FST -1

10th Part

Q.  Taking a pond as an ecosystem, write five of its biotic components and classify them as producers, consumers, and decomposers.     

A. Within an ecosystem, the organisms can be classified under three broad categories, namely, producers, consumers, and decomposers. 

Producers -

Sun is the ultimate source of energy for nearly all life on the earth. Solar energy enters life mainly through green plants, and also through some kinds of bacteria and algae which are called producers. During photosynthesis, green plants use the energy of sunlight to convert two simple, low energy substances, carbon dioxide, and water, into more complex substances, such as carbohydrates which we may call food. Photosynthesis produces oxygen as a by-product. To carry on photosynthesis and make food, green plants need not only sunlight, water, and carbon dioxide, but also small amounts of some minerals such as calcium, potassium & magnesium dissolved in the water around &he floating plants or in the soil water around plant roots.

Photosynthesis:

Carbon dioxide + water + solar energy + minerals + food + oxygen

Decomposers -

So far we have seen that green plants are called producers because they produce their own food. Plants live and die, they may be eaten up by animals who also eventually die. There are organisms - the decomposers which act on dead plants and animals and for their existence. The dead bodies of plants & animals are the principal source of food for these decomposers. The decomposers, such as bacteria, fungi, and worms, convert the dead bodies of the plants and animals back to their elementary forms.

Consumers -

Besides the producers and decomposers, there is another category of organisms - the consumers. These organisms cannot make their own food, and they depend directly or indirectly on producers, for energy and nutrients.

Q.  How do forests regulate precipitation?

A.  Forests not only add to the beauty of the landscape but make the climate salubrious and provide a suitable habitat for the wildlife. They are also described as environmental buffers. Forests consume large quantities of water through the roots of plants and lose it through respiration by the leaves. Extensive forests, to some extent also increase precipitation.

Q.  Social Forestry                          

A. Social forestry means planting trees on all unused and fallow land to meet the basic requirements of people. A farmer can partly meet his needs of wood from the fast-growing trees planted within the limits of his village, along the footpaths, roadsides, alongside railway tracks, side roads or canal,, and streams, boundaries of fields and empty spaces. The aim of social forestry is to meet the needs of fuel, fodder, fruits, timber, and other requirements. Social forestry leads to afforestation of barren and deforested lands with the purpose of helping environmental, social and rural development. Social forestry is basically for the people by the people and of the people approach. It leads to an increase in forest cover that is close to human settlement and has been degraded over the years due to human activities. The social forestry scheme was initiated in India to increase fuel availability in rural areas and to prevent soil erosion. 

Q.  Photochemical smog          

A.  Photochemical smog, a secondary Pollutant, results when the two pollutants, nitrogen oxide and hydrocarbons found in automobile exhausts, react with one another in the presence of sunlight to produce nitrogen dioxide (N02), ozone (03) and a compound called PAN (Peroxylacetyl nitrate). It forms air that appears as a yellowish-brown haze. Breathing ozone affects the respiratory and nervous system. It causes respiratory distress, affects eye membranes and stimulates tears. It also causes a headache. Ozone also damages rubber articles, textiles, and discolors paintings. It has been recently found that smog is harmful to timber. PAN is especially damaging to plants. Plants exposed to PAN exhibit leaf mottling.

Q.  Acid rain

A.  Sulphur dioxide and nitrogen oxides emanating from industrial smoke react with water in the atmosphere to give rise to sulphuric acid and nitric acids. These acids, formed in the air, come down to the Earth along with rain. The pH of acid rain depends on the concentration of sulphur dioxide and nitrogen dioxide in the atmosphere. The pH of acid rain varies from 5.6 to as low as 3.0, which makes it almost as acidic as vinegar. 

