III-Acid Rain

        While pure rain is naturally slightly acidic, the higher level of acidity in acid rain makes it a threat to plant and aquatic life and to some manmade materials and structures. The slight natural acidity of pure rain is the result of carbon dioxide in the air dissolving in water to produce a weak carbonic acid solution. This natural acid in rainfall and snowmelt is partly responsible for the long, slow weathering of soil and rocks.

    Acid rain, however, is the result of sulfur dioxide and nitrogen oxides entering the atmosphere. These two pollutants are mainly produced by human activities. Sulfur dioxide is most commonly produced by coal-fired power plants and factories, while nitrogen oxides are products of motor vehicles and off-road engines, coal-fired power plants and factories (such as pulp and paper mills in Wisconsin), and home furnaces.

    We can measure acidity with many ways and Chemists use a pH test that measures the concentration of hydrogen ions in a chemical solution to determine the solution's relative acidity or alkalinity. This test rates the solution's acidity/alkalinity on a scale from 0 to 14. A pH value of 1 is very acidic (like battery acid), while a pH value of 14 is very alkaline (like lye). A pH value of 7 is neutral, like distilled water. The pH scale is logarithmic, which means that pH 6 is 10 times more acid than pH 7, and pH 5 is 100 times more acid than pH 7.

    Rain uncontaminated by any pollutants has a pH of 5.0 to 6.0. Wisconsin Department of Natural Resources investigators consider rain with pH less than 5.0 to be "acid rain."

    And the acid rain health effects on human health results from exposure to acid aerosols inhaled from the surrounding air. Acid aerosols are mixtures of several different pollutants including particles (large and small), strong acids (e.g. sulfuric acid), weak acids and vapors (e.g. nitric acid). Long-term exposure to acid aerosols is known to damage lung tissue and contribute to the development of respiratory diseases such as asthma and chronic bronchitis, especially in children and the elderly.

    Acid deposition also has been connected to elevated mercury concentrations in fish and fish-eating wildlife such as the common loon, mink, otter, and eagles. Researchers believe that acidification of bodies of water increases the formation and movement of methylmercury--a toxic form of mercury--into the aquatic food chain. This also endangers the health of people--especially infants and children--who eat fish from affected lakes, as well as the health of fetuses carried by women who eat contaminated fish.

*Control Measures of Acid Rain

Electric utility plants account for about 70 percent of annual SO2 emissions and 30 percent of NOx emissions in the United States. Mobile sources (tranportation) also contribute significantly to NOx emissions. Overall, over 20 million tons of SO2 and NOx are emitted into

    As bad as northeastern U.S. looks, there are areas in the U.S. that have been reduced to moonscapes by the local ravages of acidic air pollution. Still, there is a place in our solar system that makes even these places look like paradise.

    Venus, with its run-away greenhouse warming, has a thick atmosphere of CO₂ and a surface temperature that approaches 460C. The planet is always shrouded in clouds, however, these clouds are not made of water but of concentrated sulfuric acid. On Venus, there is unrelenting acid rain.