ACPD Atmospheric Chemistry and Physics Discussions ACPD 1680-7375 Copernicus GmbH Göttingen, Germany 10.5194/acpd-9-13629-2009 Rapid formation of isoprene photo-oxidation products observed in Amazonia Karl T. 1 Guenther A. 1 Turnipseed A. 1 Artaxo P. 2 Martin S. 3 National Center for Atmospheric Research, 1850 Table Mesa Dr, Boulder, 80301, CO, USA Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, Brazil School of Engineering and Applied Sciences & Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA 22 06 2009 9 3 13629 13653 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys-discuss.net/9/13629/2009/acpd-9-13629-2009.html The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/9/13629/2009/acpd-9-13629-2009.pdf

Isoprene represents the single most important reactive hydrocarbon for atmospheric chemistry in the tropical atmosphere. It plays a central role in global and regional atmospheric chemistry and possible climate feedbacks. Photo-oxidation of primary hydrocarbons (e.g. isoprene) leads to the formation of oxygenated VOCs (OVOCs). The evolution of these intermediates affects the oxidative capacity of the atmosphere (by reacting with OH) and can contribute to secondary aerosol formation, a poorly understood process. An accurate and quantitative understanding of VOC oxidation processes is needed for model simulations of regional air quality and global climate. Based on field measurements conducted during the Amazonian aerosol characterization experiment (AMAZE-08) we show that the production of certain OVOCs (e.g. hydroxyacetone) from isoprene photo-oxidation in the lower atmosphere is significantly underpredicted by standard chemistry schemes. A recently suggested novel pathway for isoprene peroxy radicals could explain the observed discrepancy and reconcile the rapid formation of these VOCs. Furthermore, if generalized our observations suggest that prompt photochemical formation of OVOCs and other uncertainties in VOC oxidation schemes could result in substantial underestimates of modelled OH reactivity that could explain a major fraction of the missing OH sink over forests which has previously been attributed to a missing source of primary biogenic VOCs.

 References Atkinson,~R.: Atmospheric chemistry of VOCs and NOx, Atmos. Environ., 34, 2063–2101, 2000. Atkinson,~R., Baulch,~D L., Cox,~R A., Hampson,~R F., Jr., Kerr,~J A., Rossi,~M J., and Troe,~J.: Evaluated kinetic, photochemical and heterogeneous data for atmospheric chemistry: supplement~V, IUPAC subcommittee on gas kinetic data evaluation for atmospheric chemistry, J Phys. Chem. Ref. Data, 26, 521–1011, 1997. Bacher,~C., Tyndall,~G S., and Orlando,~J J.: The atmospheric chemistry of glycolaldehyde, J Atmos. Chem., 39(2), 171–189, 2001. Bey I., Jacob,~D J., Yantosca,~R M., Logan,~J A., Field,~B., Fiore,~A M., Li,~Q., Liu,~H., Mickley,~L J., and Schultz,~M.: Global modeling of tropospheric chemistry with assimilated meteorology: model description and evaluation, J Geophys. Res., 106, 23073–23096, 2001. Brasseur,~G P., Hauglustaine,~D A., Walters,~S., Rasch,~P J., Muller,~J.-F., Granier,~C., and Tie,~X.