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Title: Within-canopy sesquiterpene ozonolysis in Amazonia
Authors: Jardine, Kolby J.
Yáñez-Serrano, Ana Maria
Arneth, Almuth
Abrell, Leif
Jardine, Angela B.
van Haren, Joost L.M.
Artaxo, Paulo
Rizzo, L. V.
Ishida, Francoise Yoko
Karl, Thomas G.
Kesselmeier, Jürgen
Saleska, Scott Reid
Huxman, Travis E.
Keywords: Chemical Analysis
Ambient Concentrations
Atmospheric Oxidation
Concentration Measurement
Diurnal Pattern
Dry Seasons
Experimental Evidence
High Reactivity
Highly Sensitive
Monoterpene Emissions
Oxidative Damage
Ozone Flux
Ozone Uptake
Plant Canopies
Rapid Reactions
Secondary Organic Aerosols
Significant Impacts
Temperature Dependent
Time Of Day
Tropical Forest
Tropical Rain Forest
Tropospheric Chemistry
Aerosol Formation
Air Sampling
Ambient Air
Atmospheric Chemistry
Biogenic Emission
Canopy Exchange
Experimental Study
Forest Canopy
Temperature Effect
Issue Date: 2011
metadata.dc.publisher.journal: Journal of Geophysical Research Atmospheres
metadata.dc.relation.ispartof: Volume 116, Número 19
Abstract: Through rapid reactions with ozone, which can initiate the formation of secondary organic aerosols, the emission of sesquiterpenes from vegetation in Amazonia may have significant impacts on tropospheric chemistry and climate. Little is known, however, about sesquiterpene emissions, transport, and chemistry within plant canopies owing to analytical difficulties stemming from very low ambient concentrations, high reactivities, and sampling losses. Here, we present ambient sesquiterpene concentration measurements obtained during the 2010 dry season within and above a primary tropical forest canopy in Amazonia. We show that by peaking at night instead of during the day, and near the ground instead of within the canopy, sesquiterpene concentrations followed a pattern different from that of monoterpenes, suggesting that unlike monoterpene emissions, which are mainly light dependent, sesquiterpene emissions are mainly temperature dependent. In addition, we observed that sesquiterpene concentrations were inversely related with ozone (with respect to time of day and vertical concentration), suggesting that ambient concentrations are highly sensitive to ozone. These conclusions are supported by experiments in a tropical rain forest mesocosm, where little atmospheric oxidation occurs and sesquiterpene and monoterpene concentrations followed similar diurnal patterns. We estimate that the daytime dry season ozone flux of -0.6 to -1.5 nmol m -2 s-1 due to in-canopy sesquiterpene reactivity could account for 7%-28% of the net ozone flux. Our study provides experimental evidence that a large fraction of total plant sesquiterpene emissions (46%-61% by mass) undergo within-canopy ozonolysis, which may benefit plants by reducing ozone uptake and its associated oxidative damage. © 2011 by the American Geophysical Union.
metadata.dc.identifier.doi: 10.1029/2011JD016243
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