1. Acid Deposition Topic: 5 A.S: N – R

2. What is Acid Deposition?
Primary pollutants such as sulfur dioxide (SO2)from factories and nitrogen oxides (NOx) from cars form secondary pollutants that are acidic.

3. Acid Formation These primary pollutants mix with water to form acids!
These can fall as:
Wet deposition- (Acid Rain) precipitation
Dry deposition- particles and gases, which can become wet deposition when they encounter any water.
If not in the atmosphere, where might this happen?

4. Acid Rain? Normal rain has a pH of 5.6
This is because the precipitation (water) mixes with CO2 to make dilute carbonic acid.
Average pH of rain in the Eastern United States is !
10 times as acidic as normal rain!
Some California fogs, though, have pH’s as low as 2.3
This is the same as lemon juice!

5. Wet Deposition
SO2 reacts with O2 and water vapor to form dilute sulfuric acid.
NOx react with O2 and water vapor to form dilute nitric acid.
Resulting precipitation has pH of 5.5 or lower.

7. Direct Effects of Acid Deposition
Dry particles can cause human respiratory problems when inhaled
Property damage
Marble and limestone dissolve easily in very weak acids
Acid rain can even damage the clear coat on cars
Acidification can slow or inhibit decomposition.
How?
It can also cause an overproduction of mucus within fish gills, leading to suffocation.
Coniferous forests are most vulnerable to acidification because it decreases the waxy cuticle on the needles that protects the trees from excess water loss.
KILLS BACTERIA & FUNGI

9. Coniferous Trees

11. Indirect Effects of Acid Deposition
Acid water leaches toxic metals, such as mercury, aluminum, and lead out of rocks and soil. It then runs off into water, which is then absorbed by producers.
What happens after this? POISONS PLANT LIFE
Leaches nutrients out of soil, which decreases productivity of crops and forests.
Weakens trees and makes them more susceptible to severe cold, diseases, and insect attacks

12. Below 4.5, most lakes are devoid of fish!

13. Why is Acid Rain a Regional Problem?

14. Regional Problem – Not Global
Acidic components only remain in the atmosphere for a short while before they are grounded weather patterns.
Areas that are most effected are near industrial areas or areas with high traffic (emissions).
Some soils are made up of bases (limestone) and salts that can act as buffers to acid deposition.
Sensitive soils do not have these natural buffers

16. Preventing Acid Rain Altering Human Activities: Stop burning coal!
Change from using coal to cleaner burning natural gas and/or renewable energy sources.
Removal of sulfur from coal (scrubbers) before it is burned.
Ie: “clean coal”…expensive, not efficient
Regulations:
Filters on smokestacks….who regulates?
Removal of Nitrogen Oxides from automobile exhaust.
How is this regulated?
EMISSIONS TESTING

17. Restoring Acidified Soils and Water
Liming
Large amounts of crushed limestone can be deposited to neutralize lakes and soils, however:
Costly to do all areas
Can be harmful to plankton and aquatic plants if overdone.
Only a Temporary Remedy - must be done annually.