Environment is divided in following segments:
(i) Lithosphere: Lithosphere is related with edaphic factor. The solid component of earth is known as lithosphere. Lithosphere means the mantle of rocks constituting the earth’s crust.
It includes the soil, which covers the rock crust.
Soil plays an important role as it provides food for man and animals.
Soil is usually defined as “any part of earth’s crust in which plants root.”
Muddy bottoms of ponds, ravines or glacial deposits, porous rock surface, bottoms of lakes peat etc., all are thus soil.
A typical productive soil contains approximately 95 per cent inorganic matter and 5 per cent organic matter. Organic matter in the soil provides food for microorganism. This matter includes amino sugars, organic sulphur, organic phosphate, and polysaccharides.
Soil contains silicate minerals, which includes nearly 74 per cent Silicon and Oxygen, common elements in the soil are 46.4 per cent Oxygen, Silicon 27.7 per cent, Aluminium 8.1 per cent, Iron 5.6 per cent, Calcium 3.6 per cent, Sodium 2.8 per cent, Potassium 2.6 per cent, Magnesium 2.1 per cent. In some soils, manganese oxide and titanium oxide are also available.
(ii) Hydrosphere: This includes all the surface and ground water resources such as oceans, seas, rivers, streams, lakes, reservoirs, glaciers, polar ice caps, ground water and water locked in rock and crevices and minerals laying deep below the earth’s crust.
1. Earth is called blue planet because 80 per cent of its surface is covered by water (97 per cent of the earth’s water resources is locked up in the oceans and seas, 2.4 per cent is trapped is giant glaciers and polar ice caps.)
2. Water is universal solvent.
3. Water is also the main medium by which chemical constituents are transported from one part of an ecosystem to others.
4. Water has high specific heat, latent heat and relatively high freezing point.
5. Surface water contains a lot of organic matter and mineral nutrients, which feed large bacteria population and algae.
(iii) Atmosphere: The gaseous envelope surrounding the earth is composed of an entire mass of air containing N2, 02, H20, C02 and inert gases is known as atmosphere.
1. Soil contains silicate minerals, which includes nearly 74 per cent Silicon.
2. The atmosphere is a reservoir of several elements essential to life and serves many purposes and functions.
3. The atmosphere is mobile, elastic, compressible and expansible.
4. Atmosphere serves many purposes and functions.
5. It absorbs most of the harmful radiations.
6. It maintains the heat balance of the earth.
7. Different cycles those are present in the atmosphere in the form of water cycle, carbon, oxygen, nitrogen cycle etc. related to the movement of matter been an organism and its environment.
8. Atmosphere can be divided into several layers on the basic of temperature variations. They are troposphere, stratosphere, mesosphere and thermosphere.
9. (iv) Biosphere: The biosphere is the part of the earth in which life exists.
10. Biosphere is biological envelope that surrounds the globe, containing and able to support.
11. It penetrates into and is dependent on the atmosphere, hydrosphere and lithosphere. This denotes the relating of living organism and their interactions with the environment. The biosphere is a relatively thin and incomplete envelope covering most of the world.
The basic approach to the study of man-environment relationship and the core of the environment is ecological analysis of spatial attributes of inter-relationship between technologically advanced man and natural environment of the earth in terms of ecosystem.
Thus, broadly speaking, environment may be defined as the study of spatial attributes of interrelationship between living organisms and the natural environment in general and technologically advanced ‘economic man and his natural environment in particular.
The definition of environmental science may be further broadened to make it more flexible so that it may very precisely reveal the scope of the subject.
Thus, environmental science may be defined as that which studies characteristics, composition and functions of different components of the natural environment-system (including man as a biological organism – a physical man), natural dependence of different components, various processes that link the components, the interactions of different components with each other and among themselves and consequent responses in spatial and temporal contexts in terms of geoecosystem, as well as interactions of technologically advanced economic men with different components of the natural geoecosystem and resultant modifications and changes in the natural geoecosystem, leading to environmental degradation and pollution, the techniques and strategies of pollution control measures and management of ecological resources.