AirPollu)onandOzoneLoss

Chapter 19

AirPollu)onandOzoneDeple)onChapter19

Thisunitisen)relybasedonChapter19ofyourtextbook.ItcoversallofUnit6andpartofUnit9fromtheAPcurriculum.•  6.1–Introduc)ontoAirPollu)on•  6.2–PhotochemicalSmog•  6.3–ThermalInversion•  6.4–AtmosphericCO2andPar)culates•  6.5–IndoorAirPollutants•  6.6–Reduc)onofAirPollutants•  6.7–AcidRain•  6.8–NoisePollu)on•  9.1–StratosphericOzoneDeple)on

•  9.2–ReducingOzoneDeple)on

6.1 – INTRODUCTION TO AIR POLLUTION

AirPollutants

•  Criteria pollutants est. by the EPA –  CO –  NO2 –  SO2

–  PM10 (aerosols) –  O3 –  Pb

(VOCs)

•  Categorized into: –  Primary pollutants –

emitted directly into the atmosphere

–  Secondary pollutants – not directly emitted, result from reactions

Primary Pollutants

Secondary Pollutants

Sources Natural Stationary

CO CO2

SO2 NO NO2

Most hydrocarbons Most suspended

particles

SO3

HNO3 H2SO4

H2O2 O3 PANs

Most and salts NO3 –

Mobile

SO4 2 –

NitrogenDioxide(NO2)

•  Properties: reddish brown gas, formed as fuel burnt in car, strong oxidizing agent, forms Nitric acid in air

•  Effects: acid rain, lung and heart problems, decreased visibility (yellow haze), suppresses plant growth

•  Sources: fossil fuels combustion, power plants, forest fires, volcanoes, bacteria in soil

•  Class: Nitrogen oxides (NOx) •  EPA Standard: 0.053 ppm

Ozone(O3)•  Properties: colorless, unpleasant odor,

major part of photochemical smog •  Effects: lung irritant, damages plants,

rubber, fabric, eyes, 0.1 ppm can lower PSN by 50%,

•  Sources: Created by sunlight acting on NOx and VOC , photocopiers, cars, industry, gas vapors, chemical solvents, incomplete fuel combustion products

•  Class: photochemical oxidants

CarbonMonoxide(CO)

•  Properties: colorless, odorless, heavier than air, 0.0036% of atmosphere

•  Effects: binds tighter to Hb than O2, mental functions and visual acuity, even at low levels

•  Sources: incomplete combustion of fossil fuels 60 - 95% from auto exhaust

•  Class: carbon oxides (CO2, CO) •  EPA Standard: 9 ppm •  5.5 billion tons enter atmosphere/year

Lead(Pb)

•  Proper&es:grayishmetal•  Effects:accumulatesin)ssue;affectskidneys,liverandnervoussystem(childrenmostsuscep)ble);mentalretarda)on;possiblecarcinogen;20%ofinnercitykidshavehighlevelsinblood

•  Sources:par)culates,smelters,baYeries•  Class:toxicorheavymetals•  EPAStandard:1.5ug/m3

•  2milliontonsenteratmosphere/year

SuspendedPar=culateMa@er(PM10)

• Properties: particles suspended in air (<10 um)

• Effects: lung damage, mutagenic, carcinogenic, teratogenic

• Sources: burning coal or diesel, volcanoes, factories, unpaved roads, plowing, lint, pollen, spores, burning fields

• Class: SPM: dust, soot, asbestos, lead, PCBs, dioxins, pesticides

• EPA Standard: 50 ug/m3 (annual mean)

SulfurDioxide(SO2)•  Properties: colorless gas with irritating odor •  Effects: produces acid rain (H2SO4),

breathing difficulties, eutrophication due to sulfate formation, lichen and moss are indicators

•  Sources: burning high sulfur coal or oil, smelting or metals, paper manufacture

•  Class: sulfur oxides •  EPA Standard: 0.3 ppm (annual mean)

VOCs(Vola=leOrganicCompounds)

� Proper&es:organiccompoundsthatevaporateeasily,usuallyaroma)c

� Effects:eyeandrespiratoryirritants;carcinogenic;liver,CNS,orkidneydamage;damagesplants;loweredvisibilityduetobrownhaze;globalwarming

� Sources:vehicles(largestsource),evapora)onofsolventsorfossilfuels,aerosols,paintthinners,drycleaning

� Class:HAPs(HazardousAirPollutants)•  Methane•  Benzene•  Chlorofluorocarbons(CFCs),etc.

