Puricare Industrial Enterprises: WHAT YOU NEED TO KNOW ABOUT ACID RAIN - Acid rain is made up of water droplets that are unusually acidic because of atmospheric pollution, most notably the excessive amounts of sulfur and nitrogen released by cars and industrial processes. Acid rain is also called acid deposition because this term includes other forms of acidic precipitation (such as snow). Acidic deposition occurs in two ways: wet and dry. Wet deposition is any form of precipitation that removes acids from the atmosphere and deposits them on Earth’s surface. Dry deposition polluting particles and gases stick to the ground via dust and smoke in the absence of precipitation. Even though dry, this form of deposition is dangerous as well, because precipitation can eventually wash pollutants into streams, lakes, and rivers. Acid deposition can be caused by natural sources such as volcanoes, but it is mainly caused by the release of sulfur dioxide and nitrogen oxide during fossil fuel combustion. When these gases are discharged into the atmosphere, they react with the water, oxygen, and other gases already present there to form sulfuric acid, ammonium nitrate, and nitric acid. These acids then disperse over large areas because of wind patterns and fall back to the ground as acid rain or other forms of precipitation. The gases most responsible for acid deposition are a byproduct of electric power generation and the burning of coal.

Large stand of trees killed by acid rain under a gray sky.

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What You Need to Know About Acid Rain

The Causes, History, and Effects of Acid Rain

By Amanda Briney

Acid rain is made up of water droplets that are unusually acidic because of atmospheric pollution, most notably the excessive amounts of sulfur and nitrogen released by cars and industrial processes.

Acid rain is also called acid deposition because this term includes other forms of acidic precipitation (such as snow).

Acidic deposition occurs in two ways: wet and dry.

Wet deposition is any form of precipitation that removes acids from the atmosphere and deposits them on Earth’s surface.

Dry deposition polluting particles and gases stick to the ground via dust and smoke in the absence of precipitation.

Even though dry, this form of deposition is dangerous as well, because precipitation can eventually wash pollutants into streams, lakes, and rivers.

Acidity itself is determined based on the pH level (the amount of acidity or alkalinity) of the water droplets.

The pH scale ranges from 0 to 14, with a lower pH being more acidic, while a high pH is alkaline, and seven is neutral.

Normal rainwater is slightly acidic, with a pH range of 5.3-6.0.

Acid deposition is anything below that range. It is also important to note that the pH scale is logarithmic, and each whole number on the scale represents a 10-fold change.

Today, acid deposition is present in the northeastern United States, southeastern Canada, and much of Europe, including portions of Sweden, Norway, and Germany.

In addition, parts of South Asia (particularly China, Sri Lanka, and southern India) and South Africa are all in danger of being affected by acid deposition in the future.

What Causes Acid Rain?

Acid deposition can be caused by natural sources such as volcanoes, but it is mainly caused by the release of sulfur dioxide and nitrogen oxide during fossil fuel combustion.

When these gases are discharged into the atmosphere, they react with the water, oxygen, and other gases already present there to form sulfuric acid, ammonium nitrate, and nitric acid.

These acids then disperse over large areas because of wind patterns and fall back to the ground as acid rain or other forms of precipitation.

The gases most responsible for acid deposition are a byproduct of electric power generation and the burning of coal.

As such, man-made acid deposition began becoming a significant issue during the Industrial Revolution and was first discovered by a Scottish chemist Robert Angus Smith in 1852.

In that year, he discovered the relationship between acid rain and atmospheric pollution in Manchester, England.

Although it was discovered in the 1800s, acid deposition did not gain significant public attention until the 1960s, and the term "acid rain" was coined in 1972.

Public attention further increased in the 1970s when the "New York Times" published reports about problems occurring in the Hubbard Brook Experimental Forest in New Hampshire.

Effects of Acid Rain

After studying the Hubbard Brook Forest and other areas, researchers found several important effects of acid deposition on both natural and man-made environments.

Aquatic settings are the most clearly affected by acid deposition, however, because acidic precipitation falls directly into them.

Both dry and wet deposition also runs off from forests, fields, and roads and flows into lakes, rivers, and streams.

As this acidic liquid flow into larger bodies of water, it is diluted.

However, over time, acids can accrue and lower the overall pH of the body of water.

Acid deposition also causes clay soils to release aluminum and magnesium, further lowering the pH in some areas.

If the pH of a lake drops below 4.8, its plants and animals risk death.

It is estimated that around 50,000 lakes in the United States and Canada have a pH below normal (about 5.3 for water).

Several hundred of these have a pH too low to support any aquatic life.

Aside from aquatic bodies, acid deposition can significantly affect forests.

As acid rain falls on trees, it can make them lose their leaves, damage their bark, and stunt their growth.

By damaging these parts of the tree, it makes them vulnerable to disease, extreme weather, and insects.

Acid falling on a forest’s soil is also harmful because it disrupts soil nutrients, kills microorganisms in the soil, and can sometimes cause a calcium deficiency.

Trees at high altitudes are also susceptible to problems induced by acidic cloud cover as the moisture in the clouds blankets them.

Damage to forests by acid rain is seen all over the world, but the most advanced cases are in Eastern Europe.

It’s estimated that in Germany and Poland, half of the forests are damaged, while 30 percent in Switzerland have been affected.

Finally, acid deposition also has an effect on architecture and art because of its ability to corrode certain materials.

As acid lands on buildings (especially those constructed with limestone), it reacts with minerals in the stones, sometimes causing them to disintegrate and wash away.

Acid deposition can also cause concrete to deteriorate, and it can corrode modern buildings, cars, railroad tracks, airplanes, steel bridges, and pipes above and below ground.

What's Being Done?

Because of these problems and the adverse effects of air pollution has on human health, a number of steps are being taken to reduce sulfur and nitrogen emissions.

Most notably, many governments are now requiring energy producers to clean smokestacks with scrubbers that trap pollutants before they are released into the atmosphere and to reduce car emissions with catalytic converters.

Additionally, alternative energy sources are gaining more prominence and funding is being put toward the restoration of ecosystems damaged by acid rain worldwide.

Amanda Briney

Geography Expert

Education

M.A., Geography, California State University - East Bay

B.A., English and Geography, California State University - Sacramento

Introduction

Professional geographer, writer, and scholar

Certificate of Advanced Study in Geographic Information Systems (GIS)

More than 10 years of experience writing about a broad array of geographical topics

Experience

Amanda Briney is a professional geographer and writer who contributed to ThoughtCo for more than 10 years. She wrote countless articles on a wide range of topics such as an introduction to the subject of geography, reviews of ecotourism, discussions about environmental determinism, and the structure of Latin American cities. The scope of her work also includes other formats such as histories, guides, and fact sheets about many parts of the world. An ultimate scholar, Amanda also contributes work to academic venues and the GIS Lounge, an informational portal about geography.

Amanda enjoys all aspects of geography and mapping but is especially interested in examining natural landscapes through spatial analysis. As such, she holds a certificate in Geographic Information Systems (GIS) from California State University. She also attended Diablo Valley College where she studied air photo interpretation and the formation of the Earth's landscapes.

Education

Amanda Briney received a Master Arts (M.A.) in Geography from California State University–East Bay. She also holds a Bachelor Arts (B.A.) in English and Geography from California State University–Sacramento and earned a Certificate of Advanced Study in Geographic Information Systems (GIS) from California State University.

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https://www.thoughtco.com/acid-rain-definition-1434936

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