• Wildlife sanctuary, national park and biosphere reserve are names given to the areas meant for conservation and preservation of forest and wild animals.
  
• Biodiversity refers to the variety of living organisms in a specific area.  
• Plants and animals of a particular area are known as the flora and fauna of that area. 
• Endemic species are found only in a particular area. 
• Endangered species are those which are facing the danger of extinction. 
• Red Data Book contains a record of the endangered species. 
• Migration is the phenomenon of movement of a species from its own habitat to some other habitat for a particular time period every year for a specific purpose like breeding. 
• We should save, reuse and recycle paper to save trees, energy and water. 
• Reforestation is the restocking of destroyed forests by planting new trees.

• We can survive for some time without food, but we cannot survive even for a few minutes without air. This simple fact tells us how important clean air is to us.
• Air consists of a mixture of gases. By volume, about 78% of this mixture is nitrogen and about 21% is oxygen. Carbon dioxide, argon, methane, ozone and water vapour are also present in very small quantities.
• When air is contaminated by unwanted substances which have a harmful effect on both the living and the non-living, it is referred to as air pollution.
• The substances which contaminate the air are called air pollutants. Sometimes, such substances may come from natural sources like smoke and dust arising from forest fires or volcanic eruptions. Pollutants are also added to the atmosphere by human activities. 
• The sources of air pollutants are factories , power plants, automobile exhausts and burning of firewood and dung cakes. Many respiratory problems are caused by air pollution. 
• Vehicles produce high levels of pollutants like carbon monoxide, carbon dioxide, nitrogen oxides and smoke. 
• Carbon monoxide is produced from incomplete burning of fuels such as petrol and diesel. It is a poisonous gas. It reduces the oxygen-carrying capacity of the blood.
• A thick fog-like layer in the atmosphere, especially during winters. This is smog which is made up of smoke and fog. Smoke may contain oxides of nitrogen which combine with other air pollutants and fog to form smog. 
• The smog causes breathing difficulties such as asthma, cough and wheezing in children.
• Many industries are also responsible for causing air pollution. Petroleum refineries are a major source of gaseous pollutants like sulphur dioxide and nitrogen dioxide. 
• Sulphur dioxide is produced by combustion of fuels like coal in power plants. It can cause respiratory problems, including permanent lung damage. 
• Other kinds of pollutants are chlorofluorocarbons (CFCs) which are used in refrigerators, air conditioners and aerosol sprays. CFCs damage the ozone layer of the atmosphere. Recall that the ozone layer protects us from harmful ultraviolet rays of the sun.
• Automobiles which burn diesel and petrol, also produce tiny particles which remain suspended in air for long periods. They reduce visibility. When inhaled, they cause diseases. Such particles are also produced during industrial processes like steel making and mining. Power plants give out tiny ash particles which also pollute the atmosphere.
• Over the past 2 decades, India’s most famous tourist attraction, Taj Mahal located in Agra, has become a matter of concern. Experts have warned that pollutants in air are discolouring its white marble. So, it is not only living organisms that get affected by polluted air but non-living things like buildings, monuments and statues also get affected. 
• The industries located in and around Agra like rubber processing, automobile, chemicals and especially the Mathura oil refinery, have been responsible for producing pollutants like sulphur dioxide and nitrogen dioxide. These gases react with the water vapour present in the atmosphere to form sulphuric acid and nitric acid.
• The acids drop down with rain, making the rain acidic. This is called acid rain. 
• Acid rain corrodes the marble of the monument. The phenomenon is also called “Marble cancer”. Suspended particulate matter, such as the soot particles emitted by Mathura oil refinery, has contributed towards yellowing of the marble.
• The Supreme Court has taken several steps to save the Taj. It has ordered the industries to switch to cleaner fuels like CNG (Compressed Natural Gas) and LPG (Liquefied Petroleum Gas). Moreover, the automobiles should switch over to unleaded petrol in the Taj zone.
• The sun’s rays warm the earth’s surface. A part of the radiation that falls on the earth is absorbed by it and a part is reflected back into space. A part of the reflected radiation is trapped by the atmosphere. The trapped radiations further warm the earth. If you have seen a greenhouse in a nursery or elsewhere, recall that the sun’s heat is allowed to get in but is not allowed to go out.
• The trapped heat warms the green house. The trapping of radiations by the earth’s atmosphere is similar. That is why it is called the greenhouse effect. Without this process, life would not have been possible on the earth. But now it threatens life. CO2 is one of the gases responsible for this effect.
• If there is excess of CO2 in the air, it acts as a pollutant.
