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Acidic Destruction Sitting in your room late at night, you listen to the gentle pitter-patter of the rain on your window. It is so soothing and relaxing. Have you ever wondered what the rain is really made of? Is that simply water or is it acid slowly streaming down out there? That rain you hear might be acid rain, which is caused by sulfur-dioxide emissions and shown to be harmful to plants, animals, humans, and even buildings and structures. The commonly used terms “acid rain” and “acid precipitation” describe specific forms of a type of pollution described generally as “acid deposition.” Harmful gases that rise into the air mix with cloud moisture, sunlight, and oxidants. There they chemically combine into dilute sulfuric and nitric acids, which fall back to the earth. This is acid deposition. The major contributing pollutants are sulfur dioxide and nitrogen oxide (Morgan, 5). “Acid rain” is basically rainwater with a pH level lower than 5.6 (Morgan, 3). The term pH means “potential hydrogen”. When a substance has a pH level of 7, it is completely neutral with the same number of hydroxyl and hydrogen ions (Pringle, 6). Acidity in the atmosphere can be changed by many natural things. When a volcano erupts, sulfur dioxide is spewed out. Droughts produce unusually dry soil conditions allowing dust particles to be carried upward into the air, neutralizing the acids that may be present at the time (Pringle, 4). Acid rain can come in concentrations sometimes more acidic than lemon juice. These pollutants reach the earth in rain, snow, hail, sleet, or fog. The rain at the beginning of a shower is usually more acidic than the rain that follows. Dry acidic particles can also fall from the atmosphere. Because wind can carry gases and moisture for hundreds of miles, even areas far away from the source bear the effects of acid deposition (Durham, 10). There are of course, many things that we as humans do everyday to promote and support the continuation of acid rain. When the fossil fuel, coal, is used, the sulfur in it mixes with oxygen in the air to form sulfur dioxide. The sulfur dioxide is eventually turned into acid over a matter of days. Coal-fired power plants are the single greatest cause of acid rain in the United States. They account for two-thirds of all sulfur dioxide emissions in the US (Pringle 16; Morgan 75). In the mid-1980’s, the United States alone discharged about 26 million tons of sulfur dioxide (Bennet). For decades, the highest source for sulfur dioxide emissions was the huge Inco, Ltd., a copper and nickel smelter in Sudbury Ontario.
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