Air and Air PollutionAir and Air Pollution

G. Tyler Miller’sLiving in the Environment

13th Edition

Chapter 17

G. Tyler Miller’sLiving in the Environment

13th Edition

Chapter 17

INDICATOR SPECIESINDICATOR SPECIES

• Lichens are PIONEER ORGANISMS

• Lichens are a good example of MUTUALISM

• Lichens are good indicators of air pollution because they:– Are long lived– Are found in almost every ecosystem– Are non-motile– Absorb air

The AtmosphereThe Atmosphere

Troposphereweather

Troposphereweather

Stratosphere Stratosphere

78% N2 , 21% O2

water vapor

78% N2 , 21% O2

water vapor

Ozone layer-removes 95% of UV

Ozone layer-removes 95% of UV

Greenhouse effect Greenhouse effect

Alt

itu

de

(k

ilom

ete

rs)

Ozone concentration (ppm)

Alt

itu

de

(m

iles)Stratospheric ozone

Stratosphere

Troposphere

40

35

30

25

20

15

10

5

00 5 10 15 20

0

5

10

15

20

25

Photochemical ozone

Ozone is a pollutant in the troposphere

Natural Sources of Air PollutantsNatural Sources of Air Pollutants

• Dust and particulates from windstorms and soil

• Sulfur oxides and particulates from volcanoes

• Nitrogen oxides, carbon oxides, and particulates from forest fires

• Hydrocarbons and pollen from plants

• Methane and hydrogen sulfide from decaying plants

• Salts from the sea

Outdoor Air PollutionOutdoor Air Pollution

Primary pollutants: Primary pollutants:

Secondary pollutants: Secondary pollutants:

emitted directly into the troposphere in a potentially harmful formemitted directly into the troposphere in a potentially harmful form

formed in the troposphere from the interaction of primary pollutants with each other or with components of the air

formed in the troposphere from the interaction of primary pollutants with each other or with components of the air

Primary Pollutants

Secondary Pollutants

SourcesNatural

Stationary

CO CO2

SO2 NO NO2

Most hydrocarbons

Most suspendedparticles

SO3

HNO3 H2SO4

H2O2 O3 PANs

Most and saltsNO3–

Mobile

SO42 –

Photochemical SmogPhotochemical Smog

Brown-air smog ( brown color due to NO2) Brown-air smog ( brown color due to NO2)

Photochemical reaction: a chemical reaction activated by light

Photochemical reaction: a chemical reaction activated by light

Photochemical oxidants: can react with and oxidize certain compounds that are normally not oxidized. Can irritate the respiratory tract and damage crops and trees.

(NO2, O3, and PAN’s)

Photochemical oxidants: can react with and oxidize certain compounds that are normally not oxidized. Can irritate the respiratory tract and damage crops and trees.

(NO2, O3, and PAN’s)

Photochemical SmogPhotochemical Smog• N2 + O2 2NO (colorless gas formed from the

combustion of N2 within an engine or boiler)• 2NO + O2 2NO2 (noxious yellowish-brown gas

formed in the troposphere in the presence of sunlight)• 3NO2 + H2O 2HNO3 (acid rain) + NO• NO2 + UV radiation NO + O• O + O2 O3 (in troposphere is a pollutant)• Aldehydes and PAN’s (peroxyacyl nitrates) are

formed from the interaction of several primary and secondary pollutants

Solarradiation

Ultraviolet radiation

NONitric oxide

Photochemical smog

H2OWater

NO2

Nitrogendioxide

Hydrocarbons

O2

Molecularoxygen

HNO3

Nitric acid

PANsPeroxyacyl

nitratesAldehydes

(e.g., formaldehyde)O3

Ozone

OAtomicoxygen

Clear day

Smoggy day

Photochemical SmogPhotochemical Smog

• Worse in afternoon when sun is strongest

• Worse in warm sunny climates

Nitric oxide Nitrogen dioxide Ozone40

30

20

10

06 7 8 9 10 11 12 1 2 3 4 5 6 7 8A.M. Noon P.M.

Time

Par

ts p

er m

illi

on

Industrial Smog (burning coal)Industrial Smog (burning coal)

Gray-air smogGray-air smog

Industrial smogIndustrial smog

Sulfuric acidSulfuric acid

Sulfur dioxideSulfur dioxide

ParticulatesParticulates

Industrial Smog - when burning coal ----Industrial Smog - when burning coal ----

• 2C + O2 2CO

• C + O2 CO2

• S + O2 SO2

• 2SO2 + O2 2SO3

• SO3 + H2O H2SO4 (acid rain)

• 2NH3 + H2SO4 (NH4)2SO4

– Ammonium sulfate particles and soot ( C ) give the air its gray color – thus gray air smog

Industrial Smog Industrial Smog

• Is a problem in urban industrialized areas where coal is burned– China– India– Ukraine

Smog Frequency and SeveritySmog Frequency and Severity

• Depend upon:– Local climate and topography– Population density– Amount of industry– Type of fuels used

Precipitation and wind clean the air.

