UPSC PRELIMS_POWER PLAY- ENVIRONMENT SERIES (IMP TOPICS)

IMPORTANT ENVIRONMENT TOPICS FOR PRELIMS

Both bacteria and protists are unicellular. Then came multicellular organisms, the fungi followed by plants and animals.

Local environmental backlash

 (i) Salination of irrigated soils

(ii) Eutrophication

(iii) The Minamata disease

(iv)Extinction of wild life species

Regional Environmental backlash

(i) Floods

(ii) Drought

(iii)  Acid rain

(iv) Oil spills

Global backlash

 (i) Biodiversity loss

(ii) Global warming and green house effect

(iii) Collapse of marine fisheries

(iv) Ozone layer depletion

Consequences of deforestation

 •  Soil erosion

•  Landslides

•  Silting

•  Loss of wild habitat

• Loss of CO2  sink

•  Loss of medicinal and other useful plants

•  Pollution

Forests have been cleared for the various reasons-

1. Developmental activities

2. For timber and wood

3. For pasture

4. Shifting cultivation

Pure rain has a pH of 5.6 but in areas where industries burn oil and coal emit SO2 (sulphur dioxide)into the atmosphere and motor vehicles release NOx (compound of nitrogen) into air , the rain becomes more acidic reaching pH of 2.

‘Ecology may be defined as the scientific study of the relationship of living organisms with each other and with their environment.’

The term ecology was first coined in 1869 by the German biologist Ernst Haeckel. It has been derived from two Greek words, ‘oikos’, meaning home or estate and ‘logos’ meaning study .

A large community unit, characterized by a major vegetation type and associated fauna, found in a specific climatic region is a  biome

Habitat is the physical environment in which an organism lives. Each organism has particular requirements for its survival and lives where the environment provides for those needs.

Individual<population<community<eco system

The features of the habitat can be represented by its structural components namely

 (1) space

(2) food

 (3) water

(4) shelter

Earth has four major habitats-

(1) Terrestrial

(2)  Freshwater

(3)  Estuarine(Where rivers meet the ocean) &

 (4)  Ocean.

The term niche means the sum of all the activities and relationships of a species by which it uses the resources in its habitat for its survival and reproduction

.

A niche is unique for a species while many species share the habitat. No two species in a habitat can have the same niche. This is because if two species occupy the same niche they will compete with one another until one is displaced.

A species is defined as; “a group of similar populations of organisms whose members are capable of interbreeding, and to produce fertile offspring  (children)”.

Species are generally composed of a number of distinct populations which freely interbreed even though they appear to be different in appearance

SPECIES FORMATION: SPECIATION

 The primary reason for these extinctions is environmental change or biological competition.

‘Population’ is defined as a group of freely interbreeding individuals of the same species present in a specific area at a given time.

A population has traits of its own which are different from those of the individuals forming the population.

  An individual is born and dies but a population continues.

Natality:The rate at which new individuals are born and added to a population under given environmental conditions is called  natality.

Study of pug marks can provide the following information reliably if analyzed skillfully:

 • Presence of different species in the area of study .

 • Identification of individual animals.

 • Population of large cats (tigers, lions etc.).

• Sex ratio and age (young or adult) of large cats

In ecology the term community , or more appropriately ‘biotic community , refers to the populations of different kinds of organisms living together and sharing the same habitat.

Stratification of a community refers to the vertical layers of the vegetation. 

Tropical forests represent a good example of vertical stratification.

These include from the forest floor to the top

(i) Ground layer of mosses and liverworts associated with dead leaves and other  The bottom layer substances rich in organic matter .

(i) Herb or grass layer, } The lower layer

(ii) Short shrub layer  The middle layer

(iii) Tall shrub layer

(iv) Layer of under storey of short trees,

(v) Layer of canopy of lower trees and  The upper layer

(vi) Over storey or emergent tree layer formed by tall trees.

Primary succession is much more difficult to observe than secondary succession because there are relatively very few places on earth that do not already have communities of organisms.

Furthermore, primary succession takes a very long time as compared to secondary succession as the soil is to be formed during primary succession while secondary succession starts in an area where soil is already present. The community that initially inhabits a bare area is called  pioneer  community .

The terminal (final) stage of succession forms the community which is called as  climax community .  A climax community is stable, mature, more complex and long lasting. The entire sequence of communities in a given area, succeeding each other, during the course of succession is termed  sere

Succession that occurs on land where moisture content is low for e.g. on bare rock is known as  xerarch. Succession that takes place in a water body , like ponds or lake is called  hydrarch.

Competition :Adversely affects both species

Amensalism: This is a negative association between two species in which one species harms or restricts the other species without itself being adversely affected or harmed by the presence of the other species. Organisms that secrete antibiotics and the species that get inhibited by the antibiotics are examples of  amensalism. For example the bread mould fungi  Pencillium  produce penicillin an antibiotic substance which inhibits the growth of a variety of bacteria.

Parasite-host relationship

(a) Plant parasite: Dodder (Cuscuta) plant is a parasitic weed that obtains moisture and nourishment by attaching to a green, living plant.

 (b)  Animal parasite: Ascaris or round worms are internal parasites found in the human intestines

  Another example of commensalisms is the relationship between trees and epiphytic plants.

The tree gets no benefit from this relationship nor are they harmed.

Mutualism : This is a close association between two species in which both the species benefit. For example of protocorporation the sea anemone, a cnidarian gets attached to the shell of hermit crabs for benefit of transport

However, some mutualisms are so intimate that the interacting species can no longer live without each other as they depend totally on each other to survive. Such close associations are called  Symbiosis.

  An example of such close mutualistic  association is that of termite and their intestinal flagellates.

Flagellate  protists (protozoans)

  Another familiar example of symbiosis is seen in pollination of flowers where flowering plants are cross pollinated by the bees which benefit by getting nectar from the plants

Neutralism: Neutralism describes the relationship between two species which do interact but do not affect each other .

 True neutralism is extremely unlikely and impossible to prove.

Biotic interaction refers to the interaction taking place between individuals belonging to the same species (intra specific) or different species (interspecific).

 Examples are (i) competition (ii) predation (iii) parasitism (iv) mutualism (v) symbiosis (vi) commensalism (vii) neutralism

Biosphere is very huge and can not be studied as a single entity . It is divided into many distinct functional units called ecosystem.

In nature several communities of organisms live together and interact with each other as well as with their physical environment as an ecological unit.  W e call it an  ecosystem.  The term ‘ecosystem’ was coined by  A.G .  Tansley in 1935. 

An ecosystem is a functional unit of nature encompassing complex interaction between its biotic (living) and abiotic (non-living) components.

(a) Abiotic components (Nonliving): The abiotic component can be grouped into following three categories:-

(i) Physical factors:Sun light, temperature, rainfall, humidity and pressure. They sustain and limit the growth of organisms in an ecosystem.

 (ii) Inorganic substances: Carbon dioxide, nitrogen, oxygen, phosphorus, sulphur , water , rock, soil and other minerals.

 (iii) Organic compounds:Carbohydrates, proteins, lipids and humic substances.

Functions of ecosystem:  Ecosystems are complex dynamic system. They perform certain functions. These are:-

(i) Energy flow through food chain

(ii) Nutrient cycling (biogeochemical cycles)

(iii) Ecological succession or ecosystem development

(iv) Homeostasis (or cybernetic) or feedback control mechanisms

Types of ecosystems

 Ecosystems are classified as follows:

 (i) Natural ecosystems

(ii) Man made ecosystems

Natural ecosystems

(a) Totally dependent on solar radiation e.g. forests, grasslands, oceans, lakes, rivers and deserts. They provide food, fuel, fodder and medicines.

 (b) Ecosystems dependent on solar radiation and energy subsidies (alternative sources) such as wind, rain and tides. e.g tropical rain forests, tidal estuaries and coral reefs.

  Man made ecosystems

 (a) Dependent on solar energy-e.g.  Agricultural fields and aquaculture ponds.

 (b) Dependent on fossil fuel e.g. urban and industrial ecosystems.

On the basis of extent of penetration of light a pond can be divided into  euphotic(eu=true,photic=light),  mesophotic and  aphotic zones.

Pond animals can be classified into the following groups

 (a) Zooplanktons are floating animals. Cyclops, Cypris

 (b) Nektons  are the animals that can swim and navigate at will. Eg. fishes  

(c) Benthic animals 

Transfer of food energy from green plants (producers) through a series of organisms with repeated eating and being eaten is called a food chain

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During this process of transfer of energy some energy is lost into the system as heat energy and is not available to the next trophic level. Therefore, the number of steps are limited in a chain to 4 or 5.

There are two types of food chains :

 (i) Grazing food chains: which starts from the green plants that make food for herbivores and herbivores in turn for the carnivores.

(ii) Detritus food chains: start from the dead organic matter to the detrivore organisms which in turn make food for protozoan to carnivores etc.

Trophic levels in an ecosystem are not linear rather they are interconnected and make a food web. 

Thus food web is a network interconnected food chains existing in an ecosystem.

 Food webs are more realistic models of energy flow through an ecosystem

The flow of energy in an ecosystem is always linear or one way 

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Ecological pyramids are the graphic representations of trophic levels in an ecosystem. They are pyramidal in shape and they are of three types:

(1) Pyramid of number:  Always upright but in some instances the pyramid of number may be inverted, i.e herbivores are more than primary producers as you may observe that many caterpillars and insects feed on a single tree.

(2) Pyramid of biomass:This represents the total standing crop biomass at each trophic level.  Standing crop biomass is the amount of the living matter at any given time. It is expressed as gm/unit area or kilo cal/unit area. In most of the terrestrial ecosystems the pyramid of biomass is upright. 

