Our Environment

1. Environmental Science
• Living organisms live in different surroundings.
• Plants, animals, human beings survive with the interaction between them and the non-living things like air, water and land.
• Human beings depend on the resources of nature.
• These resources improve the life style of human beings.
Environmental science can be defined as the study of organisms in relation to their surroundings.
2. Air and Water Pollution
Air Pollution
• When the level of contaminants in air becomes so much that air becomes harmful for living beings; it is called air pollution. Causes of Air Pollution
(a) Exhaust from Automobiles : Most of the automobiles use fossil fuels. Burning of fossil fuel releases carbon dioxide and carbon monoxide. Carbon dioxide is a greenhouse gas. Carbon monoxide is a poisonous gas even at low concentrations.
(b) Exhaust from Factories and Power Plants : Coal is the main fuel being used in factories. Burning of coal produces carbon dioxide and oxides of sulphur. Oxides of sulphur and nitrogen form acid rain when they mix with rainwater. Acid rain is harmful for living beings and also for buildings and monuments.
(c) Chlorofluorocarbons (CFCs) : These are compounds of carbon and halogens and are used as refrigerant. These are also used in pressurized cans. Excess level of CFCs in the atmosphere damages the ozone layer. Ozone layer works like a shield and prevents the harmful ultraviolet radiations from reaching up to the living beings. Any damage in the ozone layer can be very harmful.
(d) Suspended Particulate Matters (SPMs): Some fine particles remain suspended in the air. These are called suspended particulate matters. Stone quarries and various other factories contribute to SPMs.
Effects of Air Pollution
1. Greenhouse Effect : Greenhouse gases trap solar radiation which increases the overall temperature of the atmosphere. Carbon dioxide and methane are examples of greenhouse gases. The greenhouse effect leads to global warming. Global warming has resulted in melting of the glacial ice. Scientists have predicted that many coastal cities would be completely submerged in the near future because of glacial melting. Global warming has also caused drastic changes in weather. Increased instances of flash floods and erratic weather are being attributed to global warming.
2. Smog : A mixture of fog and smoke is called smog. Smog creates a blanket of haze in the sky. This reduces visibility which can give trouble to pilots and drivers.
3. Respiratory Diseases : Cases of respiratory diseases; like asthma are on the rise because of increased levels of air pollution.
4. Acid Rain : Acid rain happens because of the presence of oxides of nitrogen and sulphur in the atmosphere. Acid rain can be very harmful for living beings. Moreover, acid rain can also damage buildings and monuments. The case of Taj Mahal is a reminder of the horrible effects of acid rain. The Taj Mahal was built by using white marbles. But now-a-days, it does not look white rather looks a pale white. Acid rain is corroding the marble of the Taj Mahal. An order by the Supreme Court of India directed all the factories to shift from the vicinity of Taj Mahal. After that order, only battery operated vehicles are allowed to be driven near this monument.
5. Deforestation : Deforestation is a major cause of air pollution. Reduced forest cover means there are less number of trees to convert carbon dioxide into oxygen. This has led to increased levels of carbon dioxide in the atmosphere.
Preventive measures to control air pollution
1. Switching to cleaner fuels; like CNG.
2. Increasing the use of public transport can also help in reducing air pollution. This will help in reducing the number of cars on the road.
3. Walking and cycling are very good for health as well as for the environment. You can walk or use a bicycle for a short distance commute. Instead of using a bus or a car; you should use a bicycle for going to school.
4. Electrostatic precipitators should be fitted in chimneys of factories. This helps in reducing the amount of SPMs in the air. Similarly, catalytic converters are fitted in the exhaust system of vehicles. This helps in reducing the poisonous substances in vehicle exhaust.
5. More trees should be planted. We know that trees convert carbon dioxide into oxygen; during photosynthesis. Thus, trees help in maintaining the balance of carbon dioxide and oxygen.
Water Pollution
• When the level of contaminants in water reaches to such a level that water becomes harmful for living beings, it is called water pollution.
Causes of Water Pollution
1. Untreated Sewage : In India, this is a common practice to discharge untreated sewage and effluents into the nearest water body. Most of the rivers and ponds in India are highly polluted because of this.
2. Age Old Practices : Many people in India use a pond or a river for bathing, for defecating and for washing clothes. Dead bodies are preferably cremated near a river bank. Sometimes, half burnt carcass is also disposed off in the rivers.
3. Use of Fertilisers and Insecticides : Increased use of fertilisers and insecticides also results in pollution of groundwater.
Effects of Water Pollution
1. Water pollution can result in contamination of groundwater.
2. Farm output is reduced because of polluted water. Fishermen are unable to carry on their traditional occupation because of low fish output.
