Acid Rain Unit 2: The Atmosphere
What IS Acid Rain? Precipitation such as rain, sleet, or snow that contains a high concentration of acids Caused by burning of fossil fuels; the oxides of sulfur and nitrogen to combine with water in the atmosphere Precipitate as nitric or sulfuric acids
Review: pH Measure of how acidic or basic a substance is What is special about the magnitude of this scale? (Log.) Normal precipitation is already slightly acidic due to atmospheric CO2 Acid rain has pH less than 5.0 Most acidic precipitation occurs around the great lakes (4.2) Logathrithmic
Effects: Soil and Plants Doesn’t seem like a big change in pH--what’s the big deal? Hint: what did we learn about the human body? Acidification causes the elimination of some essential nutrients and the addition of some toxic metals Harmful to plant roots and stomata (openings on leaves) Use this opportunity to mention transpiration!
Effects: Aquatic Ecosystems Aquatic organisms are adapted to live in a particular pH range Water may look “clear,” but a change in pH can kill many aquatic organisms Also causes aluminum (from the soil runoff) to accumulate in the gills of fish and interfere with oxygen and salt exchange Acid shock – when the snow melts and rushes into the water When fish do live, they produce fewer eggs and offspring with birth defects
Effects: Humans Toxic metals (from soil) can be released into the environment Correlation between acid rain and respiratory problems Fishing and forestry industries suffer when their products are damaged Can impact standard of living in communities Corrodes buildings that are made out of calcium carbonate Correlation does not imply causation!
International Conflict and Cooperation Problem: pollutants released in one area may fall to the ground hundreds of miles away. So who’s responsible? Canada-U.S. Air Quality Agreement in 1991: reduce emissions that flow across the Canada-U.S. boundary Offset somewhat by road traffic Europe has made similar strides, but China has been a big problem in the past.