1Reminders:• Reading Chapter 10• Homework #10 due today at 5 pm• Inquire/Inform #2 due today in class • Extra Credit #6 due Friday (in class)• Exam #3 details will be given on Wednesday.Æ The exam is in class the Wednesday after break (Dec. 3)• Deadline for changing research topics is this Friday.Exam #3 Details…The exam is in class on Wednesday, December 03, 2008. The exam will be open textbook (R&K) and calculators are allowed. You will not be allowed to use other outside notes. Thus, make sure to bring the book and a calculator to the exam! The exam will cover all of the material in Chapters 5, 6, 9, and 10 of the R&K text, homework assignments #8-10, and lecture material through and including Monday, December 1, 2008. The exam problems will be similar to homework assignments, in class worked out problems, and issues discussed in the text or in lecture. A practice exam (and solutions) are available on the web page.Measure of AcidityEach unit is factor of 10 in concentrationH2O+CO2pH value Acid Rain (Wet and Dry Deposition)pH value Typical rainwater is not neutral, but pH = 5.62Adirondack LakesVery poor conditions in the mid-1970’s due to acid rain.1990 Acid Rain Program established under the Clean Air ActNote that some measures are staged and thus only took effect later.For SO2, the program has a mandatory cap on emissions nationwide from electric utilities. These are allocated in terms of allowances which can then be “banked for future use” or sold.For NOx, emission limits are placed for each source type.Read the report carefully and let me know what you find “strange” or “inconsistent” in the scientific presentation…Report highlights some real success in reducing SO2.How would you categorize this graph over the 10 year period?Clicker QuestionA) Not much change in SO2 emission B) An increase in SO2 emission C) A small decrease is SO2 emissionsD) A decrease, punctuated by a significant decease in 1995E) None of the aboveDifferent species affected differently by acidity of the water.There have been substantial reductions in wet sulfate depositions.“In spite of declining emissions and even declining surface water sulfate concentrations in the Adirondacks, lakes in this region are not showing any measurable increase in acid neutralizing capacity.”3Particulates (Aerosols)Particles smaller than about 100 μm (10-4m)Natural sources: wind-blown dust, fog, …Produced during combustion of coalParticles scatter light, but too small to see individuallyAerosolsEPA Study4Particulates (Aerosols)Buoyant force proportionally much larger than for larger particlesSettling velocity < 0.1 m/sParticles remain suspended in the air for daysor longer…Natural Dust StormProblemsParticles scatter sunlight, reduce intensity onthe groundSmallest particles are most likely to enter lungsParticles can pick up sulfates and nitrates…Can be another form of “acid rain”Removing ParticulatesMechanical filtersElectrostatic precipitatorsSmall particles become electrically chargedOften combined with scrubbers for sulfur removalLocal, Regionally, GlobalWorst and Best CitiesLos Angeles: About at legal limitWorst:Beijing, Calcutta: 7 x Los AngelesMexico City: 6 x Los AngelesBangkok, Bombay: 5 x Los AngelesBest:New York, London, Paris: about 50% of Los Angeles5Current SituationSO2 and VOC emissions in United States are down.NOx emissions are still relatively constant.Clicker QuestionIs the Clean Air Act doing enough and fast enough?A) YesB) NoBased on 18 months of Envisat observations, this high-resolution global atmospheric map of nitrogen dioxide pollution makes clear just how human activities impact air quality. Click on image for a zoom. Data are from the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) instrument on Envisat. From European Space AgencyGlobal IssuesOzone layer→Ozone CreationO2+ UV → O + O (1)O + O2→ O3(2)UltraViolet wavelength < 240 nmShorter than UVBCreation of Ozone absorbs UVReaction (1) increases with altitudeReaction (2) decreases with
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