Question 1. What Is Environment ?
If we do not want to go into the intricacies of the term, then we can define environment as everything that surrounds us. Whatever we see around us is confined to the living component of the human eco-system. With time, the concept has undergone modifications. Today, environment means a single system of the interacting living and non-living natural components of the earth.
But the earth is not the only planet of the solar family, which again belongs to our home Galaxy — the Milky Way. There are about 100 billion such galaxies floating in the vast universe, each containing about 100 billion stars!! In this universe, not a single event can be said to be isolated, and no object is independent of the rest.
Since everything is interrelated with every other thing, logic demands-that the entire universe is our environment. But, for practical reasons, environmental study deals only with the system of interaction between non-living and living components of the globe.
In 1977, the first international conference on Environmental Education was held in Tiflis (capital city of Georgia Republic). The programme was organised by UNESCO and UNEP, and here it was noted that “the environment includes a complex of natural, built and social components in the life of humanity”.
Question 2. Describe The Principal Characteristics Of Environment?
The principal characteristics of the environment have been listed below:
- At any given point of time, the environment of any area is the sum total of all biotic elements and the a biotic elements around them.
- The three basic components that constitute the structure of the environment are biome, habitat and energy.
- The elements of the environment are systematically organised and interact with one another to maintain the integrity of the system.
Thus, the environment is a perfectly functioning system:
- The input of solar energy is responsible for the functioning of the system.
- The environment is an open system since there is a continuous inflow and outflow of matter and energy.
- The productivity of the environment is determined by the availability and amount of energy.
Question 3. Give A Brief Account Of The Components Of Environment.
The three basic components of environment are:
- Abiotic (physical or inorganic) components,
- Biotic (organic) components, and the
- Energy components.
Again, the abiotic components of the environment consist of:
- The lithosphere — the chief reservoir of mineral nutrients,
- The atmosphere — the chief reservoir of gases essential for organic life, and
- The hydrosphere — the chief reservoir of liquid water.
The biotic component of environment includes all kinds of organic life, ranging from microorganisms to plants and animals, including man.
Energy is the third component of environment, which is indispensable for the generation and sustenance of all forms of organic life. The sun is the main source of energy in the environment. Geo-thermal energy is yet another type of energy. Since photosynthesis is essential for the existence of organic life, we find that life is confined to only those regions where solar energy can be captured for photosynthesis.
This forms a narrow belt of life that extends from about 180-210 m below sea level to almost 6 km (snow-line in mountain ranges). This is known as the Biosphere, which can be said to be a thin film (1/1000th) when we consider the earth’s radius (6,370 kms).
Question 4. Explain With Examples The Natural Changes Of Environment?
- Almost everybody is fascinated by the notion of change. Right from the day they are born, till the moment they breathe their last, human beings experience a variety of change. They are all familiar with the sunshine and sunset and passage of day into night, as well as the change of the seasons.
- We all notice that the weather in one year is never quite similar to the weather in previous years. Let us take for example the Monsoon Rains in West Bengal. A few years ago, the rains arrived in Bengal by early June and October was sunny and pleasant. Now, the rains arrive much later, and the festivities of October are marred by the showers.
- Environmental change is studied by scientists from environmental, geographical and geological disciplines. The work of those scientists have delved into the intricacies of the past environments and finally confirms that environmental change is real, various and complex.
Question 5. Define Environmental Studies?
- There are several fields of study associated with the environment. With time, man realized the growing importance of maintaining his environment, and subjects such as ecology, environmental engineering, environmental sciences, environmental studies etc. gained popularity.
- There is a fundamental difference between environmental science and environmental studies. The former lays emphasis on scientific qualities and issues of environmental interest, while environmental studies focus on questions related to environmental ethics and aesthetics.
- The concern for preserving the environment is a relatively new phenomenon. There was a time when man would derive the maximum benefit from his surroundings, without thinking of the consequences. It was only since the 1950s that nations of the world started conservation and wise utilization of their natural resources — such as water, soil, fuel, flora and fauna.
