Acidic deposition that is commonly known as acid rain occurs when emissions of Sulfur Dioxide (SO2) and oxides of nitrogen (NOx) react with water, oxygen, and other oxidants in the atmosphere to form various acidic compounds. These acidic compounds fall to the ground in a dry form such as gas and/or particles or in a wet form of either rain, snow, or fog. Strong winds move these harmful compounds to different places. About 70% of annual SO2 emissions and 30% of NOx emissions come from electric utility plants in the United States.
Sources of transportation such as cars also contribute to NOx emissions. Over 20 million tons of SO2 and NOx are emitted altogether into the atmosphere each year.
Acid rain has many environmental effects. It causes acidification to lakes and streams and damages trees that are at high elevations. It also speeds up the decay of building materials and paints including irreplaceable buildings, statues, and sculptures. Acid rain contributes to visibility degradation and has an impact on public health as well.
Environmental Damage to Lakes and Streams
Acid rain affects the bodies of water that rest atop soil with a limited ability to neutralize acidic compounds. They are called sensitive bodies of water. Many lakes and streams suffer from chronic acidity.
This means that the water has a constant low pH level. Of the many lakes and streams that were surveyed in the National Surface Water Survey, acid rain has been determined to cause acidity in 75% of the acidic lakes and about 50% of the acidic streams.
