2nd PUC Biology Notes Chapter 16 Environmental Issues

Karnataka 2nd PUC Biology Notes Chapter 16 Environmental Issues

Pollution

Pollution and the Important Types of Pollutants

→ As Odum defines, pollution is the undesirable change in physical, chemical and biological characteristics of our environment, adversely affecting human health and life of domestic animals.

→ Pollution is also defined as the unfavourable alteration or contamination of our environment, largely as a result of human activities.

→ The pollution causing factors are called pollutants. Some of the important types of pollutants are described as follows:

• Bio degradable pollutant
• Non-bio degradable pollutant
• Primary pollutant
• Secondary pollutant and
• Biological pollutant.

Bio degradable pollutants: Bio degradable pollutants are those that undergo natural process of bacterial decomposition and are reduced to less stable, less toxic and less harmful substances. They,pose pollution problems only when the rate of their accumulation (dumping) exceeds the rate of decomposition, e.g. Cowdung, Sewage and organic wastes including dead bodies of plants and animals.

Non-bio degradable pollutants: Non-bio degradable pollutants are those that undergo little or no degradation and hence they are more stable, more toxic and more harmful pollutants. They pass through food chains and reach the body tissues of top consumers including man where they gradually build up to toxic level. This process is called biological magnification, e.g. Plastics, metallic dust like mercury salts at high concentration, lead, cadmium and pesticides like D.D.T., concrete, glass etc.

Primary pollutants: Primary pollutants are those that are causing pollution of the environment, as soon as they are released from their sources, like automobiles and industries, e.g. Carbon monoxide, sulphur dioxide, oxides of nitrogen, hydrocarbons, lead, smoke, soot and dust etc.

Secondary pollutants : They are formed by the combination of two or more primary pollutants. For example,
a. Sulphur dioxide combines with the atmospheric moisture to form sulphuric acid as secondary pollutant responsible for acid rains.

b. Oxides of nitrogen combine with hydrocarbons in the presence of UV rays of sunlight to
form secondary pollutants, e.g: Ozone and Peroxy acetyl nitrate (PAN). They in turn combine with atmospheric fog and dust to form a poisonous cloud called Photochemical smog.

Biological pollutants: Biological pollutants are those that have a biological origin. They include viruses, bacteria, dust mites, pollen dust and fungal spores.

Air Pollution:

It is undesirable change in physical, chemical and biological characteristics of air adversely affecting human health and life of domestic animals. It is the increase of all other gases in the atmosphere except oxygen.

Types of air pollutant and sources:
→ Carbon monoxide, sulphur dioxide, oxides of nitrogen, hydrocarbons and lead are released from the incomplete combustion of oil, coal and wood during domestic and industrial burnings, automobile exhausts and other transporters like marine vessels, railways and air crafts.

→ Benzopurines released from tobacco smoke, automobile exhaust and industrial processes.

→ Chloro fluro carbons (CFC) released from the manufacturing unit of refrigerators, airconditioners and aerosol sprays.

→ Smoke and soot released from the chimneys of industries and from forest fires.

→ Dust dump into air during dust starps and volcanic eruptions.

→ Ionising radiations like a, b and g-rays released from atomic explosions and nuclear reactors.

→ Biological pollutants like dust mites, virus, bacteria, fungal spores and pollen dust.

→ Foul smelling gases like hydrogen sulphide released from the decomposing dead bodies of plants and animals.

→ Radioactive fall outs and emissions from thermal power projects.

Effects or hazards of air pollutants:
→ CO – To main air pollutant and 2/3^rd of polluting air comes from automobile exhausts. CO combines with haemoglobin of RBC to form toxic stable compound called carboxy haemoglobin. This considerably reduces oxygen carrying capacity of blood causes suffocation and giddiness. In higher concentration, CO causes unconsciousness and even death.

→ SO₂ – Causes headache, nausea, bronchitis and asthma. Sulphur dioxide combines with atmospheric moisture to form H₂SO₄ responsible for acid rains. Acid rains cause radical pH changes in soil and water, which is injuries to both plant life and animal life.

