Wet deposition is what we most commonly think of as acid rain. The sulfuric and nitric acids formed in the atmosphere fall to the ground mixed with rain, snow, fog, or hail. Acidic particles and gases can also deposit from the atmosphere in the absence of moisture as dry deposition. The acidic particles and gases may deposit to surfaces water bodies, vegetation, buildings quickly or may react during atmospheric transport to form larger particles that can be harmful to human health.
When the accumulated acids are washed off a surface by the next rain, this acidic water flows over and through the ground, and can harm plants and wildlife, such as insects and fish.
The amount of acidity in the atmosphere that deposits to earth through dry deposition depends on the amount of rainfall an area receives. For example, in desert areas the ratio of dry to wet deposition is higher than an area that receives several inches of rain each year.
Unlike wet deposition, dry deposition is difficult and expensive to measure. When acid deposition is washed into lakes and streams, it can cause some to turn acidic. A person can see dark smoke pour from the exhaust pipes of large trucks or factories, for example.
More often, however, air pollution is invisible. Polluted air can be dangerous, even if the pollutants are invisible. It can also increase the risk of lung cancer. Sometimes, air pollution kills quickly. In , an accident at a pesticide plant in Bhopal, India, released a deadly gas into the air. At least 8, people died within days. Hundreds of thousands more were permanently injured. Natural disaster s can also cause air pollution to increase quickly. When volcano es erupt , they eject volcanic ash and gases into the atmosphere.
Volcanic ash can discolor the sky for months. After the eruption of the Indonesian volcano of Krakatoa in , ash darkened the sky around the world.
The dimmer sky caused fewer crop s to be harvested as far away as Europe and North America. Volcanic gas es, such as sulfur dioxide , can kill nearby residents and make the soil infertile for years. Mount Vesuvius, a volcano in Italy, famously erupted in 79, killing hundreds of residents of the nearby towns of Pompeii and Herculaneum.
Most victims of Vesuvius were not killed by lava or landslide s caused by the eruption. They were choked, or asphyxiate d, by deadly volcanic gases. In , a toxic cloud developed over Lake Nyos, Cameroon. Lake Nyos sits in the crater of a volcano. Though the volcano did not erupt, it did eject volcanic gases into the lake.
The heated gases passed through the water of the lake and collected as a cloud that descend ed the slopes of the volcano and into nearby valleys. As the toxic cloud moved across the landscape, it killed birds and other organisms in their natural habitat. This air pollution also killed thousands of cattle and as many as 1, people. Most air pollution is not natural, however. It comes from burning fossil fuel s—coal, oil , and natural gas. When gasoline is burned to power cars and trucks, it produces carbon monoxide , a colorless, odorless gas.
The gas is harmful in high concentration s, or amounts. City traffic produces highly concentrated carbon monoxide. Cars and factories produce other common pollutants, including nitrogen oxide , sulfur dioxide, and hydrocarbon s.
These chemicals react with sunlight to produce smog , a thick fog or haze of air pollution. The smog is so thick in Linfen, China, that people can seldom see the sun. Smog can be brown or grayish blue, depending on which pollutants are in it.
Smog makes breathing difficult, especially for children and older adults. Some cities that suffer from extreme smog issue air pollution warnings. The government of Hong Kong, for example, will warn people not to go outside or engage in strenuous physical activity such as running or swimming when smog is very thick. When air pollutants such as nitrogen oxide and sulfur dioxide mix with moisture, they change into acid s.
They then fall back to earth as acid rain. Wind often carries acid rain far from the pollution source. Pollutants produced by factories and power plants in Spain can fall as acid rain in Norway.
Acid rain can kill all the trees in a forest. It can also devastate lake s, stream s, and other waterways. Acid rain also wears away marble and other kinds of stone. It has erased the words on gravestone s and damaged many historic buildings and monument s.
The Taj Mahal , in Agra, India, was once gleaming white. Years of exposure to acid rain has left it pale. Governments have tried to prevent acid rain by limiting the amount of pollutants released into the air. In Europe and North America, they have had some success, but acid rain remains a major problem in the developing world , especially Asia. Greenhouse gas es are another source of air pollution. Greenhouse gases such as carbon dioxide and methane occur naturally in the atmosphere.
In fact, they are necessary for life on Earth. They absorb sunlight reflected from Earth, preventing it from escaping into space. By trapping heat in the atmosphere, they keep Earth warm enough for people to live. This is called the greenhouse effect. But human activities such as burning fossil fuels and destroying forests have increased the amount of greenhouse gases in the atmosphere.
This has increased the greenhouse effect, and average temperature s across the globe are rising. The decade that began in the year was the warmest on record. This increase in worldwide average temperatures, caused in part by human activity, is called global warming. Global warming is causing ice sheets and glacier s to melt. The melting ice is causing sea level s to rise at a rate of 2 millimeters 0. The rising seas will eventually flood low-lying coast al regions.
