Forest-atmosphere exchange of ozone: sensitivity to very reactive biogenic VOC emissions and implications for in-canopy photochemistry
| dc.contributor.author | Wolfe, G. M. | |
| dc.contributor.author | Thornton, J. A. | |
| dc.contributor.author | McKay, M. | |
| dc.contributor.author | Goldstein, A. H. | |
| dc.date.accessioned | 2020-09-16T18:44:47Z | |
| dc.date.available | 2020-09-16T18:44:47Z | |
| dc.date.issued | 2011-08-04 | |
| dc.description.abstract | Understanding the fate of ozone within and above forested environments is vital to assessing the anthropogenic impact on ecosystems and air quality at the urban-rural interface. Observed forest-atmosphere exchange of ozone is often much faster than explicable by stomatal uptake alone, suggesting the presence of additional ozone sinks within the canopy. Using the Chemistry of Atmosphere-Forest Exchange (CAFE) model in conjunction with summer noontime observations from the 2007 Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX-2007), we explore the viability and implications of the hypothesis that ozonolysis of very reactive but yet unidentified biogenic volatile organic compounds (BVOC) can influence the forest-atmosphere exchange of ozone. Non-stomatal processes typically generate 67 % of the observed ozone flux, but reactions of ozone with measured BVOC, including monoterpenes and sesquiterpenes, can account for only 2 % of this flux during the selected timeframe. By incorporating additional emissions and chemistry of a proxy for very reactive VOC (VRVOC) that undergo rapid ozonolysis, we demonstrate that an in-canopy chemical ozone sink of ~2 × 10⁸ molec cm⁻³ s⁻¹ can close the ozone flux budget. Even in such a case, the 65 min chemical lifetime of ozone is much longer than the canopy residence time of ~2 min, highlighting that chemistry can influence reactive trace gas exchange even when it is "slow" relative to vertical mixing. This level of VRVOC ozonolysis could enhance OH and RO2 production by as much as 1 pptv s⁻¹ and substantially alter their respective vertical profiles depending on the actual product yields. Reaction products would also contribute significantly to the oxidized VOC budget and, by extension, secondary organic aerosol mass. Given the potentially significant ramifications of a chemical ozone flux for both in-canopy chemistry and estimates of ozone deposition, future efforts should focus on quantifying both ozone reactivity and non-stomatal (e.g. cuticular) deposition within the forest. | en_US |
| dc.description.sponsorship | The authors acknowledge support from National Science Foundation grants ATM-0633897 and ATMCAREER 0846183, and for the UC Berkeley contributions to this work ATM-0922562. GMW was partially supported by a US-EPA STAR Fellowship Assistance under Agreement No. FP-91698901. This work has not been formally reviewed by EPA. The views expressed in this work are solely those of the authors; EPA and NSF do not endorse any products or commercial services mentioned. The authors also thank Sierra Pacific Industries for the use of land, Blodgett Forest Research Station staff for cooperation during BEARPEX and two anonymous reviews for insightful feedback on the manuscript. | en_US |
| dc.description.uri | https://acp.copernicus.org/articles/11/7875/2011/ | en_US |
| dc.format.extent | 17 pages | en_US |
| dc.genre | journal articles | en_US |
| dc.identifier | doi:10.13016/m2euc6-ovsy | |
| dc.identifier.citation | Wolfe, G. M., Thornton, J. A., McKay, M., and Goldstein, A. H.: Forest-atmosphere exchange of ozone: sensitivity to very reactive biogenic VOC emissions and implications for in-canopy photochemistry, Atmos. Chem. Phys., 11, 7875–7891, https://doi.org/10.5194/acp-11-7875-2011, 2011. | en_US |
| dc.identifier.uri | https://doi.org/10.5194/acp-11-7875-2011 | |
| dc.identifier.uri | http://hdl.handle.net/11603/19667 | |
| dc.language.iso | en_US | en_US |
| dc.publisher | Copernicus | en_US |
| dc.relation.isAvailableAt | The University of Maryland, Baltimore County (UMBC) | |
| dc.relation.ispartof | UMBC Joint Center for Earth Systems Technology | |
| dc.relation.ispartof | UMBC Physics Department | |
| dc.rights | This item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author. | |
| dc.rights | Attribution 3.0 Unported | * |
| dc.rights.uri | https://creativecommons.org/licenses/by/3.0/ | * |
| dc.title | Forest-atmosphere exchange of ozone: sensitivity to very reactive biogenic VOC emissions and implications for in-canopy photochemistry | en_US |
| dc.type | Text | en_US |