Laboratory research on aqueous reactions of isoprene with inorganic radicals

1. Insitute of Physical Chemistry Polish Academy of Sciences Laboratory research on aqueous reactions of isoprene with inorganic radicals Inna Kuznietsova Lech Gmachowski, Krzysztof J. Rudzinski

2. Why ? • interaction and transformation of atmospheric trace compounds • formation of secondary organic aerosols (SOA)

3. SO2 • anthropogenic sources (80 TgS/year) combustion of fossil fuels vehicles, aircraft, ships, power stations, industrial boilers industry ores smelting, scrubbing natural gas • natural sources (12 TgS/year) volcanic eruptions oxidation of organic materials in soils atmospheric oxidation of dimethylsulfide rainforests

4. SO2 + H2O SO32- / HSO3- Mn(III) SIV, O2 Mn(II) Mn(II) + SO3  - Mn(III) + SO32-/HSO3- SO3•-,SO4•- , SO5•- 2 SO32- /2 HSO3- + O2 2 SO42- /2 HSO42- Autooxidation of SIV

5. Isoprene (2-methyl-1,3-butadien) Sources: • Plants • Sea phytoplankton • Microbes • Animals and humans • Biomass burning • Combustion and evaporation of fuels • Cigarette smoking • Chemical technology

6. Importance of isoprene • Emission 500 TgC/year • High reactivity (OH•, NO3•, O3) • Precursor of Secondary Organic Aerosols • Influence on formation photochemical smog • Influence on autooxidation SIV

7. •OH NO3• R•, O3 NO R• Cl• SO3• (....) Gas-phase transformations of isoprene

8. Typical gas-phase products aldehydes ketones 3-methyl furan diols hydroxynitrates dinitrates peroxynitrates peroxyacetyl nitrates (PAN) methacrolyl nitrate (MPAN)

9. Heterogeneous and aqueous-phase transformations of isoprene hydroxyacetons 2-methyltetraols hydroxycarboxyl acids dicarboxy acids sulfate-nitrate esters sulfate esters nitrate esters keto acids

10. Na2SO3 + Na2S2O5 + O2 Isoprene MnSO4 [O2],pH ESI-MS (offline) [iso], [S(IV)] UV 25 oC pH = 4.5÷8.6 Experimental setup

11. Initial concentrations, mM: MnSO4 SIV C5H8 O2 pH 0.01 1.04 0.07 0.25 6.7 Time, substrates Time, products Recorded UV spectra of a reacting solution Wavelength, nm Absorbance, a.u.

12. Changes of O2 concentrationand pH

13. Decreasing of SIV and isoprene with time

14. Identification of products Intensity, cps Mass / charge

15. Structures of the products

16. Reaction of isoprene withSO4•-

17. Influence of isoprene on autooxidation of SIV in solution of different acidity 2SO32- /2HSO3-+ O2 2SO42- /2HSO42- experiments without isoprene (blue) and with isoprene (red) Rudziński et.al.2007 Proc. 6th Conf. Urban Air Quality, Cyprus

18. Take-Home-Messages • Aqueous-phase reactions of isoprene with sulfoxy radicals can be a source of atmospheric organosulfates and organosulfites • Influence of isoprene on aciditification of atmospheric waters • Interaction of biosphere and atmosphere

19. Thank you for your attention

20. 7 1 S2O82– → SO4•– + SO4•– SO52– + SO32– → SO42– + SO42– 7a 2 HSO5– + HSO3– → SO42– + SO42– + 2 H+ Mn(II) (+ O2, S(IV))→ Mn(III) 8-1 SO5•– + Mn(II) → SO52– + Mn(III) Mn(III) + SO32– → Mn(II) + SO3•– 3 8-2 SO5•– + Mn(II) → SO42– + Mn(III) (+ OH–) 4 SO3•– + O2 → SO5•– 9 SO5•– + SO32– → SO52– + SO3•– SO4•– + Mn(II) → SO42– + Mn(III) 5-1 5-2 SO5•– + SO32– → SO42– + SO4•– SO5•– + SO5•– → SO4•– + SO4•– + O2 10 5-1a SO5•– + HSO3– → HSO5– + SO3•– 11 SO4•– + S2O82– → SO42– + S2O8•– 12 SO3•– + SO3•– → S2O62– SO5•– + HSO3– → SO42– + SO4•– + H+ 5-2a 13 SO4•– + SO32– → SO42– + SO3•– SO4•– + SO4•– → S2O82– 6 14 SO5•– + SO5•– → S2O82– + O2 6a SO4•– + HSO3– → SO42– + SO3•– + H+