Acid Deposition

http://www.natgeoeducationvideo.com/film/1233/acid-rain

Air pollution is one of several interacting stresses that can damage, weaken, or kill trees and pollute surface and groundwater.

Acid deposition consists of rain, snow, dust, or gas with a pH lower than 5.6.As of 2010, the most acidic rain falling in the US has a pH of about 4.3

Emissions

SO2 NOxAcid deposition

H2O2 O3

Others

Direct damage to leaves & bark

Reduced photo-synthesis and growth

Susceptibility to drought, extreme cold, insects, mosses, & disease organisms

Soil acidification

Tree death

Leaching

of soil nutrients

Release of toxic metal ions

Root damage

Reduced nutrient & water uptakeAcids

Lake

Groundwater

PANs

Acid DepositionSulfur dioxides,

nitrogen oxides, and particulates can react in the atmosphere to produce acidic chemicals that can travel long distances before returning to the earth’s surface.

Tall smokestacks reduce local air pollution but can increase regional air pollution.

Acid Deposition Two main contributors

to acid deposition Sulfur Dioxide (SO2) Nitrogen Oxides

(NOx)

* 66% of all sulfur dioxides and 25% of all nitrogen oxides comes from electric power generation that produces energy by burning fossil fuels.

Acid Deposition• Acidic water flows over and

through the ground which affects a variety of plants and animals

• Dry deposition refers to acidic gases and particles.

• About half of the acidity in the atmosphere falls back to earth through dry deposition.

• The wind blows these acidic particles and gases onto/into buildings, cars, homes, and trees

Acid Deposition• Acidic water dissolves the

nutrients and helpful minerals in the soil

• It washes nutrients away before plants can use them to grow

• Acid rain also causes the release of substances, such as aluminum, that are toxic to plants

Acid DepositionAcid rain does not

usually kill trees directly

Weakens treesDamages leavesLimits nutrients

availableToxic substances

are slowly released from the soil.

Germany

Mongolia

South Carolina

Acid Deposition• Acid Deposition can release

aluminum from lake sediments which, in turn, adversely affects the gills of fish.

• Generally, the young of most species are more sensitive to environmental conditions than adults.

• At pH 5, most fish eggs cannot hatch.

• At lower pH levels, some adult fish die.

• Chronic stress leads to lower body weight and smaller size

• Some acid lakes have no fish.

Acid DepositionDuring the 1970’s and 1980’s, many lakes in

Canada and the Northeastern U.S. lost all of their fish due to lowered pH levels

Acid Deposition

Acid Deposition

pH measurements in relation to major coal-burning and industrial plants.

Acid DepositionAntiquities can be

destroyed by acid deposition

Acid DepositionLime (calcium carbonate) can be deposited

into a lake to increase the pH

ACID DEPOSITIONAcid deposition contributes to chronic

respiratory disease and can leach toxic metals (such as lead and mercury) from soils and rocks into acidic lakes used as sources for drinking water.

Solutions

Acid Deposition

Prevention Cleanup

Reduce air pollution by improving energy efficiency

Add lime to neutralize acidified lakes

Reduce coal use

Add phosphate fertilizer to neutralize acidified lakes

Increase natural gas use

Increase use of renewable energy resources

Burn low-sulfur coal

Remove SO2 particulates & NOx from smokestack gases

Remove NOx from motor vehicular exhaust

Tax emissions of SO2