-X.: MOZART. A~global chemical transport model for ozone and related chemical tracers, Part 1: Model description, J Geophys. Res., 103, 28265–28289, 1998. Carter,~W P L. and Atkinson,~R.: Development and evaluation of a~detailed mechanism for atmospheric reactions of isoprene and NO<sub>x</sub>, Int J. Chem. Kinetics, 28, 497–530, 1996. Carlo,~P D., Brune,~W H., Martinez,~M., Harder,~H., Lesher,~R., Ren,~X., Thornberry,~T., Carroll,~M A., Young,~V., Shepson,~P B., Riemer,~D., Apel,~E., and Campbell,~C.: Missing OH reactivity in a~forest: evidence for unkown reactive biogenic VOCs, Science, 304, 722–725, 2004. Claeys,~M., Graham,~B., Vas,~G., Wang,~W., Vermeylen,~R., Pashynska,~V., Cafmeyer,~J., Guyon,~P., Andreae,~M O., Artaxo,~P., and Maenhaut,~W.: Formation of secondary organic aerosols through photooxidation of isoprene, Science, 303, 1173–1176, 2004. Dibble,~T.: Isomerisation of OH-isoprene adducts and hydroxyalkoxy isoprene radicals, J Phys. Chem A, 106, 6643–6650, 2002. Dillon,~T J., Horowitz,~A., Holscher,~D., Crowley,~J N., Vereecken,~L., and Peeters,~J.: Reaction of HO with hydroxyacetone (\chemHOCH_2C(O)CH_3): rate coefficients (233–363 \unitK) and mechanism, Phys. Chem. Chem. Phys, 8, 236–246, 2006. de Gouw,~J. and Warneke,~C.: Measurements of volatile organic compounds in the earths atmosphere using proton-transfer-reaction mass spectrometry, Mass Spectrom. Rev., 26, 223–257, 2007. Emmerson, K. M. and Evans, M. J.: Comparison of tropospheric gas-phase chemistry schemes for use within global models, Atmos. Chem. Phys., 9, 1831–1845, 2009. Eerdekens, G., Ganzeveld, L., Vilà-Guerau de Arellano, J., Klüpfel, T., Sinha, V., Yassaa, N., Williams, J., Harder, H., Kubistin, D., Martinez, M., and Lelieveld, J.: Flux estimates of isoprene, methanol and acetone from airborne PTR-MS measurements over the tropical rainforest during the GABRIEL 2005 campaign, Atmos. Chem. Phys. Discuss., 8, 12903–12969, 2008. Fan,~J. and Zhang,~R.: Atmospheric oxidation mechanism of isoprene, Environ. Chem., 1, 140–149, 2004. Ganzeveld, L., Eerdekens, G., Feig, G., Fischer, H., Harder, H., Königstedt, R., Kubistin, D., Martinez, M., Meixner, F. X., Scheeren, H. A., Sinha, V., Taraborrelli, D., Williams, J., Vilà-Guerau de Arellano, J., and Lelieveld, J.: Surface and boundary layer exchanges of volatile organic compounds, nitrogen oxides and ozone during the GABRIEL campaign, Atmos. Chem. Phys., 8, 6223–6243, 2008. Greenberg,~J P. and P R. Zimmerman: Nonmethane hydrocarbons in remote tropical, continental, and marine atmospheres, J Geophys. Res., 89(ND3), 4767–4778, 1984. Gierczak,~T., Burkholder,~J B., Talukdar,~R K., Mellouki,~A., Barone,~S B., and Ravishankara,~A R.: Atmospheric fate of methyl vinyl ketone and methacrolein, J Photoch. Photobio A, 110, 1–10, 1997. Greenberg,~J P. and Zimmerman,~P R.: Nonmethane hydrocarbons in remote tropical, continental, and marine atmospheres, J Geophys. Res., 89, 4767–4778, 1984. Greenberg,~J., Lee,~B., Helmig,~D., and Zimmerman,~P.: Fully automated gas chromatograph-flame ionization detector system for the in situ determination of atmospheric non-methane hydrocarbons at low parts per trillion concentration, J Chromatogr., 676, 389–398, 1994. Guenther, A., Karl, T., Harley, P., Wiedinmyer, C., Palmer, P. I., and Geron, C.: Estimates of global terrestrial isoprene emissions using MEGAN (Model of Emissions of Gases and Aerosols from Nature), Atmos. Chem. Phys., 6, 3181–3210, 2006. Hansel,~A., Jordan,~A., Warneke,~C., Holzinger,~R., and