3. Water borne diseases; like cholera and jaundice; are on the rise because of water pollution.
How to Prevent Water Pollution?
1. Installing sewage treatment plants at strategic locations can help.
2. The Ganga Action Plan was launched in 1985 to clean up the Ganges. Billions of rupees have been poured in this Action Plan but results are nowhere to be seen. At most of the places; this holy river is highly polluted. But we need to take some drastic measures to save this river from imminent disaster.
3. Wastes
Classification of wastes
• Wastes are classified into (i) Bio – degradable wastes and (ii) Non – bio- degradable wastes
• Substances that are broken down by biological process of biological or microbial action are called bio-degradable waste. e.g. wood, paper and leather.
• Substances that are not broken down by biological or microbial action are called non-bio-degradable wastes. e.g. Plastic substances and mineral wastes.
Methods adopted for disposal of harmful waste materials
Land Fills: There are permanent storage facilities in secured lands for military related liquid and radioactive waste materials. High level radioactive wastes are stored in deep underground storage.
Deep well injection: It involves drilling a well into dry porous material below ground water. Hazardous waste liquids are pumped into the well. They are soaked into the porous material and made to remain isolated indefinitely.
Incineration: The burning of materials is called incineration. Hazardous bio-medical wastes are usually disposed of by means of incineration. Human anatomical wastes, discarded medicines, toxic drugs, blood pus, animal wastes, microbiological and bio-technological wastes etc., are called bio-medical wastes.
Solid waste management – Management of non-hazardous wastes
Reuse and recycling technique: The separating out of materials such as rubber, glass, paper and scrap metal from refuse and reprocessing them for reuse is named as reclamation of waste or recycling.
Paper : (54% recovery) can be repulped and reprocessed into recycled paper, cardboard and other products.
Glass : (20% recovery) can be crushed, remelted and made into new containers or crushes used as a substitute for gravel or sand in construction materials such as concrete and asphalt.
• Food waste and yard wastes (leaves, grass etc.,) can be composted to produce humus soil conditioner.
4. Water management
• Due to increasing demands for water and reduced availability of fresh ground water resources, urgent measures have to be taken to conserve each and every drop of water that is available.
• More than any other environmental factors, the availability of water determines the location and activities of human beings.
Sources of water
• Water in India is of two kinds. Salt water and fresh water. Fresh water is obtained from rain water, surface water and ground water.
• The main sources of water are rain and snow which form a part of the hydrological cycle.
Surface water: India is blessed with a number of rivers, lakes, streams and ponds.
Ground water: Aquifers are underground reserves of fresh water. In the water table, water that percolates into the ground through porous rocks is ground water. These porous rocks are saturated with water to a certain level. The upper layer of water level is the water table. The ground water is important for plant growth, man also taps this water through tube wells and bore wells. Scanty rainfall and unnecessary felling of trees affect the ground water level.
Fresh water management
Seeding clouds
• Seeding clouds with dry ice or potassium iodide particles sometimes can initiate rain if water laden clouds and conditions that favour precipitation are present.
Desalination: (Reverse osmosis)
Desalination of ocean water is a technology that has great potential for increasing fresh water.
Desalination is more expensive than most other sources of fresh water.
• In desalination, the common methods of evaporation and recondensation are involved.
Dams, reservoirs and canals
• Dams and storage reservoirs tap runoff water in them and transfer the water from of excess to areas of deficit using canals and underground pipes.
Water shed management
The management of rainfall and resultant run-off is called water shed management.
• Water shed is an area characterized by construction of small dams to hold back water which will provide useful wildlife habitat and stock watering facilities.
Rain water harvesting
Rain water harvesting essentially means collecting rain water from the roof of building or courtyards and storing it underground for later use.
• The main idea in harvesting rain water is to check the run-off water.
The rain water that falls on the roofs of buildings or in courtyards is collected through pipes and stored in underground tanks of the buildings fitted with motor for lifting water for use.
• The process of rain water harvesting is not only simple but also economically beneficial.
It helps in meeting the increased demand for water, particularly in urban areas and prevent flooding of living areas.
Wetland conservation
• It preserves natural water storage and acts as aquifer recharge zones.
Domestic conservation
As an individual, everyone can reduce the water loss by taking shower, using low-flow taps, using recycled water for lawns, home gardens, vehicle washing and using water conserving appliances.
Industrial conservation
• Cooling water can be recharged and waste water can be treated and reused.
5. Wild life
• All non-domesticated and non-cultivated biota found in natural habitat are termed ‘wildlife’. It includes all the natural flora and fauna of a geographic region.
• There are approximately 400 varieties of reptiles, 200 varieties of amphibians, 3000 varieties of fishes, 3000 species of birds 20,000 species of flowering plants and 4100 species of mammals found in our country according to the latest census estimate.