           It causes direct damage to the leaves of p!ants. Forests in many parts of the industrialized world are drying because of acid rain. It also causes the leaching of nutrients out of the soil, some of which are very essential for plant growth, e.g., calcium and magnesium. These nutrients are carried out of the soil into streams and ponds. Acid rain also affects lakes. Their waters become devoid of life, except for some algae and fungi that grow at the bottom. Acidity leads to an increase in dissolved metals, particularly aluminium. This element affects the gills of the fish. and they die of suffocation. Birds living near lakes that have high aluminium content are poisoned by aluminium because they feed on the aquatic insects. Acid rain also corrodes materials such as marble stonework and metals.

Q.  Oceans are known as the largest and thickest ecosystems. Justify this statement.                               

A. Oceans are known as the largest and thickest ecosystem. Tiny plants and animals exist in it, in immense numbers. A cubic meter of seawater may contain as many as 200,000 organisms. Living forms occur, more or less, throughout the depth of the oceans, but they are denser around the continents and islands. Sunlight is the principal source of energy in all ecosystems including Ocean. Energy is provided by sunlight either directly as in the case of plants, or indirectly to other forms of life via the plants. In oceanic waters, the intensity of light decreases rapidly with depth. Animal life is also distributed zone-wise in oceans. In the upper layers, small animals co-exist with phytoplankton and derive energy from them. A little below, the energy for animal life is obtained from wastes and dead bodies of organisms that sink, or from the living animals that swim down.

         The nutrients in the upper layers of water are constantly being taken up by the phytoplankton, who are the producers, and then these pass on to the herbivores, and the carnivores. When these latter organisms die, they are either eaten up by other animals or they get decayed by the decomposers. Some of the decomposed matter sinks to the ocean floor. It means the nutrients taken up by the producers from the upper layers of seawater are constantly being drained to the lower layers of seawater thus supporting the life.

Q.  Discuss the impact of increasing population on the environment.     

A.  The increasing population puts a strain on the resources of the world, including environmental resources. All the things we dig out of the earth such as coal, iron, petroleum, copper, and so on, are available in limited supply and all of them are going to be exhausted within a limited number of years and if the population keeps growing, world consumption of these materials will keep increasing, advancing the date of resource exhaustion.

            A larger and larger population also requires more production of food. Agriculture requires land and in many countries, the land is not available to grow the crops needed for the doubling or tripling population. There is a tremendous strain on resources of drinking water, and on facilities to remove filth and muck. The larger population could mean a shortage of housing, congestion on roads, slums going from bad to worse, and pollution. 

#  More population means an increase in waste in the environment. As the man-made waste is not transformed, it leads to the degradation of the environment causing pollution. Further, waste leads to air, soil and water pollution.

#  Increasing population forces Man to establish new housing colonies. National highways, industries, hydropower projects, etc. are built by cutting down forests. These destructive activities to meet the needs of the increasing population led to ecological imbalance.

#  Rapid growth of population has led to urbanization which has adversely affected the environment. Due to population pressure, natural resources in the cities are depleted at a fast rate.

#  intensive farming and excessive use of fertilizers and pesticides have led to over-exploitation of land and water resources. These have led to land degradation in the form of soil erosion, waterlogging and salination.

#  The increase in consumption of fossil fuels due to transportation also led to environmental degradation. The automobiles release huge quantities of poisonous gases such as carbon monoxide, nitrogen oxides, and hydrocarbons. The development of ports and harbors have led to oil spills from ships adversely affecting fisheries, coral reefs, mangroves, and landscapes.

Q.  What are persistent pollutants ? Give an example.        

A. The pollutants that remain in an environment in an unchanged form for a very long time period are known as persistent pollutants, e.g. pesticides, nuclear wastes, and plastics, etc. Many POPs(persistent organic pollutants) are currently or were in the past used as pesticides, solvents, pharmaceuticals, and industrial chemicals. Although some POPs arise naturally, for example during volcano eruptions they are released in the environment. The POPs are resistant to environmental degradation through chemical, biological, and photolytic processes. Because of their persistence, POPs bioaccumulate with potential adverse impacts on human health and the environment.