Lindinger,~W.: Improved detection limit of the proton-transfer reaction mass spectrometer: on-line monitoring of volatile organic compounds at mixing ratios of a~few pptv, Rapid Commun. Mass Sp., 12, 871–875, 1998. Holzinger,~R., Millet,~D B., Williams,~B., Lee,~A., Kreisberg,~N., Hering,~S V., Jimenez,~J., Allan,~J D., Worsnop,~D R., and Goldstein,~A H.: Emission, oxidation, and secondary organic aerosol formation of volatile organic compounds as observed at Chebogue Point, Nova Scotia, J Geophys. Res., 112, D10S24, doi:10.1029/2006JD007599, 2007. Kanakidou, M., Seinfeld, J. H., Pandis, S. N., Barnes, I., Dentener, F. J., Facchini, M. C., Van Dingenen, R., Ervens, B., Nenes, A., Nielsen, C. J., Swietlicki, E., Putaud, J. P., Balkanski, Y., Fuzzi, S., Horth, J., Moortgat, G. K., Winterhalter, R., Myhre, C. E. L., Tsigaridis, K., Vignati, E., Stephanou, E. G., and Wilson, J.: Organic aerosol and global climate modelling: a review, Atmos. Chem. Phys., 5, 1053–1123, 2005. Karl,~T., Potosnak,~M., Guenther,~A., Clark,~D., Walker,~J., Herrick,~J D., and Geron,~C.: Exchange processes of volatile organic compounds above a~tropical rain forest: implications for modeling tropospheric chemistry above dense vegetation, J Geophys. Res., 109, D18306, doi:10.1029/2004JD004738, 2004. Karl,~T., Guenther,~A., Yokelson,~R J., Greenberg,~J., Potosnak,~M., Blake,~D R., and Artaxo,~P.: The tropical forest and fire emissions experiment: emission, chemistry, and transport of biogenic volatile organic compounds in the lower atmosphere over Amazonia, J. Geophys. Res., 112, D18302, doi:10.1029/2007JD008539, 2007. Karl, T. G., Christian, T. J., Yokelson, R. J., Artaxo, P., Hao, W. M., and Guenther, A.: The Tropical Forest and Fire Emissions Experiment: method evaluation of volatile organic compound emissions measured by PTR-MS, FTIR, and GC from tropical biomass burning, Atmos. Chem. Phys., 7, 5883–5897, 2007. Kesselmeier,~J., Ciccioli,~P., Kuhn,~U., Stefani,~P., Biesenthal,~T., Rottenberger,~S., Wolf,~A., Vitullo,~M., Valentini,~R., Nobre,~A., Kabat,~P., and Andreae,~M O.: Volatile organic compound emissions in relation to plant carbon fixation and the terrestrial carbon budget, Global Biogeochem. Cy., 16, 1126, doi:10.1029/2001GB001813, 2002. Kroll,~J H., Ng,~N L., Murphy,~S M., Flagan,~R C., and Seinfeld,~J H.: Secondary organic aerosol formation from isoprene photooxidation, Environ. Sci. Technol., 40, 1869–1877 2006. von Kuhlmann, R., Lawrence, M. G., Pöschl, U., and Crutzen, P. J.: Sensitivities in global scale modeling of isoprene, Atmos. Chem. Phys., 4, 1–17, 2004. Kuhn, U., Andreae, M. O., Ammann, C., Araújo, A. C., Brancaleoni, E., Ciccioli, P., Dindorf, T., Frattoni, M., Gatti, L. V., Ganzeveld, L., Kruijt, B., Lelieveld, J., Lloyd, J., Meixner, F. X., Nobre, A. D., Pöschl, U., Spirig, C., Stefani, P., Thielmann, A., Valentini, R., and Kesselmeier, J.: Isoprene and monoterpene fluxes from Central Amazonian rainforest inferred from tower-based and airborne measurements, and implications on the atmospheric chemistry and the local carbon budget, Atmos. Chem. Phys., 7, 2855–2879, 2007. Kwok,~E S.C., Aschmann,~S M., and Atkinson,~R.: Rate constants for the gas-phase reaction of selected carbamates and lactates, Environ. Sci. Technol., 30, 329–34, 1996. Lindinger,~W., Jordan,~A., and