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Roger Weller, geology instructor

Acid Rain
by Victoria Frederico
Physical Geology
Fall 2015

                                                                   Acid Rain



What is acid rain?

     Acid rain is rainfall made sufficiently acidic by atmospheric pollution that it causes environmental harm, typically to forests and lakes. The main cause is the industrial burning of coal and other fossil fuels, the waste gases from which contain sulfur and nitrogen oxides, which combine with atmospheric water to form acids.




Where is acid rain most common?


            Acid rain is present in many places of the world. Places that are most significantly impacted around the globe include most of Eastern Europe, Eastern United States, and Southeastern Canada. Although these are the most effected, other places such as China and Taiwan are also effected greatly due to acid rain.



How does limestone and marble react to acid rain?

            Acid rain can effect many wild life, plant life, and minerals thought the entire world primarily in two ways: dissolution and alteration. In particular, with limestone and marble’s calcite get in contact with acid rain, the sulfur and nitric acids in polluted air reacts and the calcite dissolves. Structures such as buildings and statues start to form rough surfaces, minerals start to dissipate, and details are lost. Some blackened crusts can also from on some limestone and marble structures that are sheltered. This crust that peels off revealing a crumbled stone. The crust itself is composed of gypsum. This occurs when a mineral that forms from the reaction between calcite, water, and sulfuric acid. This gypsum is soluble in water and is usually washed away.


How are aquatic environments effected?

Impacts on lakes, streams, wetlands, and many other aquatic environments are greatly affected by acid rain. Acid rain makes waters extremely acidic and caused them to absorb the aluminum that makes its way from the soil to the lakes and streams. The average pH level of lakes should be 6.5. Acid rain, however, has cause many lakes in certain places to have a much lower pH level. The aluminum that is released into the soil ends up also ends up in the lakes. The increase in acid and aluminum can be deadly to aquatic wildlife. Many including rainbow trout, bass, frogs, salamanders, crayfish, and many more. During heavy down pours or rain or when snow falls then melts in the spring are known as episodic acidification. This can be a very devastating time for the creatures of aquatic wildlife.


How is the forest effected?

            Although acid rain does not kill trees directly, it weakens them by damaging their leaves, limiting the nutrients and exposing them to toxins substances slowly released from the soil. Trees can also be damaged by acid rain when forest in high mountain regions are exposed to more amount of acid than other forests because they are surrounded by acidic clouds and fog that are more acidic than the rainfall itself. Leaves that are frequently bathed in acidic fog, essential nutrients in their leaves are stripped away. The loss of the nutrients from these leaves makes trees more susceptible to damage by other factors in the environment, especially in the cold winder seasons.

            While on the surface of the forest floor, spring showers in the wash the leaves exposed. As leaves may fall or travel into streams, rivers, or lakes, the contaminated water soaks into the soil. The soil may or may not have the ability to neutralize some of the acidity of the rainwater. This is called buffering capacity. It depends on the thickness and composition of the soil, as well as the type of bedrock beneath the forest floor. A higher buffer capacity means that the soil can absorb more acid without a significant change in pH. Clay soils have higher buffer capacity than sandy soils, and a higher organic matter content tends to increase buffering capacity. Buffering capacity is important because it helps to the pH return to the suitable level. Changes in pH can affect plants in a many ways, especially by diminishing the nutrients in soil that are available to the plants and increasing unwanted minerals like aluminum.



How do we stop acid rain?

            Although some plants are changing the way they burn coal, the way to reduce acid rain is to produce energy without using fossil fuels. People can use renewable energy sources such as solar and wind power. To clean up the environment, we must clean up smokestacks and exhaust pipes. Most of the electricity that powers modern life comes from burning fossil fuels such as natural gas, oil, and coal. Acid rain is caused by pollutants that are released into the air when the fuels are burned. For reducing emissions, coal containing less sulfur, and washing coal could be a good contributor for reducing acid rain.

 Also using an alternate energy source will help the environment greatly. Nuclear power, hydropower, wind energy, geothermal energy, and solar energy are many alternatives that we can become more embracive on. All sources of energy have environmental costs and benefits. Some are more expensive than others, but can change the future and make the air and earth a much heathier environment.

With all the damage already caused by what we have done, we must also take the time and restore the world that was damaged. Acid rain penetrates deeply into the ecosystem, changing the soil and streams, these could be places where certain plants and animals can survive. Because of the change, it can take years for the ecosystem to recover, however there are some things that people can do to bring back lakes and streams quicker. Limestone, can be added to contaminated lakes to “cancel out” the acidity. This being called liming, has been used a great deal in Europe. This is once again an expensive process. It also does not solve the problems of changes in the soil chemistry and forest health. Liming will, however, promote fish life in the lake and allows the population to survive in places where the acid had once flourished.






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