However , in case of aquatic ecosystems the pyramid of biomass may be invertede.g. in a pond phytoplankton are the main producers, they have very short life cycles and a rapid turn over rate (i.e. they are rapidly replaced by new plants). Therefore, their total biomass at any given time is less than the biomass of herbivores supported by them

 (3) Pyramid of energy

The amount of energy decreases at each subsequent trophic level. This is due to two reasons:

 1. At each trophic a part of the available energy is lost in respiration or used up in metabolism.

2. A part of energy is lost at each transformation, i.e. when it moves from lower to higher trophic level as heat.

 It is the ratio between the amount of energy acquired from the lower trophic level and the amount of energy transferred from higher trophic level is called  ecological efficiency.

 Lindman in 1942 defined these ecological efficiencies for the 1st time and proposed 10% energy is lost during every transaction from lower tropic level to higher tropic level.

  Atmospheric nitrogen can be fixed by the following three methods:-

(i) Atmospheric fixation: Lightening, combustion and volcanic activity help in the fixation of nitrogen.

 (ii) Industrial fixation:  At high temperature (400 o C) and high pressure (200 atm.), molecular nitrogen is broken into atomic nitrogen which then combines with hydrogen to form ammonia.

(iii)  Bacterial fixation: There are two types of bacteria-

(i) Symbiotic bacteria  e.g. Rhizobium in the root nodules of leguminous plants.

(ii) Freeliving or symbiotic  e.g. 1.  Nostoc 2.  Azobacter  3. Cyanobacteria can combine atmospheric or dissolved nitrogen with hydrogen to form ammonia.

 Nitrification: It is a process by which ammonia is converted into nitrates or nitrites by  Nitrosomonas and  Nitrococcus  bacteria respectively . Another soil bacteria Nitrobacter  can convert nitrate into nitrite.

Assimilation: In this process nitrogen fixed by plants is converted into organic molecules such as proteins, DNA, RNA etc. These molecules make the plant and animal tissue.

  Ammonification: Living organisms produce nitrogenous waste products such as urea and uric acid. These waste products as well as dead remains of organisms are converted back into inorganic ammonia by the bacteria This process is called ammonification.  Ammonifying bacteria help in this process.

  Denitrification: Conversion of nitrates back into gaseous nitrogen is called denitrification. Denitrifying bacteria live deep in soil near the water table as they like to live in oxygen free medium. Denitrification is reverse of nitrogen fixation.

 Almost 95 % of the total water on the earth is chemically bound to rocks and does not cycle.

 Out of the remaining 5%, nearly 97.3% is in the oceans and 2.1% exists as polar ice caps. Thus only 0.6% is present as fresh water in the form of atmospheric water vapours, ground and soil water .

The driving forces for water cycle are 1) solar radiation 2) gravity .

On an average 84% of the water is lost from the surface of the through oceans by evaporation.  While 77% is gained by it from precipitation.  Water run of f from lands through rivers to oceans makes up 7% which balances the evaporation deficit of the ocean. On land, evaporation is 16% and precipitation is 23%.

Note that in a homeostatic system, negative feed back mechanism is responsible for maintaining stability in a ecosystem.

• The main components of all the biogeochemical cycles are:-

a) the reservoir pool that contains the major bulk of the nutrients soil or atmosphere.

 b) cycling pool which are the living organisms (producers, consumers and decomposers), soil, water and air in which it stays temporarily .

Coniferous forests are also known as ‘Taiga’.  They extend as a continuous belt across north  America and north Eurasia below the arctic tundra. There is no counterpart of these forests in southern hemisphere as there is no land at this latitude.

Some common birds are crossbill, thrushes, warblers, flycatchers, robin and sparrow .

India Grassland, Savanna

  Desert plants

In some plants even the stem contains chlorophyll for photosynthesis.

The word tundra means a “barren land” since they are found in those regions of the world where environmental conditions are very severe. There are two types of tundra-  arctic and  alpine.

Alpine tundra  occurs  at high mountains above the tree line. Since mountains are found at all latitudes therefore alpine tundra shows day and night temperature variations.

 Animals of tundra are reindeer, musk ox, arctic hare, caribous, lemmings and squirrel.

Salix arctica  that is arctic willow has a life span of 150 to 300 years. They are protected from chill by the presence of thick cuticle and epidermal hair . Mammals of the tundra region have large body size and small tail and ear to avoid the loss of heat from the surface. The body is covered with fur for insulation.

Osmoregulation is the process by which a constant osmotic pressure is maintained in blood.

Tropical deciduous forests

Important trees of these forests are teak, sal, and sandalwood.

(iii)  Temperate broad leaf forests It mainly occur between 1500-2400 m altitudes in western Himalayas. Several species of Oak (Quercus) are found in these forests. Oak species are evergreen in the Himalayan

These species show peak leaf fall during summer but never become leafless.

(iv)  Temperate needle leaf or coniferous forests This type of forests are found in the Himalaya over 1700 to 3000 m altitude. These forests contain economically valuable gymnospermous trees like pine , deodar ,Cypress, Spruce and siver fir.

  Vegetation growing at altitudes above 3600 m is usually known as alpine vegetation and it can be noticed that with the increment of the altitude, the plants show stunted growth. The trees like silver fir , pine, juniper and birch belong to this category .

 Chir pine grows throughout the northwest Himalayas, with the exception of Kashmir

The  Thar desert in Rajasthan is an extension of the Sahara deserts through  Arabian and Persian deserts. They extend from Punjab, Haryana, Rajasthan to Gujarat state. Indian deserts are divided into four main types: • hills, • plains with hills, • marshes and • plains with sand dunes.

The distinct Rann of Kutchch–Bhuj in Gujarat forms a separate zone with in Thar deserts due to its different climatic conditions. It represents vast saline flats.

Indian deserts support many threatened species of birds and mammals, such as  Asiatic lion, wild ass, bats, scaly ant eater , desert fox, Indian gazzel, four horned antelope , white browed Bushchat, Great Indian Bustard, Cranes and Sandgrouse.

Gulf of Kuchch is distinguished by the presence of living corals, pearl oyster , sea turtles and a large number of migratory birds like kingfisher , cranes ibis and herons.

Himalayas completely over 12 states

Western ghats

 The rainfall may vary from 100 to 500 cm. Soil is mainly red or black in most of the regions and rich in nutrients. 3500 species of flowering plants have been recorded from western ghats of which nearly1500 are endemic species. Nearly 209 species of fresh water fishes occur in these ghats of which 120 are endemic. Similarly out of 219 species of amphibians found here 106 are endemic.

Estuaries are richer in nutrients than fresh waters or marine waters therefore; they are highly productive and support abundant fauna.

Characteristics of mangrove ecosystem:-

(1) The mangrove forests include a diverse composition of trees and shrubs

(2) Plants are well adapted to high salinity(halophytic).

 (3) Resistant to tidal effect.

(4) Tolerant to high temperature.

(5) Roots bear pneumatophores ( or aerial roots ), which is an aerating system.

The animal communities are of two types:

1. Permanent fauna mainly bentic are molluscs, crustaceans, polychaetes, insects and birds like kingfishers.

 2. Visiting fauna includes mollusks, echinomerms, crustaceans and birds which come from adjacent terrestrial ecosystems and rivers .  Tree frogs, crocodiles, turtles and snakes are also found in these forests. They are breeding and spawning ground for many commercially important fishes.

  Sunderban mangroves are the only mangroves where tiger population is found.

Mangroves in India have been reduced to more than 50% during the last forty years.

They are subjected to both natural as well as anthropogenic threats

For example in Sunderbans collection of tiger prawn seeds for trade has greatly affected the other animals found in these forests.

Ecotone is a zone of junction between two or more diverse ecosystems e.g. the mangrove forests. They represent an ecotone between marine and terrestrial ecosystem. Some more examples of ecotone are – grassland, estuary and river bank

Characteristics of ecotone:

 (1) It may be very narrow or quite wide.

 (2) It has the conditions intermediate to the adjacent ecosystems. Hence ecotone is a zone of tension.

(3) It is linear as shows progressive increase in species composition of one in coming community and a simultaneous decrease in species of the other outgoing adjoining community .

 (4) A well developed ecotones contain some organisms which are entirely different from that of the adjoining communities.

 (5) Sometimes the number of species and the population density of some of the species is much greater in this zone than either community.  This is called edge effect.

 

The organisms which occur primarily or most abundantly in this zone are known as  edge species.

In the terrestrial ecosystems edge effect is especially applicable to birds. For example the density of song birds is greater in the mixed habitat of the ecotone between the forest and the desert

Natural ecosystems can be classified into two types: 1) terrestrial and 2) aquatic.

 The main reasons for the modification of natural ecosystems are and

 1) increasing human population

 2) increasing human needs and

3) changing life styles.

Some examples of human modified ecosystems are:

 (1) Agro-ecosystems

 (2) Plantation forests

 (3) Urban ecosystems

(4) Rural ecosystems

 (5) Aquaculture

(6) Industrial areas

 (7) Laboratory cultures

Characteristics of human modified ecosystems

 (1) Highly simplified

(2) Species diversity is very low .

 (3) Food chains are simple and small.

(4) Depend on human (anthropogenic) support for survival; need for fossil fuel energy , fertilizers, irrigation etc.

 (5) Attract large number of weeds

 (6) More susceptible to epidemic diseases.

(7) Suffer from soil erosion.

(8) Highly unstable.

Pollution refers to the addition of any substance in the environment that has direct or indirect adverse effect on humans

Urban areas consume 75% of the earth’s resources and produce 75% of the waste.

 The maximum population density is observed in Malta  Africa. It is 1 100 persons/sq km. Next ranking is Bangladesh with 888persons/sq. km., Bahrin 759 persons/sq km, Netherland 441 persons/sq km and Japan 328 persons/sq km.

