1. ACID DEPOSITION AND FOREST ECOSYSTEMS
Chapter 3.11

2. Acid Deposition
Technology is great in many ways but it also contributes to acid deposition.

3. Progress?
Coal-burning plants, cars, and trucks, metal smelters, and oil refineries provide energy, transport, and materials for the industrial world, but at the same time produce oxides of sulfur and nitrogen, among the most dangerous of air pollutants.

4. The Problem of Combustion
Sulfur dioxide (SO2) and Nitrogen oxides (NOx) are released into the atmosphere by burning fossil fuels and metal ores.
If Sulfur and Nitrogen enter the atmosphere they may combine with water droplets to form acids.
Because of the Water Cycle the acids return to the surface of the Earth in the form of snow or rain, called ACID PRECIPITATION.

5. Acid Rain is 40X more acidic than normal rain.

6. ACID PRECIPITATION KILLS:
Fish
Soil Bacteria
Aquatic Plants
Terrestrial Plants
The sulfur and nitrogen oxides released from tailpipes and smokestacks do not always enter the water cycle in the atmosphere.

7. Some areas are more susceptible to the affects of acid rain while other are more resistant. Some types of soils are basic and can neutralize the acid.
The unfortunate thing is that most of southeastern Canada does not offer natural protection against acid rain.

9. Sulfur and nitrogen compounds may remain airborne and settle out in the dry state – DRY DEPOSITION
Dry Deposition enter the water cycle and form acid as it combines with water found on the ground, (ie. run-off, dew, the inside of your lungs!).
CAN BE FOUND:
Dew on lawns
Surface of lakes
Water inside your respiratory tract

10. THE EFFECTS OF ACID PRECIPITATION
Direct effects on Humans:
Medical effects
Accelerated respiratory problems
Examples: Asthma, bronchitis
Cause eyes to water
Irritate skin
Dissolving marble statues
Corroding metal
Dulling car finishes
Damage to buildings

11. Effects on Ecosystems Damage to leaves
Damaged to tissues of trees become more susceptible to fungal or bacterial infections.

12. EFFECTS OF ACID RAIN Important to Nitrogen Cycle Acid falls to soil
Promotes growth of moss
Kills Bacteria
Releases aluminum in the soil
Reduces nutrients in trees
Damage tree roots

13. pH – Potential Hydrogen
pH is a measure of the acidity or alkalinity (basic) in the solution. What pH stands for is not clear.
Measured using pH meter
pH is a scale from 0 – 14 where:
0 – 6.9 = Acidic
= neutral
= Basic
A pH of 3 is 10 times more acidic than pH of 4
More Basic
More Acidic

14. pH of Normal rain water pH of Acid Rain pH of 5.6
Range from 4.5 to 5.6; average 5.0

15. pH Scale

16. pH corresponds to the
concentration of Hydrogen
Ie. Low pH = high H

17. Class Work/Homework Read and Review pages 116 -118 in the text.
Answer Questions #1-4 page 118