Components or segments of environment are given below:
1. Atmosphere - the sphere of air.
2. Hydrosphere - the sphere of water.
3. Lithosphere - the sphere of soil, rock, etc.
4. Biosphere - the sphere of living organisms.
The thick, gaseous cover of air surrounding the earth is called atmosphere. It sustains life on earth by removing harmful cosmic and ultraviolet rays through absorption, maintaining heat balance, providing oxygen for respiration and carbon dioxide for photosynthesis.
On the basis of temperature gradients, the atmosphere can be segmented as follows:
Approximately 70 per cent of the earth's surface is made up of water and constitutes the hydrosphere. The water resources include oceans, seas, rivers, lakes, streams, ponds, glaciers, polar ice caps and ground water.
Of this, about 97 per cent of the water is salty and is present in oceans and seas, 2 per cent is present as ice caps and the remaining 1 per cent as fresh water which we use variously.
Water near the poles is very cold and freezes to form polar ice caps, glaciers or icebergs. However, at the equator water evaporates into gas due to high temperature.
The frozen water in its own sphere is known as 'cryosphere'. Water is very essential for life and it is believed that the first signs of life were found in water.
Lithosphere (Land) :
Lithosphere is the solid component of earth. It consists of three layers: crust, mantle and core. Generally speaking, lithosphere means the hard surface (crust) of earth and not the entire inside of the planet.
The uppermost part of the solid earth, consisting of weathered rocks, minerals and organic matters together, is known as soil.
Land is very important for use in agriculture, industrialization, transportation, recreation, etc. The interior of the lithosphere consists of mantle followed by core.
It is that part of earth where living (biotic) organisms exist and interact with one another and also with the non-living (abiotic) components. The living organisms include all of the micro-organisms, plants and animals.
Biosphere reaches well into the other three spheres, although there are no permanent inhabitants in the atmosphere.
Relative to the volume of the earth, the biosphere constitutes only a very thin surface layer, which extends from 11,000 meters below sea level to 15,000 meters above it.
In general, biosphere includes most of the hydrosphere as well as parts of lower atmosphere and upper lithosphere.
The biosphere contains large quantities of elements such as carbon, nitrogen and oxygen. Other essential elements like phosphorus, calcium and potassium are present in smaller amounts.
Bulk of the functioning in the eco-system is based on the input of solar energy and there is continual recycling of materials at the ecosystem and biosphere levels.
For example, green plants use carbon dioxide for photosynthesis and release oxygen into the atmosphere, which is then inhaled by the animals for respiration who in return release carbon dioxide.
In the biosphere, there exist interactions among the organisms. When an organism interacts with members of its own kind, it is an intra-specific interaction like colonization and then aggregation, etc.
On the other hand, interaction between different species is known as inter-specific interaction like neutralism, competition and prey-predator relationships.
The interactions may be harmful or beneficial to the participants but are very important for the survival, growth, reproduction and continuance of the species.