  Presently there seems to be an urban revolution as people all over the world are moving into towns and cities. In year 1800, only 5% of the world population was urban-dwelling (50 million people) and in 1985 it increased to 2 billion.  At present 45% of the world population is urban population and by 2030 there will be more than 60% people living in cities.

Aquaculture is the artificial cultivation of aquatic plants or animals. It is primarily carried out for cultivating certain commercially important edible species of fresh and marine water fishes, molluscs, crustaceans and aquatic plants.

 Fisheries  include the extraction of food from the sea and the fresh water where as  aquaculture  is rearing of the aquatic organisms in artificially made water bodies

There are two types of aquaculture:

 1. Fish farming is cultivation of fish in a controlled environment often a coastal or inland pond, lake, reservoir or rice field (paddy) and harvesting when they reach the desired size.

2. Fish ranching  is a practice of keeping which fishes in captivity for the first few years in floating cages in coastal lagoons and releasing them from captivity into water bodies.

Tilapia is a very favourite fish of many . It is also known as aquatic chicken. 

Merits of aquaculture

(1) Ecological efficiency is high. 2 kg. of grains are required to add 1 kg live weight.

(2) High yield in small volume of water .

(3) Improved qualities of fish obtained by selection and breeding and genetic engineering.

(4) Aquaculture reduces over harvesting of fisheries.

 (5) High profit.

Demerits of aquaculture

 (1) Large inputs of feed, water and land are required.

 (2) Loss of native aquatic biodiversity .  As it replaced by  monoculture of a commercially important fish species.

(3) Produces large amounts of fish wastes that pollute water bodies.

 (4) Destroys mangrove forests or coastal vegetation.

 (5) Aquaculture fishes are very sensitive to pesticide runoff from croplands.

 (6) In aquaculture ponds high population density is maintained that makes them highly vulnerable to diseases leading to total collapse of the crop.

(7) Aquaculture tanks or reservoirs are often get contaminated after a few years.

Secondary air pollutants formed from complex reactions between primary pollutants, such as smog and acid rain, which are harmful to all living organisms, buildings and monuments.

•   Human health
•  Increased sensitivity to diseases:
•  Genetic resistance :
•  Effect on native populations:
•  Stress due to  overharvesting:
•  Effect on nutrient recycling:

METHODS  TO MINIMIZE HUMAN IMP ACTON NATURAL  ECOSYSTEMS

·        Reduce our needs

·        Eco-industrial revolution

•      Quinine is used to treat malaria (from the cinchona tree);
•      Digitalis is used to treat chronic heart trouble (from the foxglove plant,  Cinchona          officinalis);
•      Morphine and Cocaine are used to reduce pain;
•      Drug for leukemia from  Vinca rosea,  taxol fromTaxus brevifolia  etc
•      Drugs which are derived from natural compounds amount to at least $40 billion worldwide  sales annually .
•       Asprin, which is probably the world’s most widely used drug was developed according to a chemical “blueprint”, from a compound extracted from the leaves of tropical willow trees.

Deforestation is a very broad term, which consists of cutting of trees including repeated lopping, felling, and removal of forest litter , browsing, grazing and trampling of seedlings. It can also be defined as the removal or damage of vegetation in a forest to the extent that it no longer supports its natural flora and fauna.

Almost 44% of the total global wood produced fulfils the fuel requirements of the world

 India consumes nearly 135-170 Mt (Million tonnes) of firewood annually and 10-15 ha of

About 4% the world’s population lives in special territories .These indigenous or tribal people have claims on a particular place

Deforestation affects both physical and biological components of the environment

.  Soil erosion and flash flood

• Climatic change

 • Loss of biodiversity

The loss of top soil is in India, is 18.5% of the global soil loss. This is indeed very serious, considering the fact that India has only 2.4% of the land area of the world. (2)Climatic change Forests enhance local precipitation and improve water holding capacity of soil,

Biodiversity - (biological diversity) is a measure of variation, the number of different varieties, among living things.

Biodiversity can be expressed in number of ways, which includes the number of genetic strains (differences) within species and the number of different ecosystem in an area.

The most common expression of biodiversity is the number of different species, within a particular area (local biodiversity), or in a specific habitat (habitat biodiversity) or in the world (global biodiversity).

 Biodiversity is not static. It changes over the time during evolution new species have come up while some species become extinct.

Over the past 2000 years, 600 species of animals have become extinct or are going to be extinct from the earth.

The shrinkage of green cover has adverse effects on the stability of the ecosystem. Poaching is another factor causing depletion of wildlife.  The roll call of victims is endless

In  Africa, in recent years, nearly 95 per cent of the black rhino population has been exterminated by poachers for their horns and over one third of  Africa’s elephants have been wiped out for ivory . 

The scarlet macaw once common throughout South  America has been eliminated from most of its range in Central  America. Several species of spotted cats such as the ocelot and jaguar are in danger of extinction due to demand of their fur .

India has nearly 45,000 species of plants and 75,000 species of animals. This biological diversity  ought to be preserved for maintaining stability of ecosystems.

 Deforestation coupled with desertification has destroyed the natural treasure of the earth to a large extent. The population of elephant, lion and tiger is fast diminishing. ‘Cheetah’ is already extinct. Elephants once found all over India have now disappeared from  Andhra Pradesh, Madhya Pradesh and Maharashtra.

 The  Asiatic lion which was very common in  Asia has practically vanished from  Asia except for a few hundred sq km (square kilometer) of Gir forest in India. In India four species of mammals and three species of birds have been extinct in the last 100 years.  Another 40 species of mammals, 20 species of birds and 12 species of reptiles are considered highly endangered due to overexploitations, of forests.

It can be defined as ‘the diminution or destruction of the biological potential of the land which can ultimately lead to desert like conditions’.

Desertification is a systemic phenomenon resulting from excessive felling of trees which manifests itself in the loss of soil fertility , high wind velocity , low precipitation, increasing aridity and extremes of temperatures in the affected area.

Most of the deserts of recent origin have resulted form any one or more of the following human activities.

(i) Uncontrolled and overexploitation of grazing land, indiscriminate cutting of trees and forest resources leading to drought, soil erosion, deterioration of soil fertility which results in stunted plant growth.

 (ii) Excessive mining in arid and semi-arid regions for extraction of minerals, coal or limestone resulting in loss of trees, and green cover , and leading to total destruction of conditions conducive to vegetation growing.

(iii) Uneconomic land use for agriculture by cultivation on marginal lands affecting adjacent fertile lands and causing soil erosion.

 (iv) Intensive and uneconomic exploitation of water resources leading to fall in water table, seepage and problems of excessive salinisation of soil.

About 76.15% of the total Indian desert area has resulted from manmade desertification process.  Another 19.5% of the total area is subjected to medium or slight desertification. This area is concentrated mostly along the eastern Rajasthan in the north-east to south-west zone parallel to the foothills of  Aravalis.

The large terrestrial reptile, the rock python found on the foothills of  Aravali is also vanishing from the desert.

There are three major functions of the forests i) productive functions .ii) protective functions iii) regulative functions.

Plant Medicinal use

 a. Cinchona Officinalis Treatment of malaria

 b. Dititalis purspusla Treatment of chronic heart disease c. Vinca rosea Treatment of cancer

d. T axus brevifolia Treatment of cancer

 Tehri town, at the junction of Bhagirathi and Bhilganga.

 Pollution may be defined as addition of undesirable material into the environment as a result of human activities. The agents which cause environmental pollution are called  pollutants.  A pollutants may be defined as a physical, chemical or biological substance unintentionally released into the environment which is directly or indirectly harmful to humans and other living organisms.

 Tetraethyl lead (TEL) is used as an anti-knock agent in petrol for smooth and easy running of vehicles. The lead particles coming out from the exhaust pipes of vehicles is mixed with air . If inhaled it produces injurious effects on kidney and liver and interferes with development of red blood cells. Lead mixed with water and food can create cumulative poisoning. It has long term effects on children as it lowers intelligence.

 Loss of chlorophyll in plants (chlorosis)

Sulphur compounds- Power plants and refineries

 •Respiratory problems in humans (So2 and H 2 S)

Nitrogen Compound- Motor vehicle exhaust

 •Irritation in eyes and lungs (NO and N2O) atmospheric reaction

 •Low productivity in plants

 Use of biogas &CNG (Compressed Natural Gas) need to be encouraged. Those species of trees such as baval (Acacia nilotica) which are least smoky should be planted and used. Charcoal is a comparatively cleaner fuel. Indoor pollution

Noise level is measured in terms of decibels (dB).  W .H.O. (World Health Organization) has prescribed optimum noise level as 45 dB by day and 35 dB by night.  Anything above 80 dB is hazardous.

Prevention and control of noise pollution

 Following steps can be taken to control or minimize noise pollution-

• Road traffic noise can be reduced by better designing and proper maintenance of vehicles.

 • Noise abatement measures include creating noise mounds, noise attenuation walls and well maintained roads and smooth surfacing of roads

 • Retrofitting of locomotives, continuously welded rail track, use of electric locomotives or deployment of quieter rolling stock will reduce noises emanating from trains

.

• Air traffic noise can be reduced by appropriate insulation and introduction of noise regulations for take off and landing of aircrafts at the airport.

• Industrial noises can be reduced by sound proofing equipment like generators and areas producing lot of noise.

• Power tools, very loud music and land movers, public functions using loudspeakers, etc should not be permitted at night. Use of horns, alarms, refrigeration units, etc. is to be restricted. Use of fire crackers which are noisy and cause air pollution should be restricted.

 • A green belt of trees is an efficient noise absorber .

When pollutants are discharged from a specific location such as a drain pipe carrying industrial effluents discharged directly into a water body it represents  point source pollution

Non-point sources  include discharge of pollutants from diffused sources or from a larger area such as run off from agricultural fields, grazing lands, construction sites, abandoned mines and pits, roads and streets.

