DYNAMICS OF ENVIRONMENT
 

1. INTER CONNECTEDNESS OF ENVIRONMENTAL COMPONENTS

All major components of the environment viz., Air, Water, Land, Energy and Living beings including man are inter-related and inter- connected in one way or the other. Living beings are dependent upon their physical environment - the land, water, air and energy for their existence. At the same time they also affect the physical components just as the changed physical conditions again have a direct impact on living beings.

One of the fundamental aspects in ecology that helps us understand the inter-relationship between plants and animals, animals and animals. animals and human beings is their requirement of food. Green plants are the primary producers of food. They make simple carbohydrates during the process of photosynthesis with the help of carbon dioxide and. water by the utilization of energy received from the Sun. When herbivore animals eat plants. they get energy through this food. Herbivores are eaten by carnivores for their food and energy requirement and life activities, These interlinkages account for what we call as food chains. An interconnected network of differ- ent food chains that occur among the inhabitants of a particular natural habitat makes a food-web. The food-web is a delicate network of inter-relationships between the species involved, representing a balanced and self-contained living system. Destruction of any one link in this food-web has an adverse impact on the other or the entire system itself.

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Inter relationships in nature take many forms-plants and vegetation provide home for animals, insects and birds pollinate flowers. animals help the dispersal of seed of plants, parasites infest plants or animals. There are also the nature's clean-up crew- the crow, the eagle, the hyena and others who act as scavengers. The bacteria aid in decomposing the dead which play an important role in returning the organic and inorganic components of dead animals and plants back to nature, to be used and reused by subsequent living organisms.

Plants take nature's raw material of earth, water, air and sunlight and organise them into living substance. But without the help of animals, plants would long ago have organised themselves out of existence, for they would have locked up in the earth the world's available supply of carbon and then died of starvation. Fortunately, the animals came along in time to eat the plants and thus release the carbon and keep the cycle functioning. The carbon not released in this way is still available to us today in the form of coal. Plants

The earth does not belong to man, man belongs to earth. All things are connected like the blood which unites one family. Whatever befalls the earth befalls the son of the earth. Man did not weave the web of life; he is merely a strand in it. Whatever he does to the web, he does to himself.

- Chief Seattle

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therefore, build food that makes life possible for animals and in turn depends on animals to keep the cycle of life moving.

The components of the physical environment - the energy, land, water and air together determine the existence of any kind of life on earth. The solar energy, for example, is crucial for production of food by plants which in turn provide food to living beings. Similarly, soil, another component of nature provides an essential medium for the growth of plants. Its formation involves physical, chemical and biological changes and is thus affected by climatic conditions as well as the presence of living beings. Water and air together complete the complex and intricate network of inter- relatedness and interdependence.

Thus there exists a very complex, yet balanced, inter- connectedness between different components of the environment. Together with the bio-geo-chemical cycles such as the water cycle, carbon cycle, nitrogen cycle, mineral cycle, etc., recycling essential elements between living organisms and the environment, all life on earth is interconnected. It is essential to understand these ecological relationships and other inter-linkages in order to conserve nature and protect the non-living resources that nature has provided on our planet earth.

Keeping CBSE syllabi at secondary stage as the base, an effort has been made in the following pages to bring out these inter-linkages more clearly and in greater detail.

We may utilise the gifts of Nature just as we choose but in her books, the debits are always equal to the credits.

- Mahatma Gandhi

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2. CO - RELATION BETWEEN COMPONENTS

Sowing the seed my hand is one with the earth

Wanting the seed to grow my mind is one with the light

Hoeing the crop my hands are one with the rain

Having cared for the plants. my mind is one with the air

Hungry and trusting my mind is one with the earth

Eating the fruit my body is one with the earth

(Earth Prayers)

AIR

Air, the gaseous envelope around the earth, is the most essential natural resource for the survival of any living organism. All air- breathing animals inhale and exhale the air directly while aquatic animals like fishes use the air dissolved in water.

Green plants make use of air in two ways - take in CO2 for making food in the presence of water and sunlight and take in O2 for respiration in the absence of sunlight. Air also penetrates the soil for use by the plant roots. The balance of CO2 and O2 in the air is maintained both by plants and animals. Plants use up CO2 in food making and give out oxygen whereas animals use up oxygen and give out CO2.

