Explain the causes and impact of acid rain. How can acid rain be controlled?

Causes of Acid Rain:

Acid rain means rainfall with a pH of less than 5.6. The main compounds that lead to acid rain are:

1. Oxides of Sulphur — About 80% of oxides of sulphur come from burning of fossil fuels in industries and power plants. Sulphur trioxide reacts with water to form sulphuric acid (H₂SO₄), which is the principal (60-70%) cause of acid rain.

2. Nitrogen Compounds — Nitrogen oxides are released by vehicles and industries, forming nitric acid in the atmosphere.

3. Chlorine and Hydrochloric Acid — Industrial emissions also release these acid-forming substances.

4. Natural Causes — Chemicals contributing to acid rain are also produced by lightning, volcanic activities and forest fires.

Impact of Acid Rain:

1. Impact on Buildings and Monuments — Acid rain is corrosive and corrodes buildings, monuments, metals and rock structures. Structures containing limestone or marble are particularly affected.

2. Impact on Human Health — Acid causes irritation in eyes and skin, reduces visibility and causes respiratory disorders. It may lead to bronchitis and lung cancer.

3. Impact on Wildlife — Acid buildup in lakes disrupts the reproduction of aquatic animals. It causes loss of food and habitat for wildlife.

4. Impact on Trees — Acids damage or destroy plants by reducing soil fertility, damaging leaves and causing loss of sensitive plants.

5. Impact on Microorganisms — Long-term acid rain causes shifts in microorganism communities. Useful microorganisms in soil may be replaced by disease-causing fungi.

Control of Acid Rain:

1. Reduce burning of fossil fuels by promoting renewable energy sources.
2. Use scrubbers and filters in industries to reduce sulphur dioxide and nitrogen oxide emissions.
3. Use cleaner fuels like CNG in vehicles in place of petrol and diesel.
4. Promote use of electric vehicles to reduce vehicular emissions.
5. Implement strict government regulations on industrial emissions.
6. Plant more trees to absorb pollutants and CO₂.