Pollution of water bodies by mercury causes Minamata disease in humans and dropsy in fishes Lead causes  displexia, Cadmium poisoning causes  Itai – Itai disease etc

 

(i) Pollution due to pesticides and inorganic chemicals

• Pesticides like DDT and others used in agriculture may contaminate water bodies.

Metals like lead, zinc, arsenic, copper, mercury and cadmium in industrial waste waters adversely affect humans and other animals.

 Arsenic pollution of ground water has been reported from   West Bengal, Orissa, Bihar,  Western U.P  Consumption of such arsenic polluted water leads to accumulation of arsenic in the body

Oil pollution of sea occurs from leakage from ships, oil tankers, rigs and pipelines. Accidents of oil tankers spill large quantity of oil in seas which kills marine birds and adversely affects other marine life and beaches.

(ii) Thermal pollution

Discharge of hot water may increase the temperature of the receiving water by 10 to 15 °C above the ambient water temperature. This is  thermal pollution. 

Ground water pollution

Eutrophication: Discharge of domestic waste, agricultural surface runoff, land drainage and industrial effluents in a water body leads to rapid nutrients enrichment in a water body .  The excessive nutrient enrichment in a water body encourages the growth of algae duckweed, water hyacinth, phytoplankton and other aquatic plants.

Sources of soil pollution

 Plastic bags –Plastic bags made from low density polyethylene (LDPE), is virtually indestructible, create colossal environmental hazard.

Industrial sources –It includes fly ash, chemical residues, metallic and nuclear wastes.

Agricultural sources –   Agricultural chemicals especially fertilizers and pesticides pollute the soil. Fertilizers in the run off water from these fields can cause eutrophication in water.

                                                    RADIATION  POLLUTION

Radiation pollution is the increase in over the natural background radiation. There are many sources of radiation pollution such as nuclear wastes from nuclear power plants, mining and processing of nuclear material etc.

When a gamma ray passes through a cell, the water molecules near the DNA might be ionized and the ions might react with the DNA causing it to break. They can also cause chemical changes by breaking the chemical bonds, which can damage living tissues.

Radiation damage can be divided into two types:

1)  Somatic damage (also called  radiation sickness)

 Somatic damage refers to damage to cells that are not associated with reproduction. Effects of somatic radiation damage include reddening of the skin, loss of hair , ulceration, fibrosis of the lungs, the formation of holes in tissue, a reduction of white blood cells, and the induction of cataract in the eyes. This damage can also result in cancer and death.

2) Genetic damage

Genetic damage refers to damage to cells associated with reproduction. This damage can subsequently cause genetic damage from gene mutation resulting in abnormalities. Genetic damages are passed on to next generation.

A traditional unit of human-equivalent dose is the  rem , which stands for  radiation equivalent in man.

At low doses, such as what we receive every day from background radiation (< 1  m rem), the cells repair the damage rapidly .  At higher doses (up to 100  rem), the cells might get mutated.

it is important to realize that the biological damage caused by a particle depends not only on the total energy deposited but also on the rate of energy loss per unit distance traversed by the particle (or “linear energy transfer”). For example, alpha particles do much more damage per unit energy deposited than do electrons.

Non-ionizing radiations are constituted by the electromagnetic waves at the longer wavelength of the spectrum ranging from near infra-red rays to radio waves.

These waves have energies enough to excite the atoms and molecules of the medium through which they pass, causing them to vibrate faster but not strong enough to ionize them.

 In a microwave oven the radiation causes water molecules in the cooking medium to vibrate faster and thus raising its temperature

.

 Ionizing radiations  cause ionization of atoms and molecules of the medium through which they pass. Electromagnetic radiations such as short wavelength ultra violet radiations (UV)

X-rays and gamma rays and energetic particles produced in nuclear processes, electrically charged particles like alpha and beta particles produced in radioactive decay and neutrons produced in nuclear fission, are highly damaging to living organisms.

A. Bacterial diseases:

Cholera- Vibrio cholerae

B. Viral diseases

Hepatitis

C. Protozoan diseases

Dysentery

Diarrhoea

Malaria- Plasmodium Vivax

Dengue  caused by- Aedes aegypti-- Man Sudden onset of moderately high fever,

 Asbestos, nickel, cadmium, radon, vinyl chloride, benzidine and benzene -carcinogens.

 An allergic person’s immune system believes allergens to be damaging and so produces a special type of antibody immunoglobulin E (IgE) to attack the invading material. This leads other blood cells to release further chemicals (including histamine) which together cause the symptoms of an allergic reaction.

Blue Baby disease- Modern agriculture uses a lot of nitrogenous fertilizers and manures. This leads to increased levels of nitrates in the ground water as nitrates being soluble in water easily leach into the soil. Once the level exceeds 10 ppm it may become harmful and contaminate  source of drinking water , this causes  methaemoglobinaemia( blue baby syndrome)  particularly in bottle fed infants who are very sensitive to this pollutant

When water containing nitrates is consumed and it reaches intestines, the intestinal bacteria convert nitrates into nitrites. The nitrite ions combine with haemoglobin to form methaemoglobin which inhibits the oxygen carrying capacity of the blood causing a kind of anaemia known as  methaemoglobinaemia.

Methaemoglobin is formed when iron in the haemoglobin molecule is oxidized from Fe 2 + (ferrous) to Fe  3 +  (ferric) form.

 Nitrates can be removed from the water by processes like electrodialysis and reverse osmosis. Nitrites in the water can be oxidized to nitrates by introducing a strong oxidant like ozone in the water .

Heavy metals cannot be destroyed by biological degradation

Lead enters the atmosphere from automobile exhaust.It is a carcinogen of the lungs and kidneys

Mercury kills cells in the body and damages organs which come in contact with mercury and thus impairs their functioning. Inhalation of mercury vapours is more dangerous than its ingestion. Chronic exposure causes lesions in the mouth and skin and neurological problems.

Largest source of mercury pollution is through aquatic animals such as fish which accumulate mercury as methyl mercury .

 Arsenic is emitted from fossil fuel burning. Liquid effluents from fertilizer plants also contain arsenic.

Chronic arsenic poisoning leads to loss of appetite, weight, diarrhoea, gastrointestinal disturbances and skin cancer .

  Alternatively the tube well/ hand pump water should be purified to remove arsenic before consumption

If a person drinks water contaminated with arsenic for about 10 years, dark spot develop on the upper chest, back and arms known as  melanosis.The next stage is keratosis in which palms become hard and patient may suffer from diarrohea, stomach pain, breathing problems, etc.

Mining especially of zinc and metallurgical operations, electroplating industries, etc. release cadmium in the environment. It may enter the human body by inhalation or from aquatic sources including fish, etc. It may cause hypertension, liver cirrhosis, brittle bones, kidney damage and lung cancer . Itai-itai disease first reported from Japan in 1965 was attributed to cadmium contamination in water and rice

Metals such as zinc, chromium, antimony and tin enter food from cheap cooking utensils. Preserved foods stored in tin cans also cause contamination by tin.

         Black lung disease is the common name for pneumoconiosis  (CWP) or anthracosis, a lung disease of older workers in the coal industry , caused by inhalation over many years, of small amounts of coal dust.

        Silicosis first reported from Kolar gold mines in 1947 is a common disease among miners, pottery and ceramic industry workers.

 Pneumoconiosis & byssinosis are common among mica and textile industry workers respectively .

Floods are caused by rains, high winds, cyclones, tsunami, melting snow or dam burst. 

(ii)  Effects

 •  Casualties

•  Structural damage :During floods mud huts and buildings built on weak foundations collapse endangering human lives and property . Damage may also  cause to roads, rail, dams, monuments

•  Material loss

•  Utilities damage :Utilities such as water supply , sewerage, communication lines, power -lines, transportation network and railways are put at risk.

•  Crop loss

Ø Dengue is also called Breakbone Fever, or  Dandy Fever. It is an acute, infectious, mosquito- borne hemorrhagic fever.

Ø Dengue is caused by a virus transmitted through a mosquito called  Aedes aegypti or  Asian tiger mosquito.

Water on earth is classified into following three types:

 a) Fresh water: It is inland water and its salt content is less than 5 ppt or 0.5%;

 b) Marine water: It occurs in seas, oceans and its salt content is more than 35 ppt or 3.5%.

 c) Brackish water: It’ s salt content is more than 5 ppt but less than 35ppt. It is present in estuaries, salt marshes and salt lakes.  A lot of underground water in Rajasthan, Gujarat, Haryana and Punjab is brackish

The ultimate source of this water is rainfall. India receives about 2750 km   of rainfall per year .  About 600 km  of its seeps into the ground and about 900 km 3 evaporates water vapour back into environment.

Nitrogen oxides (N 2 O)--- Burning of fossil fuels, fertilizers; burning of wood and crop residue.

Biodiversity could be classified as

(a) Species biodiversity: It includes total number of different taxonomical or biological species. There are more than 200000 species in India of which several are confined to India (endemic).

 (b) Genetic biodiversity: It includes land traces; horticultural varieties; cultivers, ecotypes (related types differing due to difference in the ecological condition); all within a biological species.

(c) Ecosystem biodiversity: It includes various biological zones, like lake, desert, coast, estuaries, wetlands, mangroves, coral reefs etc

 A high value fish is  the one which is captured  prior to completing its  life cycle.

Ultra violet (UV) radiation, with wavelengths shorter than visible spectrum has high energy .  UV  radiations can be divided into three forms:

 UV-A (wavelength between 320-400nm),

 UV-B (wave length lesser than 280  nm), and

 UV-C (wavelength lesser than 280  nm).  UV-C is most damaging to biological systems.

                                                  OZONE LAYER

Ozone (O3) layer can be destroyed both by natural and man-made causes-

(i) Natural causes:  A number of naturally occurring substances destroy stratospheric ozone. Most important of these compounds are: Hydrogen oxide (HO x ), Methane (CH 4 ), Hydrogen gas (H 2 ), Nitrogen oxides (NO x ).

