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Jason D. Surratt

Trees, Volatile Organic Compounds, and Fine Organic Aerosol Formation: Implications for Air Quality, Climate and Public Health in the Southeastern U.S. Jason D. Surratt Department of Environmental Sciences and Engineering, Gillings School of Global Public Health

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Jason D. Surratt

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  1. Trees, Volatile Organic Compounds, and Fine Organic Aerosol Formation: Implications for Air Quality, Climate and Public Health in the Southeastern U.S. Jason D. Surratt • Department of Environmental Sciences and Engineering, Gillings School of Global Public Health Air Quality Concerns in a Changing Climate: Professional Development Workshop for Teachers Saturday, September 13, 2014

  2. Research Questions We are Currently Addressing • What are the exact environmental conditions (e.g., seed aerosol compositions, • acidities, RH) that lead to SOA from reactive uptake of isoprene-derived epoxides in • the S.E. USA? • What are the potential effects of this SOA type on climate (brown carbon?)? • What are the spatial and temporal variations of SOA formation from isoprene-derived • epoxides in the S.E. USA? • What are the exact kinetics of reactive uptake of isoprene-derived epoxides leading • to SOA formation? • What are the potential effects of isoprene-derived SOA on human health?

  3. My Group’s CurrentResearchApproach UNC 120-m3 Gillings Outdoor Smog Chamber UNC 274-m3 DualOutdoor Smog Chamber UNC 10-m3 Indoor Smog Chamber

  4. Organic Synthesis to Confirm Role of IEPOX and MAE in Isoprene SOA Formation – 1H NMR Data • Details of synthesis for epoxides and cis/trans-3-MeTHF-3,4-diols have been published • GC/MS and LC/ESI-MS confirm high-purity standards (>99%) • 2-methyltetrols have been synthesized by hydrolysis ofd-IEPOX; 2-methylclyceric acid has been • recently synthesized by dihydroxylation of 2-methyl-acrylic acid [Lin et al., 2012, ES&T; Zhang et al., 2012, ACP; Lin et al., PNAS]

  5. Controlled Indoor Smog Chamber Experiments Experimental conditions Temp: 23-25°C, RH: <10% (Dry) and ~50-60% (Wet) 1. Introduce seed aerosols Nebulizer Acidic seed: MgSO4+H2SO4 Neutral seed: (NH4)2SO4 On-line aerosol size measurements 3. Collect filters (off-line aerosol product analysis) Manifold Heated nitrogen 10-m3 indoor flexible smog chamber 2. Introduce gas-phase synthetic epoxide GC/MS LC/DAD-ESI-HR-QTOFMS ACSM & HR-ToF-AMS FTIR UV-Vis [Lin et al., 2012, ES&T; Lin et al., 2013, PNAS; Lin et al., 2014, ES&T. under review]

  6. Controlled Indoor Smog Chamber Experiments Experimental conditions Temp: 23-25°C, RH: <10% (Dry) and ~50-60% (Wet) 1. Introduce seed aerosols Nebulizer Acidic seed: MgSO4+H2SO4 Neutral seed: (NH4)2SO4 On-line aerosol size measurements 3. Collect filters (off-line aerosol product analysis) Manifold Heated nitrogen 10-m3 indoor flexible smog chamber 2. Introduce gas-phase synthetic epoxide GC/MS LC/DAD-ESI-HR-QTOFMS ACSM & HR-ToF-AMS FTIR UV-Vis [Lin et al., 2012, ES&T; Lin et al., 2013, PNAS; Lin et al., 2014, ES&T. under review]

  7. Controlled Indoor Smog Chamber Experiments Experimental conditions Temp: 23-25°C, RH: <10% (Dry) and ~50-60% (Wet) 1. Introduce seed aerosols Nebulizer Acidic seed: MgSO4+H2SO4 Neutral seed: (NH4)2SO4 On-line aerosol size measurements Reactive uptake 3. Collect filters (off-line aerosol product analysis) Manifold Gas phase Aerosol phase Heated nitrogen 10-m3 indoor flexible smog chamber GC/MS LC/DAD-ESI-HR-QTOFMS ACSM & HR-ToF-AMS FTIR UV-Vis 2. Introduce gas-phase synthetic epoxides [Lin et al., 2012, ES&T; Lin et al., 2013, PNAS; Lin et al., 2014, ES&T. under review]

