CHAPTER 2CHAPTER 2

EXAMPLES EXAMPLES

OF AIR POLLUTION PROBLEMSOF AIR POLLUTION PROBLEMS

EXAMPLES EXAMPLES

OF AIR POLLUTION PROBLEMSOF AIR POLLUTION PROBLEMS

• Classical urban Air PollutionClassical urban Air Pollution

• Modern urban Air PollutionModern urban Air Pollution

• Acid rainAcid rain

• Greenhouse effectsGreenhouse effects

• Ozone depleptionOzone depleption

Classical urban Air PollutionClassical urban Air Pollution

• "smog" = smoke + fog (London, 1952)"smog" = smoke + fog (London, 1952)

• sulphur, soot, water vapour => acid sulphur, soot, water vapour => acid aerosolaerosol

Modern urban Air PollutionModern urban Air Pollution

• Stagnant airStagnant air• Continuing emissionsContinuing emissions• "summer" (photochemical) smog:"summer" (photochemical) smog:

NO, NO2, CxHy, UV-rad: ==> ONO, NO2, CxHy, UV-rad: ==> O33

(reactions worked out on blackboard)(reactions worked out on blackboard)• Winter (cold weather) smog:Winter (cold weather) smog:

fine or ultra-fine particles ==> health effectsfine or ultra-fine particles ==> health effects• Mixture is different in different citiesMixture is different in different cities• Traffic important sourceTraffic important source• Toxicological mechanism still unknownToxicological mechanism still unknown• Health effects even at low concentrationsHealth effects even at low concentrations

(from 40 mg/m(from 40 mg/m33?)?)

Acid RainAcid Rain

DryDry and and WetWet depositiondeposition of of (potentially) acidifying(potentially) acidifying substances substances onto the earth's onto the earth's surface.surface.

* so: not just * so: not just rainrain!!

ACID RAIN FORMATION

Acid Rain ProcessAcid Rain Process

Acidifying compoundsAcidifying compounds

• SOSO22 and NOx (direct) and NOx (direct) H H22SOSO44 and and HNO3HNO3

• NHx (indirect by nitrification):NHx (indirect by nitrification):

(NH(NH44))22SOSO44 + 4O + 4O22 2HNO 2HNO33-- + +

HH22SOSO44 + 2H + 2H22O O

Effects of acid rainEffects of acid rain

• Plant injury (direct by SOPlant injury (direct by SO22, NH, NH33, (NO), NO, (NO), NO22))

• Change in mineral balance in soils (=> Change in mineral balance in soils (=> heavy metals)heavy metals)

• Acidification of watersAcidification of waters

Effects of acid rains

DepositionDeposition

• drydry deposition (direct from air to surface): deposition (direct from air to surface): – proportional to concentrationproportional to concentration– important close to source (areas)important close to source (areas)

• wetwet deposition (by rain, snow, hail, etc.) deposition (by rain, snow, hail, etc.)– rain cloud "washes" air massrain cloud "washes" air mass– origin of air mass importantorigin of air mass important– only when it rainsonly when it rains

• occultoccult deposition (direct from fog or clouds) deposition (direct from fog or clouds)– only in areas with many fogs (mountainous areas)only in areas with many fogs (mountainous areas)

Critical loads conceptCritical loads concept

That amount of (total) deposition that an That amount of (total) deposition that an ecosystem can "handle" for a prolonged ecosystem can "handle" for a prolonged timetime

Geographic distribution of acid rainGeographic distribution of acid rain

Greenhouse effectsGreenhouse effects

Radiation balance of the earthRadiation balance of the earth (figure 2.2) (figure 2.2)• Incoming solar radiation (short wave)Incoming solar radiation (short wave)• Outgoing black-body radiation (long wave - Outgoing black-body radiation (long wave -

infrared)infrared)• (figure)(figure)• Temperature of earth is equilibriumTemperature of earth is equilibrium• Natural greenhouse effectNatural greenhouse effect• Change in any term changes temperatureChange in any term changes temperature

Projected temperature changeProjected temperature change

Radiative forcingRadiative forcing

Any change in the balance Greenhouse Any change in the balance Greenhouse gases: COgases: CO22, CH, CH44, N, N22O, CFC's, (OO, CFC's, (O33))

Increasing concentrations (figures)Increasing concentrations (figures)

=> => enhancedenhanced greenhouse effect greenhouse effect

Factors of importanceFactors of importance

• Concentration increase rateConcentration increase rate

• Atmospheric lifetimeAtmospheric lifetime

==> ==> Global warming potentialGlobal warming potential

(Table 2.2 and 2.3)(Table 2.2 and 2.3)

Ozone depletionOzone depletion

• Ozone layer (20 - 50 km height; figure)Ozone layer (20 - 50 km height; figure)• Absorbs UV-B (figure 2.3)Absorbs UV-B (figure 2.3)• Thickness of ozone layerThickness of ozone layer

30 km but 30 km but 3 mm3 mm pure O pure O33 at 100 hPa! at 100 hPa!

3 O3 O22 2 O2 O33 (UV-B radiation needed)(UV-B radiation needed)

NONO22 NO + ONO + O (UV-A radiation)(UV-A radiation)

• Four groups of substances interfere (eq. 2.15 - Four groups of substances interfere (eq. 2.15 - 2.22)2.22)

Ozone holeOzone hole

due to heterogeneous reactions:due to heterogeneous reactions:

• in Antarctic winter Polar Stratospheric in Antarctic winter Polar Stratospheric CloudsClouds

• collect chlorine compoundscollect chlorine compounds

• set free in Spring (September)set free in Spring (September)

• eq. 2.17eq. 2.17

Health Effects

Thank youThank you