Chlorine monoxide (ClO); during volcanic eruptions, significant amount of chlorine may be released in the stratosphere.  Tiny particulate matter in the stratosphere, known as stratospheric aerosols, may also lead to ozone destruction.

  A small amount of uv-radiation is necessary for well-being of human beings and other organisms, such as UV-B promote synthesis of vitamin-D. UV -radiation also act as a germicide to control   micro-organisms.

Acid precipitation affects both aquatic and terrestrial organisms. It also damages buildings and monuments.

 (i) Effects on aquatic life: The pH of the surrounding or medium is very important for metabolic processes of aquatic organisms. The eggs or sperms of fish, frogs and other aquatic organisms are very sensitive to pH change.  Acid rain kills their gametes affecting the life cycles and productivity .

Acidic lake waters may kill bacteria/microbes/planktons and the acidic lakes become unproductive and life less. Such acidic and lifeless ponds/lakes adversely affect fisheries and livelihood.

(ii) Effect on terrestrial life: Acid rain damage cuticle of plant leaves resulting etiolation of foliage.

 This in turn reduces photosynthesis. Reduced photosynthesis accompanied by leaf fall reduces plant and crop productivity . Acidic medium promotes leaching of heavy metals such as aluminum, lead and mercury . Such metals when percolate into ground water affect soil microflora/ micro fauna.

(iii) Effects on forests: Acid rains damage forests and kill vegetation and causes severe damage to the landscape.

 (iv) Effect on buildings and monuments: Many old, historic, ancient buildings and works of art/textile etc. are adversely affected by acid rain. Limestone and marble are destroyed by acid rain. Smoke and soot cover

Biological diversity is usually considered at three different levels – a) genetic diversity i.e. at genetic level , b) species diversity i.e. at the level of species, and c) ecosystem diversity i.e. at the level of ecosystem.

                                                          DIVERSITY

Species diversity can be measured in terms of:

(a) Species richness –refers to the number of various species in a defined area.

(b) Species abundance –refers to the relative numbers among species. For example, the number of species of plants, animals and microorganisms may be more in an area than that recorded in another area.

(c) Taxonomic orphylogenetic diversity –refers to the genetic relationships between different groups of species.

India is a country of vast diversity and it is among the 12 “mega-diversity” countries in the world

Species diversity is not evenly distributed across the globe. The overall richness of species is concentrated in equatorial regions and tends to decrease as one moves from equatorial to polar regions. In addition, biodiversity in land ecosystems generally decreases with increasing altitude. The other factors that influence biodiversity are amount of rainfall and nutrient level in soil. In marine ecosystems, species richness tends to be much higher in continental shelves.

Norman Myers, a British Ecologist, developed the concept of hot spots in 1988 to designate priority areas for  insitu  conservation.  According to him, the hot spots are the richest and the most threatened reservoirs of biodiversity on the earth.

The criteria for determining a hot spot are:

 i) The area should support >1500 endemic species

 ii) It must have lost over 70 % of the original habitat

India accounts for only 2.4 % of the land area of the world; but it contributes approximately 8% species to the global diversity due to existence of such pockets.

 The threat to survival or loss may be caused in the following three ways:

• Direct ways: Deforestation, hunting, poaching, commercial exploitation.

 • Indirect ways:  Loss or modification of the natural habitats, introduction of exotic species, pollution, etc.

 • Natural causes - Climate change.

  Exotic species  (new species entering geographical region) may wipe out the native ones.  A few examples are

(i) Parthenium hysterophorus (Congress grass- a tropical  American weed) has invaded many of the vacant areas in cities, towns and villages in India leading to removal of the local plants and the dependent animals.

(ii) Nile perch, an exotic predatory fish introduced into Lake  Victoria (South  Africa) threatened the entire ecosystem of the lake by eliminating several native species of the small Cichlid fish that were endemic to this freshwater aquatic system.

iii) Water hyacinth clogs lakes and riversides and threatens the survival of many aquatic species. This is common in Indian plains.

 (iv) Lantana camara  (an  American weed) has invaded many forest lands in various parts of India and wiped out the native grass species.

 

 A Biosphere Reserve consists of core, buffer and transition zones.

(a) The  core zone is fully protected and natural area of the Biosphere Reserve least disturbed by human activities. It is legally protected ecosystem in which entry is not allowed except with permission for some special purpose. Destructive sampling for scientific investigations is prohibited.

(b) The buffer zone surrounds the core zone and is managed to accommodate a greater variety of resource use strategies, and research and educational activities.

 (c) The  transition zone, the outermost part of the Biosphere Reserve, is an area of active cooperation between the reserve management and the local people, wherein activities like settlements, cropping, forestry , recreation and other economic that are in harmony with the conservation goals.

 In-situ methods

i) Protection of habitat:The main strategy for conservation of species is the protection of habitats in representative ecosystems. Currently , India has ninety six National Parks, five hundred  Wildlife Sanctuaries, thirteen Biosphere Reserves, twenty seven  Tiger Reserves and eleven Elephant Reserves

ii) Species-oriented projects:  Certain species have been identified as needing a concerted and specifically directed protection effort. Project  Tiger , Project Elephant and Project crocodile are examples of focusing on single species through conserving their habitats.

This project  was started in 1976 with FAO – UNDP assistance to save three endangered crocodilian species, namely , the fresh water crocodile, salt water crocodile and the rare gharial.

(iii) Sacred forests and sacred lakes:  A traditional strategy for the protection of biodiversity has been in practice in India and some other  Asian countries in the form of sacred forests. These are small forest patches protected by tribal communities due to religious sanctity .  These have been free from all disturbances.

 Khecheopalri lake in Sikkim, have been declared sacred by the people, leading to protection of aquatic flora and fauna.

 Ex-situ Conservation

(i) Botanical gardens, zoos, etc.

(ii) Gene Banks :

(iii) Cryopreservation:(“freeze preservation”) is particularly useful for conserving vegetative propagated crops. Cryopreservation is the storage of material at ultra low temperature of liquid nitrogen (-196 0 C) and essentially involves suspension of all metabolic processes and activities.

(iv) Conservation at molecular level (DNA level):

Natural gas contains methane and smaller amounts of propane and butane. When a natural gas field is tapped, propane and butane gases are liquefied and removed as liquefied petroleum gas (LPG). The rest of the gas (mostly methane) is dried to remove water vapour, cleansed of poisonous hydrogen sulphide and pumped into pressurized pipelines for distribution.  At a very low temperature, natural gas can be converted into liquefied natural gas (LNG).

Ferrous metallic minerals Non-ferrous metallic minerals (Iron, Mangnese, Chromite). Gold, Silver, Copper ,  Tin, Zinc, Aluminium (Bauxite ore)

Haematite is red in colour, called ‘red ore’ and has 68% iron. Magnetite is dark brown in colour called ‘black ore’ and has 60% iron. Limonite is yellow in colour and has 35% iron.

India ranks third in the production of manganese ore in the world.

It is also used in the manufacture of dry batteries, in photography , leather and match industries

 Bauxite is also used in the manufacture of white colour cement and certain chemicals

Zinc is mainly used in tyre industry . It is also used in dye, casting, dry batteries, textile etc.

Limestone, phosphorite, kaolin, gypsum and magnesite are significant non-metallic minerals

Almost 76% of country’ s total consumption is used in cement industry , a lar ge amount is used in iron and steel industry .

India is the leading producer of sheet mica. Bihar and Jharkhand produce the high quality ruby-mica

.

These are mainly used for manufacturing of phosphate fertilizers. Rajasthan is the leading producer followed by Uttaranchal, Madhya Pradesh and Uttar Pradesh.

One way to improve mining technology is to use microorganisms to extract metals from its ores known as “biomining” or ‘ecological engineering’

Slight degradation refers to the condition that where crop yield potential is reduced by 10%.

Moderate degradation refers to 10-50% reduction in yield potential and in severely degradation means that the land has yield potential is lost more than 50% of its potential yield capacity (productive capacity).

 Some causes of land degradation are:

• use of agrochemical (chemical fertilizers and pesticides)

• excessive irrigation

 • cultivation of high yielding plant varieties.

Conservation of cultivable land cause can be achieved not only through preventive and remedial measures in order to control land erosion and degradation about which you will read in section 1but also by using innovative agricultural technologies which involve use of:

(i) organic farming or green manures

(ii) biofertilisers

 (iii) biological pest control

The cottony cushion scale pest (Icerya pur cahsi) (Fig. 17.13a) is controlled biologically on a large scale by its predator, the lady bird beetle

Our ecological foot prints –the amount of biologically productive area of the earth needed to produce the required resources as well as to absorb the wastes produced from such resources use.

On his recommendation two semi dwarf varieties namely Lerma Rajo and Sonora-64 were chosen and were released for cultivation in irrigated fields. These varieties gave very high yield and brought in revolution in wheat production.

Dr. M.S. Swaminathan an outstanding mutation geneticist produced ‘Sharbati Sonara’ and released it for cultivation in 1967.

Dr . Borlaug :In 1970 he was awarded Nobel prize for “Green Revolution” which helped India.

Sustainable Agriculture is one that,

• supports profitable production; 

• protects environmental quality;

 • uses natural resources efficiently; 

• provides consumers with affordable, high-quality products;

 • decreases dependency on non-renewable resources;

 • enhances the quality of life for farmers and rural communities;

 • and will last for generations to come.

 Several methods adopted in sustainable agriculture are:

 • cultivation practices to increase biological and economic stability .

 • selection of improved varieties to suit the need.

• soil management by proper method of tillage.

(a)  Mixed cropping or diverse cropping

The various plans followed in diverse or mixed cropping practices are-

• Poly-varietal cultivation where several genetic varieties of the same crop are planted.