  8. Typical SOA Growth from IEPOX More gas-phase epoxides are converted to particle mass under acidic conditions Chamber pre-seeded (Step 1) [Lin et al., 2012, ES&T] (Step 2) Inject gas-phase IEPOX

  9. Extract filters with 20 mL CH3OH Aerosol Composition Analyses • Concentrate the extracts under nitrogen dryer • Reconstitution in 150 μL H2O/CH3OH (1:1) with 0.1% acetic acid • Trimethylsilylation with BSTFA and pyridine • GC/MS Analysis • LC/ESI-HR-Q-ToFMS Analysis

  10. Acid-Catalyzed Enhancement of SOA Tracers GC/MS Data: LC/ESI-MS Data: m/z262 = 3-methyltetrahydrofuran-3,4-diols m/z231 = C5-alkene triols m/z219 = [Lin et al., 2012; ES&T] 2-methyltetrols IEPOX-SOA tracers are significantly enhanced in the presence of acidified sulfate seed aerosols m/z335 = IEPOX-derived dimer m/z215 = Effects of acid-catalyzed enhancement on ambient SOA formation remain unclear IEPOX-derived organosulfate m/z333 = Tracers account for ~ 60-90% of mass, depending on conditions

  11. Comparison of SOA mass growthfrom IEPOX uptake onto MgSO4 vs. (NH4)2SO4 seed aerosols • Same amount of initial seed (~40-50 g m-3) and IEPOX (~300 ppb) injected in each experiment • Aerosol acidifiedby adding additional 0.06 M H2SO4 into seed solutions • Conclusion: Aerosol acidity (and to some extent RH) critical in promoting IEPOX SOA formation Why brown carbon only in the dry MgSO4 + H2SO4 seed experiment? [Limbeck et al., 2003, GRL] [Lin et al., 2014, under review]

  12. UV-Vis Indicates Browning of IEPOX-Derived SOA Formed from Dry Acidified MgSO4 Aerosol {MAC}290-700nm= 344 (cm2 g-1) Consistent with other SOA types measured by Updyke et al. (2012, Atmos. Environ.); they Observed {MAC} between 50-500 cm2 g-1 for other biogenic SOA with NH3 present [Lin et al., 2014, under review]

  13. Chemical Characterization of Non-Brown Carbon OligomersFrom IEPOX Multiphase Chemistry Tandem MS2 ofm/z495 (1 DBE Oligomer): [Lin et al., 2014, under review]

  14. Chemical Characterization of Brown Carbon From IEPOX Multiphase Chemistry Tandem MS2 ofm/z569 (10 DBE Oligomer): Note that m/z83 is protonated 3-methylfuran [Lin et al., 2014, under review]

  15. Summary of Non-Brown Carbon and Brown CarbonOligomers from Laboratory Studies Non-Brown Carbon Oligomers Brown Carbon Oligomers in PM2.5 from YRK, GA: [Lin et al., 2014, under review]

  16. Tentatively Proposed Mechanism for Brown Carbon Oligomer Formation We propose that IEPOX oligomers with low DBEscyclodehydrate; this alone cannot explain the higher DBE oligomers Additional DBEs gained by dehydrative loss of ether oxygens leading to C-C coupled 5-membered rings (ex., > 3 DBEs) Dehydration of ethers has been documented to occur both under strong acid conditions and on coordination of ethers to metal ions (Mn+): [Lin et al., 2014, under review]

  17. Bulk Solution Experiments with Synthetic Standards Provide Insights into Browning 1 2 3 Synthetic standards (500 ug; solvent dried off) + H2SO4 (100 ul): 4 5 1. cis-β-IEPOX +H2SO4 2. trans-β-IEPOX +H2SO4 3. trans-3-MeTHF-3,4-diols +H2SO4 4. cis-3-MeTHF-3,4-diols +H2SO4 5. MAE +H2SO4 • Notably, 2-methyltetrol &2-methylglyceric acid standards in presence of concentrated • H2SO4do NOT yield brown carbon. • However, isomeric 3-MeTHF-3,4-diols yields brown carbon, indicating that their further reaction • might have role or share similar pathway • Could the isomeric 3-MeTHF-3,4-diols observed in ambient aerosols serve as tracers for • browning and is this relevant to ambient aerosol?