- It has been accepted that nature is a treasure-house that provides us with food, water, energy, medicine and various other amenities. No wonder the prevention and protection of the environment has become so crucial.
- Developed countries have made considerable progress in the field of protection and conservation of the environment on a-long-term basis. However, the developing nations, were quite late in understanding the gravity of the situation, and, hence, they are lagging behind.
Question 6. Explain The Necessity Of Environmental Studies?
The natural resources of the earth — which include air, water, soil, flora and fauna represent our environment. For the benefit of the present and future generations, these priceless resources should be safeguarded, by means of careful planning and management.
At the end of the 20th century, we are realising the acute environmental crisis as an impact of indiscriminate and ignorant utilisation of natural resources. The rise in population and demand for space and basic amenities has led to overutilization of the available resources.
In order to create an awareness among the masses about the importance of proper utilization and conservation of the resources, environmental education has become a must.
Question 7. What Is The Meaning And Objective Of Environmental Education ?
Environmental education is the process in order to create awareness and sensitivity to the total environment by developing appropriate attitudes and acquiring adequate knowledge and skills with the purpose of solving environmental problems.
The following may be suggested as the objectives of any environmental education programme:
- To develop proper attitudes and skills for understanding and appreciating the interdependence of man and his environment,
- To use natural resources carefully and adequately,
- To formulate a new behavioural code with the aim of improving the overall quality of life for the future generations.
Question 8. What Do You Mean By Environmental Change ?
Environmental factors are, naturally, variable. For instance, air temperature varies on a diurnal and annual basis. In order to measure sustained temperature changes, we take average values for days, months, seasons, years, and even longer periods.
Then, the similar averages are compared when it is found that the mean temperature for one year is greater than that in the previous year; we know that a change has occurred.
It must be kept in mind that average values should not be treated as some sort of norm. Average values for all the principle atmospheric variables over a period of thirty years are used to defined “climatic norms”. This term is often misleading, since it tries to establish that the climatic norms are somehow permanent.
However, current thinking suggests that the climate is ever changing. The climatic norms of one generation may be another generation’s climatic extremes. Thus, we may conclude from this argument that — change is the norm, constancy the exception.
In this context, scientists have found that environmental variables display three basic types of changes:
- A discontinuity, which is an abrupt and permanent change in the average value,
- A trend, which is a smooth increase or decrease (not necessarily linear in nature) in the average, and
- A function, which is a regular or irregular change characterized by at least two maxima (or minima) and one minimum (or maximum).
Question 9. What Are The Causes Of Environmental Change ?
The ecosphere is the first source of environmental change, since the interactions between the atmosphere, biosphere, hydrosphere, pedosphere and toposphere produce environmental cycles, trends and steady states. Directional changes or trends occur when a threshold within the ecosphere is crossed, just as what happened when the Antarctic ice expanded during the Late Eocene atmospheric cooling. The ice-‘sheet has lasted ever since through, recently (December 2000) an area of 20,000 sq. miles (51,000 sq. kms) has been satellite- observed as melted! This has caused grave concern to the environmentalists.
The sun is the most important source of power of the ecosphere. Steady state changes about periodic and quasi-periodic fluctuations are promoted by solar influences. A number of ecospheric processes are finely adjusted to solar cycles. Also some ecospheric processes are attuned to various astronomical pulses, such as orbital changes in the sun and the planets, the solar system’s passage around our galaxy, Milky Way, and the Milk Way’s interactions with the neighbouring galaxies. The bombardment by asteroids and comets may also instigate and encourage biospheric trends.
Cycles, steady states and trends in the ecosphere are also produced by geological forces, and the ultimate seat of change lies in the core and mantle process. The core and mantle processes act through the agency of the lithosphere. The mechanism of plate-tectonics influences sea-level change, volcanic and mountain building activities, continental drift and true polar wander. Geological changes have caused long-term bio-diversity trends, since it is largely dependent on relative fragmentation of land-masses.
