CHAPTER 2 EXAMPLES OF AIR POLLUTION PROBLEMS. EXAMPLES OF AIR POLLUTION PROBLEMS Classical urban Air PollutionClassical urban Air Pollution Modern urban

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<ul><li><p>CHAPTER 2EXAMPLES OF AIR POLLUTION PROBLEMS </p></li><li><p>EXAMPLES OF AIR POLLUTION PROBLEMS Classical urban Air PollutionModern urban Air Pollution Acid rainGreenhouse effectsOzone depleption</p></li><li><p>Classical urban Air Pollution"smog" = smoke + fog (London, 1952)sulphur, soot, water vapour =&gt; acid aerosol</p></li><li><p>Modern urban Air PollutionStagnant airContinuing emissions"summer" (photochemical) smog:NO, NO2, CxHy, UV-rad: ==&gt; O3(reactions worked out on blackboard)Winter (cold weather) smog:fine or ultra-fine particles ==&gt; health effectsMixture is different in different citiesTraffic important sourceToxicological mechanism still unknownHealth effects even at low concentrations(from 40 mg/m3?)</p></li><li><p>Acid RainDry and Wet deposition of (potentially) acidifying substances onto the earth's surface.</p><p>* so: not just rain!</p></li><li><p>ACID RAIN FORMATION</p></li><li><p>Acid Rain Process </p></li><li><p>Acidifying compoundsSO2 and NOx (direct) H2SO4 and HNO3</p><p>NHx (indirect by nitrification):(NH4)2SO4 + 4O2 2HNO3- +H2SO4 + 2H2O </p></li><li><p>Effects of acid rainPlant injury (direct by SO2, NH3, (NO), NO2)Change in mineral balance in soils (=&gt; heavy metals)Acidification of waters</p></li><li><p>Effects of acid rains</p></li><li><p>Depositiondry deposition (direct from air to surface): proportional to concentrationimportant close to source (areas)wet deposition (by rain, snow, hail, etc.)rain cloud "washes" air massorigin of air mass importantonly when it rainsoccult deposition (direct from fog or clouds)only in areas with many fogs (mountainous areas) </p></li><li><p>Critical loads concept</p><p>That amount of (total) deposition that an ecosystem can "handle" for a prolonged time</p></li><li><p>Geographic distribution of acid rain</p></li><li><p>Greenhouse effectsRadiation balance of the earth (figure 2.2)Incoming solar radiation (short wave)Outgoing black-body radiation (long wave - infrared)(figure)Temperature of earth is equilibriumNatural greenhouse effectChange in any term changes temperature</p></li><li><p>Projected temperature change</p></li><li><p>Radiative forcingAny change in the balance Greenhouse gases: CO2, CH4, N2O, CFC's, (O3)Increasing concentrations (figures)=&gt; enhanced greenhouse effect</p></li><li><p>Factors of importanceConcentration increase rateAtmospheric lifetime==&gt; Global warming potential (Table 2.2 and 2.3)</p></li><li><p>Ozone depletionOzone layer (20 - 50 km height; figure)Absorbs UV-B (figure 2.3)Thickness of ozone layer30 km but 3 mm pure O3 at 100 hPa!3 O22 O3 (UV-B radiation needed)NO2 NO + O(UV-A radiation)Four groups of substances interfere (eq. 2.15 - 2.22)</p></li><li><p>Ozone holedue to heterogeneous reactions:in Antarctic winter Polar Stratospheric Cloudscollect chlorine compoundsset free in Spring (September)eq. 2.17</p></li><li><p>Health Effects </p></li><li><p>Thank you</p></li></ul>