  18. Ambient Sampling Sites in S.E. USA Downwind Urban Site: Look Rock (LRK), TN 2013 Urban Sites: Atlanta (JST), GA 2011-2012 & 2014 Birmingham (BHM), AL 2013 Rural Sites: Yorkville (YRK), GA 2010 Centerville (CTR), AL 2013

  19. Conditional Sampling of PM2.5 at Yorkville, GA [Zhang et al., 2012, ACP] • Rural site within the SEARCH network • High isoprene emissions • Influenced by anthropogenic activities • SO2from local coal-fired power plants: • ≥ 0.50 ppbv (high) and ≤ 0.25 ppbv (low) • NH3 from local poultry operations: • ≥ 2 ppbv (high) and ≤ 1 ppbv (low) High Low Two high-volume samplers operated side by side

  20. Field Observations Match Chamber Samples Yorkville, GA Chamber samples 3-methyltetrahydrofuran-3,4-diols C5-alkene triols 2-methyltetrols • dimers [Lin et al., 2012, ES&T; Lin et al., 2013; ACP]

  21. Atmospheric Abundance of IEPOX-Derived SOA atYorkville, GA During Summer NH3 conditions (07/29/10-08/06/10) SO2 conditions (06/25/10-07/14/10) Paired t-test (n=9); p= 0.830 Paired t-test (n=16); p= 0.012* No statistical significance for NH3 conditional samples More IEPOX SOA tracers measured under high-SO2 conditions; weakly acid [Lin et al., 2013, ACP]

  22. Real-Time Measurements in S.E. USA Also Show Importance of Aerosol from Isoprene Epoxides Apply Positive Matrix Factorization (PMF) to Organic Mass Spectra to Obtain Sources [Budisulistiorini et al., 2013, Environ. Sci. Technol.] What are the diurnal variations of these sources?

  23. Chemical Characterization of Look Rock Organic Aerosol During SOAS 2013

  24. BVOC Emissions and Certain Oxidation Products Average Diurnal Profiles PTR-MS Data Indicate isoprene > monoterpenes

  25. PM1 Chemical Composition and Size Distribution During SOAS at Look Rock 2013

  26. ACSM OA Source Apportionment During SOAS At Look Rock 2013 Fraction of IEPOX-OA of similar magnitude as what we have observed in downtown Atlanta, GA [Budisulistiorini et al., 2013, ES&T]

  27. Isoprene-Derived SOA Tracers From Off-line Chemical Analyses vs. ACSM IEPOX-OA Factor IEPOX-derived SOA Tracers correlate strongly (R2 ~ 0.8) only with IEPOX-OA PMF Factor! IEPOX Tracers Account for Upwards of 25% of the total Fine Organic Mass!!

  28. Understanding the Biological Effects of Isoprene-Derived SOA Exposed to Human Bronchial Epithelial Cells Electrostatic Aerosol In Vitro Exposure System (EAVES): Injection: 5 ppmv isoprene 400 ppbv NO 100 mg m-3 MgSO4 + H2SO4 [de Bruijne et al., 2009, Inhal. Tox.] [Lichtveld et al., 2012, ES&T]

  29. Model Predictions and Chemical Measurements Indicate IEPOX-derived SOA will dominate the Exposure to BEAS-2B Cells Chamber Sample EAVES Exposure Yorkville, GA • EAVES operated 1hr • Cells transferred to clean media • Cell material collected 9hr post-exposure

  30. Gene Expression Measured by qRT-PCR Indicates Exposure of BEAS-2B Cells to 20mg m-3 Isoprene-derived SOA Enhances Markers for Inflammation and Oxidative Stress Inflammation Marker Oxidative Stress Marker These results suggest that it is potentially important for field studies like SOAS to improve our fundamental understanding of isoprene SOA formation

  31. Implications & Conclusions • IEPOX-derived epoxides appears to be major source (~1/3) of fine organic • aerosol mass in both rural and urban areas of S.E. U.S. during summer • Brown carbon from IEPOX occurs in the laboratory due to light-absorbing • oligomer formation; results from field suggest some could be there but • further work is needed to determine how important (abundant) in order to fully • assess impact on radiative budgets. • IEPOX-derived SOA appears to yield potential inflammation and oxidative • stress in human bronchial epithelial cells; more work is underway • systematically examining gene arrays and investigating individual SOA • components • Importantly, further reductions in sulfate (SO2) emissions will likely decrease • the amount of fine organic aerosol from isoprene in the S.E. USA region

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