Acid Rain - Best Information Water

Best Information - Acid Rain or acid deposition,form of precipitation (rain, snow, sleet, or hail) containing high levels of sulfuric or nitric acids (pH below 5.5–5.6). Produced when sulfur dioxide and various nitrogen oxides combine with atmospheric moisture, acid rain can contaminate drinking water, damage vegetation and aquatic life, and erode buildings and monuments.

Automobile exhausts and the burning of high-sulfur industrial fuels are thought to be the main causes, but natural sources, such as volcanic gases and forest fires, may also be significant. It has been an increasingly serious problem since the 1950s, particularly in the NE United States, Canada, and W Europe, especially Scandinavia.

Acid rain became a political issue in the 1980s, when Canada claimed that pollutants from the United States were contaminating its forests and waters. Since then regulations have been enacted in North America and Europe to curb sulfur dioxide emissions from power plants; these include the U.S. Clean Air Act (as reauthorized and expanded in 1990) and the Helsinki protocol (1985), in which 21 European nations promised to reduce emissions by specified amounts. To assess the effectiveness of reductions a comprehensive study, comparing data from lakes and rivers across N Europe and North America, was conducted by an international team of scientists in 1999.

ACID RAIN

The results they reported were mixed: while sulfates (the main acidifying water pollutant from acid rain) were lower, only some areas showed a decrease in overall acidity. It remained to be determined whether more time or a greater reduction in sulfur emissions was needed to reduce freshwater acidity in all areas. See air pollution; forest; pollution.

All Related Information:
Cation-Exchange:
In cation exchange, the ions of calcium, magnesium, potassium, and other metals are attached to the clay and humus particles in the soil. The attractive forces of positive metal ions to the negatively charged clay particles is strong enough to hold the metal ions in the soil despite the passage of water through the soil.

Effect of Acid:
The hydrogen ions in the sulfuric acid trade places with the metal ions. The hydrogen ions are retained and neutralized by the soil. The calcium, potassium, and magnesium ions are leached or washed out of the top soil into lower inaccessible subsoil. These ions are then not available as nutrients or fertilizers needed for tree and plant growth.