Domains of the Environment

There are four domains in the Environment, the atmosphere, lithosphere, hydrosphere and biosphere. The Venn diagram in the “Lesson: The Earth’s Crust (in Week 6), Topic: The Outer Zone of the Earth” shows how these four domains are related.

The four main domains of the environment are:

1. Lithosphere
2. Atmosphere
3. Hydrosphere
4. Biosphere

The Lithosphere:

This is the rigid, outermost layer of the Earth’s rocks and minerals, it consists of the crust and upper mantle. It is the solid portion of the Earth and consists of rocks and minerals.

The Atmosphere:

The Atmosphere is a mixture of gases with different characteristics and proportions. Most of the atmosphere exists close to the Earth’s surface with 99% of the atmosphere lying within 30 km from the Earth’s surface. The atmosphere is not just oxygen, it also contains water vapour and other gases. The atmosphere consists of four main zones which are differentiated based on their temperature, distance from the Earth’s surface and other characteristics. They are; the troposphere, the stratosphere, the mesosphere and the thermosphere (or ionosphere). 

Hydrosphere:

The Hydrosphere is the liquid portion of the Earth, it consists of all water bodies from oceans, seas, rivers, streams, lakes, lagoons etc. About 70% of the earth’s surface is occupied by water bodies.

Biosphere:

The Biosphere is the portion of the Earth where all life exists. The Biosphere includes all living things found in the lithosphere, atmosphere and hydrosphere. These living things include animals, man, plants and minute organisms such as fungi and bacteria.