Acid rain is a form of precipitation that contains high levels of sulfuric or nitric acids. In simple terms, acid rain is hail, rain, snow, or sleet that is more acidic than normal. Precipitation naturally is a little acidic but when the pH level drops below a set standard it is acid rain. In general, acid rain is a very complicated problem that is caused by many factors. In this paper, I will discuss how emissions caused by humans effect pH level in precipitation. First, I will define, in detail, what acid rain is.
Acid rain is precipitation that has a pH less than 5. 6. The pH scale is a scale that measures if a compound is acidic, basic, or neutral. Neutral is in the middle which has a pH of 7. Basic has a pH between 7. 1 and 14 and acidic has a pH between 6.
9 and 0. For example, vinegar is acidic with a pH reading of 2. 4. Normal precipitation has a pH between 6.
9 and 5. 9. Acid rain is formed when sulfur dioxide and various nitrogen oxides combine with atmospheric moisture. Sulfur dioxide is produced by the emissions of electric utilities, industrial companies, commercial and residential heating, smelters and diesel engines.
Sulfur dioxide produces sulfuric acid, which will produce acid rain. Nitrogen oxides are produced mostly by transportation (cars, trucks, planes, etc. ). Nitrogen oxides produce nitric acid, which will also produce acid rain. The main contributor to acid rain is sulfur oxides (SO 2 and SO 3). Sulfur oxides are produced naturally but not in the concentration that humans produce.
The burning of fossil fuels, such as coal, can be largely blamed for the production of sulfur oxides. The process of acid rain starts when photons from the sun hit ozone molecules (O 3) to form oxygen (O 2). Next, the O 2 molecules react with water (H 2 O) to form a negatively charged hydroxyl radicals (OH-). It is the hydroxyl radicals that are responsible for oxidizing sulfur dioxide. This will produce sulfuric acid.
Oxidation occurs in clouds mostly above cities with heavily polluted air. These clouds contain ammonia and ozone that can catalyze the reaction. This means that the ammonia and ozone will produce more sulfuric acid fast and the ammonia and ozone will not be consumed in the reaction. Nitrogen oxides are produce from power plants and exhaust fumes from automobiles. The reactions to make nitric acid are similar to the reactions to make sulfuric acid. Nitrogen oxides produce nitric acid.
Acid rain is very bad for the environment. When acid rain comes in contact with ponds, streams, rivers, and lakes, it produces harmful results. For example, when acid rain freezes to form snow, there is sulfuric and nitric acid in the snow. When the temperature changes and melts the snow, the acids in the snow are released into the ecosystem. The acid will follow the stream until it reaches a larger body of water. With the addition of the acid to the lake it will raise the pH of the water.
The ecosystem will not have time to adjust due to the extreme change. This can cause deformities in aquatic species during reproduction. The change in pH can also kill whole species. There are not to many solutions that we can do to stop acid rain. In my opinion, we need to avoid causing it. The governments of the world need to get together to make laws that regulate the amount of sulfur dioxide and nitrogen oxides that are polluting the air.
In 1980, Canada and United States signed a Memorandum of Intent. This is an attempt to have Canada and United States change the laws and regulations regarding pollution. Unfortunately, the attempts have been minimal. The United State government request more testing and studies while the Canadian government qualify acid rain as a minor problem. There is also several procedures to treating the problems that acid rain causes.
The acidity of lakes and streams can be reduced by adding lime or pulverized limestone. Lakes can buffer there own system to a certain degree naturally but sometimes we need to intervene when the acidic level is to low. For instance, we put lime into the lake. This is when a boat transports a liming agent and a person shoots a mixture of lime and water into the lake.
This technique is very effective because the lime is already dissolved in the solution and when it is put into the lake the limewater will diffuse more quickly. We can also release the liming agent from a helicopter or a land based hose. Streams are much harder to treat. One method is to have a turbine mix the stream water and the liming agent.
Then the neutralized water is released back into the stream. I think the only way to reduce acid rain is to recycle materials, carpool and reduce emissions. The hardest part will be reducing emissions. To keep the planet a its natural state we will need to reduce acid rain.
References 1. He ij, G. J. and J.
W. Eris man (Editors). Acid Rain research: Do we have enough answers? New York: Elsevier, 1995. 2.
The Columbia Encyclopedia, Edition 5, 1993 p 2553. Acid Rain 2000, "The Facts." (web).