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Acid Rain

Michael Forlini | Aug 1, 2008

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Acid rain is a broad term that refers to a mixture of wet and dry deposition (deposited material) from the atmosphere containing higher than normal amounts of nitric and sulfuric acids. Chemical forerunners, known as precursors, of acid rain formation result from both natural and man made sources. The sources can include volcanoes and decaying vegetation. However, the most significant source is the emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) from fossil fuel combustion. In the United States, roughly 2/3 of all SO2 and 1/4 of all NOx come from electric power generation that relies on burning fossil fuels, like coal. Acid rain is bonded together when these gases react in the atmosphere with water, oxygen, and other chemicals forming various acidic compounds. The result is a mild solution of sulfuric acid and nitric acid. Although these solutions are mild, constant exposure to these solutions results in degradation of exposed objects. Unfortunately, exposure is wide spread when SO2 and NOx are released from power plants and other sources. Prevailing winds blow these compounds across state and national borders, sometimes over hundreds of miles. Acid rain causes acidification of lakes and streams and contributes to the damage of trees at high elevations (for example, red spruce trees above 2,000 feet) and many sensitive forest soils. In addition, acid rain accelerates the decay of just about anything left exposed to the weather elements, including building materials and paints, irreplaceable buildings, statues and sculptures that are part of our nation's cultural heritage. Prior to falling to the earth, SO2 and NOx gases and their particulate matter derivatives—sulfates and nitrates—contribute to poor visibility and harm public health. More Information

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