Air, when heated by solar energy, moves and causes winds which carry clouds over long distances. Dry wind, on the other hand, sweeping over barren land. causes, soil erosion and even contributes to the making of deserts. The presence of CO2 in the air traps solar radiations and maintains the appropriate temperature on the earth's surface for the existence of life. The presence of N2, O2 and CO2 in air maintains different gaseous cycles and thus helps in the exchange of matter and energy between different components. The ozone gas present in the uppermost layers of the atmosphere protects living beings from harmful ultraviolet radiations.

With the growth of human population and the rise of industrial culture, much harm is being done to the air in the form of emission of large quantities of harmful gases and particulate matter with it. The harmful oxides of nitrogen and sulphur emitted from industries and vehicles result in acid rain which causes irreparable loss to vegetation as well as to architectural structures. More dangerous chemicals emitted in the form of chloro fluoro carbons (CFCs) are not only harming the life-supporting quality of air but are also causing the depletion of the UV absorbing Ozone layer. The burning of fossil fuels in large quantities and decreasing forest cover due to human interventions is likely to cause an increase in the percentage of CO2 in the atmosphere. The resulting global warming may cause excessive melting of ice caps and submergence of coastal habitations under water. The threats posed are real and serious efforts need to be initiated without delay to avert possible disaster.

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WATER

Water, as a natural source, is not only essential for life but is the predominant inorganic constituent of living matter. It generally forms nearly three-quarter of the weight of a living cell and makes up about 65 percent of the body weight of an adult human being. The water present in the body cell not only makes up its substance but also performs numerous chemical and physical activities including the moderation of body temperature.

Water sources determine the growth of human civilizations. Ancient civilizations such as the Egyptians and Aryans flourished along the banks of the rivers Nile and Indus respectively. Even today, most of the human dwellings are situated close to rivers. There are as many as 112 towns and cities along Ganga river atone.

The status of water resources is very intimately related to the status of soil. vegetation, air and living beings. Green plants need water as a raw material to produce glucose by combining with CO2 from the air in the presence of light energy. The food thus produced not only supports plants themselves but through them, the entire world of animals, including man. Plants and specially the forest trees transpire water vapours which contribute to the rains and help in completion of the water cycle in nature.

Water resources are important for the generation of energy. River systems of Central and Southern India alone contribute more than 40% of the potential source of hydro power for the southern, eastern and western regions. Water is also an essential resource used for generation of energy by thermal and nuclear power plants. Waterways also provide an important means of transportation. Tidal energy is being considered to be one of the sources of energy for future generations.

The presence of water in the soil in appropriate quantity is a key factor for all agricultural activities. Shortage and non- availability of water has caused famines many a time in the human history..

Activities like large scale deforestation, excessive irrigation, and over-exploitation of ground water have disrupted natural processes resulting in ecological imbalances. The pouring of large scale indus- trial effluents and domestic sewage into rivers is posing a serious threat not only to aquatic life but to human beings as well through the food chain. The fact that only 1% of the total quantity of water on earth is in the form of fresh water demands serious consideration for its conservation and the continuance of life on earth.

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LAND

Land is an important natural resource and manifests itself in different forms such as planes, hills, mountains, deserts, etc. The processes of land formation and its exploitation by man over the years have created a wide impact on other natural resources and human life. The presence of a thin layer of soil over the land is a major determinant of all types of vegetation as well as the formation of the water cycle and land use patterns. The physical and chemical characteristic of the soil determine the type of vegetation and its water retention capacity. Plants penetrate their roots into the soil for fixation and for obtaining water and nutrient mineral elements. Vegetation., in turn also performs a key function by its role in the formation and maintenance of soil and the control of microclimate.

Land is the home of a vast variety of animal life including man. Some animals live on the surface of the ground, some in caves and some under the ground and some other animals like birds and insects rest on land and carry out different activities. Man himself carries out most of his activities on the land surface.

There exists a close inter-relationship between soil and atmospheric air. The gaseous exchange between soil and the air is essential to maintain the fertility of the soil. Oxygen is needed by the roots for respiration. Nitrogen and nitrogeneous compounds are needed by a variety of micro-organisms in the soil. The leguminous plants make use of the soil nitrogen very efficiently through the bacteria in their roots.

