Bisosphere Introduction

Biosphere is the habitable part of earth and its atmosphere consists of both biotic and abiotic components. It extends s22.5 km in thickness from ocean bottom to mountain peaks. However, all parts are not equally occupied. Maximum density of organisms is found in tropical rain forests and coral reefs. Very few live in tundra, snow capped mountains, deserts, hot springs or ocean bottoms. Biosphere has three main sub-divisions:

1.Lithosphere.
It is the solid crust of earth comprising of rock and soil. It is 20 km n thickness. It contains minerals and is exploited for this.

2. Hydrosphere.
It is the liquid mantle of earth present in water bodies-ocean, sea, lakes, rivers etc,-oceans and sea occupy about 70% of total earth’s surface and have a high salinity. Inland water is normally fresh water.

3. Atmosphere.
It is the gaseous mantle that envelope the biosphere. Atmosphere contains-nitrogen (78.03%), oxygen (21%), argon (0.94%), CO₂ (0.03%), water vapour, dust particles etc. It is differentiated into four parts-troposphere, stratosphere, ozonosphere, ionosphere.