Segments of Environment

Environment is divided in following segments:

1. Lithosphere

2. Hydrosphere

3. Atmosphere

4. Biosphere

(1) Lithosphere:

The lithosphere consists of upper mantle and the crust.
The crust is the earth's outer skin that is accessible to human.
The crust consists of rocks and soil of which the latter is the important part of lithosphere.

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.

(2) 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.) Only 1% of the total water supply is available as fresh water in the form of rivers, lakes, streams and ground water for human consumption and other uses.

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.

(3) 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.

The following points highlight the vital role played by atmosphere in the survival of life in this planet.

    • The atmosphere is the protective blanket of gases which is surrounding the earth. It protects the earth from the hostile environment of outer space.

    • It absorbs IR radiations emitted by the sun and reemitted from the earth and thus controls the temperature of the earth.

                 • It allows transmission of significant amounts of radiation only in the regions of 300 – 2500 nm (near UV, Visible, and near IR) and 0.01 – 40 meters (radio waves). i.e it filters tissue damaging UV radiation below 300 nm.

                • It acts as a source for CO2 for plant photosynthesis and O2 for respiration

                • It acts as a source for nitrogen for nitrogen fixing bacteria and ammonia producing plants.

                • The atmosphere transports water from ocean to land.

• 50% of the atmosphere by mass is below an altitude of 5.6 km (18,000 ft).
• 90% of the atmosphere by mass is below an altitude of 16 km (52,000 ft). The common altitude of commercial airliners is about 10 km (33,000 ft) and Mt. Everest's summit is 8,848 m (29,029 ft) above sea level.

 

(4) Biosphere:

        The biosphere refers to the realm of living organisms and their interactions with the environment (VIZ: atmosphere, hydrosphere and lithosphere)

•   The biosphere is very large and complex and is divided into smaller units called ecosystems.
•   Plants, animals and microorganisms which live in a definite zone along with physical factors such as soil, water and air constitute an ecosystem.
•   Within each ecosystems there are dynamic inter relationships between living forms and their physical environment 

The biosphere is the part of the earth in which life exists.

Biosphere is biological envelope that surrounds the globe, containing and able to support.

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.