Regional-Scale Pollution: What Causes Acid Rain and What are the Effects

 

Source: erika8213/elements.envato.com

Acid rain or acidification is the result of air pollution at a regional level. It is caused by a chemical reaction that begins when compounds like sulfur dioxide (SO2) and nitrogen dioxide (NO2) are released into the air. These compounds are released when we burn fossil fuels to generate electricity, manufacture cement, steel and copper, and drive our vehicles.

The wind can carry these substances very far and rise very high into the atmosphere, mixing and reacting with water, oxygen, and other chemicals. They dissolve very quickly in water and become part of the rain, snow, and fog we experience on certain days. 

Specifically, when sulfur dioxide (SO2) is diluted in water in the atmosphere, it forms acidic pollutants called sulphuric acid (H2SO4) and falls as acid rain. Similarly, nitrogen dioxide (NO2) forms nitric acid (HNO3).

Serious air pollution problem in Hong Kong City.
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The resulting acid rain is well known for its damage to aquatic biota. The acid rain leaches minerals from the soil, causing the release of heavy metals that harm microorganisms and affect the food chain. Many species of animals, fish, and other aquatic animals and plant life are sensitive to water acidity.

Acid rain also causes severe damage to buildings and structural materials of marble, limestone, etc. The Taj Mahal in India is an example of architecture damaged by acid rain. India is one of the world's most polluted countries. Acid rain has corroded the marble (calcium carbonate) of Taj Mahal, causing this incredible structure to turn yellow. Read here.