• Polyculture, in which different plants maturing at various times are planted together .

(b)  Crop rotation

(i) Leguminous crop should be grown after non-leguminous crop

 (ii) Crops require less water (irrigation) should be grown after one – that requires more water .

 (iii) Crops requiring less manure should be sown after one that requires more manure

Important crop patterns of crop rotation

 1. Green gram - Wheat – Moong

2. Ground nut – Wheat – Moong

3. Arhar – Sugarcane – Wheat – Moong

4. Paddy – Wheat – Moong

·        First, growing crops only on more level land and pastures or forages on steeper slopes will reduce soil erosion.

·        Second, pasture and leguminous forage crops in rotation enhance soil quality and reduce erosion; livestock manure, in turn, contributes to soil fertility . 

·        Third, livestock can buffer the negative impacts of low rainfall periods by consuming crop residue that in “plant only” systems would have been considered crop failures.

·        Finally , feeding and marketing are flexible in animal production systems.

                                                     Soil Management:

Methods of protection include using cover crops, compost, reducing tillage, conserving soil moisture by dead mulches, this increases water hold capacity of the soil.

Some of the objectives of varietal improvement are:

(i) development of high yielding varieties of crop plants.

 (ii) food crops developed for better and higher nutritional quality like protein quality

(iii) development of crop varieties resistance to diseases and pests.

 (iv) improving varieties for resistance against heat, cold, frost, draught and water logging.

 Bio-fertilizers are living or biologically active products or microbial inoculants of bacteria, algae and fungi (separately or in combination) which are able to enrich the soil with nitrogen, phosphorus, organic matter etc.

Rhizobium biofertilizer:  Rhizobium is a symbiotic bacteria forming root nodules in legume plants. These nodules act as miniature nitrogen production factories in the fields.

Azotobacter biofertilizer:  Azobacter are aerobic free living nitrogen fixers.

Azospirillium biofertilizer:These are aerobic free living nitrogen fixers which live in associative symbiosis
.

Blue green algae: Blue green algae (BGA or cyanobacteria) like Nostoc and Anabaena are free living phostosynthetic organisms also capable of fixing atmospheric nitrogen. In the flooded rice fields blue green algae serves as a nitrogen biofertilizer
.

Azolla biofertilizers:  Azolla is a water fern inside which grows the nitrogen fixing blue green algae  Anabaena.

This can be grown in a cooler regions. But there is a need to develop a strain that can tolerant to high temperature, salinity and resistant to pests and diseases.

The only constraint in  Azolla is that it is an aquatic plant and water becomes limiting factor in growing it particularly in summer .

Phosphorus solubilising  biofertilizer:   Mycorrhizal fungi acts as biofertilizer are known to occur naturally on roots of forest trees and crop plants.The fungus has the ability to dissolve and absorb phosphorus that plant roots cannot readily absorb.

                                                        Organic farming

Organic farming is a type of agriculture or farming which avoids the use of synthetic fertilizers, pesticides, growth regulators, and livestock feed additives.

Organic farming systems rely on crop rotation, crop residues, animal manures, legumes, green manure, off-farm organic wastes and biofertilizers, mechanical cultivation, mineral bearing rocks to maintain soil productivity to supply plant nutrients and biological pest control, controlling weeds, insects and other pests.

 All kinds of agricultural products can be produced organically , including grains, meat, dairy , eggs, fibres such as cotton, jute, flowers etc.  Thus organic farming creates a sustainable lifestyle for generations to come.

Organic farmers build healthy soils by nourishing the living component of the soil, the microbial inhabitants that release, transform, and transfer nutrients.

Soil organic matter contributes to good soil structure and water-holding capacity .

Organic farmers feed soil biota and build soil organic matter with cover crops, compost, and biologically based soil amendments. These produce healthy plants that are better able to resist disease and insect predation.

Organic farmers’ primary strategy in controlling pests and diseases is prevention through good plant nutrition and management. Organic farmers use cover crops and sophisticated crop rotations to change the field ecology , effectively disrupting habitat forweeds, insects, and disease organisms. Weeds are controlled through crop rotation, mechanical tillage, and hand-weeding, as well as through cover crops, mulches, flame weeding, and other management methods.

Organic farmers rely on a diverse population of soil organisms, beneficial insects, and birds to keep pests in check. When pest populations get out of balance, growers implement a variety of strategies such as the use of insect predators, mating disruption, traps and barriers.

It has been found that by switching to organic farming, conventional farmer can actually reduce its production cost by over 25% as compared to the cost of conventional farming. This is eliminate the use of expensive synthetic fertilizers and pesticides, minimizing soil erosion by up to 50% and increasing crop yields up to five-folds.

 Not only does wildlife benefit, but entire ecosystems and ground water are improved by simply following organic farming methods.

When dairies feed their cows organic feed and graze them on organic fields, the cows experience better health, less sickness, diseases and ultimately produce better tasting milk for consumers.

Organic farming promotes healthy soils that are teaming with life and rich in micro nutrients and which can be used for decades to grow crops without getting exhausted.

• Consumers purchasing organically grown foods are tastier . Regardless of minimal price differences, consumers can smell, taste and see the difference in the quality of organically grown food products.

• Organically grown products are free from harmful chemicals, artificial flavors and preservatives that ultimately cost consumers more money than non-organically grown products

The most sustainable way to control pests is a carefully designed integrated pest management (IPM) program. In this approach, each crop and its pests are evaluated as parts of an ecological system. Then farmers develop a control programe that includes cultivation, biological and chemical methods applied in proper sequence and with the proper timing. The aim of IPM is not to eradicate the pest population completely but to keep the crop damage to economically tolerable level

Farmers monitor the field and when they find the pest level to be high enough, they first use biological methods and cultivation practices to control and then use small amounts of insecticides mostly insecticides derived from plants as a last resort.

 (a) Biological control includes natural predators, parasites and pathogens of the pests are used. Examples are: • Pest on cucumber plant called red spider mite

Citrus fruits in California heavily damaged by scale insects which were controlled by Australian ladybird which ate away the insects.

(b)  Cultivation practices:  A variety of cultivation practices like crop rotation, polyculture and inter cropping etc. can be used to get rid of the pests.

(c) Some amounts of insecticides, mostly of plant origin (e.g. Pyrethrum and Rotenone neem product) are applied as a last resort.

(d) Pest and disease resistant crop :plants can be produced by genetic engineering. Ex - Bt cotton

Pest control method has some disadvantages:

 • Farmer should have an expert knowledge about each pest.

• It acts more slowly than conventional pesticides

• Methods developed for a crop in one area might not apply to areas with even slightest different growing conditions.

• Initial cost may be higher but in the long-term cost become very low .

By slowing down and controlling ripening in tomato by introducing a bacterial gene that prevents ethylene formation thus delays ripening.

Frost resistant tomatoes have been produced by introducing gene for antifreeze proteins from polar fish living in ice water .

Controversies on GM products

 (i)  Safety

• Potential human health impact: allergens, transfer of antibiotic resistance markers, unknown effects.

 • Potential environmental impact: unintended transfer of transgenes through cross-pollination, unknown effects on other organisms (e.g., soil microbes) and loss of flora and fauna biodiversity

(ii)  Access and intellectual property

(iii)  Ethics

 • Violation of natural organisms’ intrinsic values.

 • Tampering with nature by mixing genes among species.

• Objections to transferring animal genes in plants and vice versa.

• Stress for animal.

 (iv)  Labeling

(v)  Society

 • New advances may be skewed to interests of rich countries.

Industries may interact in such a way that they establish a “resource exchange” programme in which waste of one industry or manufacturer is utilized as raw material by another-industry- similar to food web in nature.

Bioremediation is the process in which a living organism (plant/animal/bacteria) is deployed to make a hazardous wastes harmless.

 For example bacteria and enzymes help to destroy toxic and hazardous substances or convert them in harmless compounds.

Radiation emitted natural sources is known as  “background radiation”,because it is present everywhere, all the time.

Huge amount of heat is generated in nuclear power plants, only one third of the heat is used in generating electricity and two third is lost as waste heat.

When the world entered the atomic age, the problem or the dangers of disposal of nuclear waste were not fully realized. It is now becoming increasingly clear that safe disposal of nuclear waste is not easy and simple. Radioactive wastes are of two types

(1) low level radioactive wastes (LLW) which include civilian applications of radio nuclides in medicine, research and industry , materials from decommissioned reactors, protection clothing worn by persons working with radioactive materials or working in nuclear establishments.

(2) High level radioactive wastes (HLW) results from spent nuclear fuel rods and obsolete nuclear weapons.

Some proposed methods of disposing nuclear waste are:

• bury it deep underground in insulated containers. This is a strategy being pursued in United States.

• shoot it into the space or into the sun. The cost would be very high and a launch accident should be disastrous.

 • bury it under the ice sheet of  Antarctica or Greenland ice cap. The ice could be destabilized by heat from the waste. The method has been prohibited by international law

 • Dump it into deep oceans by keeping the waste into glass and steel cases. But the containers might leak and contaminate the ocean. Both HLWand LLW into the  Atlantic ocean.  The method is prohibited by international law .

Until 1983, European countries had been dumping .After 1983 when dumping  was stopped, by law 90,000 metric tons waste had been disposed in the ocean. • change it into harmless or less harmful isotopes. Currently no method is known to do that and the method would be too costly .

 • Presently waste fuel rods are being stored in special storage ponds at reactor sites or sent to reprocessing plants. Even though reprocessing is more expensive but some countries use reprocessing as an alternative to waste storage.

Potentially usable sites or locations where nuclear waste can be disposed off should have some characteristics

• low precipitation;

• absence of surface waters;

• low possibility of tectonic movement;

 • adequate buffer zone (in case the waste gets loose)

Labeling of environmentally beneficial goods and resources extracted by more sustainable methods can help consumers decide which goods and services to buy. Product eco-labelling can encourage companies to develop green products and services and help consumers select more environmentally beneficial products and services.