Temperature InversionsTemperature Inversions

Warmer air

Inversion layer

Cool layer

MountainMountain

Valley

Decreasing temperature

Incr

easi

ng

alt

itu

de

Polluted air cannot rise and escapeMEXICO CITY

Temperature InversionTemperature Inversion

Inversion layer

Mountainrange

Sea breeze

Descending warm air mass

Decreasing temperature

Incr

easi

ng

alt

itu

de

Polluted air cannot rise and escape

Los Angeles

Regional Outdoor Air Pollution from Acid DepositionRegional Outdoor Air Pollution from Acid Deposition

Most air pollutant emitters use tall smokestacks to release pollutants above the inversion layer. This reduces local air pollution but increases regional air pollution downwind.

ACID DEPOSITION (Acid Rain) – fallout of the acid components from these air contaminants. (pH < 5.6)

Wind

Transformation tosulfuric acid (H2SO4)and nitric acid (HNO3)

Nitric oxide (NO)

Acid fog

Ocean

Sulfur dioxide (SO2)and NO

Windborne ammonia gasand particles of cultivated soilpartially neutralize acids andform dry sulfate and nitrate salts

Dry aciddeposition(sulfur dioxidegas and particlesof sulfate andnitrate salts)

Farm

Lakes indeep soilhigh in limestoneare buffered

Lakes in shallowsoil low inlimestonebecomeacidic

Wet acid deposition(droplets of H2SO4 andHNO3 dissolved in rainand snow)

Acid Deposition in the USAcid Deposition in the US

Fig. 17-11 p. 429

Acid BufferingAcid Buffering

• Soils with calcium carbonate (limestone) (CaCO3) can neutralize (buffer) some acid input.

[CaCO3 + 2H+ Ca2+ + CO2 + H2O]

• The areas most sensitive to acid deposition are those containing thin acidic soils and those already damaged from years of exposure to acid rain

Acid Deposition and HumansAcid Deposition and Humans

Respiratory diseases Respiratory diseases

Toxic metal leaching: decreased soil pH increases the solubility of certain metal ions in the soil (can result in loss of soil fertility and increase in toxic metals)

Toxic metal leaching: decreased soil pH increases the solubility of certain metal ions in the soil (can result in loss of soil fertility and increase in toxic metals)

Decreased visibility Decreased visibility Damage to structures, especially

containing limestone

Damage to structures, especially containing limestone

Decreased productivity and profitability of fisheries, forests, and farms

Decreased productivity and profitability of fisheries, forests, and farms

Acid Deposition and Aquatic SystemsAcid Deposition and Aquatic Systems

Fish declines Fish declines

Undesirable species

Undesirable species

Aluminum toxicity

Aluminum toxicity

Acid shock- from rapid runoff

Acid shock- from rapid runoff

Aluminum ToxicityAluminum Toxicity

• Lake acidification can result in the solubilizing of aluminum from the surrounding soil and underlying rock. Increased levels of aluminum in the water can stimulate the overproduction of mucus in the gills of certain fish, clogging their gills and asphyxiating them.

Acid Deposition, Plants, and SoilAcid Deposition, Plants, and Soil

Nutrient leaching

Nutrient leaching

Heavy metal release

Heavy metal release

Weakens trees Weakens trees

Emission

Aciddeposition

SO2

H2O2

PANs

NOX

O3

Others

Direct damageto leavesand bark

Reducedphotosynthesis

and growth

IncreasedSusceptibilityto drought,

extreme cold,insects, mosses,

and diseaseorganisms

Soil acidification

Leaching ofsoil

nutrientsAcid

Release oftoxic

metal icons

Rootdamage

Reducednutrient

andwater

uptake

Tree death

• The 1990 amendments to the Clean Air Act have helped to reduce some of the harmful impacts of acid deposition in the United States.

• However, there is still a long way to go.