Q.  Non-persistent pollutants.

A.  those that break down, into simple products, and are known as non-persistent pollutants, e.g., garbage. If this breakdown process is facilitated by living organisms, then such pollutants are referred to as biodegradable pollutants, e.g., wastes from animal sheds

Q.  Describe the ways to manage water resources. 

A. Management of water resources means 

(i) the water of the right quality is made available for all kind of Uses and 

(ii) there is no misuse or wastage of this precious resource.

Water management includes recharging the reserves of groundwater and diverting supply from an area of surplus to the region of scarcity. Recharging of groundwater is the most important aspect of water management. 

           In the mountains and hills, the watersheds are covered with vegetation. The litter-covered soil of the watershed allows the infiltration of rainwater, which finds its way to the aquifers.

    In urban and rural areas, stormwater used water or domestic drains can be fed into pits, trenches, or any depression, where water can filter down to underground reserve. The excess flow of normal, as well as floodwater, can be diverted to areas where there is a scarcity of water. By proper treatment of the domestic and municipal wastewater, one can obtain a supply fit for many industrial & agricultural purposes. The treatment of wastewater involves the removal of pollutants, germs, and toxic elements.

Desalination of seawater

By use of solar energy, seawater can be distilled, thus freshwater of good quality can be obtained. This method of desalination of seawater is being used in our country at places like Bhavanagar in Gujarat and Chum in Rajasthan.

Reducing over consumption

Using more water than necessary is an unpardonable waste of the precious and scarce resource. In our country, a lot of water is wasted due to leaking taps and bad plumming. There is also a need for a check on excessive irrigation.

Q.  What do you understand by recycling? How the recycling of wastes improves resource utilization?                 

A. Some of the materials once used do not go waste, these materials can be re-used again. The process through which the waste resources or used materials are again made usable is known as recycling.

     Scraps and used metals

Scrap metal is produced in large quantities in mills and factories. Old used metal of discarded vehicles, machine, aircrafts, ships, buildings, etc. can be melted and recycled for useful purposes. For ex. used aluminium utensils, can be collected, melted and shaped into new utensils. We can meet the ever-growing demand of such scarce metals as copper, zinc, lead, platinum, etc. by recycling the used old discarded materials.

Waste water

Domestic and municipal waste water is rich in organic nutrients. If this kind of water is treated and made free from disease-carrying germs, pollutants, and poisonous elements, it can be used for the irrigation of farms, gardens, and other vegetations.

          For the removal of germs and toxic elements, the waste water or sewage is treated in a tank or in ponds for several days. In doing so, firstly, the heavy particles settle down to the bottom by themselves, while the finer particles are made to settle down by adding alum and caustic soda. The clear liquid is then allowed to pass through filters or sand or earth and finally, the air is blown through it. This treatment not only removes carbon dioxide and hydrogen sulphide which is generally dissolved in waste water, but also adds oxygen to the filtered water, thus helping in purification. Treatment of water with appropriate doses of chlorine, known as chlorination, kills all the harmful germs and makes water usable.

Solid waste

Solid waste in some cases can be a resource. In our country, the main street of Patna city is being illuminated by biogas produced from the waste of the city dwellers. In Delhi, the sewage treatment plant produces cooking gas. Fermentation of wastes such as cattle dung, human excreta, garbage and aquatic weeds like algal, and water hyacinth, produces biogas which can be used for a variety of purposes. Slag, a waste product left when the metal has been extracted from its ore, can be powdered and added to cement for construction. Flyash is another material used as a valuable cementing material.

        It is clear from the above that the solid wastes can serve as a very useful resource for providing the raw material for our industries, for generating energy and for the production of manure.

Q.  What are the important environmental considerations that should be taken into account while implementing technology policy?     

A.  Some of the important environmental consideration are - 

#  The industries should have been established at safer places, away from centers of population. In addition to this, the factories must be well equipped with safety devices which would automatically minimize the chances of an accident.

