Envr 890: Lecture 1

1. Envr 890: Lecture 1 http://www.unc.edu/courses/2008fall/envr/890/001/ Department of Environmental Science and Engineering UNC, Chapel Hill

2. Class Objective:Begin Development of a Secondary Organic Aerosol mechanism for Isoprene and learn how to run the ESE Aerosol Smog Chamber in Pittsboro C=C-C=C H H H H H CH3

3. Class Objective:Begin Development of a Secondary Organic Aerosol mechanism for Isoprene and learn how to run the ESE Aerosol Smog Chamber in Pittsboro • What are organic aerosols? • What fraction of the aerosol environment are they? • What do we need to build a chemical mechanism? • What do we need to measure? • Start collecting papers on Isoprene and SOA formation

4. Aerosol Associated Organics:An Historical Perspective • Secondary organic aerosols how much is out there • Modeling approaches for SOA • Analysis • Sampling • Where do we go from here

7. What should you get from these lectures? • What are SOA • Why are they important? • How much is there? • Are they a constant fraction of TSP or the organic fraction? • How are they measured? • How are they formed? Which compounds are involved? • How do we model them?

8. What should you get from these lectures? • How do we model them? • What is equilibrium partitioning • What is a numerical solution approach • How does this differ from a chemical mechanism approach? • What are vapor pressure and activity coefficients? • Which compounds contribute to SOA? • What are two major unknowns in current models?

9. Reasons to study secondary organic aerosol formation (SOA) • Global model calculations are sensitive to fine particles in the atmosphere • Biogenic SOA particles serve as sites for the condensation of other reacted urban organics • The result is haze and visibility reductions • Do SOA push us beyond the AAQS PM2.5 standard? Are SOA more/less toxic than primary particle emissions?

10. red= +2oC, yellow=+3 oC, blue = +10C

11. red= +2oC, yellow=+3 oC, blue = +10C

12. Thailand

15. Beijing, in July 1987

16. Beijing, April 2006

17. A sunny day in Beijing, April 2006

18. Air Pollution in NorthernThailand ChiangMai is similar to Los Angeles in the US; it is surrounded by mountains

19. Mastery of Fire • 400,000 years ago in Europe • 100,000 years ago in Africa M. N. Cohne, 1977

20. From a global perspective, fire results in huge emissions of black carbon into the atmosphere • Biomass burning 6x1012 g • Fossil fuel burning 7x1012 g • Biogenic aerosols 13-60x1012g

21. What is the Composition of Particulate Matter???

22. Composition of LA Particulate Matter (adjusted for smoggy days)((Rogge &Cass et al, 1993, Turpin et al, 1991) Percent mass

23. H2SO4 Semi-volatile organics H2O What are Organic Aerosols? organic liquid layer inner solid core inorganic/carbon

24. What fraction of ambient Particulate matter is organic???

26. Fresh wood soot (0.5 m scale)

27. Benzo[ghi]perylene Benzo[a]fluorene Naphthalene Associated with combustion emissions Are PAHs

28. Professor Grimmer fractionated different exhaust extracts

29. uv orfluorescencedetector Total HPLC Total hexane MeCl2 ACN PAH 2&3 rings PAHs>3 rings Total-PAHs

30. painted on the skin of mice • implanted in the lungs of rats

32. Total minus the PAH fraction

35. In the 1980s many studies were showing that combustion particle extracts expressed Ames bacterial mutagenicityAtmospheric reactions and aging could alter the mutagenic responses of combustion particles

36. 700 600 aged wood smoke +O 3 +NO 2 500 /plate 400 300 aged wood smoke +NO 2 revertants 200 fresh wood smoke 100 0 0 100 200 300 400 500 600 ug extract/plate Kamens et al, ES&T, 1984,1985

37. NO2 Nitro-PAH were implicated in giving rise to mutagenic increases

38. OH + OH H + NO2 NO2 H OH H NO2 + H2O 2-nitrofluoranthene Gas Phase PAH reactions NPAH(Arey and Atkinson et al.) Fluoranthene

39. NO2 Kinetic models at UNC predicted nitro-PAH in the particle phase from gas phase PAH reactions in sunlight (Fan et al., Atmos. Envir.1995, 1996)

40. Do other atmospheric reactions bring about the production of new aerosol matter????

41. Secondary organic aerosols(SOA) are organic compounds thatreside in the aerosol phase as a result of atmospheric reactions that occur in either thegas or particle phases.

42. Do we see any chemical evidence for SOA formation?

43. F.W.Wentpublished papers on biogenic emissions from vegetation over 40 years ago. He posed the question, “what happens to the17.5x107 tonsof terpene-like hydrocarbons or slightly oxygenated hydrocarbons once they are in the atmosphere each year?”

44. Went suggests that terpenes are removed from the atmosphere by reaction with ozone attempts to demonstrate “blue haze” formation

45. Went suggests that terpenes are removed from the atmosphere by reaction with ozone attempts to demonstrate “blue haze” formation by adding crushed pine or fir needles to a jar with dilute ozone.

46. Over a eucalyptus forest in Portugal Kavouras et al. (1998,1999) show evidence for terpene reaction products in aerosols

47. a-pinene b-pinene Terpenes products Kavouras et al, 1998 ng m-3 pinic acid 0.4 - 85 pinonic acid 9 - 141 norpinonic acid 0.1 - 38 Pinonaldehyde 0.2 - 32 Nopinone 0.0 - 13

48. Turpin and co-workers • In the LA area (estimated on smoggy days from OC /EC ratios), as much as 50 - 80% of the aerosolorganic carbon comes from secondary aerosol formation (1984 and 1987 samples) • In Atlanta in 1999, SOA averaged 46% of the total OC but with highs of 88%

49. Turpin Approach for SOA formation • The primary aerosol elemental carbon (EC)pri and particle organic content (OC)pri in an un-reacted airshed are measured and a primary ratio of {OC /EC}pri is determined (Turpin et al for 1984 and 1987 aerosol samples) • Under SOA formation OCtot and ECtot are measured • OCsec= OCtot- OCpri • OCpri = EC {OC/EC} pri • On smoggy days in California ~50 - 80% of the organic carbon comes from secondary aerosol formation

50. Spyros Pandis also recently looked at OC/EC ratios (Pittsburgh area)He estimates that SOA formation can account for 35-50% of the organic carbon