Book/Dissertation / PhD Thesis

FZJ-2018-02671

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Gas-to-Particle Partitioning of Major Oxidation Products from Monoterpenes and Real Plant Emissions

Gkatzelis, G. (Corresponding author)FZJ*

2018
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-95806-314-3

Please use a persistent id in citations: http://hdl.handle.net/2128/18473  urn:nbn:de:0001-2018050951

Abstract: Secondary organic aerosol (SOA), formed through the oxidation of volatile organic compounds (VOCs) in the atmosphere, play a key role in climate change and air quality. Due to thousands of individual compounds involved in SOA formation, the chemical characterization of organic aerosols (OA) remains a huge analytical challenge. Defining the fundamental parameters that distribute these organic molecules between the gas and particle phases is essential, as atmospheric lifetime and their impacts change drastically depending on their phase state. In this work, an instrument called aerosol collection module (ACM) was redeveloped and automated to allow a better characterization of SOA originating from the oxidation of biogenic precursors. An inter-comparison of the ACM to different aerosol chemical characterization techniques was performed with a focus on the partitioning of major biogenic oxidation products between the gas- and particle-phase. In particular, the ACM, the collection thermal desorption unit (TD) and the chemical analysis of aerosol on-line (CHARON) are different aerosol sampling inlets utilizing a Proton-Transfer-Reaction Timeof- Flight Mass Spectrometer (PTR-ToF-MS). These techniques were deployed at the atmosphere simulation chamber SAPHIR to study SOA formation and aging from different monoterpenes (β-pinene, limonene) and real plant emissions ($\textit{Pinus sylvestris L.}$). The capabilities of the PTR-based techniques were compared among each other and to results from an Aerodyne Aerosol Mass Spectrometer (AMS) and a Scanning Mobility Particle Sizer (SMPS). Gas-to-particle partitioning values were determined based on the saturation mass concentration (C*) of individual ions by performing simultaneous measurement of their signal in the gas- and particle-phase. Despite significant differences in the aerosol collection and desorption methods of the PTR based techniques, the determined chemical composition was comparable, i.e. the same major contributing ions were found by all instruments for the different chemical systems studied. These ions could be attributed to known products expected from the oxidation of the examined monoterpenes. Averaged over all experiments, the total aerosol mass recovery compared to an SMPS was 80 ± 10%, 51 ± 5% and 27 ± 3% for CHARON, ACM and TD, respectively. Comparison to the oxygen to carbon ratios (O:C) obtained by AMS showed that all PTR based techniques observed lower O:C ratios indicating a loss of molecular oxygen either during aerosol sampling or detection. Differences in total mass recovery and O:C between the three instruments was found to result predominately from differences in the electric field strength (V cm$^{-1}$) to buffer gas density (molecules cm$^{-3}$) (E/N) ratio in the drifttube reaction ionization chambers of the PTR-ToF-MS instruments and from dissimilarities in the collection/desorption of aerosols. A method to identify and exclude ions affected by thermal dissociation during desorption and ionic dissociation in the ionization chamber of the PTRMS was developed and tested. Determined species were mapped onto the two dimensional volatility basis set (2D-VBS) and results showed a decrease of the C* with increasing oxidation state. For compounds measured [...]

Note: Universität Köln, Diss., 2017

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Contributing Institute(s):

1. Troposphäre (IEK-8)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

Appears in the scientific report 2018

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Database coverage:
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