Acid Precipitation Environmental Science Spring 2011

 Explain the causes of acid precipitation  Explain how acid precipitation affects plants, soils, and aquatic ecosystems  Describe three ways that acid precipitation affects humans  Describe ways that countries are working together to solve the problem of acid precipitation

 Acid Precipitation: precipitation such as rain, sleet, or snow that contains a high concentration of acids  Burning of fossil fuels releases oxides of sulfur and nitrogen  When oxides combine with water in atmosphere, form sulfuric acid and nitric acid and falls to ground as acid rain

 Acidic water flows over and through ground, into lakes, rivers, etc.  Can kill living things and result in decline or loss of some local animal and plant populations

 pH (power of hydrogen): measure of how acidic or basic a substance is ◦ Lower the pH number, more acidic ◦ Higher the pH number, more basic ◦ Each whole number on the pH scale indicates a tenfold change in acidity

 Pure water = pH of 7  Normal precipitation is slightly acidic, because atmospheric carbon dioxide dissolves into precipitation and forms carbonic acid ◦ Has pH of 5.6  Acid precipitation has pH of less than 5.0

 pH of precipitation varies between different geographic areas ◦ Eastern US and Canada ranges from 4.2 to 4.8 ◦ Most acidic precipitation in North America occurs around Lake Erie and Lake Ontario pH of 4.2

 Can cause drop in pH of soil and water  Acidification: increase in concentration of acid of soil and water

 Acidification can: ◦ Changed balance of soil’s chemistry ◦ Some nutrients are dissolved and washed away ◦ Can cause aluminum and other toxic materials to be released and possibly absorbed by roots of plants ◦ Aluminum can cause root damage ◦ Sulfur dioxide can clog openings on surfaces of plants

 Aquatic animals adapted to live in environment with particular pH range  Acid precipitation alters this range, can kill organisms  Causes aluminum to leach out of soil, can accumulate in gills of fish and interfere with oxygen and salt exchange, fish are suffocated

 Acid shock: sudden influx of acidic water that causes a rapid change in the water’s pH ◦ Occurs in spring, when acidic snow melts ◦ May kill large numbers of fish ◦ Affects reproduction of fish and amphibians, produce fewer eggs, eggs often do not hatch, offspring hat do hatch can have birth defects and reproduction prblems

 Toxic materials such as aluminum and mercury can be released and find their ways into crops, water and fish  Correlation between acid precipitation and respiratory problems  Decreases in fish can influence livelihood of commercial fishers and sport fishing industry and forestry industry

 Can dissolve calcium carbonate in common building materials, such as concrete, marble, and limestone  Monuments are being dissolved by acid precipitation

 Problem: pollutants may be released in one area and fall to ground hundreds of km away  Ex. Half of acid precipitation that falls in southeastern Canada results from pollution produced in northeastern US  International problem led to Canada-US air quality agreement