VII.Chapter1.Geo.Components of Environment

Chapter 1

Components of Environment
In its true sense can be defined as all that surrounds us.  Environment is our basic life support system.  It provides the air we breathe, the water we drink, the food we eat and the land where we live.  It also includes plants, animals and a large variety of man - made things which are necessary for our living.  Thus, environment has both natural and man - made elements.  The natural environment can be further bifurcated into two groups, i.e.  the Physical environment and the Biological environment.  The Physical environment includes all non - living things like land, water and air.  The Biological environment includes all living things, Our environment, We care such as plants and animals.  Man is the most important component of the biological environment who satisfies all the required needs from both parts (groups) of the environment.  The two components of the natural environment, that is the physical and the biological, are largely interdependent and cannot be separated.  Any major change in the physical environment is bound to bring a change in the accompanying biological environment.  The change can be sudden or gradual.  For example, the development of soil takes years together and cannot be visualized through our senses.  On the other hand, some changes are very sudden, like the changes brought about by the incident of an earthquake or volcano, etc.  FOUR SPHERES OF ENVIRONMENT Air Water The natural environment can be broadly divided into four spheres, i.e.  Lithosphere, Atmosphere, Hydrosphere and Biosphere.  Each of these is unique in its own way and supports others in sustaining life forms on our planet called the Mother Earth.  Let us understand the importance of each sphere of the natural environment.  Lithosphere The literal meaning of lithosphere is the 'sphere of rocks'.  The earth's solid layer is called lithosphere.  Land Life Four spheres of environment 1

The lithosphere is about 100 km in thickness.  The uppermost part of the lithosphere is composed of rocks rich in silica and aluminum called sial.  Below the sial layer, the rocks are mainly rich in silica and magnesium and are called sima, which is generally found below the bottom of the ocean basins.  Thus, lithosphere is that part of the earth which provides us land over which we live.  It provides soil for the plants and is also a source of all the mineral wealth.  Atmosphere The literal meaning of 'atmosphere' is the 'sphere of air'.  The atmosphere is composed of a mixture of gases which forms an envelope around the earth.  It is a gaseous envelope extending about 1,600 km above the earth's surface of the total mass of the atmosphere, 99 per cent exists within 32 km of height from the earth's surface.  Among the four major elements of environment, atmosphere is the most dynamic in nature where changes occur not only from one season to another but also within a short period of time say, a few hours.  These sudden changes produce changes in atmospheric conditions which affect our life both directly and indirectly.  Hydrosphere Hydrosphere refers to the 'sphere of water' which is present in oceans, rivers, lakes and other water bodies on the earth's surface.  The planet earth is often called the Water Planet or the Blue Planet because of abundance of water on its surface.  The water bodies that include rivers, lakes, seas and oceans cover 71 per cent of the earth's surface.  The distribution of water is not uniform in both the Northern and the Southern Hemispheres.  It is the sea estimated that 43 per cent of the total area covered by water in the Northern Hemisphere whereas the remaining 57 per cent lies in the Southern Hemisphere.  Oceans hold 96.5 per cent water on the earth.  Rest of the water is available in the form of ice, water vapours, underground water, rivers and lakes.  MURO ​​Biosphere The word 'biosphere' literally means the 'sphere of life'.  Biosphere is the narrow zone of contact between all the other three spheres of environment where all kinds of life exist.  Most of the living organisms like plants, animals and microbes present on the earth are found on or near the earth's surface of the land, water and air.  Human beings are an important part of the biosphere.  They are capable of changing it.  2 Biosphere

The earth is full of diversities.  There is diversity in land, soil, plants and animals.  This process of diversification has occurred largely over long period of time resulting in the emergence of new species of plants and animals.  These changes create biodiversity on the earth.  The Government of India has passed the Wildlife Protection Act in 1972 to protect and conserve this biodiversity.  Under this Act poaching and hunting are prohibited.  Violation of this Act is a punishable crime under law.  It is not only the duty of the government to protect and preserve wildlife but all of us are responsible.  Do you know?  Some critically endangered species of animals in India are Forest Owlet, Ganges Shark, Tiger Toad, Flying Frog, Leatherback Turtle, etc.  Presently, there are 102 National Parks and 515 Wildlife Sanctuaries in India.  Human beings, as an important part of the environment, are well - equipped to exploit, consume or use different plant and animal species existing on the earth's surface.  It is the need of the present times that we should live in harmony with our surroundings.  This will allow the earth to sustain all forms of life on it and to produce newer ones in the course of time.  Keywords biodiversity: it is a variety of life on earth comprising of plants, animals and micro-organisms.  microbes: very small organisms national park a well demarcated reserved area for the protection of wildlife.  It does not allow any human activity ocean: vast expense of saline water on the earth's surface.  wildlife sanctuary: a geographical area meant for the conservation of biodiversity.  Limited human activities are permitted