→ NO₂ – Causes pulmonary discomforts , irritation of eyes and nose. They combine with hydrocarbons to form ozone and PAN (Peroxy Acetyl Nitrate), which contribute to poisonous cloud formation called photochemical smog. Ozone and PAN – cause damage to the mucus membrane of respiratory system, genetic material (DNA) and destroy chloroplast. They are proved to be injuries to leafy vegetable crop plants and fruit gardens. PAN is a proven carcinogenic.

→ CFC – They reach higher altitudes of atmosphere causing peeling of the protective ozone umbrella. This allows UV – rays of sunlight to reach the earth’s surface responsible for increasing incidence of skin cancer.

→ Green house effect – Automobile and industrial activities coupled with deforestation, tend to increase carbon dioxide levels in air which, prevents escape of heat radiation from earth surfaces , resulting in global warming. This phenomenon is called green house effect. If unchecked, it is likely to raise the sea level by atleast by 60 feet, submerging coastal areas and low lying areas allover the world.

→ Radioactive ionization – causes harmful mutations in living organisms resulting in deformities in the newly born the young. Fungal spores, pollen dust and dust mites are major causes of skin and respiratory allergies.

Preventive measures:

→ Factories and industries should be situated away from residential areas to avoid pollution of cities and towns.

→ Use of electrostatic precipitators to filter out particles or matter from industrial emissions.

→ Industrial chimney lenght should be advised release smoke and soot into higher altitudes.

→ Discouraging the use of smoke producing fuel like wood, coal and oil in industrial and domestic burning, encouraging the use of smokeless fuel like cooking gas and electrical appliances.

→ Use of exhaust filters to automobiles to minimize emission of exhaust fumes.

→ Encouraging the growth of forest undertaking large-scale plantation and maintaining gardens would help to reduce air pollution.

Electrostatic Precipitator:

→ It is the most widely used method for removal of particulate matters about 99% of particulate pollutants are removed from the exhaust of thermal power plants by this method.

→ It has electrode wires and a stage of collecting plates.

→ The electrode wires are maintained at several thousand volts, which produce a corona that releases electrons.

→ These electrons get attached to the (dust) particles and give them a net negative charge within a very small fraction of a second.
The collecting plates are grounded and hence attract the charged particles.

→ The velocity of air between the plates must be low enough to allow the particles to fall on to them .

Scrubber:

→ A scrubber is used to remove gases like sulphur dioxide from industrial exhaust.

→ The exhaust is passed through a spray of water or lime.

→ Water dissolves the gases and lime reacts with sulphur dioxide to form a precipitate of calcium sulphate or sulphite.

Catalytic Converters:

→ These are used in automobiles for reducing emission of harmful gases.

→ They have expensive metals like platinum, palladium and rhodium as catalysts.

→ As the exhaust passes through the catalytic converter, unbumt hydrocarbons are converted into carbon dioxide and water. Carbon monoxide and nitric oxide are changed into carbon dioxide and nitrogen gas respectively.

→ Vehicles fitted with catalytic converters should use unleaded petrol as lead in the petrol inactivates the catalyst.

Controlling Vehicular Air Pollution: A case study of Delhi:

→ In the 1990s, Delhi ranked fourth among the 41 most polluted cities of the world. Air pollution problems in Delhi became serious. Reducing vehicular pollution included phasing out of old vehicles, use of unleaded petrol, use of low-sulphur petrol arid diesel, use of catalytic converters in vehicles, application of stringent pollution level norms for vehicles, etc.

→ The Bharat Stage II (equivalent to Euro – II norms), which is currently in place in Delhi, Mumbai, Kolkata, Chennai, Bangalore, Hyderabad, Ahmedabad, Pune, Surat, Kanpur and Agra, will be applicable to all automobiles throughout the country from 1 April 2005. All automobiles and fuel-petrol and diesel – were to have met the Euro III emission specifications in these 11 cities from 1 April 2005 and have to meet the Euro-IV norms by 1 April 2010. The rest of the country will have Euro – III emission norm compliant automobiles and fuels by 2010.

