1. Acid Rain
Unit 2: The Atmosphere

2. 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

4. 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

5. 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!

6. 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

7. 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!

8. 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.