Aliphatic amines at the Cape Verde Atmospheric Observatory: Abundance, origins and sea-air fluxes

Abstract

Aliphatic amines are important constituents of the marine environment. However, their biogenic origins, formation processes and roles in atmospheric chemistry are still not well understood. Here we present measurements of monomethylamine (MMA), dimethylamine (DMA) and diethylamine (DEA) from two intensive sampling campaigns at the Cape Verde Atmospheric Observatory (CVAO), a remote marine station in the tropical Atlantic Ocean. The amines were measured in the sea surface microlayer (SML), in bulk seawater, in the gas and the submicron particulate aerosol phase. Additionally, a 24-month record of amine concentrations in aerosol particles, together with other particle constituents and biological and meteorological parameters, is presented. In the SML, mean amine concentrations were in the range 20-50 nmol L -1 . The correlation of the amines to chlorophyll-a (R² = 0.52) and the abundance of the diatom pigment fucoxanthin may indicate that amines were formed via algal production. Amine concentrations in the gas and particulate aerosol phases were dominated by DMA, with average concentrations of 4.5 ng m -3 and 5.6 ng m -3 , respectively. Average MMA concentrations were 0.8 ng m -3 in the gas phase and 0.2 ng m -3 in the particle phase. DEA was present in the particle phase with an average concentration of 3.9 ng m -3 , but was not detected in the gas phase. Sea to air fluxes for MMA and DMA were calculated from the seawater and gaseous amine concentrations; these varied from -8.7 E-14 to +4.0 E-13 mol m -2 s -1 and from -1.9 E-12 to +2.17 E-12 mol m -2 s -1 , respectively. While the flux for MMA was mainly positive, suggesting an oceanic source for this analyte, the flux for DMA could be both positive and negative, indicating that 2-way transport may be occurring. Principal component analysis of the 24-month dataset of amines in aerosol particles revealed that the particulate amines were not directly linked to the identified sources. It seems that the transfer of amines was being determined by gas to particle conversion rather than via primary processes. The correlation of both seawater-and gas phase-amines with biological indicators suggests that they were partly linked and that the amine abundance in the atmosphere (gas phase) reflected biological processes in seawater. In contrast, particulate amine concentrations did not show such a direct response and might have other significant sources and environmental drivers.

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

“…1, Tables S2, S5) since no correlation between these parameters and the concentration or enrichment of FAAs was found. This is consistent with other publications which observed that the amino acid concentration in seawater is not related to environmental parameters such as wind, humidity and light (Kuznetsova et al, 2004;van Pinxteren et al, 2012). The results of the individual FAA concentrations in seawater (ULW, SML) and their EF SML , listed in Table S3, show clear differences between the individual amino acids and the amino acid classes.…”

“…Interestingly, in the second half of the campaign, the FAA concentration was higher than in the first part. Previous studies in different oceanic areas (Kuznetsova and Lee, 2002;Kuznetsova et al, 2004;Reinthaler et al, 2008;van Pinxteren et al, 2012;Engel and Galgani, 2016) have already reported a generally strong variability in FAA concentrations, especially in the SML. Reinthaler et al (2008) concluded that the SML in the open ocean is a highly variable environment with high concentrations of dissolved FAAs and their high enrichment in the SML is without clear diel variations in their concentrations.…”

“…They can be divided into free single amino acids (FAAs) and combined amino acids (CAAs), which include proteins, peptides and other combined forms (Mandalakis et al, 2011). Amino acids are produced in the ocean and are reported to be in the upper layer of the ocean, the sea surface microlayer (SML) (Kuznetsova et al, 2004;Reinthaler et al, 2008;van Pinxteren et al, 2012;Engel and Galgani, 2016). The SML, as the direct interface between the ocean and the atmosphere, may play an important role as a source of organic matter (OM) in aerosol particles within the marine environment (Cunliffe et al, 2013;Engel et al, 2017;Wurl et al, 2017).…”

Wintertime Airborne Measurements of Ice Nucleating Particles in the High Arctic: A Hint to a Marine, Biogenic Source for Ice Nucleating Particles

“…The samples and blank samples were analyzed using the freezing array INDA, which is based on the design ofHill et al (2016) and described in Chen et al (2018) and Hartmann et al (2019). The determination of the ambient N INP in the immersion freezing mode as a function of temperature T is based on Vali (1971). In order to make samples and blank samples comparable, the blank samples were normalized with the same air volume as the corresponding sample, though naturally no air was sucked through the blind samples.…”

Size‐Resolved Mixing States and Sources of Amine‐Containing Particles in the East China Sea

“…High concentrations (4.4 and 7.2 nmol m −3 , respectively) of particulate dimethylamine (DMA) and trimethylamine (TMA), which are probably associated with local biogenic emissions, were observed over the Yellow Sea and the Bohai Sea in May 2012 (Hu et al, 2015). In the North Atlantic, the concentrations of particulate amines were significantly higher during high biological activity periods than during low biological activity periods, and the contributions of amines to secondary organic aerosols and water-soluble organic nitrogen reached 11% and 35%, respectively (Facchini et al, 2008). Van Pinxteren et al (2019 reported that amines in the seawater and gas phase are connected to biological activity of marine and found the transfer of amines was being determined by gas-to-particle conversion rather than via primary processes.…”