Noise :
→ Noise is the undesired high level of sound. Noise causes psychological and physiological disorders in humans. A brief exposure to extremely high sound level, 150 dB or more generated by take off of a jet plane or rocket, may damage ear drums. Chronic exposure to a relatively high noise level of cities may permanently damage hearing abilities of humans. Noise also causes sleeplessness, increased heart beat, altered breathing pattern, thus considerably stressing humans.

→ Considering the many dangerous effects of noise pollution the unnecessary sources of noise pollution should be reduced immediately. Stringent following of laws laid down in relation to noise like delimitation of horn-free zones around hospitals and schools, permissible sound-levels of crackers and of loud speakers, timings after which louds speakers cannot be played, etc.

Water Pollution

It is the undesirable change in physical, chemical and biological characteristics of water resources adversly affecting human health and life of domestic animals.
The four main types of water pollution are

• Sewage pollution.
• Industrial pollution.
• Biocide pollution.
• Thermal pollution.

Sewage Pollution:
Sewage is a biodegradable pollutant concentrated with human faces, animal excreta, food residues, domestic wastes, detergents and several dissolved chemicals (sulphates, phosphates, alkalies, nitrates, acids). Sewage also contains pathogenic bacteria, eggs, cysts and spores of parasites. Sewage is discarded from homes, hotels, and choultries and hostels being dumped constantly into near by water resources like lakes, ponds, rivers and oceans causing water pollution.

Effects:
→ Presence of sewage increases turbidity of water, which reduces solubility of oxygen and penetration of light, both of which adversely affect the photosynthetic and respiratory activities of aquatic organisms.

→Sewage water provides good breeding ground for mosquitoes and favours growth of pathogenic bacteria and parasites. Thus it forms a source for the out break of diseases like malaria, typhoid, cholera, jaundice and dysentery.

→ Sewage dumping causes sudden nutrient enrichment resulting in plankton bloom. This process is called eutrophication. It creates biological oxygen demand (BOD), and oxygen shortage to fishes, which suffocate to death.

→ To prevent these effects, sewage treatment should be done before letting it out.

Note: Bio-magnification:
→ It is the process of accumulation of certain pollutants in tissues, with increased concentration, along the food chain. Most of the pesticides are non degradable and are persistent and get accumulated in increasing concentration e.g. DDT is insoluble in water and is non-biodegradable. When it is extensively used, it goes into the soil through the rainwater.

→ From the soil, DDT passes into plants, in which DDT is found to be more concentrated than in soil. Experiments have revealed that in a food chain, DDT becomes more and more concentrated and accumulated when it passes from the lower to the higher trophic levels. The accumulation and concentration of DDT in each trophic level, on an average, increases by ten times.

Industrial Effluent Pollution:
They are byproducts disposed from industries and dumped into the nearby water resources causing water pollution. Effluents includes acids, alkalies, metallic dust like mercury, lead, copper, cadmium and zinc, phenol and cyanides and oil spills the sources include factories, industries, mills, oil refineries, thermal power plants, fertilizers and detergent industries.

Effects:
→ They cause radical change in pH of water, which adversely affects growth, and survival of aquatic life.

→ They decrease oxygen solubility in water and thus affect respiratory activity of aquatic organism.

→ Most effluents are non biodegradable pollutants. Hence they pass through food chain and reach the body tissues of humans where they undergo biological magnification building up to toxic level. Mercury causes haemolysis, lead causes anaemia and cancer of brain and lungs, copper causes hypertension , cadmium causes bone damage and Zinc causes renal damage.

Control measures :

• Treatment of effluents to eliminate the toxic constituents.
• Enforcement of strict and appropriate laws to minimise release of effluents into the water resources.

