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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2018-224
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
04 Apr 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Atmospheric Chemistry and Physics (ACP).
Semi-volatile and highly oxygenated gaseous and particulate organic compounds observed above a boreal forest canopy
Ben H. Lee1, Felipe D. Lopez-Hilfiker1,a, Emma L. D'Ambro1, Putian Zhou2, Michael Boy2, Tuukka Petäjä2, Liqing Hao3, Annele Virtanen3, and Joel A. Thornton1 1Department of Atmopsheric Sciences, University of Washington, Seattle, WA, U.S.A.
2Institute for Atmospheric and Earth System Research / Physics, Faculty of Science, University of Helsinki, Finland
3Department of Physics, University of Eastern Finland, Kuopio, Finland
anow at: TofWerk AG, Thun, Switzerland
Abstract. We present hourly on-line observations of molecular compositions (CxHyOzN0–1) and abundances of oxygenated organic species in gas and submicron particle phases from April to June of 2014 as part of the Biogenic Aerosols-Effects on Cloud and Climate (BAECC) campaign. Measurements were made using the Filter Inlet for Gases and AEROsols coupled to a high-resolution time-of-flight iodide-adduct ionization mass spectrometer (FIGAERO-CIMS) located atop a 35 m tall tower, about 10 m above a boreal forest canopy at the SMEAR II research station in Hyytiälä, Finland. Semi-volatile and highly oxygenated multifunctional (HOM) organic species possessing from 1 up to 20 carbon atoms, and with as few as 2 and as many as 16 oxygen atoms were routinely observed. Utilizing non-negative matrix factorization, we determined that > 90 % and > 99 % of the organic mass in the gas and particle phases, respectively, exhibited one of three distinct diel trends; one in which abundances were enhanced at daytime, another in the early morning hours, and thirdly during nighttime. Particulate organic nitrates contributed ∼ 35 % to the total organic aerosol mass loading at night during BAECC, much higher than observed by the same instrument package at a mixed-deciduous forest site that experienced higher nighttime concentrations of nitrogen oxides. Unique HOM monomers (defined here as those with 10 carbon and 7 or more oxygen atoms) and dimers (at least 16 carbon atoms), with and without a nitrogen atom, were found in most of the three subgroups of both phases. We show the potential to connect these groupings of compounds based on their distinct behavior in time to the expected chemical conditions (biogenic VOC precursor, oxidant type, etc.) responsible for their production. A suite of nitrated dimer-like compounds was detected in both the gas and particle phases, suggesting a potential role for the formation of low volatility organics from NO3 radical driven, as well as daytime NO-influenced, monoterpene chemistry.
Citation: Lee, B. H., Lopez-Hilfiker, F. D., D'Ambro, E. L., Zhou, P., Boy, M., Petäjä, T., Hao, L., Virtanen, A., and Thornton, J. A.: Semi-volatile and highly oxygenated gaseous and particulate organic compounds observed above a boreal forest canopy, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-224, in review, 2018.
Ben H. Lee et al.
Ben H. Lee et al.

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Short summary
Molecular identities and abundances of organic compounds residing in the gas and particle phases above a Finnish boreal forest are presented. We determined that in each phase, the organic components are categorized into three subgroups based on their behavior in time. Some are more enhanced at night, others during midday, and another around sunrise. Identifying such collective behavior can potentially connect the chemical processes that evolve in time to specific distributions of products.
Molecular identities and abundances of organic compounds residing in the gas and particle phases...
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