Some consumer products to meet certain environment criteria alongwith quality requirements of Indian standards. The label is known as  ‘Eco mark’.

Eco-label is issued by the Central Pollution Control Board (CPCB) is represented by a pitcher or an  ‘earthen pot’

The 42^nd amendment Clause (g) to  Article 51A of the Indian constitution made it a fundamental duty to protect and improve the natural environment

.

The  Act vests regulatory authority in State Pollution Control Boards and empowers these Boards to establish and enforce  effluent standards for factories discharging pollutants into water bodies.

 A Central Pollution Control Board performs the same functions for Union  Territories and formulate policies and coordinates activities of different State Boards.

In the wake of the Bhopal tragedy , the government of India enacted the Environment (Protection)  Act of 1986.

A state may declare forestlands or waste lands as reserved forest and may sell the produce from these forests.  Any unauthorized felling of trees quarrying, grazing and hunting in reserved forests is punishable with a fine or imprisonment, or both. Reserved forests assigned to a village community are called  village forests. The state governments are empowered to designate protected forests and may prohibit the felling of trees, quarrying and the removal of forest produce from these forests.

There is provision for notifying  National Heritage Sites important from standpoint of biodiversity by State Governments in consultation with local self-government

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A protocol is an international agreement that stands on its own but is linked to an existing convention

The United Nations Educational, Scientific and Cultural Organisation (UNESCO) serves as the Depositary for the Convention, and its secretariat, the Ramsar Bureau, is in Gland, Switzerland.

The United Nations Environment Programme (UNEP) has been addressing this issue since 1977. Under the auspices of UNEP , the nations of the world arrived at  The Convention for the Protection of the Ozone Layer  in  Vienna in 1985.

The Montreal Protocol uses three kinds of provisions as economic incentives to encourage participation and compliance with the Protocol’ s control regime;

 (1) entry into force requirements,

 (2) controls on trade with non-parties, and

 (3) research and technology transfer benefits.

                                     ENVIRONMENTAL IMPACT ASSESSMENT

EIA is a tool which helps to evaluate environmental impact of proposed developmental projects or programs are visualized clearance accorded after mitigation strategies are included in the plan.

EIA thus proves to be a tool which improves decision making and ensures that the project under construction is environmentally sound and within limits of the capacity of assimilation and regeneration capacities of the ecosystem. Environmental clearance of developmental projects is mandatory for the new project.

The important aspects of EIA are:

• risk assessment,

• environmental management &

• post product monitoring.

EIA was introduced in India in 1978, with respect to river valley projects. Later the EIA legislation was enhanced to include other developmental sections

The goal of EIA is to ensure environmentally safe and sustainable development.

The EIA process looks into the following components of the environment.

ü Air environment

ü Noise

ü Water environment

ü Biological environment

ü Land environment

ü Biological stress (prediction).

Steps in EIA process EIA involves the steps mentioned below . However , EIA process is cyclical with interaction between the various steps.

 • Screening:The project plan is screened for scale of investment, location and type of development and if the project needs statutory clearance.

• Scoping:  The project’ s potential impacts, zone of impacts, mitigation possibilities and need for monitoring. The EIA agency has to follow the published guidelines by the Ministry of Environment and Forest (MoEF) of government of India.

• Collection of baseline data: Baseline data is the environmental status of study area.

 • Impact prediction: Positive and negative, reversible and irreversible and temporary and permanent impacts need to be predicted which presupposes a good understanding of the project by the assessment agency .

• Mitigation measures and EIA report: The EIA report should include the actions and steps for preventing, minimizing or by passing the impacts or else the level of compensation for probable environmental damage or loss.

 • Public hearing:  On completion of the EIA report, public and environmental groups living close to project site may be informed and consulted.

 • Decision making: Impact  Assessment (IA)  Authority along with the experts consult the project-in-charge along with consultant to take the final decision, keeping mind EIA and EMP (Environment Management Plan).

• Monitoring and implementation of environmental management plan: The various phases of implementation of the project are monitored. • Risk assessment: Inventory analysis and hazard probability and index also form part of EIA procedures
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The Central Pollution Control Board (CPCB), is statutory organisation, was constituted in September , 1974 under the  Water (Prevention and Control of Pollution)  Act, 1974. Further , CPCB was entrusted with the powers and functions under the  Air (Prevention and Control of Pollution)  Act, 1981.

Indian Board for Wildlife (IBWL) The IBWL is the apex advisory body in the field of  Wildlife Conservation in the country and is headed by the Honorable Prime Minister of India.

UNEP was created by United Nations General  Assembly , as an outgrowth of the United Nations Conference on the Human Environment, held in Stockholm, Sweden

It is headquartered in  Nairobi(Kenya).

One view is that humans are the dominant and important species on the planet earth. That gives them the power to manipulate and use nature for their own benefit. This view is “human centred” and thus it is called anthropocentric.

There are basically  three  approaches to environmental ethics.

Environmental wisdom talks of total dependence of humans on  nature and the nature is for all species. This is  life centric or  biocentric approach. An extension of the above view seeks respect for all life and demands reverence towards the entire environment. Such a non-anthropocentric approach that talks of ethical responsibility towards other species and even ecosystems is also called ecocentric.

Indian philosophy aims not only at the well being of all humans but also of all beings. The Sanskirt verse: “Sarve Bhavantu Sukhinah Sarve Santu Nirmayah”

Refers to “May all be sinless and may all experience happiness.” The  Vedas, Mahabharata and Ramayana all chant praises about cosmic harmony and environmental protection.

Nature and environment were given importance from Rigvedic period onwards.  Verse states- “the sky is like a father , the earth like a mother and space like their son”.

In the school curriculum activities such as 
(i) growing plants and taking care of them 
(ii) visits to national parks and sanctuaries (
iii) creating stories/ poems/ plays on nature conservation, should be included.  

Bishnois of Rajasthan had once upon a time laid down their lives to protect the local Khejdi trees

The Chipko movement (Chandi Prasad Bhatt and Sunder Lal Bahuguna), Baba  Amte and Medha Patkar (Narmada Bachao  Andolan) all derived inspiration from Gandhi.

His writings in ‘Hind Swaraj’ published in 1909 explained how the current mode of development is “exploitative of man by man and of nature by man”

“Mother Nature has enough for our needs but not enough for our greed.”

Ground water is found in two layers of the soil:-

• Zone of aeration where the gaps are completely filled with water .

 • Zone of saturation where the gaps are filled with air as well as water .

Boundary between these two zones is known as the  water table, which rises or falls as the level of ground water increases or decreases.

The annual rainfall over India is 1 170 mm. It is more than any where else in the world for a country of comparable size. From  precipitation alone, India receives 4000 billion cubic meters (BCM), including snow fall. Of this ¾ part occurs only during the monsoon.  A good part of it is lost through the process of evaporation and plant transpiration, leaving only half of it on the land for us to use.  After allowing for evapotrans-piration losses the country’ s surface flow is estimated as 1880 BCM. Due to topographical, hydrological and other constraints, it is assessed that only about 700 BCM of surface water can be put to beneficial use.

Ozone gas may also be used for disinfection of drinking water. However , since ozone is unstable, it cannot be stored and must be produced on-site, making the process more expensive than chlorination.

Ozone has the advantage of not causing taste or odour problems. It also leaves no residue in the disinfected water .

Defluoridation at domestic level is taken in the container , is mixed within adequate amount of aluminum sulphate (alum) solution, lime or sodium carbonate and bleaching powder depending upon its alkalinity (concentration of bicarbonates and carbonates in water) and fluoride contents.

Removal of iron  involves aeration of raw water over a series of coke, marble/calcite bed followed by slow sand filtration. No chemical is required

Removal of arsenic  is based on oxidation, coagulation, flocculation, sedimentation and filtration. Bleaching powder and alum are used for removal of arsenic.

Major water quality issues in Indian context

Pathogenic pollution • Water borne diseases are the most important water quality issues in India.  This is mainly due to inadequate arrangements for transport and treatment of waste waters.

Oxygen depletion • A large portion of wastewater is discharged into water resources without any treatment.  A major portion is from domestic sources. Such waste water contains high amount of organic matter . 

Eutrophication: The discharge of domestic waste water , agricultural return water or run-off water and many industrial effluents contribute nutrients like phosphates and nitrates
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Salinity • There are number of cases where salinity is increasing in both surface water and groundwater .  The increase in groundwater salinity is mainly due to increased irrigation

Toxic pollution • Due to discharge of toxic effluents from many industries and increased use of chemicals in agriculture and their subsequent contribution to the water bodies,

Throughout the world, shortage of water is growing due to increasing:

 • droughts,

 • irrigation demand,

• industrial demand,

 • pollution, reducing usability of water resources, and

 • wastage and irresponsible attitude towards water.

Rain water harvesting techniques: There are two main techniques of rain water harvesting:

 1. Storage of rain water on surface for future use

2. Recharge of  ground water

Rainwater harvesting: a success story   In the area surrounding the River Ruparel in Rajasthan is a good example of proper water conservation. The site receives very little rainfall, but proper management and conservation have ensured the water availability through out the year .

From a technical point of view the term resource when used as a measurement of mineral or fuel refers to the total amount of a mineral or fuel in a country or on earth.

 Generally only a small fraction can be recovered. On the other hand reserve means the deposits of energy fuel or minerals that are economically and geologically feasible to extract

Coal is mined from both (i) surface mines, and (ii) underground mines.

