categories :
      • Renewable resources
    • Renewable resources are those resources which can be regenerated.
    • These are mostly biological in nature and include forestry, agriculture, animals (biomass-based)
    • These can be reproduce itself in nature and we may harvest them continuously through a sustained proper planning and management. Solar energy, wind energy, water energy (tides) and geothermal energy belong to this category, since these are available in an inexhaustible form in
      • Non-renewable resources
    • They are physical resources like coal, oil deposits, natural gas, minerals, soil, metals
    • These are available in nature only in limited amounts and cannot be
    • Coal, petroleum and natural gas are the common sources of They, being of organic origin, are also called fossil fuels.
    • These account for 90% of the worlds production of commercial, energy, hydroelectric and nuclear power accounting for only 10%. The figures are :
Oil 39.5%
Coal 30.3%
Natural gas 19.6%
Hydro-electric 6.7%
  • Their formation requires millions of years which can not occur within the human scale of Similarly, metals and minerals come from deposits developed by a very slow process of geo-chemical concentration which look millions of years to form.
    • Inexhaustible resources
  • The total amount of atmosphere, water, rocks and solar energy can never get
  • Similarly solar energy is

At present all the developing countries of the world have started to realize that there is a conflict between environment and development. The problems of human environment derive essentially from these factors :

  • The first is the expansion at geometric rates of
  • The second is a one-sided application of technology to achieve certain goals without the consideration of the effects of this technology on the human environment or on man
  • The third is the lack of control over the use of




  • Conservation : It may be defined as the most efficient and most beneficial utilization of the natural Conservation is also defined as the rational use of the environment to provide a high quality of living for the mankind.
  • Aim of conservation : The true aim of conservation, thus, includes
  • To insure the preservation of a quality environment that considers aesthetic, recreational as well as product
  • To insure a continuous yield of useful plants, animals and materials by establishing a balanced cycle of harvest and
  • Living resource conservation has three specific objectives
  • To maintain the essential ecological processes and the life support system : This system has five elements (air, water, land, flora and fauna) which are interconnected, interrelated and interdependent; deterioration in one inevitably affects the other four
  • To preserve the biological diversity : It includes two related concepts genetic diversity and ecological diversity. The genetic diversity is the amount of the genetic variability among individuals of a single species (intraspecific genetic variability) as also between species (interspecific genetic variability). The ecological diversity means the species richness. It is the number of species of the flora and fauna found in a region (for example, India has about 45,000 species of plants and about 65,000 species of animals).
  • To ensure that any utilization of the species and ecosystems is sustainable : In fact, natural resources may be conserved by efficient utilization which requires a proper balance between the supply and Sustainable utilization means planned utilization so that a continuous yield of the useful plants, animals and materials may be obtained.
  • The conservation of the following resources is necessary
  • Minerals : Until recently little attention was paid to the conservation of mineral resources because it was assumed that nothing could be done to save them anyway. But now these assumptions have proved wrong and it is believed that severe shortages would develop The conservation of minerals, therefore, has become a serious concern for conservationists all over the world.
  • Forests : The need for the scientific management of forests was recognised in our country in the long But in our last five-year plans there has been a lack of appreciation of the potential of forestry which could play a great role in the economic growth of the country. Forests not only provide timber, pulpwood and fodder; they are also important in controlling soil erosion, floods etc.

Silviculture is the term for forest management which deals on ecological principles, with the establishment, growth and reproduction of timber trees and other organisms.

  • Wild life : The terms “wild life” refers to any living organisms in its natural It includes all plants, animals and microorganisms except the cultivated plants and domesticated animals.
  • Importance of wild life : Ecological value, Economic value, Scientific value, Gene banks, Sport and Enjoyment, Aesthetic value, Cultural
  • Causes of destruction of habitat : Destruction of habitat, Hunting, Introduction of exotic species, Disturbance in migratory routes, Legal




  • Concept of threatened species : The rare species of plants and animals have been categorised as under for conservation purposes by the IUCN (International Union for Conservation of Nature and Natural Resources). Conservation means “the management of human use of the biosphere so that it may yield the greatest sustainable benefit to present generation while maintaining its potential to meet the needs and aspirations of future ” The national protection programmers must be coordinated with the international programmes, especially.

