1 / 30

FINE AEROSOL COMPOSITION IN NORTH AMERICA

Annual mean PM 2.5 concentrations (NARSTO, 2004). FINE AEROSOL COMPOSITION IN NORTH AMERICA. Current air quality standard is 15 m g m -3. SULFATE-NITRATE-AMMONIUM AEROSOLS IN U.S. (2001). Sulfate. Nitrate. Ammonium. Highest concentrations in industrial Midwest (coal-fired power plants).

hope-meyers
Download Presentation

FINE AEROSOL COMPOSITION IN NORTH AMERICA

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Annual mean PM2.5 concentrations (NARSTO, 2004) FINE AEROSOL COMPOSITION IN NORTH AMERICA Current air quality standard is 15 mg m-3

  2. SULFATE-NITRATE-AMMONIUM AEROSOLS IN U.S. (2001) Sulfate Nitrate Ammonium Highest concentrations in industrial Midwest (coal-fired power plants) Acidity

  3. Ammonia and NOx emissions in the US (2006) Zhang et al. [2012]

  4. EPA network data for 2006 HNO3 (g) NO3- (aerosol) Distributions of HNO3 (g) and NO3- (aerosol) in surface air Zhang et al. [2012]

  5. Thermodynamic rules: Sulfate always forms an aqueous aerosol Ammonia dissolves in the sulfate aerosol totally or until titration of acidity, whichever happens first Nitrate is taken up by aerosol if (and only if) excess NH3 is available after sulfate titration HNO3 and excess NH3 can also form a solid aerosol if RH is low Highest concentrations in industrial Midwest (coal-fired power plants) FORMATION OF SULFATE-NITRATE-AMMONIUM AEROSOLS

  6. U.S. SO2 EMISSIONS GLOBAL UNITED STATES Sulfur emissions, Tg a-1 78 8.3

  7. Observation of SO2 point sources in US by OMI oversampling SO2 point sources, 2004-2007 3 km-resolution data enables analysis of SO2 emission trends, SO2 atmospheric lifetime OMI SO2 (3 km oversampling) AQAST PI: De Foy

  8. SAA SO2 columns observed from SCIAMACHY Andreas.Richter@iup.physik.uni-bremen.de

  9. GOME and SCIAMACHY SO2 over China Volcaniceruption • Large increase in SO2 loading observed from 2000 to 2007 Turnover in 2007 • Decrease to 2003 / 2004 levels but now increasing again. • Result of legislation requiring flue-gas desulphurization of power plants • Not all power plants have been equipped other sources are on the rise

  10. Kasatochi eruption as seen in GOME-2 SO2 • After some smaller SO2 emissions, large eruption on August 8, 2008 • SO2 rapidly distributes over the NH • GOME-2 integrated SO2 column indicates more than 1 Tg total SO2 emission Kasatochi volcano Altitude: 314 mLatitude: 52.16°NLongitude: 175.51° W http://www.avo.alaska.edu/

  11. OBSERVED TITRATION OF SO2 BY H2O2 IN CLOUD First aircraft observations by Daum et al. [1984]

  12. WORLDWIDE MEASUREMENTS OF FINE AEROSOL COMPOSITION

  13. BLACK CARBON (BC) ORGANIC CARBON (OC) CARBONACEOUS AEROSOL SOURCES IN THE U.S. 2.7 Tg yr-1 0.66 Tg yr-1 Annual mean concentrations (2001) OC BC Park et al. [2006]

  14. Annual mean concentrations Long-term trends in BC and OC aerosol over the US Observed Model National trends Leibensperger et al. [2011]

  15. RADIATIVE FORCING FROM BLACK CARBON (BC) IPCC [2007]

  16. “BC” or “soot” is optically defined and includes both graphitic elemental carbon (EC) and light-absorbing heavy organic matter BC is emitted by incomplete combustion Freshly emitted BC particle Diesel engines are large BC sources

  17. Atmospheric aging and scavenging of BC coagulation gas condensation Hydrophobic BC resistant to scavenging Hydrophilic BC coated with sulfate, nitrate Aging time scale τ ~ 1 d Scavenging Emission Implications for BC export from source continents: long-range transport aging FREE TROPOSPHERE BOUNDARY LAYER Hydrophobic BC aging scavenging OCEAN

  18. BC and OC aerosol during ARCTASaircraft campaign (spring 2008) Wang et al. [2011]

  19. ORGANIC AEROSOL IN STANDARD GEOS-Chem MODEL Global sources in Tg C y-1 20 K OH, O3,NO3 SOG SOA VOC secondary formation POA isoprene terpenes oxygenates… alkanes alkenes aromatics… alkenes aromatics oxygenates… 20 100 30 700 50 vegetation fuel/industry open fires fuel/industry open fires VOC EMISSION PRIMARY EMISSION SOA ≡ secondary organic aerosol POA ≡ primary organic aerosol

  20. TERPENES Terpenes are biogenic hydrocarbons produced in plants by combination of isoprene units (C5H8) • Monoterpenes: C10H16 β-pinene • Sesquiterpenes: C15 H24 δ-cadinene

  21. SOA MODELING AS GAS-AEROSOL EQUILIBRIUM VOC oxidation generates semi-volatile products: …which then partition between the gas and aerosol phase: Mo is the mass concentration of pre-existing organic aerosol where the partitioning coefficient is given by …and is a strong function of temperature. Values of a and p0 are fitted to smog chamber data Chung and Seinfeld, 2002

  22. Partition semi-volatile VOCs (SVOCs) between aerosol and gas: SOA MODELING USING VOLATILITY BASIS SETS Aerosol fraction for SVOCi Define SVOCs by their stability class: Donahue et al. [2006]

  23. SOA VOLATILITY BASIS SET: EFFECT OF DILUTION Donahue et al. [2006]

  24. SOA VOLATILITY BASIS SET: CHEMICAL AGING As VOCs go through successive oxidation steps, products become more oxygenated and less volatile, but eventually smaller and more volatile Donahue et al. [2006]

  25. IMPLEMENTING OC VOLATILITY CLASSES IN GEOS-Chem Mean wintertime OC concentrations: IMPROVE data shown as circles “Primary” OC is actually semi-volatile Combustion Pye and Seinfeld [2010]

  26. POSSIBLE MECHANISMS FOR DICARBONYL SOA FORMATION GAS AQUEOUS Schweitzer et al. [1998] Kalberer et al. [2004] Liggio et al. [2005a,b] Hastings et al. [2005] Zhao et al. [2006] Loeffler et al. [2006] glyoxal Oligomers oligomerization oligomerization KH* ~ 105 M atm-1 Altieri et al. [2006, 2008] oxidation methylglyoxal OH Organic acids Ervens et al. [2004] Crahan et al. [2004] Lim et al. [2005] Carlton et al. [2006, 2007] Warneck et al. [2005] Sorooshian et al. [2006, 2007] KH* ~ 103 M atm-1

  27. GLYOXAL/METHYLGLYOXAL FORMATION FROM ISOPRENE 6% 25% GEOS-Chem mechanism based on MCM v3.1 Fu et al. [JGR, 2008] molar yields

  28. Van Krevelen diagram for chemical aging of organic material Heald et al. [2010]

  29. Van Krevelen diagram: application to organic aerosol -1 slope suggests aging by adding of –COOH functionalities Heald et al. [2010]

More Related