ENVIRONMENTAL CHEMISTRY

ENVIRONMENTAL CHEMISTRY

AIR-

  • Air is a mixture of both elements and compounds.
  • It contains roughly 78%nitrogen, 21% oxygen, and smaller amounts of argon, hydrogen, carbon dioxide and others. 

 

  • The atmosphere that surrounds the earth is not of the same thickness at all heights.
  • There are concentric layers of air or regions and each layer has different density.

There are 5 layers of the atmosphere, namely

  • Troposphere
  • Stratosphere
  • Mesosphere
  • Thermosphere
  • Exosphere

Region 

Range 

Composition 

Role 

 

Troposphere 

The lowest region of atmosphere in which the human beings along with other organisms live is called troposphere

0-11 km

N2 , O2 , CO2 , H2O

Maintain heat balance

Stratosphere 

It contains much of the ozone in the atmosphere. 

The increase in temperature with height occurs 

By absorbing dangerous UV radiation, the ozone in the stratosphere protects us from skin cancer and other health damage

11-50 km

O3

Absorb UV radiation 

Mesosphere 

Here the temperature again decreases with height, reaching a minimum of about -90°C at the "mesopause".

50 – 85 km

O2+ , NO+

It does not propagate sound waves .

Thermosphere 

This is a region in which temperatures again increase with height. 

This temperature increase is caused by the absorption of energetic ultraviolet and X-Ray radiation from the sun.

This layer helps in the long-distance communication as the electrically charged gas particles present in the thermosphere reflect backs the radio waves from the Earth to space.

This layer also protects the earth from the huge meteors and satellites.

85-500 km

O2+ , NO+ , O+ , N+

In this region , ionization of gases occur