Acid Rain: Causes, Consequences & Challenges

Table of Contents

Key Concept of Acid Rain

Acid rain refers to a precipitation (rain, snow, fog or dust) which contains higher levels of nitric and sulfuric acid.
Acid rain is caused by a chemical response that activates when composites similar to sulphur dioxide (SO2) and nitrogen oxides (NO) are not restricted into the air.
The term ‘Acid rain’ does not only include rainfalls but includes all forms of precipitation.
Acid rain occurs when sulphur dioxide and nitrogen oxides released in the atmosphere mixes with water vapor to form acidic compounds.
These elements can increase very high into the atmosphere, where they combine and react with water, oxygen, and added chemicals to form further acidic impurities, identified as acid rain.
Sulphur dioxide and nitrogen oxides dissolve effortlessly in water and can be passed faraway by the airstream. Thus, the two compounds are moveable in long expanses where they convert into the portion of the rain, hail, snow, and fog that we practice on convinced days.
Generally, the pH level of acid rain is between 4.2 to 4.4 (pH of 7 is neutral, below 7 is acidic and above 7 is alkaline) and in extreme cases, it can get much lower as well.

Causes of Acid Rain

Acid rain generally forms high in the clouds where sulphur dioxide and nitrogen oxides react with water, oxygen, and oxidants.
This combination creates a mild solution of sulfuric acid and nitric acid.
Sunlight upturns the rate of these reactions.
Rainwater, snow, fog, and other customs of precipitation comprising those mild solutions of sulfuric and nitric acids drop to earth as acid rain.

Sources of Acid Rain

Burning of fossil fuels (oil, coal and natural gas) in power plants and industries.
Vehicle emissions (use of fossil fuels)
Industrial activities (use of coal, metal smelters and oil refineries)
Volcanic eruptions
Decaying of vegetation
Wildfires
Residential cooking and heating using coal or wood

Chemical Reactions Involved

Sulfur Dioxide (SO2):

Nitrogen oxide (NO):

Monitoring and Assessment

Acid rain can be measured through various ways. It includes measuring through:

Rain collectors and pH scale/levels
Ion chromatography to detect sulphate and nitrate concentrations in rainwater
Remote sensing and satellite monitoring
Ecosystem surveys which measure the pH of the soil, checks forest health and aquatic biodiversity.

Examples of Acid Rain in Different Regions

The Adirondack Mountains and Appalachian region of United States experienced acid rain resulting in damage in its ecosystem
Scandinavian lakes suffered from extreme acidification in 1970s and 1980s
Acid rain increased in India and China due to massive industrialization and poor environmental regulations.
Some states of India have suffered critical acidification resulting in its adverse effect in human health and agriculture.

Types of Acid Deposition

1. Wet deposition: It includes rain, snow, fog or sleet.

2. Dry deposition: It includes the attachment of acidic gases and particles to the soil, vegetation and buildings. These attachments are later washed away by the rainfall, causing sudden drop in the pH levels of water.

Consequences of Acid Rain

Acid rain can alternate the structure of soil, creating them uninhabitable for local animals and plants.
It has been established to be very hard on trees. It deteriorates them through washing away the protecting film on leaves, and it stunts progression.
It can additionally worsen limestone and marble structures and monuments, like gravestones.
Acid rain degrades the quality and fertility of soil by removing the vital nutrients like calcium and magnesium.
It also fosters the effects of toxic metals like aluminium to inhibit the plant root growth.
It degrades the quality of lakes and streams thus making it difficult for fishes and other aquatic animals to survive.
Moreover, it destroys the overall aquatic ecosystems.
Pollutants like SO2 and NO can cause respiratory problems like asthma and bronchitis.
Presence of acid rain in the water bodies can also introduce toxic metals in the drinking water thus affecting human health severely.
g.: Historical monuments like Taj Mahal in India have suffered significant damage due to acid rain.

Preventive and Mitigation Measures

Lessen the amount of sulphur dioxide and oxides of nitrogen released into the atmosphere.
Practice cleaner fuels.
Flue Gas Desulphurisation (FGD): It removes SO2 from exhaust gases.
Practice other sources of electricity (i.e. nuclear power, hydro-electricity, wind energy, geothermal energy, and solar energy)
Decreasing the effects of acid rain through Liming.
Use of catalytic converters in vehicles.
Health education and awareness among the community people, industrial experts etc.
Cross-border regional and global cooperation to combat the consequences.
Use of green technologies in transport, energy and other sectors.

Challenges in Acid Rain Management

Rapid, uncontrolled and unplanned industrialization and urbanization
Increasing climate change and massive emission of Green House Gases (GHG)
Lack of strong political will and commitment to protect the environment.
Gaps in policy enforcement and maintaining law and order
Lack of strong EIA (Environment Impact Assessment) before approving major industrial projects
Lack of adequate coordination and cooperation between the government agencies, private agencies and other stakeholders