# These factories shouldn’t discharge wastes directly into water bodies without treatment, as these chemical discharges contain heavy metals like mercury, lead, etc which not only destroy the marine life but also underground water thus only after treatment the industries should be allowed to discharge wastes.

# the industries should be asked to use low sulphur coal for burning or use other fuels for burning as high sulphur content destroys the environment.

# scrubbers should be used so that chimneys don’t throw toxic gases in the environment as scrubbers reduce the ash and sulphur content.

Q.  Why and how has Global warming become a serious issue?   A. The burning of fossil fuel by industry and transportation vehicles keeps adding carbon dioxide to the air and due to deforestation, CO2 can’t be removed from the atmosphere. If the amount of carbon dioxide in the air keeps on increasing, it will lead to an increase in temperature on the earth. This is because CO2 traps the heat radiation from the sun and this process is called the greenhouse effect. This will lead to an increase in the temperature of the globe and thus leads to global warming.

    Since 1958. the concentration of carbon dioxide in the atmosphere has risen by almost 6 percent and is expected to increase in the future. If the present trend continues, it is feared that a doubling of atmospheric carbon dioxide could occur sometime towards the middle of the next century, and this would cause an average annual temperature rise of 3 to 8OC. This rise in temperature could have a disastrous impact on all life. It will affect agriculture, resulting in problems in the availability of food and other agriculture-based activities. Melting of polar ice would result in the rise of sea level. This could submerge many coastal areas. It is feared that cities like London, Glasgow, Florida, Tokyo, Osaka, Montreal, Stockholm, Copenhagen, and Calcutta would lose much of their territory to the rising waters.

Q.  List any five advantages of using nuclear energy to fulfil our energy needs. 

A. # energy produced by nuclear power plant doesn’t use fossil fuels, hence it is a renewable source of energy

#  it is clean energy, that means no smoke comes out due to nuclear fission and this doesn’t pollute the environment.

# less land is required to establish a nuclear power plant.

#  Unlike coal and natural gas that are pollutants, nuclear energy does not release carbon dioxide and is cleaner. Moreover, it has lower greenhouse emissions.

#, in the long run, it is a cheap source of energy.

Q.  With the help of a suitable example, explain how a persistent pollutant gets accumulated in the organism of various trophic levels.    

Q.  What’s soil pollution

A.    Answer includes soil pollution along with above

    Soil pollution means depriving the soil of all nutrient contents making it barren or unfit for cultivation. Due to the discharge of untreated wastes, pollutants, poisonous substances, soil erosion etc soil gets polluted. Soil, which forms the uppermost layer of the land, is the most precious of all resources because it supports the whole life system on Earth. It provides food and fodder in the form of vegetation and stores water essential for life. Soil pollution is rapidly increasing in the rural, urban and industrial areas due to unscientific and irrational disposal of solid wastes generated by human beings from their domestic and industrial activities. In many rural parts of our country, daily thousands of people pollute the soil through their wastes, as toilet facilities are not available. In industrial areas, heavy metals, plastics and other persistent organic compounds including insecticides, are the major causes of soil pollution. Hazardous wastes in soil, often accumulate in the bodies of organisms including man, because they are not excreted. Once they enter the food chain, they become more concentrated at each level. 

           One of the example is DDT, a pesticide which becomes more concentrated as it passes along from producer to consumers. The story of DDT is one everybody should know. It was once a widely used pesticide. It is a substance that does not easily break down. It can persist in the environment for as long as fifteen years. It enters birds through the organisms they feed on which in turn get it from the organisms lower in the food chain. When a high concentration builds up in birds their reproductive systems are affected. As a result, they lay fragile eggs that easily break in the nests. Similarly, other pesticides are also major soil pollutants, because of their retention in soil. The pesticides not only kill the targeted pests but also kill many harmless and even beneficial insects. They cause more harm than benefit. Therefore, DDT and many such agrochemicals have been banned in many parts of the world.

