A006-0012
Eddy covariance measurements of O3 and HCOOH indicate rapid in-canopy terpene chemistry drives O3 deposition in mixed temperate forests

Monday, 7 December 2020
Poster
Michael Vermeuel1, Gordon Novak1, Patricia A Cleary2, Ankur R Desai3 and Timothy H Bertram4, (1)University of Wisconsin Madison, Chemistry, Madison, WI, United States, (2)University of Wisconsin Eau Claire, Chemistry and Biochemistry, Eau Claire, WI, United States, (3)University of Wisconsin Madison, Madison, WI, United States, (4)University of Wisconsin Madison, Department of Chemistry, Madison, WI, United States
Abstract:
Dry deposition, the second largest removal process of ozone (O3) in the troposphere, plays a controlling role in determining the natural variability of surface O3 concentrations. Terrestrial ecosystems remove O3 either through stomatal uptake or nonstomatal processes. An important, yet less-explored nonstomatal process involves the in-canopy reaction of O3 with isoprene (C5H8) and very reactive monoterpenes (MT; C10H16) and sesquiterpenes (SQT; C15H24) that are emitted from the forest canopy and can react with O3 within the residence time of the canopy to produce oxidation products. Here, we present an observed relationship between in-canopy O3 loss and the production of a biogenic terpene oxidation product, formic acid (HCOOH), using simultaneous eddy covariance measurements of O3 and HCOOH over a mixed temperate forest in Northern Wisconsin during July 2019. In the 2019 study O3 and HCOOH were detected using a chemical ionization time of flight mass spectrometer (CI-ToFMS) in oxygen anion (O2-) mode. We also present measurements of biogenic volatile organic compounds (BVOC) at the same Northern WI site during late summer 2020 using a Vocus proton transfer reaction time of flight mass spectrometer (PTR-ToFMS) coupled to a modular gas chromatography system to better quantify the impact of reactive BVOC species that contribute to the observed in-canopy ozonolysis at this site.
<< Previous Abstract | Next Abstract