Question 10. Describe The Principal Constituents Of Earth?
The principal constituents of the earth can be considered in four broad groups:
- The lithosphere, which is the outer skin of the earth made up of rocks and minerals.
- The atmosphere, which is the gas or vapor envelope around the earth.
- The hydrosphere, which is the liquid portion of the earth, including the water vapour of the atmosphere, the water present in oceans, seas, rivers and lakes, and the water present in rocks, and.
- The biosphere, which is the world Of living organisms that dwell on land, in water and in the air that we breath.
Question 11. What Are The Different Hypotheses Regarding The Origin Of The Earth ?
From the very beginning, man has been curious to know how the earth and the universe came into being. Due to this common interest, all the early civilizations developed their own explanations and versions of the origin of the earth and nature of the universe.
COSMOLOGY is the field of study, which deals with the evolution of ideas regarding the origin of the earth, its relation to the solar system, and how the solar system is related’ to the universe.
Man had to wait until the invention of the telescope, when he could peer into space and explore the universe. However, this could be done at a limited scale. After two or three hundred years, more powerful telescopes were developed. In the meantime, there had been new developments in the fields of mathematics and physics. These enable man to explore space more adequately.
There are two rival theories explaining the origin of the universe:
The super dense or “BIG BANG” theory:
This theory was put forward by Ryle. He suggested that a vast explosion of super dense matter created the universe. This explosion produced the galaxies of stars which are scattered throughout the space. The stars are also flying away from each other, at the amazing speed of 600 million km/hour.
The steady state or continuous creation theory:
This theory was elaborated by Hoyle, Bondi and Gold. They rejected the Big Bang Theory. Instead, they put forward the idea that matter is being continuously created. New galaxies are born and compensate for the ones which are receding beyond man’s ken.
Question 12. The Mystery Beneath The Crust – Explain?
- When we look upwards, we can see into space for millions of kilometers. But, when we try to penetrate downward (by boring) we can only reach down to a land depth of about 4.3 km (14,000 feet). Thus, till today, man has only been able to scratch the surface of the planet, but has only penetrated up to such a minute depth — which is even less than 0.001 % of the distance from the surface to the centre of the earth.
- The Mohole Project was taken up by American scientists with the aim of improving our knowledge of the sub-crust. The scientists planned to drill a hole, about 10 km deep, from the surface, through the crust to the material below. However, the project turned out to be so expensive that it was eventually abandoned after the early work.
- Later, much deep sea drilling was done and cores of ocean crust from sites of structural interest were obtained (D.S.D.P. or Deep Sea Drilling Project, and the I.P.O.D. or International Phase of Ocean Drilling Programmes). Valuable information was obtained regarding the behaviour of the earth’s crust and the rocks beneath.
- We do not know exactly what lies beneath and what kind of conditions prevail in the earth’s interior. The geologists have intelligently interpreted the various kinds of evidence and tried to tell us about the composition, structure and nature of the earth.
Question 13. How Many Principal Gases Are There In The Atmosphere ?
- All living organisms inhale Or No life is possible without this gas.
- It can combine with all other elements and thus can form different compounds.
- It is indispensable for combustion.
- Its main function in the atmosphere is to dilute oxygen and regulate combustion.
- Indirectly, it aids oxidation of different kinds.
Carbon Dioxide (CO2):
- Plants inhale this gas.
- Green plants utilize CO2 in photosynthesis and prepare their own food.
- It is of great climatic significance because it efficiently absorbs heat from the upper atmosphere.
- It influences the flow of energy through the atmosphere because CO returns almost half of the absorbed heat back to the earth.
During the past century, large scale fossil fuel burning has increased the concentration of CO, in the air. Ultimately, this has resulted in the warming of the lower atmosphere.