� Concentra)onsindoorsupto1000xoutdoors•  600milliontonsofCFCs

CleanAirAct

•  Originally signed 1963 – States controlled standards

•  1970 – Uniform Standards by Federal Govt. �  Nat’l Ambient Air Quality Standards (NAAQS) for

6 pollutants

– Criteria Pollutants •  Primary – Human health risk •  Secondary – Protect materials, crops, climate,

visibility, personal comfort

FactorsAffec)ngAirPollu)on� Precipitation and sea spray

� move/transfer pollutants, react with pollutants

� Wind � move/transfer pollutants

� Buildings and mountains � trap pollutants

� High temperatures � increases reaction rates

� Grasshopper effect – Movement of pollutants from warmer regions

to colder regions (i.e.: the poles) via a process similar to distillation. Mainly POPs, DDT, PCBs (semi-volatile chemicals). Explains why indigenous people of the Arctic have some of the highest concentrations of POPs in their body tissues.

6.2 – PHOTOCHEMICAL SMOG

PhotochemicalSmogForma)on

Time Description

6 - 9 am Rush hour: N2 + O2 -> 2NO

9 - 11 am NOs and UV: 2NO + O2 -> 2NO2 (brown air smog)

11 am - 4 pm

Increase sun intensity (UV): NO2 -> NO + O yields O2 + O -> O3 and 3NO2 + H2O -> 2HNO3 + NO

11 am - 4 pm

NO2 + VOCs (gasoline and natural sources like trees)-> PANs (peroxyacyl nitrates)

4 pm - Sunset

O3 production halted; Net Result: NO + VOCs + O2 + UV -> O3 +PANS

6.3 – THERMAL INVERSION

6.7 – ACID RAIN

Forma)onofIndustrialSmog

Burning of fossil fuels produces: 1.  Carbon

1. C + O2 -> CO2 & 2C + O2 -> 2CO 2. Unburned C ends up as soot

2.  Sulfur 1. S + O2 -> SO2 2. SO2 + O2 -> SO3

3. SO3 + H2O -> H2SO4 (acid rain) 4. H2SO4 + NH3 -> (NH4)2SO4 (gray air)

pHandAcidRainForma)on•  PurewaterhasapHof7.0–  NormalrainisslightlyacidicandhasapHofabout5.6

•  AnyrainfallhasapHvaluelessthan5.6isdefinedasacidrain

� Carbon: •  CO2 + H2O à H2CO3 (carbonic acid)•  Major implications in the marine environment (ocean

acidification)� Sulfur•  SO2 + H2O à H2SO3 (sulfurous acid)� Nitrogen•  NO2 + H2O à HNO2 (nitrous acid) + HNO3 (nitric acid)

Wind

Transformation to sulfuric acid (H2SO4)

and nitric acid (HNO3)

Nitric oxide (NO)

Acid fog

Ocean

Sulfur dioxide (SO2) and NO

Windborne ammonia gas and particles of cultivated soil partially neutralize acids and

form dry sulfate and nitrate salts

Dry acid deposition

(sulfur dioxide gas and particles

of sulfate and nitrate salts)

Farm

Lakes in deep soil

high in limestone are buffered

Lakes in shallow soil low in limestone become acidic

Wet acid deposition (droplets of H2SO4 and HNO3 dissolved in rain

and snow)

Acidic Precipitation

AcidDeposi)on?Pollu)onComingBacktoEarth

•  Respiratorydiseases•  Toxicmetalleaching

(Al3+,Mg2+)•  Damagetostructures

(esp.CaCO3)•  Acidshock•  Decreasedproduc)vity

offisheries,forestsandfarms

AcidDeposi)onSolu)ons

•  1990 amendments to Clean Air Act to reduce acid deposition

•  Politics •  Lime neutralization

is temporary

6.4 – ATMOSPHERIC CO2 AND PARTICULATES

6.5 – INDOOR AIR POLLUTANTS

6.6 – REDUCTION OF AIR POLLUTANTS

Solu)ons

•  Scrubbers•  Emissionstrading(capandtrade)•  Electrosta)cprecipitators•  Cataly)cconverters•  Vaporrecoverynozzle•  Burncleanerfuel•  Societalchange

CleanAirAct•  1990 version

–  Acid rain, urban smog, toxic air pollutants, ozone depletion, marketing pollution rights, VOC’s

•  1997 version –  Reduced ambient ozone levels –  Cost $15 billion/year -> save 15,000 lives –  Reduce bronchitis cases by 60,000 per year –  Reduce hospital respiratory admission 9000/year

6.8 – NOISE POLLUTION

Noisepollu)on

•  Effect on humans –  Physiological

stress and hearing loss

•  Effect on ecological systems –  Stress, changes

in migration, inability to communicate