1. Acid Deposition

2. Two Forms… Wet Refers to acid rain, fog, sleet, cloud vapor and snow.
Dry
Refers to acidic gases and particles.

3. Two main contributors to acid deposition:

4. 1. Sulfur Dioxide (SO2)
Sulfur in the atmosphere comes from burning bituminous coal, smelting, and organic decay.
90% is from human sources.

5. 2. Nitrogen Oxides (NOx)
Major sources of nitrogen oxides include gasoline engines, power stations and industry.

7. Acid Rain Normal rain is slightly acidic and has a pH of about 5.6
Any rainfall has a pH value less than 5.6 is defined as ACID RAIN

9. Chemical Rxns involved in the formation of acid rain.
CO2 + H2O  H2CO3 (carbonic acid)
(this is why rain water is naturally slightly acidic)
SO2 + H2O  H2SO3 (sulfurous acid)
NO2 + H2O  HNO HNO3
(nitrous acid) (nitric acid)
Chemical Rxns involved in the formation of acid rain.

10. Acidic Precipitation Wind Transformation to sulfuric acid (H2SO4)
and nitric acid (HNO3)
Windborne ammonia gas
and particles of cultivated soil
partially neutralize acids and
form dry sulfate and nitrate salts
Wet acid deposition
(droplets of H2SO4 and
HNO3 dissolved in rain
and snow)
Dry acid
deposition
(sulfur dioxide
gas and particles
of sulfate and
nitrate salts)
Sulfur dioxide (SO2)
and NO
Nitric oxide (NO)
Acid fog
Farm
Lakes in
deep soil
high in limestone
are buffered
Ocean
Lakes in shallow
soil low in
limestone
become
acidic

11. Effects on the Environment
Areas affected the most are where buffering capacity is low.
Ex. Soils formed from granite
Soils formed from limestone (CaCO3) have a greater buffering capacity therefore acid rain does not have as large of an impact

12. Aquatic environments
In areas where buffering capacity is low, acid rain also releases aluminum from soils into lakes and streams
Aluminum is highly toxic to many
species of aquatic organisms.
At pH 5, most fish eggs cannot hatch.
Lower pH levels can cause increased stress levels, lowering body weight and size.
Some acid lakes have no fish.

14. Forests
Acid precipitation dissolves the nutrients and helpful minerals in the soil
washes them away before trees and other plants can use them to grow.
Acid precipitation also causes the release of substances that are toxic to trees and plants, such as aluminum, into the soil.
The leaves of plants are also damaged.

15. Mountains Acid clouds greatly affect mountains in the eastern U.S. NC
New England

16. Mongolia
Germany

17. Flip through the next slides to see the progress that has been made

18. Manmade structures are also affected

19. Sulfate Ion Concentrations1985-2004
1986
1984

20. Sulfate Ion Concentrations1985-2004
1986

21. Sulfate Ion Concentrations1985-2004
1987
1988
1986

22. Sulfate Ion Concentrations1985-2004
1988
1989
1987

23. Sulfate Ion Concentrations1985-2004
1989
1990
1988

24. Sulfate Ion Concentrations1985-2004
1990
1991
1989

25. Sulfate Ion Concentrations1985-2004
1991
1992
1990

26. Sulfate Ion Concentrations1985-2004
1992
1993
1991

27. Sulfate Ion Concentrations1985-2004
1993
1994
1992

28. Sulfate Ion Concentrations1985-2004
1994
1995
1993

29. Sulfate Ion Concentrations1985-2004
1995
1996
1994

30. Sulfate Ion Concentrations1985-2004
1996
1997
1995

31. Sulfate Ion Concentrations1985-2004
1997
1998
1996

32. Sulfate Ion Concentrations1985-2004
1998
1999
1997

33. Sulfate Ion Concentrations1985-2004
1999
2000
1998

34. Sulfate Ion Concentrations1985-2004
2000
2001
1999

35. Sulfate Ion Concentrations1985-2004
2001
2002
2000

36. Sulfate Ion Concentrations1985-2004
2002
2003
2001

37. Sulfate Ion Concentrations1985-2004
2003
2004
2002

38. Sulfate Ion Concentrations1985-2004
2005
2003