This triatomic form of oxygen is the most efficient absorber of the scorching ultra-violet radiation from the sun. The ozonosphere protects us from the ill-effects of excessive quantities of UV rays. The composition of the atmosphere varies with height, latitude and time.
The light gases, especially helium and hydrogen, are found in abundance in the upper atmosphere. Water vapour constitutes almost 4% of the atmosphere by volume, only near the surface. Above 10-12 km, it is nearly absent. Ozone is found mainly between 15-35 km, in the Troposphere.
Ozone and water vapour are also the two gases whose concentrations in the atmosphere vary with latitude and season. Ozone content is low over the Equator (0°). It is high over latitudes north of 50°N, that too mostly during the spring season.
Question 14. Define Ecology?
L. De Vere Burton has defined ecology as:
“The study of relationships between living organisms and the environments in which they live is the science of Ecology.”
According to Eugene P. Odum:
“Ecology is the study of the relation of organisms or groups of organisms to their environment, or the science of the interrelations between living organisms and their environment.” Therefore, it may be concluded that ecology involves the totality of all the reciprocal interactions that take place between living organisms and their environment.
Question 15. Give An Account Of The Classification Of Ecology?
There are several subdivisions of ecology, but only a few important ones have been discussed here.
Scientists have broadly classified ecology into:
- Autecology, which involves the study of one species of organism, and
- Synecology, which is the study of communities or entire ecosystems.
The following are a few specialized branches of ecology:
Habitat ecology is the ecological study of various habitats on earth and their effects on the organisms living there.
According to the type of habitat under consideration, ecology is further classified into fresh water ecology, marine ecology, grassland ecology, desert ecology etc.
Is the study of the local distribution of animals in different habitats, the recognition and composition of community units, and succession.
Also known as population ecology, studies man’s relationship with the environment, particularly the impact of human behaviour on the environment and the implications of these effects for man.
Which is the application of ecological concepts to human needs and requirements, such as forest conservation, animal husbandry, agriculture, horticulture, wild-life management etc.
Which is a relatively modern branch of ecology, deals with the analysis and understanding of the function and structure of ecosystems, mainly by using applied mathematics.
Question 16. Define Ecosystem?
In 1971, Odum defined ecosystem as any unit that included within it all the organisms (i.e. the community) of a given area interacting with the physical environment, so that a flow of energy results in a clearly defined trophic structure, biotic diversity and material cycles.
In this context, the following terms need to be classified:
- The trophic structure is the level of nourishment. Plants form the first trophic level, herbivores form the second trophic level and carnivores form the subsequent trophic levels.
- Biotic diversity refers to the different kinds or types of organisms and their numbers.
- Material cycles refer to the exchange of materials between living and non-living parts of the system, the transfer of nutrients from one trophic level to another and their re-cyclization.
Question 17. What Are The Ways To Conserve Forest ?
With the spread of civilization and the growing demands for forest produce, the world’s forest cover is steadily diminishing by burning, clearing and felling trees for fuel, or to make space for settlements, agriculture and industry.
Finally, we have realised that forests should not only be preserved for maintaining timber supplies, but also for checking soil erosion, flood, safeguarding water supplies, and for providing recreational facilities.
We have made a list of ways in which the problems can be overcome:
Forests felled for timber supply must essentially be replanted with seedling trees. The new trees may not always be the same as those removed. Many areas which were not forested previously may also be planted in order to check soil erosion.
Selective Cutting Practices:
With the aim of better regeneration and survival, the cutting practices should be selective. The weak or diseased species, or the mature species, that are occupying space uselessly, must be removed. By this method, sufficient trees will remain to prevent soil erosion and the species can regenerate at the same time.
This is an alternative to selective cutting. By this method, all the trees are removed, irrespective of age or type. Initially, this may seem to be wasteful. But, if the area is replanted, erosion can be checked. This method is also cheaper and easier.
Protection of Forests:
- Forests should be efficiently protected from natural hazards such as fires and pests.