Q.  How to minimize soil pollution?                    

A. First of all, in India, the use of open fields and banks of ponds and tanks as open toilets should be stopped, by providing latrines. Care should be taken while dumping wastes in the soil. Substances such as heavy metals, plastics, and other substances that remain unchanged for a very long time should not be added to the soil. Instead, ways should be found for their re-utilization by various recycling processes. Utmost care should be taken so that the minimum necessary pesticides or other agrochemicals are used. In fact. biological control of pests and fixation of nitrogen should be urgently developed by research, so that dependence on the widespread use of toxic chemicals is reduced.

Q.  List five essential components of land management.  

Or  Define land management                        

A.  There are five essential components of land management:

i)  Drawing up of a land capability map indicating soil productivity and the ability to support various human activities in rural and urban areas. This kind of map is prepared with the help of aerial photos and satellite imageries. The map can also give information regarding the properties of rock and soil and the underground potentials of water reserves.

ii)  A detailed study of various aspects of land, such as type of soil, physical features of the earth's crust, water resource input, its distribution, utilization, surface flow, surface storage, for example in ponds and groundwater. A program of land use can be worked out on the basis of such information.

iii)  Changes resulting from land use have to be monitored. This can be done by remote sensing.

iv)  Investigation and estimation of the anticipated intensity of natural hazards likely to

threaten a particular area or region.

v) A comprehensive study of the programme and plan of land management with a view to preserving the land from erosion or soil sickness.                 

          Land should be used according to its suitability and capability. Since food for an increasing population requires more land for cultivation, the encroachment of fertile agricultural lands for non-agricultural purposes like construction of roads and buildings should be reduced to the minimum. Extreme care should be taken in selecting sites for the development of industries, construction of dams and water reservoirs, etc., so that the environment and socio-economic conditions of the people living in that area are not disturbed. In locating sites for the development of urban centers, the need for housing, water supply, disposal of waste and garbage, etc. should be taken into consideration.

             Hill areas, as far as possible, should be put under forest cover because forests serve as a resource for fuel, fodder, and timber, and provide space for animal farming. Besides, forests help in increasing the ground water, since they impede the free surface runoff, thus allowing water to be absorbed by the ground. In this process, soil erosion is minimized and flooding can be avoided. Forests help to maintain a balance in the ecosystem, that is, among animals, plants, air, and water, etc.

Q.  Describe the remote sensing method used for the exploration of land and water resources. Give the importance of resource mapping.  

A.  Remote sensing is a method of collecting information about ground objects like soil, water, vegetation, and minerals, from a remote place, such as an aircraft or a satellite. This technique not only enables us to locate various resources but also helps us to know about their quantity and quality. The simplest device could be a camera carried by an aeroplane to photograph large areas of land systematically. Cameras can also be mounted on satellites and they could take pictures showing details of clouds, water, forests or buildings on the earth. Both these are "optical" methods of remote sensing because visible light is used by the cameras. But one can also send out radio waves from the satellites and observe how they are reflected or absorbed on the surface of the earth. Usually, radio waves of wavelengths as small as a few centimeters called 'microwaves', are used for such studies, because these waves penetrate through clouds and their reflections also go through the clouds to reach the satellite. Similarly, infrared signals can be sent from the satellite and reflections studied to reveal the nature of the reflecting surface

Remote sensing of water resources

Radio waves of the shortest wavelength are called 'gamma rays' which are given off by atoms of several elements. As a result, the ground soil sends out gamma rays which can be picked up by detectors in the aeroplanes or satellites. This emission is affected by the presence of moisture or water in the soil and hence, it can be easily detected whether or not the soil holds water. Moreover, in the pictures taken from space, the wet soil will have an altogether different appearance compared to dry or waterless soil. Due to the presence of moisture, the water-rich soil will show day time (diurnal) variation in temperature on its surface compared to dry soil, and also will also have a cover of vegetation. Analysis of the type, density, and pattern of the vegetation growing on the wet soil helps us in locating the areas of potential ground water. Similarly. the belts of hot springs can be identified with the help of thermal or infra-red detectors.