The biosphere reserve programme of the UNESCO’s Man and the Biosphere project.

National parks and protected areas of International Union for Conservation of Nature and Natural resources.

The Government of India passed the Wild life (Protection) Act in 1972, under which national parks and sanctuaries were created. Creation of biosphere reserves has also been put into practice since 1986. A National park is an area, which is strictly reserved for the betterment of the wild life, and where activities like forestry, grazing or cultivation are not allowed. There are 66 national parks in India. In a sanctuary, protection is given only to the fauna and operations like harvesting of timber, collection of minor forest products and private ownership rights are permitted so long as they do not interfere with well being of animals. There are presently 368 sanctuaries in India

The union and state governments have launched several afforestation programmes. The Social Forestry Programme, started in 1976, seeks the use of public and common land to produce firewood, fodder, and small timber for the use of the rural community to reduce pressure on existing forests needed for soil and water conservation.

Some national parks and sanctuaries


Gir National Park, Junagarh (Gujrat)
Corbett National Park, Nainital (U.P.)
Ranthambore National Park, Savai Madhopur (Rajasthan)
Kanha National Park (M.P.)
Manas Sanctury, Barpeta (Assam)
Kaziranga National park , Jorhat (Assam)
Desert National Park, Jaiselmer(M.P.)
Bhitar Kanika Sanctuary, Cuttack (Orissa).
  • Ranges : The conservation and management of ranges or pastures for our grazing animals is also a part of the programme for the conservation of The important techniques of range management are :
  • Stock level : The number of grazing animals has to be regulated to the rate of production e., they could be maintained in normal productive years and could be sold out in drought years.
  • Deferred grazing : The range may be divided into compartments where grazing is regulated in such a way that in each component grazing year is followed by a non-grazing
  • Fire : The use of fires to regulate these useful grasses is a common
  • Soil erosion : Top soil is the vital part of the soil and serves as the chief source of nutrition for plants (feeding zone). Loss or disturbance of top soil by natural agents like water, wind, gravity or ice is called soil

Soil erosion has been called ‘creeping death of the soil’ by Rama Rao. Soil erosion is of two types :



  • Geological or Natural erosion : It is caused by
  • Accelerated or Artificial erosion : It is caused by man and

Types of soil erosion

  • Water erosion : It is caused by fast running water or by continuous heavy It may be :
  • Sheet erosion : Due to heavy rain, top fertile soil is removed in the form of thin
  • Rill erosion : Fast running water cut stream or groove like structure in
  • Gully erosion : On steep slopes, fast running water cuts the soil deep and form channel like structure called
  • Rparian erosion : During floods fast running water cut off the margins of river. Due to heavy rains the minerals are also lost from top soil and soil becomes less
    • Wind erosion : Soil erosion by wind is common in dry places and most servere in arid regions where soil is chiefly sandy and the vegetation is poor or even

The wind throws away smallest soil particles into air where they get suspended giving a dusty appearance to the air. It is called suspension. By this method the soil particles are transported to longer distance.

  • Land slide or Slip erosion : The hydraulic pressure caused by heavy rains and gravitational force cause the fall off the rocks in hilly
  • Overfelling (Deforestation) and Overgrazing erosion : These process reduce vegetation thus make the soil surface open for erosion (sheet erosion).
  • Soil conservation : Prevention of soil erosion is called as soil
    • Methods of soil conservation
  • Strip copping : Crops are arranged in bands or strips to check the flow of
  • Crop rotation : Crop rotation is the method of alternative sowing of leguminous and cereal crops (wheat , maize). The rotation of crops can be planned depending upon the climatic conditions, type, slope and properties of

Such crops which check soil erosion should be sown during the rainy season. Legumes are useful in rotation of crops because of having nodulated roots. Soil fertility is usually maintained in the field by rotation of crops. The minerals which are consumed by cereal crop in first year are again supplied by leguminous crops in the second year.

