Concerted measurements of lipids in seawater and on submicrometer aerosol particles at the Cabo Verde islands: biogenic sources, selective transfer and high enrichments

• Published in: Atmospheric Chemistry and Physics
• Main Authors: N. Triesch, M. van Pinxteren, S. Frka, C. Stolle, T. Spranger, E. H. Hoffmann, X. Gong, H. Wex, D. Schulz-Bull, B. Gašparović, H. Herrmann
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2021
• Subjects: Physics; QC1-999; Chemistry; QD1-999; North Atlantic
• Online Access: https://doi.org/10.5194/acp-21-4267-2021; https://doaj.org/article/225fded4b4684097b46924fd63dd844a

In the marine environment, measurements of lipids as representative species within different lipid classes have been performed to characterize their oceanic sources and their transfer from the ocean into the atmosphere to marine aerosol particles. The set of lipid classes includes 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); and phospholipids (PP) including phosphatidylglycerols (PG), phosphatidylethanolamine (PE), phosphatidylcholines (PC), as well as glycolipids (GL) which cover sulfoquinovosyldiacylglycerols (SQDG), monogalactosyl-diacylglycerols (MGDG), digalactosyldiacylglycerols (DGDG) and sterols (ST). These introduced lipid classes have been analyzed in the dissolved and particulate fraction of seawater, differentiating between underlying water (ULW) and the sea surface microlayer (SML) on the one hand. On the other hand, they have been examined on ambient submicrometer aerosol particle samples (PM 1 ) which were collected at the Cape Verde Atmospheric Observatory (CVAO) by applying concerted measurements. These different lipids are found in all marine compartments but in different compositions. Along the campaign, certain variabilities are observed for the concentration of dissolved ( ∑ DL ULW : 39.8–128.5 µg L −1 , ∑ DL SML : 55.7–121.5 µg L −1 ) and particulate ( ∑ PL ULW : 36.4–93.5 µg L −1 , ∑ PL SML : 61.0–118.1 µg L −1 ) lipids in the seawater of the tropical North Atlantic Ocean. Only slight SML enrichments are observed for the lipids with an enrichment factor EF SML of 1.1–1.4 (DL) and 1.0–1.7 (PL). On PM 1 aerosol particles, a total lipid concentration between 75.2–219.5 ng m −3 (averaged: 119.9 ng m −3 ) is measured. As also bacteria – besides phytoplankton sources – influence the lipid concentrations in seawater and on the aerosol particles, the lipid abundance cannot be exclusively explained by the phytoplankton tracer ...