The source, the quantity and the quality of water is also closely interlinked with the land characteristics and general climatic conditions.

Large scale human interventions and some natural factors are resulting in the deterioration and depletion of this precious natural resource. Overintensive use, urbanization, inappropriate agricultural practices, the use of chemical fertilizers and pesticides, mining, the dumping of industrial waste and irrational destruction of forest are some of the human activities responsible for the degradation of soil quality and creating an imbalance in the ecosystem. Only 10% of the land surface of the globe has soil suitable for easy cultivation. Hence serious efforts need to be made for conserving it and preventing loss of fertility.

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ENERGY

Energy is a vital factor for the existence of any kind of life on earth. Every cell of the body as well as the entire organism has to perform a variety of activities which need energy. Living organisms get energy from food which is ultimately produced by plants using sunlight. The sun's energy is thus the mainspring of all life on earth.

The solar energy also drives the geophysical and geochemical cycles that sustain life. The water cycle, the oxygen cycle, the carbon cycle and the climatic cycle are all driven and regulated by solar energy. Fossil fuels are also stored with solar energy.

The primitive humans made use of direct solar energy for warming in winter and used firewood for heating and cooking. As civilisation progressed, they made use of wind and river streams for sailing boats and running grinding mills. The source and use of energy did not affect the relationship between mankind and the biosphere much.

Urbanization, industrialisation and changed lifestyles, however, have completely changed the energy consumption patterns of societies. The use of conventional sources of energy in the form of coal, natural gas and petroleum is continuing to rise at a fast rate. Their use has adversely affected all major components of the environment. At the same time, traditional sources of energy such as firewood and animal dung continue to be used as a major source of energy in developing countries, especially in rural areas. Cattle rearing, over-grazing and fodder requirement pose a big challenge to conservation of natural resources.

Over exploitation of natural resources for obtaining energy both in the developed and developing countries are thus causing great environmental concerns. The situation demands self-regulated control on the use of nonrenewable sources and greater exploration of non- conventional energy sources. There are positive indications that modern technology will very soon be able to make these expectations a reality.

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LIVING BEINGS (BIOTIC ENVIRONMENT)

Live your life as if you might die tomorrow but look after the earth as if you might live forever.

There exists an intimate and close interdependence and interrelationship between any living organism and other living organisms as well as abiotic factors such as air. water, soil and energy.

Green plants, for instance, produce their own food by using CO2 and water in the presence of sunlight (energy). They absorb minerals from the soil or water in which they grow. Thus for their own survival and growth, they depend upon CO2 (air), water soil and energy. In turn, they become the source of energy in the form of a food chain for other living beings. All animals. including man, either derive their food directly from plants (herbivores) or feed on other animals (carnivores) which consume plants or their products.

Animal and plant wastes in the form of excrete and dead remains are decomposed by micro-organisms to return the natural minerals and other elements back to soil and air, thus completing the mineral cycle in nature. Both plants and animals contribute to the maintenance of the ecological balance. On the one hand. man himself has protected and improved a variety of plants and animals in the process of serving his own needs. On the other hand. there are various human activities which are disturbing the balance in nature, some of the processes being even irreversible.

Large scale deforestation for meeting different needs. construction activities, building dams and reservoirs have not only eliminated the natural homes of many a plant and animal species but also damaged the abiotic environment.

Fifty per cent of the tropical species are likely to be lost within another 15 to 20 years at the current rate of destruction. As plants, animals and microorganisms die, it will have an unprecedented impact on agricultural and medical products. The decline of habitat will affect the ecosystem services such as purifying water. enriching soil, protecting watersheds, regulating temperature and biochemical cycle. The changes are likely to affect the biosphere adversely.

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HOW CAN WE PROTECT ENVIRONMENT ?

1. Minimising waste.

2. Keeping surroundings clean.

3. Planting and protecting trees.

4. Saving energy.

5. Saving water.

6. Protecting ponds and rivers.

7. Using public transport.

8. Using paper wisely.

9. Reusing containers.

10. Reading books on Earth and sharing information with others.

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