Biocide Pollution of Water:
Include D.D.T, aldrin and endrin etc. that are used in agricultural fields and fruit gardens to get rid of animals and pests on plants. From fields along with run off water, they reach ponds, lakes, rivers and sea, polluting water.

Effects of D.D.T (Biocide)
→ D.D.T and other biocides are non-biodegradable pollutants. Hence they pass through food Chains finally reaching the tissues of man where they undergo biologica\ magnification. D.D.T causes neurological disorders, genetic damage and sterility and harmful mutations. Under its influence the new born may show deformities.

→ Accumulation of D.D.T in birds results in laying of weak shelled eggs, which increases the mortality of chicks.

→ D.D.T causes bleaching of leaves by destroying chloroplast an effect called as chlorosis. This causes damage to vegetation.

Control of Biocide pollution:

• Discouraging the use of D.D.T.
• Only selective pesticides in just the required quantities should be used.
• Encouraging eradication of pests by methods of biological control
• Pesticides should be used with care under the supervision of specialist.
• Persons handling pesticides should use masks and gloves.
• Food and edible items should be properly covered before spraying pesticides in houses.

Thermal Pollution:

• Thermal power stations, many industries and nuclear reactors use large quantities of water.
• The effluents as well as the residual hot water, is dumped into the nearby water resources causing thermal pollution.

Effects
Hot water decreases the oxygen solubility and alters respiratory activity of aquatic organisms and warmer water favors entry of toxic substances into bodies of aquatic ‘ organisms.

Control measures:
The concerned industries should have provision to store the residual hot water, cool it before it is discarded.

Soil Pollution:

It refers to the undesirable change in physical, chemical and biological soil adversely affecting its fertility and the activities of its living organisms. Soil pollutants include metal scraps, discarded organic wastes, papers, glass pieces, discarded herbicides, fungicides and pesticides, plastics and other chemical wastes discarded from industries.
In total, it is the loss of vigour and vitality that supports life of plants and microbes.

Effects:
→ The pollutants cause high alkalinity or acidity of soil both of which are injurious to life forms.

→ The eggs & cysts of parasites like Ascaris and hook worms are transmitted through soil to man by contamination.

Control measures:
→ Indiscriminate dumping of garbage wastes to be avoided.

→ The solid wastes like plastics metal scraps and papers, cloth rag should be separated from soil and are recycled.

Solid Wastes:
Solid wastes refer to everything that goes out in trash.
They are of the following types :
(a) Municipal solid wastes:
These are wastes from homes, offices, schools, etc. that are collected and disposed by the municipality and generally consist of paper, waste food materials, leather, textile, rubber, glass, etc. When they are dumped in the open, they provide a breeding ground for flies and other insects, which may be vectors.

(b) Fly ash:
Thermal power plants generate fly ash, which is composed of oxides of Silica, iron and aluminium and low concentrations of toxic heavy metals.

(c) Defunct ships:
Defunct ships are broken down in developing countries for scrap metal. They contain toxic „ substances like asbestos, polychlorinated biphenyls, tributylin, lead, mercury, etc.
The workers are not suitably protected and are exposed to toxic chemicals.
The coastal area in the vicinity of the ship breaking yard becomes polluted.

Hospital wastes:
→ Hospitals produce and dump many hazarduous wastes that contain pathogenic microbes, disinfectants and other harmful chemicals.

→ The use of incinerators is crucial for the disposal of hospital wastes.

Industrial wastes:
→ Industries involved in manufacture of paper, rubber, pesticides, dye, etc. produce large amounts of corrosive and highly inflammable chemicals.

Electronic wastes (e-wastes):
→ e-wastes are generated in the developed countries and are sent to developing countries where certain metals like gold, nickel, silicon, copper, iron, etc. are recovered from them.

→ Then recycling is done manually and hence, the workers are exposed to the toxic substances.