- In order to protect forests from fires, there should be close system of lookout towers and air patrol that can give an earliest possible warning. This system is very popular in the USA and Canada.
- Forests should be inspected regularly and sprayed with insecticides in order to fight insects and pests. Insects or animals that prey on the unwanted insect can also introduce into the forest.
Re-use of Waste Paper:
By recycling newsprint and other inferior paper products, timber consumption can be reduced.
Question 18. What Are The Uses Of Water ?
Domestic Water Need:
- Under this category is included the various domestic needs, such as cooking, washing, drinking, cleaning, flushing toilets etc. The consumption of water in any city depends on its population.
- The minimum rate of domestic consumption of water should be 70 to 100 liter per capita per day (lpcd). How this water can be used per head for a town-resident is shown below, but this is totally based on assumption.
- The rate of domestic water demand in a city is closely associated with the size, economic condition as well as non-domestic needs of the city. In rural communities houses do not have water connections, and supply is through hand pumps, wells, tanks etc. Here the water demand should be around 40 lpcd. But in the few houses with connections, the rate shall be 70 lpcd, to make the scheme self-paying.
Industrial Water Need:
The industrial demand for water in a town depends on the number, nature and size of industries.
Institutional Water Need:
Under this category comes the quantity of water needed by various public buildings and institutions. Therefore, since the water is used for public utility purposes, it is sometime known as public demand. Watering of parks and gardens, cleaning streets, roadside fountains and other beautification measures’, maintaining public swimming pools and other entertainment centers etc. come under this kind of demand,
Water is stored for fighting sudden fire-outbreaks. The tanks are filled from nearby water bodies by water tankers wherever possible and then used when needed. High-rise buildings (above 25 m height) must be provided with their own water storage, other than the water used for domestic purposes,
Unaccounted Use of Water:
A huge quantity of water is lost due to thefts, negligence, ignorance etc. Some loss also occurs due to technical problems, such as leakages at the joints and valves. Proper vigilance, inspection and timely maintenance can reduce unaccounted loss of water to a large extent.
Question 19. What Do You Mean By Waste Water ?
Waste water is defined as a combination of domestic and industrial waste water, with or without rain runoff. Domestic waste water is sewage only and does not include rain runoff. Therefore, waste water is a complex mixture of natural inorganic and organic materials mixed with man-made substances.
It contains everything discharged to the sewer, including materials washed from roads, railways and roofs, and, of course, where the sewer is damaged, ground water will also gain entry. In the broadest sense, waste water can be split into domestic (sanitary) waste water, also known as sewage, industrial waste water and, finally, municipal waste water which is a mixture of both.
The principal objectives of waste water treatment are:
- To convert the waste materials present in waste water into stable oxidized end products. It can be safely disposed off to inland water without any adverse ecological effects;
- To protect human health in the society;
- To recover and recycle the valuable components of waste water;
- To ensure waste water is effectively disposed off on a regular and reliable basis;
- To provide an economic method of disposal.
Question 20. Define Water Pollution?
Water pollution may be defined as any physical change in the natural water by the addition of any foreign material that adversely affects human and aquatic life, directly or indirectly, in the short run or in the long run.
Water is considered to be polluted when it is contaminated with:
- Suspended impurities, such as sand, mud, clay and organic matter;
- Dissolved gases like CO2, NH3, N2, H2S;
- Dissolved minerals like calcium, sodium and magnesium salts;
- Isotopes or radio-logically active substances; and
- Microorganisms like bacteria, viruses, protozoa’s and worms.
The pollution of water alters the physical properties of water, such as colour, odour, turbidity and temperature. The presence of dissolved or suspended chemical pollutants can make the water acidic or saline.
Question 21. What Are The Sources Of Water Pollution ?
The principal reasons behind water pollution are the problems like population increase, agricultural and industrial waste generation, sewerage disposal, radioactive waste generation, etc.
