1. 1 Global simulation of glyoxal and methylglyoxal, and implications for SOA Tzung-May Fu, Daniel J. Jacob Harvard University April 11, 2007 Work supported by EPRI Thomas Kurosu, Kelly Chance Harvard/SAO CfA CHOCHO CH 3 C(O)CHO

2. 2 SOA formation through uptake of dicarbonyls CHOCHO SOA Isoprene (350 Tg C yr -1 ), monoterpenes, acetone, MBO, C 2 H 4, C 3 H 6 Reversible? Photolysis Oxidation Deposition [OH] RH pH nuclei Oligomers? organic acids? H* ~ 10 5 C 2 H 2, C 2 H 4, C 3 H 6, aromatics, acetone, glycolaldehyde, hydroxyacetone CH 3 C(O)CHO H* ~ 10 3 OH, O 3, NO 3

3. 3 Is dicarbonyl uptake irreversible? Organic / sulfate [g/g] [Glyx] g = 5 ppb [Liggio et al., 2005b] Irreversible Time   = 2. x 10 3 For [Glyx] g = 0.1 ppb, ∆[Glyx] particle = 3  g m -3 hr -1 [Kroll et al., 2005] Reversible [Glyx] g = 200 ppb K H * = 2.6 x 10 7 M atm -1 For [Glyx] g = 0.1 ppb, [Glyx] particle = 0.003  g m -3 Organic/sulfate [  g  g -1 ]

4. 4 What are the irreversible processes in the aqueous phase? H2OH2O H2OH2O Oligomers + hydrates + H 2 O Kalberer et al. [2004] Liggio et al. [2005] Hastings et al. [2005] Zhao et al. [2006] 1 Organic acids + OH ? Ervens et al. [2004] Lim et al. [2005] Warneck et al. [2005] Sorooshian et al. [2006] 2 Altieri et al. [2006] 3 H* ~ 10 5 H* ~ 10 3

5. 5 Tracers emitted, non-standard –ISOP, MONX, MBO, C 2 H 4, PRPE, C 2 H 2, ACET, HAC, BENZ, TOLU, XYLE, GLYX, MGLY, GLYC, MVK, MACR, PAN, PMN, ACRPAN, ENPAN, GPAN, GLPAN, MPAN, NIPAN Chemistry –New chemical mechanism from MCM v3.1, University of Leeds –JPL 2006 rate constants and photolysis (p-dependent) –Standard SOA from BVOC –Reactive uptake of dicarbonyls by aqueous aerosol and cloud droplets [Liggio et al., 2005b; Zhao et al., 2006] Standard emissions –FF + BF: GEIA + regional –BB: GFED2 –BG: MEGAN Non-standard emissions –FF + BF for C 2 H 2 : Xiao et al. [2007] –FF + BF for C 2 H 4, arom.: RETRO –BB: Scale GFED2 CO w/ EFs –BG: MEGAN Dry/wet deposition: –GLYX, MGLY, GLYC, PANs GEOS-Chem v736 4x5 2005/12 – 2006/11 (GEOS4)

6. 6 New isoprene oxidation – adapted from MCM v3.1 ISOP IALD GLYCMGLY OH, O 3 OH HAC GLYX MVKOHNIALD MVKMACR NO 3 9.8h1h1.5h 2.7h 1.5h0.7h High NO x, no RO 2 recycling ISOP + OH  0.045 GLYX + 0.508 GLYC + 0.233 MGLY + 0.197 HAC + 1.033 CH 2 O 2h1h 0.7h 0.3h Production of glyoxal Larger yield of methgylglyoxal, GLYC, HAC Larger yield of CH 2 O

7. 7 Are the two Isoprene  SOA pathways additive? SOA via partitioning of semi-volatile products from isoprene SOA via irreversible uptake of glyoxal from isoprene Y = 1~2 %at high [NO x ] Y = 3 %at low [NO x ] Y GLYX ~ 10 %at high [NO x ] Y GLYX < 5 %at low [NO x ] Experiments by [Kroll et al., 2006] Mechanism from MCM v3.1 (U of Leeds) Methacrolein is an important intermediate Methyl vinyl ketone is an important intermediate Two pathways of SOA formation from isoprene are additive

8. 8 C 2 H 2 + OH  0.636 GLYX MONX + O 3  0.05 GLYX + 0.05 MGLY MBO + OH  0.63 GLYC + (0.63 ACET) BENZ + OH  0.252 GLYX TOLU + OH  0.162 GLYX + 0.124 MGLY XYLE + OH  0.156 GLYX + 0.230 MGLY Parameterized chemistry (0.16 - 0.29) (0.08 - 0.39) (0.03 – 0.40) (0.03 - 0.18) (0.11 - 0.42) High NO x C 2 H 4 + OH  0.995 [  GLYC + (1-  ) ∙ 2 HCHO + HO 2 ],  = 0.3 ~ 1 C 2 H 4 oxidation – from MCM v3.1

9. 9 @ sfc @ 2 km [ppb] Monthly mean [GLYX], Jul 2006 10 -1 ~ 10 -2 ppb ~ 10 -2 ppb

10. 10 @ sfc @ 2 km [ppb] Monthly mean [MGLY], Jul 2006 10 -1 ~ 10 -2 ppb ~ 10 -2 ppb

11. 11 [ppt] Hourly mean [MGLY], [GLYX] Local time [h] Blodgett Forest, CA Aug-Sep 2000 Spaulding et al. [2003] Tomakomai Forest, Japan Sep 2003 [ppt] Ieda et al. [2006]

