Marine carbohydrates in Arctic aerosol particles and fog – diversity of oceanic sources and atmospheric transformations

• Published in: Atmospheric Chemistry and Physics
• Main Authors: S. Zeppenfeld, M. van Pinxteren, M. Hartmann, M. Zeising, A. Bracher, H. Herrmann
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2023
• Subjects: Physics; QC1-999; Chemistry; QD1-999; Arctic; Arctic Ocean; Barents Sea; Fram Strait; Sea ice
• Online Access: https://doi.org/10.5194/acp-23-15561-2023; https://doaj.org/article/5ea8a14e6b144768804312260abf87e6

Carbohydrates, originating from marine microorganisms, enter the atmosphere as part of sea spray aerosol (SSA) and can influence fog and cloud microphysics as cloud condensation nuclei (CCN) or ice-nucleating particles (INP). Particularly in the remote Arctic region, significant knowledge gaps persist about the sources, the sea-to-air transfer mechanisms, atmospheric concentrations, and processing of this substantial organic group. In this ship-based field study conducted from May to July 2017 in the Fram Strait, Barents Sea, and central Arctic Ocean, we investigated the sea-to-air transfer of marine combined carbohydrates (CCHO) from concerted measurements of the bulk seawater, the sea surface microlayer (SML), aerosol particles and fog. Our results reveal a wide range of CCHO concentrations in seawater (22–1070 µ g L −1 ), with notable variations among different sea-ice-related sea surface compartments. Enrichment factors in the sea surface microlayer (SML) relative to bulk water exhibited variability in both dissolved (0.4–16) and particulate (0.4–49) phases, with the highest values in the marginal ice zone (MIZ) and aged melt ponds. In the atmosphere, CCHO was detected in super- and submicron aerosol particles (CCHO aer,super : 0.07–2.1 ng m −3 CCHO aer,sub : 0.26–4.4 ng m −3 ) and fog water (CCHO fog,liquid : 18–22 000 µ g L −1 CCHO fog,atmos : 3–4300 ng m −3 ). Enrichment factors for sea–air transfer varied based on assumed oceanic emission sources. Furthermore, we observed rapid atmospheric aging of CCHO, indicating both biological/enzymatic processes and abiotic degradation. This study highlights the diverse marine emission sources in the Arctic Ocean and the atmospheric processes shaping the chemical composition of aerosol particles and fog.