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Abstract. Dry deposition of ozone (O3) to the ocean surface and the ozonolysis of organics in the sea surface microlayer (SSML) are potential sources of volatile organic compounds (VOCs) to the marine atmosphere. We use a gas chromatography system coupled to a Vocus proton-transfer-reaction time-of-flight mass spectrometer to determine the chemical composition and product yield of select VOCs formed from ozonolysis of coastal seawater collected from Scripps Pier in La Jolla, California. Laboratory-derived results are interpreted in the context of direct VOC vertical flux measurements made at Scripps Pier. The dominant products of laboratory ozonolysis experiments and the largest non-sulfur emission fluxes measured in the field correspond to Vocus CxHy+ and CxHyOz+ ions. Gas chromatography (GC) analysis suggests that C5–C11 oxygenated VOCs, primarily aldehydes, are the largest contributors to these ion signals. In the laboratory, using a flow reactor experiment, we determine a VOC yield of 0.43–0.62. In the field at Scripps Pier, we determine a maximum VOC yield of 0.04–0.06. Scaling the field and lab VOC yields for an average O3 deposition flux and an average VOC structure results in an emission source of 10.7 to 167 Tg C yr−1, competitive with the DMS source of approximately 20.3 Tg C yr−1. This study reveals that O3 reactivity to dissolved organic carbon can be a significant carbon source to the marine atmosphere and warrants further investigation into the speciated VOC composition from different seawater samples and the reactivities and secondary organic aerosol (SOA) yields of these molecules in marine-relevant, low NOx conditions.
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Biogenic Emissions and Aerosol Response on the North Slope (BEAR-oNS) datasets for Utqiagvik, Alaska in the summer of 2023
Climate in the Arctic is changing at a rapid pace. When vegetation reacts to these changes, chemicals called biogenic volatile organic compounds (BVOCs) can be released into the atmosphere in new ways. This project seeks to investigate how climate change affects the quantity and type of BVOCs released into the atmosphere on the North Slope of Alaska (NSA). In addition, we are interested in the chemical reactions these BVOCs undergo in the Arctic atmosphere. Project goals will be accomplished through field work on the NSA, and collection and laboratory analysis of atmospheric samples. Specifically, the project intends to measure the concentration of BVOCs and their secondary organic aerosol products during North Slope of Alaska field campaigns. In addition to BVOCs and organic acids, the measurements include additional baseline measurements of other volatile organic compounds (VOC) and aerosol components. We are reporting inorganic ions, alkanes, and polycyclic aromatic hydrocarbons (PAHs) for aerosol composition and select aromatic and oxidized VOCs. The time period for these detailed measurements is Jun - Aug 2023 for Utqiagvik, Alaska (AK). VOC measurements were made by proton transfer reaction mass spectrometry. The proton transfer reaction mass spectrometer (PTR-MS) was operated with Hydronium (H3O+) ion at the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) site in Utqiagvik, AK from 170623 to 130823. Total suspended particulate matter samples were collected on quartz fiber filters at a roughly weekly schedule. These filters were then used for offline analysis. Offline measurement of cations and anions was conducted using ion chromatography. Offline measurement of alkanes and PAH was conducted using thermal desorption gas chromatography - mass spectrometry.
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- Award ID(s):
- 2041240
- PAR ID:
- 10621307
- Publisher / Repository:
- NSF Arctic Data Center
- Date Published:
- Subject(s) / Keyword(s):
- VOC aerosol composition
- Format(s):
- Medium: X Other: text/xml
- Sponsoring Org:
- National Science Foundation
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