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| Titel |
Revisiting the dry depositional sink of oxidized organic vapors to vegetation |
| VerfasserIn |
Thomas Karl, Peter Harley, Luisa Emmons, Brenda Thornton, Alex Guenther, Chhandak Basu, Andrew Turnipseed, Kolby Jardine |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250037058
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| Zusammenfassung |
| Large quantities of volatile organic compounds (VOC) enter the atmosphere. The annual production of VOC (600 -2000 TgC/a) likely exceeds that of methane and CO (~500 TgC/a each). Together these gases fuel tropospheric chemistry. Oxidation of VOC leads to the formation of aerosol (Hallquist et al., 2009) via complex organic chemistry (e.g. Atkinson and Arey, 2003; Paulot et al., 2009) in the gas and aerosol phase thereby modulating the oxidation capacity of the atmosphere (Lelieveld et al., 2008). Currently one of the biggest uncertainties in constraining budgets of VOC is the amount of dry and wet deposition to vegetation, which acts as a major source and sink for organic trace gases on a global scale. This has consequences for constraining secondary species produced in the gasphase, which will either oxidize to CO and CO2, condense on or form organic aerosol (OA) and be rained out, or directly deposit to the surface via dry and wet deposition. Two recent bottom-up assessments of the tropospheric OA budget (Hallquist et al., 2009, Goldstein and Galbally, 2007) were based on varying assumptions for wet and dry deposition of organic vapors (e.g. 130-200 TgC/a vs 800 TgC/a) and consequently derived significantly different global production rates for secondary organic aerosol (SOA). We present a synthesis of ecosystem scale flux measurements showing that the removal of oxygenated VOC (OVOC) via dry deposition is significantly larger than currently assumed for deciduous ecosystems. Laboratory experiments indicate that exposure to ozone, MVK or mechanical wounding can enhance the uptake of OVOCs. Since the general route of atmospheric photo-oxidation of VOCs goes through the formation of carbonyls and hydroxycarbonyls these findings have consequences for understanding the atmospheric evolution of organic carbon. A revised VOC uptake scheme was incorporated into a chemistry-transport model to investigate the impact on a global scale.
References:
Atkinson R. and J. Arey, 2003. Atmospheric Degradation of Volatile Organic Compounds, Chemical Reviews, 103, 4605-4638.
Goldstein AH, and I. Galbally 2007. Known and Unexplored organic constituents in the Earth’s Atmosphere. Environmental Science & Technology, 1515-1521.
Hallquist M, Wenger JC, Baltensperger U, Rudich Y, Simpson D, Claeys M, Dommen J, Donahue NM, George C, Goldstein AH, Hamilton JF, Herrmann H, Hoffmann T, Iinuma Y, Jang M, Jenkin ME, Jimenez JL, Kiendler-Scharr A, Maenhaut W, McFiggans G, Mentel TF, Monod A, Prévôt ASH, Seinfeld JH, Surratt JD, Szmigielski R, and J Wildt 2009. The formation, properties and impact of secondary organic aerosol: current and emerging issues, Atmos. Chem. Phys., 9, 5155-5235.
Paulot, F., Crounse, J.D., Kjaergaard, H.G., Kurten, A., St Clair, J.M., Seinfeld, J.H., and Wennberg, P.O. 2009: Unexpected epoxide formation in the gas-phase photooxidation of isoprene, Science, 325, 730-733.
Lelieveld J, Butler TM, Crowley JN, Dillon TJ, Fischer H, Ganzeveld L, Harder H, Lawrence MG, Martinez M, Taraborrelli D, and J. Williams 2008. Atmospheric oxidation capacity sustainted by a tropical forest. Nature, 452, 737-740. |
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