• It is essential to protect and conserve wildlife because they have aesthetic, ecological, educational, historical and scientific values, a good biotic diversity is essential for ecological balance.
• Wildlife also adds aesthetic value and from this, eco-tourism is being promoted in a big way by several countries.
• Wildlife and their products could be of great economic value if utilized properly. The invulnerable plants could yield products of immense medicinal value in future.
• Wildlife also forms as store of vast genetic diversity which could be properly used with advances in genetic engineering.
Wild Life sanctuaries
• Wildlife sanctuary is an area constituted by competent authority in which hunting or capturing of animals is prohibited except by or under control of the highest authority responsible for management of the area.
• Wildlife sanctuaries were established in India in the pursuit of conserving wildlife which was suffering due to ecological imbalance caused by human activities.
• There are 89 National parks, 500 wildlife sanctuaries, 27 Tiger reserves, 200 Zoos and 13 Biosphere reserves in the country covering an area of 1.6 lakh sq.km.
6. Ecosystem
A community of organisms that interact with one another and with the environment is called an ecosystem.
• The Ecosystem is of two types, namely aquatic and terrestrial.
• There are four major components, namely: (i) Abiotic factors (ii) Producers (iii) Consumers (iv) Decomposers.
• Producers, consumers and decomposers are biotic factors.
Abiotic factors: It includes light, temperature, hydrogen ion concentration, inorganic substances like CO2, H2, O2, N2, PO4, CO3 and S and organic substances like carbohydrates, proteins and lipids.
Biotic factors: It includes producers and consumers. Producers are the water living plants like hydrilla, Vallisneria etc., and phytoplankton like Chlamydomonas, Volvox and Spirogyra.
Primary consumers or herbivores: Zooplanktons like insects, larvae of Dragon-fly consume the phytoplanktons.
Secondary Consumers: These are certain fishes, frogs, water beetles etc., which feed on the primary consumers in the pond.
Tertiary Consumers: These are big fishes and kingfisher that feed on small fishes.
Decomposers: Several bacteria and fungi form the decomposers in the pond.
Food chain and Food web
• A food relationship exists between plants and animals. In this relationship, one living thing is consumed by another, and is shown by a food chain.
• Various organisms are linked by food chains in which the food energy is passed from one organism to another in a linear fashion.
Examples of Food chain
(a) Plants Human beings
(b) Grass [Rabbit/Deer/Sheep] Lion
(c) Grass Insects Birds
(d) Algae Insects Small fish Large fish
(e) Grass Insects Frog Snake Eagle
(f) Small plants and animals in water Small fish Large fish
Food web: The food chains are interlinked to form food webs, So every component of the ecosystem is connected to one another.

Flow of energy in Ecosystem

SUNLIGHTPRODUCERSHERBIVORESCARNIVORSTOPCARNIVORES

Balance in ecosystem
• A balanced ecosystem is an ecological community together with its environment and functioning as a complex unit.
• An ecosystem maintains the balance between the number of resources and the number of users or the balance between prey and predators.
Eg: Hawks & mice, Monkeys and banana trees.
Maintenance of Ecosystem
• Killing animals, cutting down the trees, polluting land, air and water disturb the balance in nature.
• In order to maintain the eco-balance in an ecosystem, there should be recycling of nutrients, minerals, and water.
• Careful use of natural resources will maintain the eco-balance.
• Eco-balance or ecological balance is the maintenance of balance between living components and its resources of an ecosystem, so that it remains a stable environment community for the better functioning of the organisms.
7. Bio – Geo Chemical Cycles
• In an ecosystem, the energy from the sun, fixed by the plants, is transferred to herbivores and carnivores i.e. the energy flows in one direction only.
• Minerals required in the ecosystem are continuously absorbed by the plants and transferred to animals.
• Minerals are returned to the soil by the decomposition of dead and decaying materials by saprophytic organisms such as bacteria and fungi.
8. Coal
• Coal is a compost primarily of carbon along with variable quantities of other elements chiefly sulphur, hydrogen, oxygen and nitrogen.
• Coal is a fossil fuel and is the largest source of energy for the generation of electricity worldwide, as well as one of the largest worldwide sources of CO2 emissions.
• Gross CO2 emission from coal usage is high and more than those from petroleum and about double the amount from natural gas.
• Coal is obtained through mining or in open pits.
• Coal is primarily used as a solid fuel to produce electricity and heat through combustion.
• When coal is heated in air, coal burns and produces mainly carbon-di-oxide gas.
• Coal is processed in industry to get some useful products such as coke, coal tar and coal gas.