Search for mineral deposits

Aerial photos and satellite pictures show very clearly if there is a break in the continuity of layers of rock or other unusual features on the surface of the earth. The distinctive linear features are found to be very common where mineral deposits and ground water are accumulated. Radio waves & magnetic measurements also provide information about minerals and oil under the surface.

Survey of the vegetation cover

Forests of deciduous trees shed leaves during the autumn season which can be easily identified with the help of pictures taken from the spacecraft. During the autumn season when the deciduous trees shed leaves and there is no snowfall as yet to conceal the vegetation pictures becomes helpful. Vegetation cover can be studied by measuring and analyzing infra-red reflection, or with the help of photographs. The density of vegetation, shape, and size of the plants and even the size, orientation and health of the leaves can be studied from afar.

Q.  In what way human activities have caused intrusion into the carbon cycle, Nitrogen cycle and water cycle?

A.  Intrusion into the Nitrogen Cycle

Human intervention can disturb the nitrogen cycle. When we grow and harvest crops, there is a loss of nitrogen from the soil, as it is utilized in the building up of plant body. Similarly, harvesting of timber results in a heavy outflow of nitrogen from our forest ecosystem. On the other hand, the heavy addition of commercial fertilizers can cause an excessive build-up of nitrogen in the soil and groundwater. Automobile and industrial exhausts add nitrogen, especially nitrogen dioxide, at an alarming rate to the atmosphere causing acid rain. Nitrogen dioxide reacts with moisture in the atmosphere to form weak nitric acid, which is carried to the soil during rainfall, and ultimately to the water table. This results in nutrient enrichment of rivers, lakes, etc; the presence of excessive nitrogen oxides in the atmosphere; and the excessive availability of nitric acid to the soil.

Intrusion into the Carbon Cycle

In the present century, the carbon cycle has been impaired by non-judicious utilization of fossil fuels, indiscriminate cutting of forests and changes in land use from agriculture to the cement and concrete roads and buildings, which reduces the area under plantation. The burning of fossil fuel by industry and transportation vehicles keeps adding carbon dioxide to the air and due to deforestation, CO2 can’t be removed from the atmosphere. If the amount of carbon dioxide in the air keeps on increasing, it will lead to an increase in temperature on the earth. This is because CO2 traps the heat radiation from the sun and this process is called the greenhouse effect. This will lead to an increase in the temperature of the globe and thus leads to global warming.

    Since 1958. the concentration of carbon dioxide in the atmosphere has risen by almost 6 percent and is expected to increase in the future. If the present trend continues, it is feared that a doubling of atmospheric carbon dioxide could occur sometime towards the middle of the next century, and this would cause an average annual temperature rise of 3 to 8OC. This rise in temperature could have a disastrous impact on all life. It will affect agriculture, resulting in problems in the availability of food and other agriculture-based activities. Melting of polar ice would result in the rise of sea level. This could submerge many coastal areas. It is feared that cities like London, Glasgow, Florida, Tokyo, Osaka, Montreal, Stockholm, Copenhagen, and Calcutta would lose much of their territory to the rising waters.

Intrusion into the Water Cycle

Water management is one of the leading concerns of man today. Due to human actions, the water table has been disturbed. The amount of water that is fit for human consumption has decreased over the years and its quality has deteriorated. To a large extent, this is because of increased population, higher demands of water for personal use, agriculture and industry. Deforestation due to the indiscriminate cutting of trees and the ultimate depletion of the vegetation cover is another major reason. Deforestation, not only reduces the humidity in the atmosphere but also leads to a chain of other undesirable events, for instance, the vegetation that helps to hold the soil together, when reduced considerably, is not able to hold the topsoil. This eventually results in washing away of fertile, topsoil during rainfall or by blowing winds, thus exposing harder infertile rocks. Not much water seeps down the hard soil, and the underground water reservoirs are not properly replenished. The loosely bound soil is carried along by running water on its surface and is ultimately deposited in river beds and dams, thus choking them.

