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Causes of Acid Rain

Acid deposition can occur via natural sources like 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 oxides of nitrogen, or NOx, and sulfur dioxide, or SO2, are the two main

sources of acid rain. Sulfur dioxide, which is a colorless gas, is given off as a by-product

when fossil fuels that contain sulfur are burned. This gas is produced due to various

industrial processes, like the processing of crude oil, utility factories, and iron and steel

factories. Natural means and disaster can also result in sulfur dioxide being released intothe atmosphere, such as rotting vegetation, plankton, sea spray, and volcanoes, all of

which emit about 10% sulfur dioxide.

The principal cause of acid rain is sulfur and nitrogen compounds from human

sources, such as electricity generation, factories, and motor vehicles. Coal power plants

are one of the most polluting. The gases can be carried hundreds of kilometers in the

atmosphere before they are converted to acids and deposited. In the past, factories had

short funnels to let out smoke but this caused many problems locally; thus, factories now

have taller smoke funnels. However, dispersal from these taller stacks causes pollutants

to be carried farther, causing widespread ecological damage.

For many years, there was considerable debate and disagreement over what caused

acid rain. Recent scientific work, however, has helped to clarify this

The primary causes of acid rain are sulfur dioxide and nitrogen oxides. These

chemicals are released by certain industrial processes, and as a result, the more

industrialized nations ofEurope as well as the US suffer severely from acid rain.

Most sulfur dioxide comes from power plants that use coal as their fuel. These plants

emit 100 million tons of sulfur dioxide, 70% of that in the world.

Automobiles produce about half of the world's nitrogen oxide. As the number of

automobiles in use increases, so does the amount of acid rain. Power plants that

burn fossil fuels also contribute significantly to nitrogen oxide emission.

Though human causes are primarily responsible for acid rain, natural causes exist as

well. Fires, volcanic eruptions, bacterial decomposition, and lightening also greatly

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increase the amount of nitrogen oxide on the planet. However, even the gigantic

explosion of Mt. St. Helens released only about what one coal power plant emits in a

year.

Once the tiny pollutant molecules have entered the atmosphere, they can travel for

thousands of miles. Eventually, the particles will combine with other compounds toproduce new, often harmful, chemicals.

Acid rain comes down to the earth in the form of rain, snow, hail, fog, frost, or dew.

Once it reaches the ground, the acidity in the substance can harm and even destroy

both natural ecosystems and man-made products, such as car finishes.

Effects of Acid Rain

On Surface Waters and Aquatic Animals: The ecological effects of acid rain aremost clearly seen in the aquatic, or water, environments, such as streams, lakes,

and marshes. Acid rain flows into streams, lakes, and marshes after falling on

forests, fields, buildings, and roads. Acid rain also falls directly on aquatic

habitats. It causes a cascade of effects that harm or kill individual fish, reduce fish

population numbers, completely eliminate fish species from a water body, and

decrease biodiversity.

On plant life:Acid rain seeps into the earth and poisons plants and trees bydissolving toxic substances in the soil, such as aluminum, which get absorbed by

the roots. This rain also dissolves the beneficial minerals and nutrients in the soil,which are then washed away before the plants and trees have a chance of using

them in order to grow.

When there is frequent acid rain, it corrodes the waxy protective coating of the

leaves. When this protective coating on the leaves is lost, it results in making the

plant susceptible to disease. When the leaves are damaged, the plant loses its

ability to produce sufficient amounts of nutrition for it to stay healthy. Once

weakened, the plant becomes vulnerable to the cold weather, insects, and disease,

which can lead to its death.

On man-made objects:Apart from causing harm to natural ecosystems, acid rainalso damages man-made structures and materials. For example, acid rain dissolves

sandstone, limestone, and marble. It also corrodes ceramic, textiles, paints, and

metals. Rubber and leather deteriorate if exposed to acid rain. Stone monuments

and carvings begin losing their features when exposed to this contaminated rain.

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On humans:Most of all, acid rain affects human health adversely. It has the abilityof harming us via the atmosphere as well as the soil where the food we eat is

grown. Acid rain results in toxic metals breaking loose from the chemical

compounds they occur in naturally. While toxic metals may be dangerous, but as

long as they exist in combination with other elements, they are not harmful. Once

rain causes these toxic metals to be released they can infiltrate into the drinkingwater, and the animals or crops that humans use as sources of food. This

contaminated food can damage the nerves in children, or result in severe brain

damage, or even death. Scientists suspect that aluminum, one of the toxic metals

affected by acid rain, is associated with Alzheimer's disease.

Another adverse health effect on humans is the respiratory problems it causes. The

emissions of nitrogen oxide and sulfur dioxide cause respiratory problems like

throat, nose and eye irritation; headache; asthma; and dry coughs. Acid rain is

particularly harmful for those who have difficulty in breathing or suffer from

asthma. In fact, even the lungs of healthy people can be damaged by the pollutantsin acid air.