Environmental effects of coal burning
• Generation of waste products which contain mercury, uranium, thorium, arsenic and other heavy metals, which are harmful to human health and environment.
• Sulphur particles present in the coal will cause acid rain..
• Interference with ground water and water table levels.
• Contamination of land and water ways.
• Dust nuisance.
• Release of CO2, a greenhouse gas, which causes climate change and global warming.
• Coal is the largest contributor to the man-made increase of CO2 in the air.
9. Petroleum
• Petroleum or crude oil is a naturally occurring, toxic, flammable liquid consisting of a complex mixture of hydrocarbons and other organic compounds that are found beneath the earth’s surface.
• Petroleum was formed from organisms living in the sea. After the death of those organisms, their bodies settled at the bottom of the sea and were covered with layers of sand and clay. Over millions of years, absence of air, high temperature and high pressure transformed the dead organisms into petroleum and natural gas.
• Many useful substances are obtained from petroleum and natural gas. These are used in the manufacture of detergents, fibers (polyester, nylon, acrylic etc.), polythene and other plastic substances. Hydrogen gas, obtained from natural gas, is used in the production of fertilizers (urea).
• Due to its great commercial importance, petroleum is also called ‘Black Gold’.
Environmental effects of Petroleum extraction
• Crude oil (refined fuel) spills from tanker ship and accidents have damaged natural ecosystem.
• Oil Spills at sea are generally causing more damage than those on land. This can kill sea birds, mammals, shellfish and other organisms, because of their lateral spreading on water surface.
• A tar ball is a blob of oil which has been weathered after floating on the ocean. Tar balls are aquatic pollutants in most of the seas.
Alternatives to petroleum – based vehicle fuels
• Internal combustion engines (Bio-fuel or combustion hydrogen)
• Electricity (for e.g. all electric (or) hybrid vehicles), Compressed air or fuel cells (hydrogen fuel cells).
• Compressed natural gas used by natural gas vehicles.
10. Green Chemistry
• Green chemistry is the design of chemical products and processes to reduce or eliminate the use and generation of hazardous substances.
• The concept of green chemistry was introduced in 1995.
• The Green Chemistry Institute was recently created and the Presidential Green Chemistry challenge awards were established in 1999.
• Greener reaction conditions for an old synthesis e.g. replacement of an organic solvent with water or the use of no solvent at all)
• A greener synthesis for an old chemical (e.g. a synthesis which uses biomass rather than petrochemical feed stock or the use of catalytic rather than stoichiometric reagents).
• The synthesis of a new compound that is less toxic but has the same desirable properties as an existing compound. (e.g. a new pesticide that is toxic only to target organisms and bio-degrades to environmentally benign substances)
• Green chemistry / technology has been developed in almost all branches of chemistry including organic, biochemistry, inorganic, polymer, toxicology, environmental, physical, industrial etc.
The Principles of Green Chemistry
• It is better to prevent waste generation than to treat or clean up waste after it is generated.
• Wherever practicable, synthetic methodologies should be designed to use and generate substances that possess little or no toxicity to human health and the environment.
• Chemical products should be designed to preserve efficacy of function while reducing toxicity.
Products produced by the process of green chemistry
• Lead free solders and other product alternatives to lead additives in paints and the development of cleaner batteries.
• Bio-plastics: Plastics made from plants including corn, potatoes or other agricultural products.
• Flame resistant materials.
• Halogen free flame retardants. e.g. silicon based materials can be used.
Future products
• A raw material feedstock should be renewable rather than depleting whenever technically and economically practical.
• Catalytic reagents are superior to stoichiometric reagents.
• Green Chemistry is applicable to all aspects of the product life cycle as well. Finally, the definition of green chemistry includes ‘The term “hazardous”. It is important to note that green chemistry is a way of dealing with risk reduction and pollution prevention.
PVC and Lead
• New lead free solders with lower heat requirements are being developed.
Beware of Green washing
• Green chemistry is not a panacea. We must be vigilant in making sure that what is called
• “Green Chemistry” really pushes towards a more sustainable world or not.
11. Science today towards a global village
• Global village is the term used to mean that world had shrunk into a village by means of different media types, most especially the world wide web, making
• It is easy to pass across messages (like news) thereby making the world becomes a single village where people can easily contact each other quicker.
What is global village?
• A term that compares the world to a small village, where fast and modern communication allows news to reach quickly.
• The use of electronics for faster communication is a global village concept.
What is the global electronic village?
• Global electronic village (GEV) is a term used to refer to a village without borders; it refers to connecting people around the world technologically through Information Communication Technologies (ICTS).
• The term global village was coined by Marshall McLuhan. He emphasized that “this forces us to become more involved with one another from countries around the world and be more aware of our global responsibilities”.
