Beschreibung: In a tank experiment under controlled conditions, the so-called sea spray aerosol chamber, the amino acid and sodium concentrations on the size-segregated aerosol particles were investigated in 3 cycles (experimental approaches, named as Cycle C1, C2 and C3 within the data set). The seawater samples are ambient North Sea water samples sampled on three different days sampled in April 2017 in the Wadden Sea region of the south-eastern North Sea. The seawater samples were first desalted and concentrated, and for the aerosol samples, the aqueous extract was also concentrated. The concentrated samples were divided into aliquots for analysis of free amino acids and hydrolyzed amino acids (hydrolysis by HCl, 110 ºC for 20 h with addition of ascorbic acid). The processed samples were filtered, derivatized using the AccQ-Tag™ precolumn derivatization method (Waters, Eschborn, Germany), and measured by ultrahigh performance liquid chromatography with electrospray ionization and Orbitrap mass spectrometry (UHPLC/ESI Orbitrap-MS). Exact details of the method used can be found under Triesch et al., 2021a (doi:10.5194/acp-21-163-2021) and Triesch et al. 2021b (doi:10.1021/acsearthspacechem.1c00080). From these, nascent sea spray aerosol particles were generated in the sea spray aerosol chamber using a plunging jet system. These nascent sea spray aerosol particles were collected in a low pressure impactor (LPI) size resolved and the individual stages are described in the dataset with LPI. The data set reflects the free and combined amino acids and sodium levels on the size-segregated aerosol particles. Using this data set, conclusions were made about a selective transfer of amino acids from the ocean to the atmosphere under controlled conditions on molecular level. This information could be relevant in the future when parameterizing the organic matter content based on organic compounds and compound classes on marine aerosol particles.

Beschreibung: In a tank experiment under controlled conditions, the so-called sea spray aerosol chamber, the amino acid and sodium concentrations in the seawater were investigated in 3 cycles (experimental approaches, named as Cycle C1, C2 and C3 within the data set). The seawater samples are ambient North Sea water samples sampled on three different days sampled in April 2017 in the Wadden Sea region of the south-eastern North Sea. The seawater samples were first desalted and concentrated, and for the aerosol samples, the aqueous extract was also concentrated. The concentrated samples were divided into aliquots for analysis of free amino acids and hydrolyzed amino acids (hydrolysis by HCl, 110 ºC for 20 h with addition of ascorbic acid). The processed samples were filtered, derivatized using the AccQ-Tag™ precolumn derivatization method (Waters, Eschborn, Germany), and measured by ultrahigh performance liquid chromatography with electrospray ionization and Orbitrap mass spectrometry (UHPLC/ESI Orbitrap-MS). Exact details of the method used can be found under Triesch et al., 2021a (doi:10.5194/acp-21-163-2021) and Triesch et al. 2021b (doi:10.1021/acsearthspacechem.1c00080). From these, nascent sea spray aerosol particles were generated in the sea spray aerosol chamber using a plunging jet system. The data set reflects the free and combined amino acids and sodium levels in the seawater. Using this data set, conclusions were made about a selective transfer of amino acids from the ocean to the atmosphere under controlled conditions on molecular level. This information could be relevant in the future when parameterizing the organic matter content based on organic compounds and compound classes on marine aerosol particles.

Beschreibung: The sea surface microlayer (SML) covers more than 70% of the Earth’s surface and is the boundary layer interface between the ocean and the atmosphere. This important biogeochemical and ecological system is critical to a diverse range of Earth system processes, including the synthesis, transformation and cycling of organic material, and the air–sea exchange of gases, particles and aerosols. In this review we discuss the SML paradigm, taking into account physicochemical and biological characteristics that define SML structure and function. These include enrichments in biogenic molecules such as carbohydrates, lipids and proteinaceous material that contribute to organic carbon cycling, distinct microbial assemblages that participate in air–sea gas exchange, the generation of climate-active aerosols and the accumulation of anthropogenic pollutants with potentially serious implications for the health of the ocean. Characteristically large physical, chemical and biological gradients thus separate the SML from the underlying water and the available evidence implies that the SML retains its integrity over wide ranging environmental conditions. In support of this we present previously unpublished time series data on bacterioneuston composition and SML surfactant activity immediately following physical SML disruption; these imply timescales of the order of minutes for the reestablishment of the SML following disruption. A progressive approach to understanding the SML and hence its role in global biogeochemistry can only be achieved by considering as an integrated whole, all the key components of this complex environment. Highlights ► The sea surface microlayer is a biogenic film layer at the air-ocean interface. ► Distinct microbial assemblages have defining roles in microlayer functions. ► The sea surface microlayer is fundamentally involved in air-ocean transfer. ► The sea surface microlayer is linked to aerosol production. ► The sea surface microlayer is reservoir of pollutants.

Beschreibung: MILAN was a multidisciplinary, international study examining how the diel variability of sea-surface microlayer biogeochemical properties potentially impacts ocean-atmosphere interaction, in order to improve our understanding of this globally important process. The sea-surface microlayer (SML) at the air-sea interface is 〈 1 mm deep but it is physically, chemically and biologically distinct from the underlying water and the atmosphere above. Wind-driven turbulence and solar radiation are important drivers of SML physical and biogeochemical properties. Given that the SML is involved in all ocean-atmosphere exchanges of mass and energy, its response to solar radiation, especially in relation to how it regulates the air-sea exchange of climate-relevant gases and aerosols, is surprisingly poorly characterised. MILAN (sea-surface MIcroLAyer at Night) was an international, multidisciplinary campaign designed to specifically address this issue. In spring 2017, we deployed diverse sampling platforms (research vessels, radio-controlled catamaran, free-drifting buoy) to study full diel cycles in the coastal North Sea SML and in underlying water, and installed a land-based aerosol sampler. We also carried out concurrent ex situ experiments using several microsensors, a laboratory gas exchange tank, a solar simulator, and a sea spray simulation chamber. In this paper we outline the diversity of approaches employed and some initial results obtained during MILAN. Our observations of diel SML variability, e.g. the influence of changing solar radiation on the quantity and quality of organic material, and diel changes in wind intensity primarily forcing air-sea CO2 exchange, underline the value and the need of multidisciplinary campaigns for integrating SML complexity into the context of air-sea interaction.