Ch 19 Acid Rain

Acid rain Outdoor/ Indoor Pollution

Factors Influencing Levels of Outdoor Air Pollution

• Outdoor air pollution can be reduced by:– settling out, precipitation, sea spray, winds, and

chemical reactions.

• Outdoor air pollution can be increased by:– urban buildings (slow wind dispersal of pollutants),

mountains (promote temperature inversions), and high temperatures (promote photochemical reactions).

Temperature Inversions

• Cold, cloudy weather in a valley surrounded by mountains can trap air pollutants (left).

• Areas with sunny climate, light winds, mountains on three sides and an ocean on the other (right) are susceptible to inversions.

Figure 19-5Figure 19-5

Fig. 19-5, p. 447

Warmer air Descending warm air mass

Inversion layer Inversion layer

Sea breezeIncreasing altitude

Decreasing temperature

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ACID DEPOSITION

• Sulfur 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.

Animation: Acid Deposition

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ACID DEPOSITION

• Acid deposition consists of rain, snow, dust, or gas with a pH lower than 5.6.

Figure 19-6Figure 19-6

Fig. 19-6, p. 448

WindTransformation 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 depostion (droplets of H2SO4 and HNO3 dissolved in rain and snow)Nitric oxide (NO)

Sulfur dioxide (SO2) and NO

Dry acid deposition (sulfur dioxide gas and particles of sulfate and nitrate salts)

Acid fogFarm

OceanLakes in deep soil Lakes in deep soil high in limestone high in limestone

are bufferedare buffered

Lakes in shallow soil Lakes in shallow soil low in limestone low in limestone

become acidicbecome acidic

ACID DEPOSITION

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

Figure 19-7Figure 19-7

ACID DEPOSITION

• Acid 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.

ACID DEPOSITION

Figure 19-8Figure 19-8

ACID DEPOSITION• Air pollution is

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

Figure 19-9Figure 19-9

Fig. 19-9, p. 451

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

Animation: Effects of Air Pollution in Forests

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Fig. 19-10, p. 452

SolutionsAcid 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

INDOOR AIR POLLUTION• Indoor air pollution usually is a greater threat to

human health than outdoor air pollution.• According to the EPA, the four most dangerous

indoor air pollutants in developed countries are:– Tobacco smoke.– Formaldehyde.– Radioactive radon-222 gas.– Very small fine and ultrafine particles.

Chloroform

Benzo--pyrene

Styrene

Radon-222

Methylene Chloride

Tobacco Smoke

Carbon Monoxide

Asbestos

Nitrogen Oxides

1, 1, 1-Trichloroethane

Particulates

FormaldehydeTetrachloroethylene

Para-dichlorobenzene

Fig. 19-11, p. 453

Interactive Home

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PVC Exposure

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INDOOR AIR POLLUTION• Household dust mites that

feed on human skin and dust, live in materials such as bedding and furniture fabrics.– Can cause asthma attacks

and allergic reactions in some people.

Figure 19-12Figure 19-12

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Case Study: Radioactive Radon

• Radon-222, a radioactive gas found in some soils and rocks, can seep into some houses and increase the risk of lung cancer.

Sources and paths of entry Sources and paths of entry for indoor radon-222 gasfor indoor radon-222 gas.

Figure 19-13Figure 19-13

Fig. 19-13, p. 454

Outlet vents for furnaces and dryers

Open window

Openings around pipes

Cracks in wall

Slab joints

Wood stove

Cracks in floorClothes dryer

Sump Sump pumppumpFurnace

Slab Radon-222 gas Uranium-238

Soil

HEALTH EFFECTS OF AIR POLLUTION

• Your respiratory system can help protect you from air pollution, but some air pollutants can overcome these defenses. Figure 19-14Figure 19-14

Fig. 19-14, p. 455

Epithelial cellCilia

Nasal cavity

Oral cavity

Goblet cell (secreting mucus)

Pharynx (throat)

MucusTrachea (windpipe)

BronchusBronchioles

Right lung

Bronchioles

Alveolar sac (sectioned)

Alveoli

Alveolar duct

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HEALTH EFFECTS OF AIR POLLUTION

Normal human lungs (left) and the lungs of a person who died of emphysema (right).

Figure 19-15Figure 19-15

Air Pollution is a Big Killer

• Each year, air pollution prematurely kills about 3 million people, mostly from indoor air pollution in developing countries.– In the U.S., the EPA estimates that annual deaths

related to indoor and outdoor air pollution range from 150,000 to 350,000.

– According to the EPA, each year more than 125,000 Americans get cancer from breathing diesel fumes.

Air Pollution is a Big Killer

• Spatial distribution of premature deaths from air pollution in the United States.

Figure 19-16Figure 19-16

Video: Air Pollution in China

The Daily Show with Jon Stewart

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