• The concept of global village has implications for forming new sociological structures within the context of culture.

1. Environmental Science
• Living organisms live in different surroundings.
• Plants, animals, human beings survive with the interaction between them and the non-living things like air, water and land.
• Human beings depend on the resources of nature.
• These resources improve the life style of human beings.
Environmental science can be defined as the study of organisms in relation to their surroundings.
2. Air and Water Pollution
Air Pollution
• When the level of contaminants in air becomes so much that air becomes harmful for living beings; it is called air pollution. Causes of Air Pollution
(a) Exhaust from Automobiles : Most of the automobiles use fossil fuels. Burning of fossil fuel releases carbon dioxide and carbon monoxide. Carbon dioxide is a greenhouse gas. Carbon monoxide is a poisonous gas even at low concentrations.
(b) Exhaust from Factories and Power Plants : Coal is the main fuel being used in factories. Burning of coal produces carbon dioxide and oxides of sulphur. Oxides of sulphur and nitrogen form acid rain when they mix with rainwater. Acid rain is harmful for living beings and also for buildings and monuments.
(c) Chlorofluorocarbons (CFCs) : These are compounds of carbon and halogens and are used as refrigerant. These are also used in pressurized cans. Excess level of CFCs in the atmosphere damages the ozone layer. Ozone layer works like a shield and prevents the harmful ultraviolet radiations from reaching up to the living beings. Any damage in the ozone layer can be very harmful.
(d) Suspended Particulate Matters (SPMs): Some fine particles remain suspended in the air. These are called suspended particulate matters. Stone quarries and various other factories contribute to SPMs.
Effects of Air Pollution
1. Greenhouse Effect : Greenhouse gases trap solar radiation which increases the overall temperature of the atmosphere. Carbon dioxide and methane are examples of greenhouse gases. The greenhouse effect leads to global warming. Global warming has resulted in melting of the glacial ice. Scientists have predicted that many coastal cities would be completely submerged in the near future because of glacial melting. Global warming has also caused drastic changes in weather. Increased instances of flash floods and erratic weather are being attributed to global warming.
2. Smog : A mixture of fog and smoke is called smog. Smog creates a blanket of haze in the sky. This reduces visibility which can give trouble to pilots and drivers.
3. Respiratory Diseases : Cases of respiratory diseases; like asthma are on the rise because of increased levels of air pollution.
4. Acid Rain : Acid rain happens because of the presence of oxides of nitrogen and sulphur in the atmosphere. Acid rain can be very harmful for living beings. Moreover, acid rain can also damage buildings and monuments. The case of Taj Mahal is a reminder of the horrible effects of acid rain. The Taj Mahal was built by using white marbles. But now-a-days, it does not look white rather looks a pale white. Acid rain is corroding the marble of the Taj Mahal. An order by the Supreme Court of India directed all the factories to shift from the vicinity of Taj Mahal. After that order, only battery operated vehicles are allowed to be driven near this monument.
5. Deforestation : Deforestation is a major cause of air pollution. Reduced forest cover means there are less number of trees to convert carbon dioxide into oxygen. This has led to increased levels of carbon dioxide in the atmosphere.
Preventive measures to control air pollution
1. Switching to cleaner fuels; like CNG.
2. Increasing the use of public transport can also help in reducing air pollution. This will help in reducing the number of cars on the road.
3. Walking and cycling are very good for health as well as for the environment. You can walk or use a bicycle for a short distance commute. Instead of using a bus or a car; you should use a bicycle for going to school.
4. Electrostatic precipitators should be fitted in chimneys of factories. This helps in reducing the amount of SPMs in the air. Similarly, catalytic converters are fitted in the exhaust system of vehicles. This helps in reducing the poisonous substances in vehicle exhaust.
5. More trees should be planted. We know that trees convert carbon dioxide into oxygen; during photosynthesis. Thus, trees help in maintaining the balance of carbon dioxide and oxygen.
Water Pollution
• When the level of contaminants in water reaches to such a level that water becomes harmful for living beings, it is called water pollution.
Causes of Water Pollution
1. Untreated Sewage : In India, this is a common practice to discharge untreated sewage and effluents into the nearest water body. Most of the rivers and ponds in India are highly polluted because of this.
2. Age Old Practices : Many people in India use a pond or a river for bathing, for defecating and for washing clothes. Dead bodies are preferably cremated near a river bank. Sometimes, half burnt carcass is also disposed off in the rivers.
3. Use of Fertilisers and Insecticides : Increased use of fertilisers and insecticides also results in pollution of groundwater.
Effects of Water Pollution
1. Water pollution can result in contamination of groundwater.
2. Farm output is reduced because of polluted water. Fishermen are unable to carry on their traditional occupation because of low fish output.
