Seasonal signatures in SFG vibrational spectra of the sea surface nanolayer at Boknis Eck Time Series Station (SW Baltic Sea)

Abstract

The very thin sea surface nanolayer on top of the sea surface microlayer, sometimes just one monomolecular layer thick, forms the interface between ocean and atmosphere. Due to the small dimension and tiny amount of substance, knowledge about the development of the layer in the course of the year is scarce. In this work, the sea surface nanolayer at Boknis Eck Time Series Station (BE), southwestern Baltic Sea, has been investigated over a period of three and a half years. Surface water samples were taken monthly by screen sampling and were analyzed in terms of organic content and composition by sum frequency generation spectroscopy, which is specifically sensitive to interfacial layers. A yearly periodicity has been observed with a pronounced abundance of sea surface nanolayer material (such as carbohydrate-rich material) during the summer months. On the basis of our results we conclude that the abundance of organic material in the nanolayer at Boknis Eck is not directly related to phytoplankton abundance alone. We speculate that indeed sloppy feeding of zooplankton together with photochemical and/or microbial processing of organic precursor compounds is responsible for the pronounced seasonality

Calcium enrichment in sea spray aerosol particles

“…However, it should be noted that the VSFS analysis of the North Atlantic seawater, conducted after the experiments, also showed no signs of organic compounds at the water surface. The reason for this is unknown and the apparent lack of surface-active organic compounds in the North Atlantic seawater contrasts other measurements in the literature [Laß et al, 2013]. However, it is noteworthy to mention that Laß et al [2013] did not observe surface-active organic compounds for water samples collected during winter months.…”

“…The two most likely explanations for the Ca 2+ enrichment are complexation of the Ca 2+ to organics and the presence of inorganic Ca 2+ (e.g., CaCO 3 ). However, it is noteworthy to mention that Laß et al [2013] did not observe surface-active organic compounds for water samples collected during winter months. However, to rule out a potential contamination of the Sigma sea salt by organics two methods were used to determine the contribution of surface active organic substances.…”

The organic sea-surface microlayer in the upwelling region off the coast of Peru and potential implications for air–sea exchange processes

“…Thus, organic matter accumulation and composition in the SML may also reflect the sensitivity of marine microorganisms in the surface ocean to environmental changes, which was shown during previous mesocosms studies Riebesell et al, 2009;Schulz et al, 2013). Distinct from the SML and on top of it lies the nanolayer, a monomolecular film, which, like the SML, shows seasonality features with carbohydrate-rich polymeric material being most abundant during the summer months and possibly related to a combination of primary production (phytoplankton abundance) and photochemical and/or microbial reworking of organic matter (Laß et al, 2013).…”

OCEANFILMS‐2: Representing coadsorption of saccharides in marine films and potential impacts on modeled marine aerosol chemistry

“…In addition, a secondary pool of less surface active but longer‐lived (semilabile) organic compounds accumulates over the course of a phytoplankton bloom, leading to partial decoupling of [Chl a ] and OMF in OCEANFILMS. This is consistent with recent laboratory and observational studies suggesting that a time lag can occur between peaks in [Chl a ] during a bloom and in OMF of sea spray [ Laß et al ., ; Wang et al ., ; Schwier et al ., ].…”

“…The utility of this approach for systems of organic species having markedly different solubilities is qualitatively supported by laboratory experiments that our team has performed on a dipalmitoylphosphatidylcholine (DPPC)‐glucosamine model system (Figure ). DPPC is a common model biological membrane phospholipid with similar vibrational spectral signatures as those observed with sum frequency generation vibrational spectroscopy (SFG‐VS) in studies of sea surface microlayer material [ Laß et al ., ]. In these surface‐specific vibrational spectroscopy experiments, DPPC monolayers were studied at the aqueous/vapor interface as glucosamine concentrations varied between 500 μM to 19.9 mM.…”