Entire nation s, such as the island s of Maldives, are threatened by this climate change. Global warming also contributes to the phenomenon of ocean acidification.
Ocean acidification is the process of ocean waters absorbing more carbon dioxide from the atmosphere. Fewer organisms can survive in warmer, less salty waters. The ocean food web is threatened as plants and animals such as coral fail to adapt to more acidic oceans. Scientists have predicted that global warming will cause an increase in severe storm s. It will also cause more drought s in some region s and more flooding in others.
The change in average temperatures is already shrinking some habitats, the regions where plants and animals naturally live. Polar bears hunt seals from sea ice in the Arctic. The melting ice is forcing polar bears to travel farther to find food, and their numbers are shrinking. People and governments can respond quickly and effectively to reduce air pollution. Chemicals called chlorofluorocarbons CFCs are a dangerous form of air pollution that governments worked to reduce in the s and s.
CFCs are found in gases that cool refrigerators, in foam products, and in aerosol can s. When people are exposed to more ultraviolet radiation, they are more likely to develop skin cancer, eye diseases, and other illnesses.
In the s, scientists noticed that the ozone layer over Antarctica was thinning. But Australia, the home of more than 22 million people, lies at the edge of the hole. In the s, the Australian government began an effort to warn people of the dangers of too much sun. Water Pollution Some polluted water looks muddy, smells bad, and has garbage floating in it. Polluted water is unsafe for drinking and swimming. Some people who drink polluted water are exposed to hazardous chemicals that may make them sick years later.
Others consume bacteria and other tiny aquatic organisms that cause disease. The United Nations estimates that 4, children die every day from drinking dirty water.
Sometimes, polluted water harms people indirectly. They get sick because the fish that live in polluted water are unsafe to eat. They have too many pollutants in their flesh. There are some natural sources of water pollution.
Oil and natural gas, for example, can leak into oceans and lakes from natural underground sources. These sites are called petroleum seep s. The Coal Oil Point Seep releases so much oil that tar ball s wash up on nearby beaches. Tar balls are small, sticky pieces of pollution that eventually decompose in the ocean.
Human activity also contributes to water pollution. Chemicals and oils from factories are sometimes dumped or seep into waterways. These chemicals are called runoff. Chemicals in runoff can create a toxic environment for aquatic life.
Runoff can also help create a fertile environment for cyanobacteria , also called blue-green algae. Cyanobacteria reproduce rapidly, creating a harmful algal bloom HAB. Harmful algal blooms prevent organisms such as plants and fish from living in the ocean. Mining and drilling can also contribute to water pollution. Acid mine drainage AMD is a major contributor to pollution of rivers and streams near coal mines.
Acid helps miners remove coal from the surrounding rocks. The acid is washed into streams and rivers, where it reacts with rock s and sand.
It releases chemical sulfur from the rocks and sand, creating a river rich in sulfuric acid. Sulfuric acid is toxic to plants, fish, and other aquatic organisms. Sulfuric acid is also toxic to people, making rivers polluted by AMD dangerous sources of water for drinking and hygiene. Oil spill s are another source of water pollution. In April , the Deepwater Horizon oil rig exploded in the Gulf of Mexico, causing oil to gush from the ocean floor. In the following months, hundreds of millions of gallons of oil spewed into the gulf waters.
The spill produced large plume s of oil under the sea and an oil slick on the surface as large as 24, square kilometers 9, square miles. The oil slick coated wetland s in the U.
Birds, such as pelicans, became coated in oil and were unable to fly or access food. More than 2 million animals died as a result of the Deepwater Horizon oil spill. Buried chemical waste can also pollute water supplies.
For many years, people dispose d of chemical wastes carelessly, not realizing its dangers. In the s, people living in the Love Canal area in Niagara Falls, New York, suffered from extremely high rates of cancer and birth defect s.
In , families living in Love Canal had to abandon their homes. If not disposed of properly, radioactive waste from nuclear power plants can escape into the environment. Radioactive waste can harm living things and pollute the water.
Sewage that has not been properly treated is a common source of water pollution. Many cities around the world have poor sewage systems and sewage treatment plants.
Forgot password? You could not be signed in, please check and try again. Sign in with your library card Please enter your library card number. Introduction 2. Sewage collection and treatment 3. Eutrophication 4. Pollution from farming 5.
Fish farming 6. Tip drainage 7. Mine-water pollution 8. Acid Rain 9. Air pollution Global warming Biological indicators of the quality of the environment Measuring the quality of the environment Postscript Appendix Useful addresses Index.
Acid Rain Acid Rain Chapter: p.
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