3. Water borne diseases; like cholera and jaundice; are on the rise because of water pollution.
How to Prevent Water Pollution?
1. Installing sewage treatment plants at strategic locations can help.
2. The Ganga Action Plan was launched in 1985 to clean up the Ganges. Billions of rupees have been poured in this Action Plan but results are nowhere to be seen. At most of the places; this holy river is highly polluted. But we need to take some drastic measures to save this river from imminent disaster.
3. Wastes
Classification of wastes
• Wastes are classified into (i) Bio – degradable wastes and (ii) Non – bio- degradable wastes
• Substances that are broken down by biological process of biological or microbial action are called bio-degradable waste. e.g. wood, paper and leather.
• Substances that are not broken down by biological or microbial action are called non-bio-degradable wastes. e.g. Plastic substances and mineral wastes.
Methods adopted for disposal of harmful waste materials
Land Fills: There are permanent storage facilities in secured lands for military related liquid and radioactive waste materials. High level radioactive wastes are stored in deep underground storage.
Deep well injection: It involves drilling a well into dry porous material below ground water. Hazardous waste liquids are pumped into the well. They are soaked into the porous material and made to remain isolated indefinitely.
Incineration: The burning of materials is called incineration. Hazardous bio-medical wastes are usually disposed of by means of incineration. Human anatomical wastes, discarded medicines, toxic drugs, blood pus, animal wastes, microbiological and bio-technological wastes etc., are called bio-medical wastes.
Solid waste management – Management of non-hazardous wastes
Reuse and recycling technique: The separating out of materials such as rubber, glass, paper and scrap metal from refuse and reprocessing them for reuse is named as reclamation of waste or recycling.
Paper : (54% recovery) can be repulped and reprocessed into recycled paper, cardboard and other products.
Glass : (20% recovery) can be crushed, remelted and made into new containers or crushes used as a substitute for gravel or sand in construction materials such as concrete and asphalt.
• Food waste and yard wastes (leaves, grass etc.,) can be composted to produce humus soil conditioner.
4. Water management
• Due to increasing demands for water and reduced availability of fresh ground water resources, urgent measures have to be taken to conserve each and every drop of water that is available.
• More than any other environmental factors, the availability of water determines the location and activities of human beings.
Sources of water
• Water in India is of two kinds. Salt water and fresh water. Fresh water is obtained from rain water, surface water and ground water.
• The main sources of water are rain and snow which form a part of the hydrological cycle.
Surface water: India is blessed with a number of rivers, lakes, streams and ponds.
Ground water: Aquifers are underground reserves of fresh water. In the water table, water that percolates into the ground through porous rocks is ground water. These porous rocks are saturated with water to a certain level. The upper layer of water level is the water table. The ground water is important for plant growth, man also taps this water through tube wells and bore wells. Scanty rainfall and unnecessary felling of trees affect the ground water level.
Fresh water management
Seeding clouds
• Seeding clouds with dry ice or potassium iodide particles sometimes can initiate rain if water laden clouds and conditions that favour precipitation are present.
Desalination: (Reverse osmosis)
Desalination of ocean water is a technology that has great potential for increasing fresh water.
Desalination is more expensive than most other sources of fresh water.
• In desalination, the common methods of evaporation and recondensation are involved.
Dams, reservoirs and canals
• Dams and storage reservoirs tap runoff water in them and transfer the water from of excess to areas of deficit using canals and underground pipes.
Water shed management
The management of rainfall and resultant run-off is called water shed management.
• Water shed is an area characterized by construction of small dams to hold back water which will provide useful wildlife habitat and stock watering facilities.
Rain water harvesting
Rain water harvesting essentially means collecting rain water from the roof of building or courtyards and storing it underground for later use.
• The main idea in harvesting rain water is to check the run-off water.
The rain water that falls on the roofs of buildings or in courtyards is collected through pipes and stored in underground tanks of the buildings fitted with motor for lifting water for use.
• The process of rain water harvesting is not only simple but also economically beneficial.
It helps in meeting the increased demand for water, particularly in urban areas and prevent flooding of living areas.
Wetland conservation
• It preserves natural water storage and acts as aquifer recharge zones.
Domestic conservation
As an individual, everyone can reduce the water loss by taking shower, using low-flow taps, using recycled water for lawns, home gardens, vehicle washing and using water conserving appliances.
Industrial conservation
• Cooling water can be recharged and waste water can be treated and reused.
5. Wild life
• All non-domesticated and non-cultivated biota found in natural habitat are termed ‘wildlife’. It includes all the natural flora and fauna of a geographic region.
