Concerted measurements of lipids in seawater and on submicron aerosol particles at the Cape Verde Islands: biogenic sources, selective transfer and high enrichments

• Main Authors: Triesch, Nadja, van Pinxteren, Manuela, Frka, Sanja, Stolle, Christian, Spranger, Tobias, Hoffmann, Erik Hans, Gong, Xianda, Wex, Heike, Schulz-Bull, Detlef, Gašparović, Blaženka, Herrmann, Hartmut
• Format: Article in Journal/Newspaper
• Language: English
• Published: European Geosciences Union 2021
• Subjects: Interdisciplinary Natural Sciences; North Atlantic
• Online Access: http://fulir.irb.hr/6389/; http://fulir.irb.hr/6389/1/Triesch_Atmos.%20Chem.%20Phys_2021.pdf; https://acp.copernicus.org/articles/21/4267/2021/acp-21-4267-2021-discussion.html; https://doi.org/10.5194/acp-2020-432

Measurements of lipids as representative species for different lipid classes in the marine environment have been performed to characterize their oceanic sources and their transfer from the ocean into the atmosphere to marine aerosol particles. To this end, a set of lipid classes (hydrocarbons (HC), fatty acid methyl esters (ME), free fatty acids (FFA), alcohols (ALC), 1, 3-diacylglycerols (1, 3 DG), 1, 2-diacylglycerols (1, 2 DG), monoacylglycerols (MG), wax esters (WE), triacylglycerols (TG), phospholipids (PP) including phosphatidylglycerols (PG), phosphatidylethanolamine (PE), phosphatidylcholines (PC), glycolipids (GL) including sulfoquinovosyldiacylglycerols (SQDG), monogalactosyl-diacylglycerols (MGDG), digalactosyldiacylglycerols (DGDG) and sterols (ST)) is investigated in both the dissolved and particulate fraction in seawater, differentiated between underlying water (ULW) and the sea surface microlayer (SML), and in ambient submicron aerosol particle samples (PM1) at the Cape Verde Atmospheric Observatory (CVAO) applying concerted measurements. The different lipids are found in all marine compartments but in different compositions. At this point, a certain variability is observed for the concentration of dissolved (∑DLULW: 39.8–128.5 μg L−1, ∑DLSML: 55.7–121.5 μg L−1) and particulate (∑PLULW: 36.4–93.5 μg L−1, ∑PLSML: 61.0–118.1 μg L−1) lipids in seawater of the tropical North Atlantic Ocean along the campaign. Only slight SML enrichments are observed for the lipids with an enrichment factor EFSML of 1.1–1.4 (DL) and 1.0–1.7 (PL). On PM1 aerosol particles, a total lipid concentration between 75.2–219.5 ng m−3 (averaged: 119.9 ng m−3) is measured with high atmospheric concentration of TG (averaged: 21.9 ng m−3) as a potential indicator for freshly emitted sea spray. Besides phytoplankton sources, bacteria influence the lipid concentrations in seawater and on the aerosol particles, so that the phytoplankton tracer (chlorophyll-a) cannot sufficiently explain the lipid abundance. The concentration and ...