  • Reforestation or Afforestation : Growing of forest trees is most effective in controlling soil Afforestation also helps in prevention of floods. Indiscriminate felling of trees have resulted in the formation of extensive ravines along Yamuna and Chambal area. The Government of India has introduced the festival of ‘Van Mahotsava’. In this festival planting of trees is done on open waste land.
  • Terracing : Hilly slopes are divided into small flat fields called as terraces to check the flow of
  • Contour farming : It is the oldest method in low rain fall area. Field is divided in furrow and ridges. Ridges at same level called as
  • Green manuring : Basically its practice is meant for increasing soil fertility but it also checks soil
  • Dry farming : A practice for cultivation of crops in low and moderate rainfall
  • Mulching : Basal plants parts are used to make a soil cover which help in moisture




  • Water : Water is one of the most important renewable resources and the conservation of our natural sources of water is very In many places water is the chief and most powerful erosive factor and floods result due to the overflow of water from the river banks. Thus, the control of floods is also a serious concern for the conservationists. It has been already pointed out that afforestation helps a lot to minimise losses caused by floods and siltation of dams.
  • Fisheries : Fishes are also one of the important biotic resources and are greatly valued by man as food. Unfortunately, in the last few year fish fauna of our inland waters has greatly deplected on account of overexploitation and pollution of natural waters due to sewage and industrial wastes. It is therefore, necessary that these colourful creatures of our aquatic environment should be preserved. Fishery managers have developed many techniques to improve fish Some are :
  • Large, artificial fielding reefs in the offshore waters of the oceans and freshwater lakes to provide hiding places and additional food which attracts the
  • Spawning channels to replace vital spawning areas destroyed or no longer
  • Fix toxicants to destroy undesirable fish populations and restore the balance in favour of the game or commercial
  • Weed
  • Fertilization and artificial
  • Various in-stream devices to make pools, provide cover, wash out slit,
  • Aeration and recirculation of lakes and
  • Conservation of biological diversity
  • Lately it has been felt throughout the world that the conservation of biological diversity is one of the most important challenges of the present and immediate Diversity characterizes most living organisms and our earth supports something like 5 to 10 million species of plants ands animals (IUCN, 1980).
  • Two convenient approaches for conservation of biological diversity are in-situ conservation and ex-situ


  • In-situ conservation : It means the conservation of living resources through their maintenance within the natural ecosystems in which they It includes a comprehensive system of protected areas such as the national parks, sanctuaries, nature reserves, natural monuments, cultural landscapes, biosphere reserves and several others.
  • Ex-situ conservation : It includes conservation outside the habitats by perpetuating sample populations in genetic resource centres, zoos, botanical gardens, culture collections , or in the form of gene pools and gamete storage for fish; germplasm banks for seeds, pollen, semen, ova, cells, etc.

Important Tips

  • Biological diversity day : 29th
  • National Pollution Preservation day : 2nd
  • Ganga action plan for controlling pollution in Gange’s started in
  • Chipko movement was born in March 1973 in Gopeshwar in Chamoli when trees were not allowed to be cut by village The movement has two leaders Chandi prasad Bhatt of Gopeshwar and Sunderlal Bahuguna of Silyara in Tehri. A similar appiko movement was under taken by Pondurang Hedgo in South.
  • Van Mahotsav was started by M. Munshi in 1950.
  • Richard Barbibaker is known as “tree saint in India”.
  • Wild life Institute of India is located at Dehradun (Uttaranchal).
  • Red Data Book : It is the compilation of data on species threatened with
  • Some Abbreviations




CAZRI : Central Arid Zone Research Institute (Jodhpur).

CPCB : Central Pollution Control Board.

IBP : International Biological Programme.

IUCN : International Union for Conservation of Nature and Natural Resources.

MAB : Man and Biosphere Programme.

NEERI : National Environmental Engineering Research Institute.

WWF : World Wild life Fund (World Wide Fund for Nature).

UNEP : United Nations Environment Programme.

CPHERI : Central Public Health Engineering Research Institute at Nagpur.

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