 (a)Surface mining :-Surface mining disrupts and drastically changes the natural landscape and destroys the natural vegetation and the habitat of many species, some of which may already be endangered. Mining operations, involving digging, blasting, removal of rocks and soil lying over the coal seam, cause serious problems of air and noise pollution. Surface mining may also cause soil erosion and silt loading (the discharge of silts into streams) and nallas that disrupt and pollute the aquatic ecosystems as well as ground water in places where aquifers are located near or associated with coal seams.

(b) Underground mining:- Underground mining may cause collapse or land subsidence in the mining areas during or after mining operations are over . In case of some mines acid mine drainage from the mine waste and OBD piles polluted long stretches of streams. Coal fires in underground mines may happen which naturally caused give out much smoke and hazardous fumes caused several respiratory disease to people living nearby .

Problems associated with oil and gas Leakage of natural gas from pipelines, storage tanks and distribution tanks is potential cause of explosion

Methane being major component of natural gas, happens to be a green house gas and its leakage contributes to global warming. But being a clean fuel has advantages over coal and oil and preferred as a better fuel option or energy resource.

Extraction of oil and gas may cause sinking of land or subsidence. For example, in Long Beach Harbor area, in Los  Angeles, USA, intensive oil extraction beginning in 1928 caused severe land subsidence. Over the well sites, the ground dropped 9 metres. Extensive subsidence created a need for flood control measures along the coastline.

  Another major problem in the past with onshore oil wells has been brine (salt water).  Typically , for every barrel of oil production ten barrels of brine are also extracted. In early days the brine was simply discarded into nearby streams or on the soil.  Today most brine is reinjected into the well. However, brine can contaminate fresh water aquifers if the casing lining the well is missing or corroded.

But the natural gas that comes out along with oil is often looked as unwanted by product and is burned off. Burning of associated natural gas represents a waste of a valuable energy resource and emissions carbon dioxide into the atmosphere from its burning.

Apart from these two problems, oil also contaminates the oceans.  About half of the oil that contaminates the ocean comes from natural seepage from offshore deposits (annually approximately 600,000 metric tonnes of oil seeps into the ocean from natural sources). 20% of the oil contaminating the ocean comes from oil well, blowouts, pipeline breaks and tankers.

 One Becquerel = 1 radioactive decay which is a very small amount. It may surprise you to know that every substance is radioactive to some extent. For example, One loaf of bread = 70 Bq One kg of coffee = 1000 Bq

 Direct use of solar energy can be used through various devices broadly directed into three types of systems a) passive, b) active c) photovoltaic.

The more recent passive uses of solar energy is for cooking, heating, cooling and for the daylighting of homes and buildings. The effectiveness of passive solar energy depends on good building design; no mechanical means are employed in passive use of solar energy .

Active use of solar energy: Active solar heating and cooling systems rely on solar collectors which are usually mounted on roofs. Such systems also requires pumps and motors to move the fluids or blow air

Huge arrays of computer-controlled mirrors called heliostats track the sun and focus sunlight on a central heat collection tower .

 (a) wind energy , (b) tidal energy and (c) hydroelectric energy and (d) biomass energy .

La Rance in France is the only commercial power station operating in the world. In India a major power project costing Rs. 5000 crores is proposed to be set up in the Hanthal Creek in the Gulf of Kutch in Gujarat.

Eco house :It is a residential building and was constructed in mid seventies. It was equipped with solar cooker and a multifeed biogas plant. Rain water harvesting is also used in this house.  A roof mounted wind generator was also contemplated but not installed.

Multifeed biogas plant, usable as septic tank, if required.

• Three different types of experimental roofs (hollow concrete tiles, Prefab brick jack arches, Madras terrace roof). • Design for ventura (ventilation via inner courtyard).

Ventura system of using high and low pressure for sucking in cool air and pushing out hot air through roof ventilato

Biomass is a renewable energy resource derived from plants and animal waste. The energy from biomass (biomass conversion) is released on burning or breaking the chemical bonds of organic molecules formed during photosynthesis. Thus biomass represents an indirect form of solar energy . Biomass fuels can be used directly or they can be transformed into more convenient form and then used.

Burning of biomass does not increase atmospheric carbon dioxide because to begin with biomass was formed by atmospheric carbon dioxide and the same amount of carbon dioxide is released on burning.

Any biodegradable (that which can be decomposed by bacteria) substance can be ferented anaerobically (in absence of oxygen) by methane-producing (methanogenic) bacteria.

GOING GREEN starts from the top, and in the capital the President’ s Estate is taking the lead. Besides lighting an entire auditorium wing with solar power , the Rashtrapati Bhavan is using cow dung-fuelled biogas in its kitchen for the President’s bodyguards.

Many such promising species belong to the families Asclepiadaceae, Asteraceae, Anacardiaceae Euphorbiaceae, Convolvulaceae, Caprifoliaceae, Lamiaceae, and Moraceae. Jatropa curcasis an important petro plant

This biocrude can be obtained by tapping the latex, followed by coagulation, or by extraction of the dry biomass using a suitable solvent in cases where latex tapping is not possible.

Geothermal resource falls into three major categories:

 i) Geopressurized zones,

ii) hot-rock zones and

iii) Hydrothermal convection zones.

 Of these three only the first is currently being exploited on a commercial basis:

In India, Northwestern Himalayas and the western coast are considered geothermal areas. The Geological Survey of India has already identified more than 350 hot spring sites, which can be explored as areas to tap geothermal energy
 .

  The Puga valley in the Ladakh region has the most promising geothermal field.  An experimental  1-kW generator is already in operation in this area

Geothermal energy can pose several environmental problems which includes on-site noise, emissions of gas and disturbance at drilling sites, disposal sites, roads and pipelines and power plants during its development. The steam contains hydrogen sulphide gas, which has the odour of rotten eggs, and cause air pollution. The minerals in the steam are also toxic to fish and they are corrosive to pipes, and equipment, requiring constant maintenance.

Fuel cells are highly efficient power-generating systems that produce electricity by combining fuel (hydrogen) and oxygen in an electrochemical reaction or fuel cells are electrochemical devices that convert the chemical energy of a fuel directly and very efficiently into electricity (DC) and heat, thus doing away with combustion

Hydrogen and phosphoric acid are the most common type of fuel cells, although fuel cells that run on methanol, ethanol, and natural gas are also available.

In chemical fuel cells on the other hand, chemical energy is converted directly into electricity , thus are more efficient and do not produce harmful gases.

In order to maintain this reaction, hydrogen and oxygen are added as needed.  Waste products are only oxygen and water when hydrogen is used in a fuel cell.

Additionally , the efficiency of a fuel cell is largely independent of its size and energy output

They can also be used to store energy to be used as needed.

Fuel cells have efficiency levels up to 55% as compared to 35% of conventional power plants. The emission of green house gases is significantly low C 2 as water vapour is being the only emission.

                     DIFFERENT METHODS OF WATER CONSERVATION

 (a)Conservation by surface water storage: Storage of water by construction of various water reservoirs have been one of the oldest measures of water conservation.

(b)Conservation of rain water

(c)  Ground water conservation

Some of the techniques of ground water management and conservation are described below

 (i)  Artificial recharge

(ii) Percolation tank method- Percolation tanks are constructed across the water course for artificial recharge. The studies conducted in a Maharashtra indicates that on an average, area of influence of percolation of 1.2 km  , the average ground water rise was of the order of 2.5 m

(d)  Catchment area protection (CAP)

Catchment protection plans are usually called  watershed protection or management plans. These form are an important measure to conserve and protect the quality of water in a watershed. It helps in withholding runoff water albeit temporarily by a  check bund constructed across the streams in hilly terrains to delay the run off so that greater time is available for water to seep underground. Such methods are in use in north-east states, in hilly areas of tribal belts.  This technique also helps in soil conservation.  Afforestation in the catchment area is also adopted for water and soil conservation.

(e)Inter -basin transfer of water

(f) Adoption of drip sprinkler irrigation -Surface irrigation method

(g)Management of growing pattern of crops

i) In water scarce areas, the crop selection should be based on efficiency of the crop to utilize the water

(ii)Nutritional management: Potassium plays a major role under stress conditions. It improves the tissue water potential by osmoregulation, ultimately increasing the water use efficiency .

(iii)Role of anti-transpirants: Application of anti-transpirants reduces transpiration maintaining thereby the tissue water potential. Plants then take up less water from soil.  Anti-transpirants can prolong the irrigation intervals by slowing down soil water depletion.

 (h)Reducing evapo-transpiration

This can be prevented by placing water tight moisture barriers or water tight mulches on the soil surface. Non-porous materials like papers, asphalt, plastic foils or metal foils can also be used for preventing evaporation losses.

(i)Reducing evaporation from various water bodies

(j)Recycling of water

Grey water is defined as untreated household waste-water , which has not come into contact with toilet waste

                                             WATERSHED MANAGEMENT

In Gandhigram, a coastal village in Kutch district, the villagers had been facing a drinking water crisis for the past 10 to 12 years. The groundwater table had fallen below the sea level due to over extraction and the seawater had seeped into the ground water aquifers. The villagers formed a village development group, Gram  Vikas Mandal.  The Mandal took a loan from the bank and the villagers contributed voluntary labor (Shramdan).  A check dam was built on a nearby seasonal river , which flowed past the village.

Success stories like the revival of the  Aravari river basin by the waterman of Rajasthan-Rajender Singh –are already well known.

BS discuss these issues with villagers in the chosen hill areas through hundreds of hours of meetings over several months until they all agree to suspend browsing by cows for 3 years, goats for 5 years and camels for 7 years.

 Issues of use and sharing have been settled before construction began rather than later . Such works are forever and the 5 years of deliberation recedes into significance.

This agreements leads to what TBS calls ‘social fencing’ which, in contrast with physical fences, is virtual; only in mind.  With great fanfare, elders lead villagers on a walk through the entire line of the agreed ‘social fence’, sanctify it by sprinkling a mixture of scared waters and milk.