Wednesday, November 6, 2013

Acid rain - Formation, Effects and Control measures

Acid rain

Normally rain water is slightly acidic due to the fact that CO2 present in the atmosphere gets dissolved in it. Because of the presence of Oxides of Nitrogen and Sulphur (NOx and SOx) as pollutants in the atmosphere, the pH of rain water is lowered further. This type of precipitation of water is called acid rain or acid deposition.

Formation of Acid Rain
Acid rain means the presence of excessive acids in rain water. Thermal power plants, industries and vehicles release nitrous oxide and sulphur dioxide into the atmosphere by burning of coal and oil. When these gases react with water vapour in the atmosphere, they form acids and descend on Earth as "acid rain" through rain water.
SOx   +   H2O   =    H2SO4
NOx   +  H2O    =   HNO3

Due to the drifting of these gases in the atmosphere by wind, their presence is felt as far as 2000 km away. Air pollution in one nation can cause acid rain in another nation.

Effects of Acid Rain

Effect of acid rain on human beings:
  1. Acid rain has been found to be very dangerous to living organisms as it can destroy life. Human nervous system, respiratory system and digestive system are affected by acid rain.
  2. It can also cause premature death from heart and lung disorders such as asthma and bronchitis
Effect of acid rain on buildings
  1. The 'Taj Mahal' in Agra is affected from the acid fumes being emitted from 'Mathura Refinery'. Crystals of CuSO4 and MgSO4 are formed as a result of corrosion due to acid rain.
  2. Acid rain corrodes houses, monuments, statues, bridges and fences.