Disposal of solid wastes:

• Municipal solid wastes are burnt to reduce their volume. But, they are not burnt completely and the open dumps serve as breeding grounds for flies and rats.
• Sanitary landfills have been adopted as an alternative to open-burning dumps.
• Municipal wastes are incinerated and the heat emitted is used to generate electricity.
• They are also recycled for various components.
• Fly ash is used in construction industry or buried as landfill. It is also used for soil augmentation as it increases water retention and aeration of soil.
• e-wastes are buried as landfills or incinerated. They are also recycled.

Agro – Chemicals and their effects:
In the wake of green revolution, use of inorganic fertilisers and pesticides has increased manifold for enhancing crop production. Pesticides, herbicides, fungicides, etc., are being increasingly used. These incidentally, are also toxic to non-target organisms, that are important components of the soil ecosystem.

Radioactive wastes:
→ Radiation, which is given off by nuclear waste is extremely damaging to organisms, because it causes mutations at a very high rate. At high doses nuclear radiation is lethal but at lower doses, it creates various disorders, the most frequent of all being cancer. Therefore, nuclear waste is an extremely potent pollutant and has to be dealt with utmost caution.

→ It has been recommended that storage of nuclear waste, after sufficient pre-treatment, should. be done in suitable shielded containers, buried within the rocks, about 500 m cleep below the earth’s surface.

Global Issues:

Because of the increase in human population and rising human aspirations, a number of transformations are going on in the biosphere They include land use changes, disturbed life support system, industrial development, increased energy production from fossil fuels and urbanization.

Global Warming and Green House Effect:

Green house gases:
They are gaseous components of atmosphere which allow the short wave radiations to pass through but absorb the long wave heat (infra-red) radiations. Presence of green house gases (CO₂, CH₄, N₂O, CFCs) in the atmosphere, convert it into a window glass pane like cover around the earth (as found in a glass houses). It allows most of the solar radiations which have shorter wave length (0-2 – 4-0nm) to reach up to earth’s surface. As the solar radiations are reflected from earth’s surface they are changed into long wave radiations.

A part of this energy is re-radiated back to the surface of earth. The downward flux of long wave radiation by green house gases is called green house flux. It is important in keeping the earth warm with an average or mean annual temperature of about 15° C. In the absence of this flux, the earth’s mean temperature would drop to 20°C at which temperature water will freeze and kill most life forms.

Effect of global warming:
Global warming, a consequence of higher concentration of green house gases, has the potential to affect weather and climate, stratosphere and thermosphere, rise in sea level, species distribution and food production.

1. Weather and climate: Global mean temperature rose by 0-6° C during the 20th century. It is going to increase further by 1-4° – 5-8°C between 1990 – 2100 AD.

2. Stratosphere and thermosphere: Warming of troposphere will cause cooling of stratosphere and thermosphere. The whole atmosphere will shrink. Cooling of stratosphere will increase the size of ozone holes and thinning of ozone shield at other places. Cooling of thermosphere will disrupt communications and the shielding effect of ionosphere.

3. Sea level change: It is believed that sea level has risen by 15cm during the 20th century, a rise of 1 -2 mm every year. By the year 2100 AD, the global mean sea level is going to rise by 0-88m over that of 1990 sea level. Rise in sea level is due to thermal expansion of oceans as the temperature rises, melting of glaciers and Greenland ice sheets.

4. Range of species distribution : Each species has a particular range of temperature. Global warming will push tropics into temperate areas and temperate areas towards poles and higher altitudes in mountains Arise of 2°-5° C can cause pushing of temperate, range vegetation some 250-600km towards the pole.

5. Food production : Rise in global temperature is going to have a negative impact on food production despite beneficial effect of CO₂ fertilization. The various reasons are increase in basal rate of respiration by plants.

• Lesser storge of food and hence less productivity.
• Explosive growth of weeds.
• Higher incidence of pathogens and pests.
• Increased evaporation of soil water and higher transpiration from plants resulting in water deficiency.

Approaches to deal with global warming:
→ Limiting the use of fossil fuels so as to reduce emission of green house gases.

