- What is acid rain?
- Major sources of acid deposition
- Impacts of acid rain
- Areas – most sensitive to a rain
- Soil chemistry & its role
- How can soil acidity be increased?
- Acid rain a complex but natural phenomenon
Acid rain is polluted rain. The pollutants go up to the atmosphere and when it rains it brings the pollution down with it. Sulfur dioxide and nitrogen oxide are the gases that form the acid rain. When these gases mix with moisture it can make rain, snow, hail, or even fog. The scientific term for acid rain is acid deposition, which means when the acid is taken from the air and is deposited on the earth. Major industries, coal-burning factories, power plants and automobile engines are the main sources of sulfur dioxide and nitrogen oxide, which causes acid rain. Volcanoes and forest fires also cause sulphur dioxide and nitrogen oxide.
Some of the many problems that come from acid rain are the killing of many plants and underwater life in thousands of lakes and streams around the world. It strips forest soils of nutrients and damages farm crops. Acid rain can also corrode stone buildings, bridges, and priceless monuments. Acid rain can also be harmful to humans because acid rain kills the crops and fish we eat, ruins homes, and the acid can release lead in the pipes and the lead could go into our drinking water. It is hard to determine where acid rain may fall next, because the wind from a polluted area could carry pollution to another area and the acid rain could fall there.
The regions affected more by acid rain are large parts of eastern North America, Scandinavia, and central Europe. The soil in these places can not neutralize acid rain deposits, then the nutrients are stripped which means the crops in those places may not survive. In a lot of places acid rain isn’t a problem because some soils can neutralize the acid and it doesn’t affect the crops. Acid rain can damage and ruin soils by stripping the soil’s nutrients. But some soils can neutralize and weaken acid deposits that fall from the sky. These soils are called alkaline soil, also called a base. In 1838 the German chemist Justus von Liebig offered the first really useful definition of an acid, namely, a compound containing hydrogen that can react with a metal to produce hydrogen gas. Soil is formed when rocks are broken up by the weather and ‘erosion and mixed with organic matter from plants and animals. The term soil generally refers to the loose surface of the Earth, made from solid rock. To the farmer, soil is the natural medium for growth of all land plants. The rocks that make up soil could be acid, neutral, or alkaline another name for a base. Limestone and chalk are rocks that are formed from tiny shells that are rich in calcium. Alkaline is made up of calcium. When acid rain falls on alkaline soil the calcium makes the acid become weaker or neutralize. Farmers put lime (a very strong alkaline substance) and special fertilizers in there soil neutralize the acid in the soil on a regular daily basis.
In general, soil structure is classified as sandy, clay, or loam, although most garden soils are mixtures of the three in varying proportions. A sandy soil is very loose and will not hold water. A clay soil is dense and heavy, sticky when wet, and almost brick hard when dry. Loam is a mixture of sand and clay soils, but it also contains large quantities of humus, or decayed organic material, which loosens and aerates clay soil and binds sandy soil particles together. In addition, humus supplies plant nutrients. Then, soil structure can be improved by digging in compost, manure, peat moss, and other organic matter.
Many factors, including the soil chemistry and the type of rock determine the environment’s ability to neutralize the acid deposits from the rain. Soils naturally contain small amounts of poisonous minerals such as mercury, aluminium, and cadmium. Normally, these minerals do not cause serious problems, but as the acidity of the soil increases, chemical reactions allow the minerals to be absorbed by the plants. The plants are damaged and any animals that eat the plants will absorb the poisons, which will remain in the animals body and can hurt them or even kill them. The harmful minerals can also leach out of the soil into streams and lakes where they can kill fish and other types of living creatures.
The problem gets even bigger and bigger when pollution dumps more–minerals in the soil. For example, in some parts of Poland vegetable crops have been found to contain ten times more lead than is considered safe. Some plants need and require soil, and the farmers do not want lime to be put in there soil. If acid requiring plants, such as some types of shrubs, are put in alkaline Soil those plants are very likely to start to look yellow and very sickly very soon.
So acid rain is good for some plants in some places with alkaline soil because some of the plants want acid. Soils can be acid, alkaline, or neutral. The amounts of alkaline and acid in the soil influence the biological and chemical processes that take place in the soil. Highly alkaline or acid soils can harm many plants. Neutral soils can support most of the processes. Florida’s sandy soils are naturally acidic, but the soil is easily changed from acid to neutral or even a base (base is alkaline soil) by the small amounts of lime and calcium that come from tiny shells often found sandy beaches.
When acid rain falls from the sky it gets into the soil. The plants only have time to absorb and store the water when the soil is wet. Then the leftover water in the soil evaporates back into the sky where it becomes water vapour, forms into clouds, and gets ready to rain again. It is the same thing with acid rain. The acid doesn’t stay in the soil. The acid evaporates back into the sky.