• There are approximately 400 varieties of reptiles, 200 varieties of amphibians, 3000 varieties of fishes, 3000 species of birds 20,000 species of flowering plants and 4100 species of mammals found in our country according to the latest census estimate.
• It is essential to protect and conserve wildlife because they have aesthetic, ecological, educational, historical and scientific values, a good biotic diversity is essential for ecological balance.
• Wildlife also adds aesthetic value and from this, eco-tourism is being promoted in a big way by several countries.
• Wildlife and their products could be of great economic value if utilized properly. The invulnerable plants could yield products of immense medicinal value in future.
• Wildlife also forms as store of vast genetic diversity which could be properly used with advances in genetic engineering.
Wild Life sanctuaries
• Wildlife sanctuary is an area constituted by competent authority in which hunting or capturing of animals is prohibited except by or under control of the highest authority responsible for management of the area.
• Wildlife sanctuaries were established in India in the pursuit of conserving wildlife which was suffering due to ecological imbalance caused by human activities.
• There are 89 National parks, 500 wildlife sanctuaries, 27 Tiger reserves, 200 Zoos and 13 Biosphere reserves in the country covering an area of 1.6 lakh sq.km.
6. Ecosystem
A community of organisms that interact with one another and with the environment is called an ecosystem.
• The Ecosystem is of two types, namely aquatic and terrestrial.
• There are four major components, namely: (i) Abiotic factors (ii) Producers (iii) Consumers (iv) Decomposers.
• Producers, consumers and decomposers are biotic factors.
Abiotic factors: It includes light, temperature, hydrogen ion concentration, inorganic substances like CO2, H2, O2, N2, PO4, CO3 and S and organic substances like carbohydrates, proteins and lipids.
Biotic factors: It includes producers and consumers. Producers are the water living plants like hydrilla, Vallisneria etc., and phytoplankton like Chlamydomonas, Volvox and Spirogyra.
Primary consumers or herbivores: Zooplanktons like insects, larvae of Dragon-fly consume the phytoplanktons.
Secondary Consumers: These are certain fishes, frogs, water beetles etc., which feed on the primary consumers in the pond.
Tertiary Consumers: These are big fishes and kingfisher that feed on small fishes.
Decomposers: Several bacteria and fungi form the decomposers in the pond.
Food chain and Food web
• A food relationship exists between plants and animals. In this relationship, one living thing is consumed by another, and is shown by a food chain.
• Various organisms are linked by food chains in which the food energy is passed from one organism to another in a linear fashion.
Examples of Food chain
(a) Plants Human beings
(b) Grass [Rabbit/Deer/Sheep] Lion
(c) Grass Insects Birds
(d) Algae Insects Small fish Large fish
(e) Grass Insects Frog Snake Eagle
(f) Small plants and animals in water Small fish Large fish
Food web: The food chains are interlinked to form food webs, So every component of the ecosystem is connected to one another.

Flow of energy in Ecosystem

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Balance in ecosystem
• A balanced ecosystem is an ecological community together with its environment and functioning as a complex unit.
• An ecosystem maintains the balance between the number of resources and the number of users or the balance between prey and predators.
Eg: Hawks & mice, Monkeys and banana trees.
Maintenance of Ecosystem
• Killing animals, cutting down the trees, polluting land, air and water disturb the balance in nature.
• In order to maintain the eco-balance in an ecosystem, there should be recycling of nutrients, minerals, and water.
• Careful use of natural resources will maintain the eco-balance.
• Eco-balance or ecological balance is the maintenance of balance between living components and its resources of an ecosystem, so that it remains a stable environment community for the better functioning of the organisms.
7. Bio – Geo Chemical Cycles
• In an ecosystem, the energy from the sun, fixed by the plants, is transferred to herbivores and carnivores i.e. the energy flows in one direction only.
• Minerals required in the ecosystem are continuously absorbed by the plants and transferred to animals.
• Minerals are returned to the soil by the decomposition of dead and decaying materials by saprophytic organisms such as bacteria and fungi.
8. Coal
• Coal is a compost primarily of carbon along with variable quantities of other elements chiefly sulphur, hydrogen, oxygen and nitrogen.
• Coal is a fossil fuel and is the largest source of energy for the generation of electricity worldwide, as well as one of the largest worldwide sources of CO2 emissions.
• Gross CO2 emission from coal usage is high and more than those from petroleum and about double the amount from natural gas.
• Coal is obtained through mining or in open pits.
• Coal is primarily used as a solid fuel to produce electricity and heat through combustion.
• When coal is heated in air, coal burns and produces mainly carbon-di-oxide gas.
• Coal is processed in industry to get some useful products such as coke, coal tar and coal gas.
Environmental effects of coal burning
• Generation of waste products which contain mercury, uranium, thorium, arsenic and other heavy metals, which are harmful to human health and environment.