12. 12 Comparison with SCIAMACHY [Wittrock et al., 2006] SCIAMACHY GLYX VC (10LT) SCIAMACHY HCHO VC HCHO VC Dec05-Nov06 GLYX VC Dec05-Nov06 (12-15LT)

13. 13 @ surface @ 4.2 km SOA glyx +SOA mgly SOA from isoprene (Y isop = 1~3%) SOA from monoterpenes etc P ~ 6 Tg yr -1 P glyx ~ 12 + 6 Tg yr -1 P mgly ~ 21 + 17 Tg yr -1 [ug m -3 ] P ~ 10 Tg yr -1 [0.1 ug m -3 ] 30%12% 58% 27%23% 50%

14. 14 Conclusions I. Global simulation of glyoxal and methylglyoxal –Model sfc concentration same order as rural measurements –Model glyoxal VC <~ satellite VC measurements –Isoprene oxidation products well simulated w/ new mechanism –Isoprene is the largest source  dicarbonyls in the free troposphere –Direct emissions from biomass burning  large surface concentrations II. Reactive uptake of dicarbonyls is significant SOA source –Produces > 18 Tg yr -1 SOA, comparable to other biogenic SOA sources –SOA from isoprene via glyoxal is independent of SOA from isoprene via semi-volatile gaseous products –Anthropogenic and biomass burning emissions produce significant SOA via uptake of dicarbonyls

15. 15 WHAT DON’T WE UNDERSTAND ABOUT SOA FORMATION? dicarbonyls Oxidation by OH, O 3, NO 3 Direct Emission Terpenes Nucleation or Condensation Aromatics OC Isoprene Cloud Processing FF: 45-80 TgC/yr BB: 10-30 TgC/yr SOA: >20 Tg/yr Fossil Fuel Biomass Burning ANTHROPOGENIC SOURCES BIOGENIC SOURCES Heterogeneous Reactions PRECURSORS CHEMISTRY 1. NOx, SO2/acidity 2. Multi-step oxidation FORMATION PATHWAYS C/o Colette Heald

16. 16 “Reactive uptake of dicarbonyl” is an attractive mechanism, because it … is a sustained SOA source in aged air masses and free troposphere works for both biogenic and anthropogenic precursors takes place rapidly in clouds, consistent with field evidence produces SOA quickly near the source region. Diurnal variations of SOA concentration more similar to measurements with maximum concentration in the afternoon may explain large, heterogeneous source of oxalic acid in aerosols may explain observed oligomers in aerosols

17. 17 Experiments needed to determine … Photolysis quantum yield in the visible band Reversibility of uptake Uptake sensitivity to pH Uptake sensitivity to ionic strength Total mass contribution of oligomers Presence/ID of organic acid hydrate oligomers Consistency with ambient aerosol mass spectra

18. 18 Pabstthum, Germany Jul-Aug 1998 Grossmann et al. [2003] Mexico City Apr 2003 Volkamer et al. [2005b] [ppt] Hourly mean [MGLY], [GLYX] Local time [h]

19. 19 Blodget Forest, CA Aug-Sep 2000 Spaulding et al. [2003] GEOS-Chem Aug-Sep 2006 Local time [h]

20. 20 Isoprene oxidation – GEOS-Chem ISOP IALDMVKMACR GLYCMGLY OH, O 3, NO 3 OH HACGLYX High NO x, no RO 2 recycling ISOP + OH  0.317 GLYC + 0.198 MGLY + 0.158 HAC + 0.969 CH 2 O 2h1h 9.8h1h1.5h 2.7h 0.8h No glyoxal production from isoprene 0.3h

21. 21 ORGANIC CARBON AEROSOL Reactive Organic Gases Oxidation by OH, O 3, NO 3 Direct Emission Fossil Fuel Biomass Burning Monoterpenes, etc Nucleation or Condensation Aromatics ANTHROPOGENIC SOURCES BIOGENIC SOURCES OC FF: 45-80 TgC/yr BB: 10-30 TgC/yr Secondary Organic Aerosol (SOA): 8-40 TgC/yr Goldstein and Galbally [2007] 510-910 TgC/yr *Numbers from IPCC [2001] Global Model Representation of SOA: 1.“Effective primary” yield of semivolatile gas 2.Two-product empirical fit to smog chamber data Isoprene 350 TgC/yr Partitioning of semivolatile gas? Heterogeneous rxn of soluble gas? Other mechanisms? Volkamer et al. [2006] C/o Colette Heald

22. 22 [Glyoxal] in ambient air Rural 10 -1 ~10 -2 ppb Remote and FT 10 -1 ~ 10 -2 ppb

23. 23 [Methyglyoxal] in ambient air Rural >1 ~10 -2 ppb Remote and FT ~ 10 -2 ppb

24. 24 What are the irreversible processes in the aqueous phase? I. Hydrate + OH  glyoxylic acid, pyruvic acid  Oxalic acid II. Hydrate + H 2 O  Oligomers Ervens et al. [2004]; Lim et al. [2005]; Warneck et al. [2005]; Sorooshian et al. [2006] Kalberer et al. [2004]; Liggio et al. [2005]; Hastings et al. [2005]; Zhao et al. [2006]

25. 25 III. Hydrate + OH  glyoxylic acid, pyruvic acid  oligomers  oxalic acid  oligomers Altieri et al. [2006] T = 10 min T = 202 min