→ Early use of hydrogen fuel.

→ Increasing use of alternative, renewable, nonpolluting sources of energy like solar energy, wind energy, hydropower, etc.

→ Increasing vegetation cover and forest area so as to use more CO₂ in photosynthesis.

→ Reducing release of N₂O from agricultural fields by minimizing use of nitrogen fertilizers. More attention should by paid on nitrogen fixing organisms.

→ Replacing chlorofluorocarbons with chemicals which do not possess greenhouse effect.

Ozone Layer Depletion (Stratospheric Ozone Depletion):
Stratosphere O₃ layer

→ Ozone is triatomic gas with a formula O₃. It is formed independently in the troposphere and stratosphere. In the stratosphere, O₂ splits up into nascent oxygen (O) under the influence of UV radiations. Nascent oxygen combines with the molecular oxygen (O₂) to form ozone O₃ (Molina and Molina, 1992).

→ Ozone (O₃) is formed naturally in the upper stratosphere by short wavelength ultraviolet radiation. Wavelengths less than 240 nanometers are absorbed by oxygen molecules (O₂), which break up to give O atoms. The O atoms combine with other oxygen molecules to make ozone.

→ Photodissociation of oxygen and ozone dissipates major amount of UV radiations as heat. An equilibrium is produced between generation and destruction of O₃ resulting in steady state concentration in the stratosphere at a height of 20-26km above the sea level.

Ozone Hole:

It is not an actual hole but an area of extreme reduction in ozone concentration in the ozone shield. Ozone hole was first discovered in 1985 by Farman et al over Antarctica. A small hole was also discovered over Arctic in 1990. Ozone holes are not permanent. They ‘ appear during polar springs. ODS. Certain substances react with ozone present in the stratosphere and destroy the same. They are called ozone depleting substances or ODS. The major ODS are chlorofluorocarbons (CFCs), halons (gases used in fire extinguishing like bromochloro- difluoromethane, N₂O, CH₄, chlorine, etc. They are either released by jets and rockets in the stratosphere or slowly pasainto stratosphere from troposphere. Both halons and CFCs produce active chlorine (CIO) in the presence of UV-radiations.

A small amount of atomic chlorine, Cl, and chlorine monoxide, ClO, which can catalyse the destruction of ozone by a number of mechanisms. The steps are

Step 1: “Photolysis” (splitting by sunlight) of CFC’s in the stratosphere
Cl₂CF₂ + UV light → ClCF₂ + Cl

Step 2 : Catalytic destruction of ozone
Cl + O₃ → ClO + O₂
CIO + O₃ → Cl + 2O₂

Effects of ozone depletion:
Thinning of ozone layer and development of ozone holes increases the amount of UV-B radiations reaching the earth’s surface. A 5% ozone depletion increases UV-B radiations by 10%. Increased incidence of UV-B radiations on earth will have the following adverse effects.

→ Skin Cancers: There is an increase in the incidence of skin cancers. 1% fall in ozone concentration increase UV load of earth by 2% that causes addition of 50,000 cases of skin cancer. In Australia which lies near the area of ozone hole, every second middle aged person suffers from skin cancer while in old persons the incidence is nearly 100%.

→ Blinding: Many land animals would lose their eye sight and become blind. In human beings the cases of photo-burning, cataract and dimming of eye sight are on the increase. 1% fall of ozone concentration in stratosphere will blind another 1 lakh persons.

→ Immune System: It is partially suppressed. Incidence of herpes and other immune system related diseases are likely to increase.

→ Larval Stages: More larvae and young ones of aquatic animals will die.

→ Photosynthesis: Photosynthetic machinery is impaired. Photosynthesis decreases by 10-25%. There is a corresponding fall in the yield of crops.

→ Nucleic Acids: UV radiation damages nucleic acids by forming dimers. Incidence of harmful mutations increases.