Hansel,~A.: Proton-transfer-reaction mass spectroscopy (PTR-MS): on-line monitoring of volatile organic compounds at pptv levels, Chem. Soc. Rev., 27, 347–534, 1998. Nemitz,~E., Sutton,~M A., Gut,~A., Jose,~R S., Husted,~S., and Schjoerring,~J K.: Sources and sinks of ammonia within an oilseed rape canopy, Agr. Forest Meteorol., 105, 385–404, 2000. Park,~J., Candice,~G J., Zhang,~R., and North,~S W.: Cyclization reactions in isoprene derived $\beta $-hydroxy radicals: implications for the atmospheric oxidation mechanism, Phys. Chem. Chem. Phys., 5, 3638–3642, 2003. Paulot, F., Crounse, J. D., Kjaergaard, H. G., Kroll, J. H., Seinfeld, J. H., and Wennberg, P. O.: Isoprene photooxidation: new insights into the production of acids and organic nitrates, Atmos. Chem. Phys., 9, 1479–1501, 2009. Pfister,~G G., Emmons,~L K., Hess,~P G., Lamarque,~J F., Orlando,~J J., Walters,~S., Guenther,~A., Palmer,~P I., and Lawrence,~P J.: Contribution of isoprene to chemical budgets: a~model tracer study with the NCAR CTM MOZART-4, J Geophys. Res., 113, D05308, doi:10.1029/2007JD008948, 2008. Pinho,~P G., Pio,~C A., and Jenkin,~M E.: Evaluation of isoprene degradation in the detailed tropospheric chemical mechanism, MCM v3, using environmental chamber data, Atmos. Environ., 39, 1303–1322, 2005. Raupach,~M R.: A~practical Lagrangian method for relating scalar concentrations to source distributions in vegetation canopies, Quart J. Roy. Meteor. Soc., 115, 609–632, 1989. Sinha, V., Williams, J., Crowley, J. N., and Lelieveld, J.: The Comparative Reactivity Method – a new tool to measure total OH Reactivity in ambient air, Atmos. Chem. Phys., 8, 2213–2227, 2008. Spaulding,~R S., Schade,~G W., Goldstein,~A H., and Charles,~M J.: Characterization of secondary atmospheric photooxidation products: evidence for biogenic and anthropogenic sources, J Geophys. Res., 108, D84247, doi:10.1029/2002JD002478, 2003. Stockwell,~W R., Kirchner,~F., Kuhn,~M., and Seefeld,~S.: A~new mechanism for regional atmospheric chemistry modeling, J Geophys. Res., 102, 25847–25879, 1997. Stroud,~C., Makar,~P., Karl,~T., Guenther,~A., Geron,~C., Turnipseed,~A., Nemitz,~E., Baker,~B., Potosnak,~M., and Fuentes,~J D.: Role of canopy-scale photochemistry in modifying biogenic-atmosphere exchange of reactive terpene species: results from the CELTIC field study, J Geophys. Res., 110, D17303, doi:10.1029/2005JD005775, 2005. Taraborrelli, D., Lawrence, M. G., Butler, T. M., Sander, R., and Lelieveld, J.: Mainz Isoprene Mechanism 2 (MIM2): an isoprene oxidation mechanism for regional and global atmospheric modelling, Atmos. Chem. Phys., 9, 2751–2777, 2009. Warneke,~C., Holzinger,~R., Hansel,~A., Jordan,~A., Lindinger,~W., Poeschl,~U., Williams,~J., Hoor,~P., Fischer,~H., Crutzen,~P J., Scheeren,~H A., and Lelieveld,~J.: Isoprene and its oxidation products methyl vinyl ketone, methacrolein, and isoprene related peroxides measured online over the 5 tropical rain forest of Surinam in March 1998,~J Atmos. Chem., 38, 167–185, 2001. Williams,~J., Poeschl,~U., Crutzen,~P J., Hansel,~A., Holzinger,~R., Warneke,~C., Lindinger,~W., and Lelieveld,~J.: An atmospheric chemistry interpretation of mass scans obtained from a~proton transfer mass spectrometer flown over the tropical rainforest of Surinam, J Atmos. Chem., 38, 133–166, 2001.