What is acid rain?

Motor vehicles and industrial activity release tons of pollutants into the air. When mixed together, the pollutants form sulfuric and nitric acids that later fall to the ground in rain or snow. This precipitation is known as acid rain. Acid rain is responsible for damaging lakes by killing plant and animal life and for killing trees around the world. Canada has been especially hard hit by acid rain caused by industrial activities in the United States.

Who first described the phenomenon of acid rain?

Scottish chemist Robert Angus Smith (1817-1884), who was very interested in water pollution and other issues regarding the environment and public health, conducted research in which he discovered, in 1852, that air pollution was causing acid rain. Smith also helped found the discipline of chemical climatology and was the author of the influential 1872 book Air and Rain.

Acid rain destroyed trees in the Bavarian Forest, but pollution controls are helping the forest to recover somewhat.

Acid rain destroyed trees in the Bavarian Forest, but pollution controls are helping the forest to recover somewhat.

What key event brought the issue of acid rain to prominence?

During the 1960s, fish began to die in Scandinavian lakes at an alarming rate. When investigated, it was found that the lake water had become so acidic as to be unlivable for many species. The source of the acid was European industrial emissions creating acid rain and snow. Further research found that lakes in the United States, Canada, and other nations were suffering the same fate.

What is the National Acid Precipitation Assessment Program (NAPAP)?

Initiated by the Acid Precipitation Act of 1980, the NAPAP studied acid deposition throughout the United States. After 10 years, the researchers reported to Congress that, while acid rain was a problem, the danger was not quite as severe as initially feared. About four percent of the lakes in the United States were deemed unacceptably acidic, and 25 percent of these lakes had acidic water due to natural causes (for example, decaying vegetation debris can raise water acidity levels).

How clean is rain water?

Rain water—at least, when it is not acid rain—is normally very pure, except for the small particle around which the raindrop originally formed. Once the raindrop hits the ground and is absorbed into the soil or evaporates, it leaves behind this nucleus, which is often formed from such matter as a dust spec or tiny grain of salt.

What is the difference between normal rain pH and acid rain pH?

The normal pH of rain water is 5.0 to 5.6, while acid rain has a pH of about 4.3 (compared to distilled water, with a neutral pH of 7.0). Natural rain water is slightly acidic because of dissolved carbon dioxide, which actually makes it similar to club soda without the bubbles. Under some conditions, such as after dust storms, rain can become more alkaline, and volcanoes can add sulfur to clouds and contribute to acid rain. One extreme example of the latter happened in 1783, when Iceland's Laki volcano erupted and spewed so much sulfur into the air that acid rain killed the island's crops and polluted the air over Europe.

Does rain come in any other colors or is it always clear?

Yes, rain showers have occurred consisting of yellow or even reddish droplets. This usually happens when dust storms have seeded clouds heavily with nuclei rich in iron or other minerals. Yellow rain has also been observed as the result of pollens entering into clouds and then being absorbed into raindrops.

What is eutrophication?

Eutrophication is the excessive build up of nutrients in lakes, ponds, and other water bodies as a result of river and stream runoff containing pollution from fertilizer, sewage, and other waste products. While more nutrients in the water might at first sound like a good thing, it actually has harmful side effects, such as algae blooms that deplete water of oxygen and kill off aquatic species and other wildlife. Factory farms and private residents who fertilize their lawns are major culprits of this type of pollution. If you live by a fresh water source, such as a pond or stream, you can lessen the negative effects of runoff by creating a natural plant barrier between your lawn and the water. Among the plants that make ideal buffers are willow trees, birch, green ash, red maples, buttonbush, spice bush, some dogwood species, water oak and pin, sycamore, and smooth alder. These and other plants absorb the excess nutrients while also preventing erosion.

What is a London killer fog?

Despite its history of air pollution dating back centuries, Londoners seemed slow to learn from their mistakes. Air pollution from coal burning continued into the 1960s. The sulfur dioxide combined with London's famous fog, with the result being acid fog. In 1952, the thick fog became so dense that people could not see to walk or drive. Influenza, bronchitis, and pneumonia cases skyrocketed, and about 4,000 people died and another 100,000 were sickened that year from illnesses related to this killer fog.

What is acid fog?

Acid fog is just like acid rain. When sulfur dioxide is present in the air, it can be captured by water vapors of all sorts, including fog. If this weren't bad enough, acid fog tends to be much more acidic than acid rain—up to 10 times as acidic! This acid

Farmland irrigation is responsible for redistributing vast amounts of water to the point that agriculture is affecting rain patterns.

Farmland irrigation is responsible for redistributing vast amounts of water to the point that agriculture is affecting rain patterns.

fog, which can linger in the air for hours or even days, can be as bad as walking through clouds of floating vinegar and is very destructive to plant life, as well as building materials ranging from iron to concrete.

How have dams affected the planet's water cycle in a significant way?

Currently, there are about 40,000 large dams (dams higher than 15 feet [5 meters]) in the world, with 19,000 of those being in China and about 5,500 in the United States. By erecting dams that block effectively 15 percent of the fresh water flow on the planet's surface, people have changed the Earth's water cycle significantly. Water cycle changes can, in turn, change such things as temperature and cloud formation. Naturally, the bigger the dam, and the reservoir created behind it, the greater the effect. China's Three Gorges Dam, located on the Yangtze River, is a huge dam that creates 20 times the kilowatts as America's famous Hoover Dam. The reservoir created by Three Gorges contains over 5 trillion gallons (19 trillion liters) of water and is over 400 square miles (1,036 square kilometers) in surface area. Scientists have observed that the climate around the dam has cooled and that rainfall has also changed.

Does irrigation of farmland affect the climate?

Extensive land irrigation can, indeed, affect the weather. As of 2000, the total amount of land on Earth that has been irrigated is about 689 million acres. About 60 percent of the world's fresh water supplies are used toward this purpose, representing 137 billion gallons (518.5 billion liters) of water daily. As one might imagine, when all of this water is spread over cropland, a certain amount of it will evaporate into the atmosphere. Hydrologists believe that this amount of evaporation is enough to increase the number of rainstorms that would otherwise occur.

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