The sources of water pollution can be of two types:
Natural Sources –
Soil erosion, volcanic eruption, landslides, storms, earthquakes.
volcanic eruption and dead and decaying organic matter.
(iii) Organic Matter:
Decaying bodies of plant and animals in swamps or deep ponds.
(iv) Rain Water:
Acid rain, especially in industrialized countries.
Man-made or Anthropogenic Sources –
Animal waste and human sewage
(ii) Organic Wastes:
Human and Domestic Sewage, Animal and Plant Waste, Wastes from agro-based industries.
(iii) Inorganic chemicals and minerals:
Agricultural runoff, domestic sewage, animal wastes, wastes from petrochemical, fertilizer and similar other industries, mining activities.
Cooling water from industrial and power generating installation
Question 22. What Do You Mean By Noise Pollution ?
J. Tiffen, an industrial psychologist, has defined it as —
“Noise is a sound which is disagreeable for the individual and which disturbs the normal way of an individual.”
According to the Encyclopedia Americana:
“Noise by definition is unwanted sound. What is pleasant to some ears may be extremely unpleasant to others depending on a number of psychological factor. The sweetest music, if it disturbs a person, who is trying to concentrate or to sleep, is a noise to him, just as the sound of a pneumatic riveting hammer is noise to nearly everyone. In other words any sound may be noise if circumstances cause it to be disturbing.”
We can conclude by saying that any sound which is disagreeable to the individual and which hampers the normal way of the individual is noise.
Question 23. What Is The Meaning Of Odour Pollution ?
Smell causes distress and discomfort, while odour, under different conditions, can be pleasing. The osmogenic molecules (smell) enter the nasal cavity through the nostrils. They excite the osmoceptors. The specific impulse travels along the myelinated nerve fibers to the receptor centres in the brain in the form of specific electric discharges.
The message is. processed and delivered to the evaluation centres in the brain. Here olfactory information is compared with stored experience (the memory), and finally the interpretation of message is relayed back along other nerve paths.
Question 24. Discuss The Sources Of Odour Pollution?
Stale air is characteristic of areas that are populated or overpopulated — whether residential, commercial or industrial. Stale air is deprived of its full oxygen value.
Instead, it carries a considerable surplus of carbon dioxide:
- Perspiration is probably the most common metabolic sources of odours. A worker in a hot and humid environment is, likely to lose up to 900 g sweat per hour. Normal sweat from a healthy person does not have any particular odour.
- It becomes repulsive when the urea content (normally about 0.03%) or butyric acid (normally about 0.001%) increases slightly. Sometimes sweat also contains valeric acid, which, in combination with butyric acid, forms the characteristic body odour.
- Various diseases may also create odour and pollute the air, such as cancer in advanced stages, tinea versicolor, osteomyelitis, ozaena etc.
- Certain pathological conditions, such as bromidrosis produced by decomposing keratin of the feet, are characterized by offensively smelling sweat.
- Stale or fermented urine smells of ammonia as well as cyclohexene-3-one.
- The odours of the alimentary tract are dependent upon the type of digestion taking place. Stools give off highly offensive smells when they are alkaline, indicating protein putrefaction.
- Objectionable cooking odour originates from the production of sulphur compounds together with steam — while cooking vegetable or animal matter.
- Industries give off various kinds of smells, according to the type of solvent used for the numerous natural and synthetic materials employed in the finishing trade.
Solvent vapours are extremely volatile and give rise to photochemical smog.
Question 25. What Are The Measures To Control Odour Pollution ?
- The concentration of odour in houses, schools, office, factories etc. must be checked once in a month and controlled when necessary.
- The sudden outbreaks of steam smoke and other odour-producing fumes must be controlled.
- A mobile laboratory fitted with a radio telephone transmitter and receiver for communication is needed to check the odoriferous dusts and fumes.
- In localities around industrial areas, the concentration of oxides of carbon, nitrogen, sulphur and other pollutants must be evaluated every half an hour.
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