→ Phytoplankton: Both photosynthetic activity as well as function of phytoplankton are disturbed by UV-radiations. 6-22% fall in productivity will occur.

→ Global Warming: Decreased primary productivity over land and inside oceans will increase carbon dioxide concentration resulting in global warming, despite reduction in CO₂ emissions from industries and automobiles.

→ Deforestation: Removal, decrease or deterioration of forested area is called deforestation. Deforestation has been going on since the beginning of civilization. The decline has been maximum in the tropics (more than 40%) and minimum in temperate regions (1% or less).

→ The reasons for deforestation are several:

• Demand for wood for fuel, timber and paper,
• Building of dams and reservoirs for hydroelectric projects,
• Overgrazing,
• Human settlements,
• Forest fires,
• Practice of shifting cultivation,
• Mining and quarrying,
• Digging of canals,
• Building of roads, etc.

Causes of deforestation:
→ Slash and Burn agriculture/ Jhum cultivation: It is ‘an agricultural technique in which an area of forest is cleared by cutting and burning and is abandoned to return to a more natural state over time’.

→ It is also known as shifting cultivation,- swidden agriculture, or simply jhum.

→ Here, the farmers cut down trees and burn the plant remains. The ash is used as fertilizer and the land for grazing and farming.

Population growth: It is a major cause and in order to meet the immediate needs of growing population, forests are indiscriminately exploited for, timber, wood, paper, fuel etc.
Cattle are allowed to graze for a year or two. Once the soil is exhausted by over grazing, they move on to the next area

Extensive fire wood collection: Fire wood is the primary fuel for cooking and heating in developing countries. The outright destruction of living trees to meet fuel need occurs most commonly around cities and towns.

Effects of deforestation:

• Global warming,
• Soil erosion and flooding,
• Drought and desertification,
• Decrease in rainfall,
• Loss of microorganisms,
• Loss of unique species,

Reforestation: Reforestation is the process of restoring a forest that once existed but was removed at some point of time in the past. Reforestation may occur naturally in a deforested area.
Afforestation is growing trees for the first time in treeless regions.

Waterlogging and soil salinity: Irrigation without proper drainage of water leads to waterlogging in the soil. Besides affecting the crops, waterlogging draws salt to the surface of the soil. The salt is then deposited as a thin crust on the land surface or starts collecting at the roots of the plants. This increased salt content is inimical to the growth of crops and is extremely damaging to agriculture.

Case study of people’s participation in conservation of forests:
People’s participation has a long history in India. In 1731, the King of Jodhpur in Rajasthan asked one of his ministers to arrange wood for constructing a new palace. The minister and workers went to a forest near a village, inhabited by Bishnois, to cut down trees. The Bishnoi community is known for its peaceful co-existence with nature.

The effort to cut down trees by the King was thwarted by the Bishnois. A Bishnoi woman Amrita Devi showed exemplary courage by hugging a tree and daring King’s men to cut her first before cutting the tree. The tree mattered much more to her than her own life. Sadly, the King’s men did not heed to her pleas, and cut down the tree along with Amritha Devi. Her three daughters and hundreds of other Bishnois followed her, and thus lost their lives saving trees.

Now here in history do we find a commitment of this magnitude when human beings sacrificed their lives for the cause of the environment. The Government of India has recently instituted the Amrita Devi Bishnoi Wildlife Protection Award for individuals or communities from rural area that have shown extraordinary courage and dedication in protecting wildlife.

You may have heard of the Chipko Movement of Garhwal Himalayas in 1974, local women showed enormous bravery in protecting trees from the axe of contractors by hugging them. People all over the world have acclaimed the Chipko movement.

Realising the significance of participation by local communities, the Government of India in 1980s has introduced the concept of Joint Forest Management (JFM) so as to work closely with the local communities for protecting and managing forests. In return for their services to the forest, the communities get benefit of various forest products [e.g., fruits, gum, rubber, medicine, etc), and thus the forest can be conserved in a sustainable manner.

2nd PUC Biology Notes