          The other human activities that disrupt the water cycle are: excessive use of agrochemicals which when percolates pollute underground water. Domestic and industrial wastes are often released into the water streams without treatment, adversely affecting life in the water.

Q.  In the present condition, why is it important to manage our resources? Suggest ways to manage our forest and water resources.  

A. Our resources are available in limited quantity and if they are not used judiciously they will get exhausted soon. It is, therefore, necessary for us to make proper planning, to use of our limited resources.

 Management of Forest Resources

It has become necessary to find alternative fuels as well as raw materials to manufacture paper, printing material, sports goods, packing cases, furniture and beams used in Building construction, etc. Another way is to cultivate quick-growing trees in large numbers in selected areas of degraded or wastelands. This will provide us fodder, fuelwood, timber, fruits, and seeds. If deforestation has to be stopped some necessary steps have to be taken:

i) adoption of a scientific method of harvesting forest stocks,

ii) developing a mechanism of monitoring forest growth rate and depletion,

iii) establishing an effective mechanism of fighting forest fires,

iv) strictly enforcing laws to deal with unauthorized cutting down of trees.

Tree plantation

Plantation of fast-growing trees such as poplar, casuarina, etc. should be undertaken on a mass scale. The productivity of tree plantation is found to be greater than that of natural forests. In a well-irrigated tree farm, the productivity may be as high as 45 tonnes per hectare per year.

Social forestry

A farmer can partly meet his needs of wood from the fast-growing trees planted within the limits of his village, along the footpaths, roadsides, alongside railway tracks, side roads or canal, and streams, boundaries of fields and empty spaces. The aim of social forestry is to meet the needs of fuel, fodder, fruits, timber, and other requirements.

Q.  How air pollution is the major problem. How to control air pollution    

A.  Wastes in the form of smoke from industry, power plants, automobiles and homes; and also due to the burning of fossil fuels, spread pollution into our atmosphere. Aircraft also release large amounts of burnt or unburned fuel into the air. The burning of coal, wood, diesel oil, kerosene, petrol, etc. produces the following five

categories of pollutants:

i)   Carbon monoxide

ii) Hydrocarbons

iii) Particulates

iv) Sulphur.dioxide

v) Nitrogen oxides

These five categories of primary pollutants react with one another, producing secondary pollutants that are even more dangerous to animal and plant life.

Carbon monoxide is produced when organic materials such as gasoline, coal, charcoal, and trash are incompletely burnt. Virtually all stoves, furnaces, fires in open places and forests, factories, power plants give off carbon monoxide. The other significant source is from the incomplete burning of tobacco when smoked. This gas combines with hemoglobin, and reduces the oxygen-carrying capacity of the blood, causing blurred vision, headache & in extreme cases unconsciousness & even death.

Harmful impacts are -

Photochemical Smog

Acid rain

Global warming

Depletion of the ozone layer

Controlling Air Pollution 

i) Photochemical smog-eliminating this would require large scale changes in lifestyle and culture. Life has become fast, and quicker modes of transport are preferred. Every year hundreds of thousands of vehicles are added to the existing large number of automobiles. So the net result is an increased production of oxides of nitrogen, and the photochemical smog. The alternative is to develop transport of a very different kind, perhaps electrically operated cars, and two-wheelers rather than those burning petrol, or to make the automobile industry develop devices that could be fitted to the vehicles to minimize the discharge of pollutants.

ii)  Particulates generated largely by industries can be controlled by scrubbers, precipitators, and filters.

iii)  To control sulphur dioxide, which is produced largely by coal furnaces and coal-fired steam generators. several possibilities are available. One is to change from high sulphur to low sulphur fuel, such as natural gas. oil or nuclear fuel.

iv) The amount of smoke emanating from the kitchens can be minimized by the use of smokeless chulhas solar cookers and biogas. These have a dual advantage. One. they are within the easy reach of people and secondly, there is minimum pollution.