English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

Abstract. Measurements of free amino acids (FAAs) in the marine environment toelucidate their transfer from the ocean into the atmosphere, to marineaerosol particles and to clouds, were performed at the MarParCloud (marine biological production,organic aerosol particles and marine clouds: a process chain) campaignat the Cabo Verde islands in autumn 2017. According to physical and chemicalspecifications such as the behavior of air masses, particulate MSAconcentrations and MSA∕sulfate ratios, as well as particulate massconcentrations of dust tracers, aerosol particles predominantly of marineorigin with low to medium dust influences were observed. FAAs wereinvestigated in different compartments: they were examined in two types ofseawater underlying water (ULW) and in the sea surface microlayer (SML), aswell as in ambient marine size-segregated aerosol particle samples at twoheights (ground height based at the Cape Verde Atmospheric Observatory, CVAO, andat 744 m height on Mt. Verde) and in cloud water using concertedmeasurements. The ∑FAA concentration in the SML varied between0.13 and 3.64 µmol L−1, whereas it was between 0.01 and 1.10 µmol L−1 in the ULW; also, a strong enrichment of ∑FAA(EFSML: 1.1–298.4, average of 57.2) was found in the SML. In thesubmicron (0.05–1.2 µm) aerosol particles at the CVAO, thecomposition of FAAs was more complex, and higher atmospheric concentrationsof ∑FAA (up to 6.3 ng m−3) compared to the supermicron(1.2–10 µm) aerosol particles (maximum of 0.5 ng m−3) wereobserved. The total ∑FAA concentration (PM10) was between1.8 and 6.8 ng m−3 and tended to increase during the campaign. Averaged∑FAA concentrations in the aerosol particles on Mt. Verde werelower (submicron: 1.5 ng m−3; supermicron: 1.2 ng m−3) compared tothe CVAO. A similar contribution percentage of ∑FAA to dissolvedorganic carbon (DOC) in the seawater (up to 7.6 %) and to water-solubleorganic carbon (WSOC) in the submicron aerosol particles (up to 5.3 %)indicated a related transfer process of FAAs and DOC in the marineenvironment. Considering solely ocean–atmosphere transfer and neglecting atmosphericprocessing, high FAA enrichment factors were found in both aerosol particlesin the submicron range (EFaer(∑FAA): 2×103–6×103) and medium enrichment factors in thesupermicron range (EFaer(∑FAA): 1×101–3×101). In addition, indications for a biogenic FAAformation were observed. Furthermore, one striking finding was the high andvarying FAA cloud water concentration (11.2–489.9 ng m−3), as well asenrichments (EFCW: 4×103 and 1×104 compared to the SML and ULW, respectively), which were reported here forthe first time. The abundance of inorganic marine tracers (sodium,methanesulfonic acid) in cloud water suggests an influence of oceanicsources on marine clouds. Finally, the varying composition of the FAAs in thedifferent matrices shows that their abundance and ocean–atmosphere transferare influenced by additional biotic and abiotic formation and degradationprocesses. Simple physicochemical parameters (e.g., surface activity) arenot sufficient to describe the concentration and enrichments of the FAAs inthe marine environment. For a precise representation in organic matter (OM)transfer models, further studies are needed to unravel their drivers andunderstand their composition.

Concerted measurements of free amino acids at the Cabo Verde islands: high enrichments in submicron sea spray aerosol particles and cloud droplets