• Sulphur particles present in the coal will cause acid rain..
• Interference with ground water and water table levels.
• Contamination of land and water ways.
• Dust nuisance.
• Release of CO2, a greenhouse gas, which causes climate change and global warming.
• Coal is the largest contributor to the man-made increase of CO2 in the air.
9. Petroleum
• Petroleum or crude oil is a naturally occurring, toxic, flammable liquid consisting of a complex mixture of hydrocarbons and other organic compounds that are found beneath the earth’s surface.
• Petroleum was formed from organisms living in the sea. After the death of those organisms, their bodies settled at the bottom of the sea and were covered with layers of sand and clay. Over millions of years, absence of air, high temperature and high pressure transformed the dead organisms into petroleum and natural gas.
• Many useful substances are obtained from petroleum and natural gas. These are used in the manufacture of detergents, fibers (polyester, nylon, acrylic etc.), polythene and other plastic substances. Hydrogen gas, obtained from natural gas, is used in the production of fertilizers (urea).
• Due to its great commercial importance, petroleum is also called ‘Black Gold’.
Environmental effects of Petroleum extraction
• Crude oil (refined fuel) spills from tanker ship and accidents have damaged natural ecosystem.
• Oil Spills at sea are generally causing more damage than those on land. This can kill sea birds, mammals, shellfish and other organisms, because of their lateral spreading on water surface.
• A tar ball is a blob of oil which has been weathered after floating on the ocean. Tar balls are aquatic pollutants in most of the seas.
Alternatives to petroleum – based vehicle fuels
• Internal combustion engines (Bio-fuel or combustion hydrogen)
• Electricity (for e.g. all electric (or) hybrid vehicles), Compressed air or fuel cells (hydrogen fuel cells).
• Compressed natural gas used by natural gas vehicles.
10. Green Chemistry
• Green chemistry is the design of chemical products and processes to reduce or eliminate the use and generation of hazardous substances.
• The concept of green chemistry was introduced in 1995.
• The Green Chemistry Institute was recently created and the Presidential Green Chemistry challenge awards were established in 1999.
• Greener reaction conditions for an old synthesis e.g. replacement of an organic solvent with water or the use of no solvent at all)
• A greener synthesis for an old chemical (e.g. a synthesis which uses biomass rather than petrochemical feed stock or the use of catalytic rather than stoichiometric reagents).
• The synthesis of a new compound that is less toxic but has the same desirable properties as an existing compound. (e.g. a new pesticide that is toxic only to target organisms and bio-degrades to environmentally benign substances)
• Green chemistry / technology has been developed in almost all branches of chemistry including organic, biochemistry, inorganic, polymer, toxicology, environmental, physical, industrial etc.
The Principles of Green Chemistry
• It is better to prevent waste generation than to treat or clean up waste after it is generated.
• Wherever practicable, synthetic methodologies should be designed to use and generate substances that possess little or no toxicity to human health and the environment.
• Chemical products should be designed to preserve efficacy of function while reducing toxicity.
Products produced by the process of green chemistry
• Lead free solders and other product alternatives to lead additives in paints and the development of cleaner batteries.
• Bio-plastics: Plastics made from plants including corn, potatoes or other agricultural products.
• Flame resistant materials.
• Halogen free flame retardants. e.g. silicon based materials can be used.
Future products
• A raw material feedstock should be renewable rather than depleting whenever technically and economically practical.
• Catalytic reagents are superior to stoichiometric reagents.
• Green Chemistry is applicable to all aspects of the product life cycle as well. Finally, the definition of green chemistry includes ‘The term “hazardous”. It is important to note that green chemistry is a way of dealing with risk reduction and pollution prevention.
PVC and Lead
• New lead free solders with lower heat requirements are being developed.
Beware of Green washing
• Green chemistry is not a panacea. We must be vigilant in making sure that what is called
• “Green Chemistry” really pushes towards a more sustainable world or not.
11. Science today towards a global village
• Global village is the term used to mean that world had shrunk into a village by means of different media types, most especially the world wide web, making
• It is easy to pass across messages (like news) thereby making the world becomes a single village where people can easily contact each other quicker.
What is global village?
• A term that compares the world to a small village, where fast and modern communication allows news to reach quickly.
• The use of electronics for faster communication is a global village concept.
What is the global electronic village?
• Global electronic village (GEV) is a term used to refer to a village without borders; it refers to connecting people around the world technologically through Information Communication Technologies (ICTS).
• The term global village was coined by Marshall McLuhan. He emphasized that “this forces us to become more involved with one another from countries around the world and be more aware of our global responsibilities”.
• The concept of global village has implications for forming new sociological structures within the context of culture.

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