Prevention Cleanup

Reduce air pollutionby improving energyefficiency

Reduce coal use

Increase natural gasuse

Increase use of renewable resources

Burn low-sulfur coal

Remove SO2 particulates, and NOx

from smokestack gases

Remove Nox frommotor vehicular exhaust

Tax emissions of SO2

Add lime to neutralizeacidified lakes

Add phosphatefertilizer to neutralizeacidified lakes

Indoor Air PollutionIndoor Air Pollution

• Levels of common pollutants are generally 2 – 5 times higher inside homes and buildings than outside.

• Levels of particulates can be up to 60% higher indoors than outdoors.

• Pesticides approved for outdoor use only, were 10 times higher inside than outside monitored homes.

• Pollution levels inside cars in traffic-clogged areas can be up to 18 times higher than outside the vehicle.

Indoor Air Pollution/Sick Building SyndromeIndoor Air Pollution/Sick Building Syndrome

Fig. 17-17p. 434

RadonRadon

Radon-222 Radon-222

4 picocurie level 4 picocurie level

Occurs in certain areas based on geology

Occurs in certain areas based on geology

Associated with uranium and organic material in rock

Associated with uranium and organic material in rock Fig. 17-18

p. 436

Effects of Air Pollution on Living Organisms and MaterialsEffects of Air Pollution on Living Organisms and Materials

Damage to mucous membranesDamage to mucous membranes

Respiratory diseases (see Fig. 17-19 p. 438)Respiratory diseases (see Fig. 17-19 p. 438)

Damage to plant leaves and rootsDamage to plant leaves and roots

Reduction in primary productivityReduction in primary productivity

Deterioration of materials (See Table 17-3 p. 440)

Deterioration of materials (See Table 17-3 p. 440)

Indoor Exposure

Developingcountries(rural) 67%

Developing countries(urban) 23%

Developed countries(rural) 1%

Total deaths 2.8 million

Developed countries(urban) 9%

Outdoor Exposure

Developing countries(urban) 93% Developed

countries(urban) 7%

Total deaths 0.2 million

Solutions: Preventing and Reducing Air PollutionSolutions: Preventing and Reducing Air Pollution Clean Air Act (1970, 1977, 1990) Federal government established air pollution regulations which are enforced by each state and major city

Clean Air Act (1970, 1977, 1990) Federal government established air pollution regulations which are enforced by each state and major city

National Ambient Air Quality Standards (NAAQS) for CO, NO2, SO2, SPM (suspended particulate matter), O3, and Pb in outdoor air.

National Ambient Air Quality Standards (NAAQS) for CO, NO2, SO2, SPM (suspended particulate matter), O3, and Pb in outdoor air.

Primary standard: set to protect human healthSecondary standards: set to prevent environmental

and property damage

Primary standard: set to protect human healthSecondary standards: set to prevent environmental

and property damage

Output control vs. input control Output control vs. input control

Emissions Trading PolicyEmissions Trading Policy

• Clean Air Act of 1990 enables the 110 most polluting power plants in 21 states to buy and sell SO2 pollution rights.

• A utility that emits less than its limit receives more pollution credits. It can use these to:– Avoid reductions in SO2 emissions from some of

its other facilities– Bank them for future plant expansions– Sell them to other utilities

Emission ReductionEmission Reduction

Electrostatic Precipitator

Dirty gas

Dust discharge

ElectrodesCleaned gas

Cleaned gas

Dirty gas

Baghouse Filter Dust discharge

Bags

Cyclone Separator

Dirty gas

Dust discharge

Cleaned gas

Dirty gas

Dirty water

Cleanwater

Wet Scrubber

Wetgas

Cleaned gas

Prevention Cleanup

Mass transit

Bicycles and walking

Less polluting engines

Less polluting fuels

Improve fuel efficiency

Get older, pollutingcars off the road

Give buyers tax write-offs for buying low-polluting, energy-efficient vehicles

Restrict driving inpolluted areas

Emission controldevices

Car exhaustInspectionstwice a year

Stricter emissionstandards

Methods for Reducing Emissions from Motor Vehicles

Prevention Cleanup orDilutionCover ceiling

tiles and liningof AC ducts toprevent releaseof mineral fibers

Ban smoking orlimit it to well-ventilated areas

Set stricterformaldehydeemissionsstandards forcarpet,furniture,and buildingmaterials

Prevent radoninfiltration

Use officemachines inwell-ventilatedareas

Use lesspollutingsubstitutes forharmfulcleaningagents, paints, and other products

Use adjustablefresh air ventsfor work spaces

Increase intakeof outside air

Change airmore frequently

Circulate building’s airthrough rooftopgreenhouses

Use exhausthoods for stoves andappliances burning naturalgas

Install efficientchimneys forwood-burningstoves

Ways to Prevent and Reduce

Indoor Air Pollution