• Area under forests is decreasing. Plants utilise CO2 from the atmosphere for photosynthesis, thereby decreasing the amount of CO2 in the air. Deforestation leads to an increase in the amount of CO2 in the air because the number of trees which consume CO2 is reduced. Human activities, thus, contribute to the accumulation of CO2 in the atmosphere. CO2 traps heat and does not allow it to escape into space. As a result, the average temperature of the earth’s atmosphere is gradually increasing. This is called global warming.
• Other gases like methane, nitrous oxide and water vapour also contribute towards this effect. Like CO2, they are also called greenhouse gases.
• Global warming has become a major concern for governments worldwide. Many countries have reached an agreement to reduce the emission of greenhouse gases. The Kyoto Protocol is one such agreement.
• Global warming can cause sea levels to rise dramatically. In many places, coastal areas have already been flooded. Global warming could result in wide ranging effects on rainfall patterns, agriculture, forests, plants and animals. Majority of people living in regions which are threatened by global warming are in Asia. A recent climate change report gives us only a limited time to keep the greenhouse gases at the present level. Otherwise, the temperature may rise by more than 2 degrees Celsius by the end of the century, a level considered dangerous.
• Van Mahotsav, when lakhs of trees are planted in July every year.
• Whenever harmful substances such as sewage, toxic chemicals, silt, etc., get mixed with water, the water becomes polluted. The substances that pollute water are called water pollutants.
• Ganga is one of the most famous rivers of India. It sustains most of the northern, central and eastern Indian population. Millions of people depend on it for their daily needs and livelihood.
• World Wide Fund for Nature (WWF) found that Ganga is one of the ten most endangered rivers in the world. The pollution levels have been rising for many years. We have reached this stage because the towns and cities, through which the river flows, throw large quantities of garbage, untreated sewage, dead bodies, and many other harmful things, directly into the river. In fact the river is “dead” at many places where the pollution levels are so high that aquatic life cannot survive.
• An ambitious plan to save the river, called the Ganga Action Plan was launched in 1985. It aimed to reduce the pollution levels in the river. However, the increasing population and industrialisation have already damaged this mighty river beyond repair.
• Many industries discharge harmful chemicals into rivers and streams, causing the pollution of water. Examples are oil refineries, paper factories, textile and sugar mills and chemical factories. These industries cause chemical contamination of water. The chemicals released include arsenic, lead and fluorides which lead to toxicity in plants and animals. 
• There are regulations to prevent this. Industries are supposed to treat the waste produced before discharging it into waters, but quite often the rules are not followed. The soil is also affected by impure water, causing changes in acidity, growth of worms, etc.
• the importance of pesticides and weedicides for the protection of crops. However, all these chemicals dissolve in water and are washed into water bodies from the fields. They also seep into the ground to pollute ground water.
• Have you seen ponds which look green from a distance because they have a lot of algae growing in them? This is caused by excessive quantities of chemicals which get washed from the fields. These act as nutrients for algae to flourish. Once these algae die, they serve as food for decomposers like bacteria. A lot of oxygen in the water body gets used up. This results in a decrease in the oxygen level which may kill aquatic organisms.
• Water contaminated with sewage may contain bacteria, viruses, fungi and parasites which cause diseases like cholera, typhoid and jaundice. 
• The bacteria present in the faeces of mammals are indicators of the quality of water. If water has these bacteria, it means that it has been contaminated by fecal matter. If such water is used by us, it can cause various infections.
• Hot water can also be a pollutant ! This is usually water from power plants and industries. It is released into the rivers. It raises the temperature of the waterbody, adversely affecting the animals and plants living in it.
• Water which is suitable for drinking is called potable water.
• Water can be made safe for drinking: 

1. Water is filtered. This is a physical method of removing impurities. A popular household filter is a candle type filter. 
2. Many households use boiling as a method for obtaining safe drinking water. Boiling kills the germs present in the water. 
3. Chlorination is a commonly used chemical method for purifying water. It is done by adding chlorine tablets or bleaching powder to the water. We must be cautious. We should not use more chlorine tablets than specified.

• Air pollution is the contamination of air by impurities which may have a harmful impact on the living organisms and the non-living components. 
• Pollutants are the substances which contaminate air and water. 
• Carbon monoxide, nitrogen oxides, carbon dioxide, methane and sulphur dioxide are the major pollutants of air.
• Increasing levels of greenhouse gases like CO2 are leading to global warming. 
• Water pollution is the contamination of water by substances harmful to life. 
• Sewage, agricultural chemicals and industrial waste are some of the major contaminants of water. 
• Water which is purified and fit for drinking is known as potable water. 
• Water is a precious natural resource. We must learn to conserve it.

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