Acid rain comes in many forms: rain, snow, sleet, hail and fog (wet deposition), and as deposits of acid particles, aerosols and gases (dry deposition). It is formed when sulfur dioxide (SO2) and nitrogen oxides (NOx) combine with moisture in the atmosphere to produce sulfuric acid and nitric acid.
Causes of Acid Rain
Several sources that contribute to creating acid rain include:
- Combustion of fossil fuels (coal, oil, natural gas, wood, etc.) for energy.
- Emissions from motor vehicles, airplanes, power plants and industries.
- Emissions of SO2 and NOx from the Midwest.
Effects of Acid Rain on the Environment
Aquatic - Freshwater macroinvertebrates, plants, and fish populations are damaged when acidic water disrupts their reproductive cycle. Aluminum leaches from the soil into the water, altering the chemistry and clogging the fish's gills. As water bodies become acidified, one species after another disappears. In addition to sensitive lakes, the Adirondack region includes thousands of miles of streams and rivers that are also sensitive to acidic deposition.
Wildlife - Acid rain lowers the biological productivity of lakes and reduces the amount of forage fish available to loons. Toxicity from mercury pollution of water bodies can lead to decreased reproductive success of loons as well.
Forests - Sulfur and nitrogen deposition have caused adverse impacts on certain highly-sensitive forest ecosystems, most notably the high-elevation, spruce-fir forests in the eastern United States. Forests are damaged because acid precipitation drains nutrients from the soil. Excess nitrogen in the air also may adversely affect tree growth. Evidence of decreased growth and dieback has been found in the Adirondacks.
Visibility - Dry acidic particles in the air lessen visibility. When winds blow from the southwest at Whiteface Mountain in the Adirondacks, visibility can be reduced from 50 miles to fewer than 5 miles.
Architecture - For materials, buildings, bridges and cultural resources, dry deposition is now considered to be more damaging to stone than wet deposition.
Human Health - High concentrations of fine-particulate sulfate and nitrate can enter the cardiovascular and respiratory systems, resulting in disease or even death. Metals, such as mercury and cadmium from soil deposits in lakes, streams, and reservoirs, can accumulate in the tissues of fish, making them toxic to humans. Metals also can be leached from the soil into reservoirs, or from old lead and copper pipes directly into home water supplies, causing serious illness.
Things You Can Do to Help
- Conserve energy in your home and office.
- Utilize public transportation, car pool, or walk.
- Purchase clean electric power.
- Learn more about acid rain on EPA's Acid Rain information webpage.
More about Acid Rain:
- Sources and Environmental Impacts of Acid Rain and Acid Deposition - Sources and impacts of acid rain, and the programs and strategies aimed at reducing the effects.
- New York's Acid Deposition Monitoring Network - The New York State's Atmospheric Deposition Monitoring Network measures acid deposition, its precursors and related factors to establish the effectiveness of current sulfur control policy and other strategies aimed at reducing the effects of acid rain.
- Acid Deposition Large Graphic - Detailed graphic of acid deposition