Biogenic Characterisation of the Sea Surface Microlayer in the Peruvian Upwelling Regime

The Peruvian upwelling regime is known for its high biological productivity and has recently been highlighted as an important source for the climate-relevant trace gas N₂O. At the interface between sea and air, the sea surface microlayer (SML) plays an important role in mediating exchange processes of gases and particles between the ocean and the atmosphere. The SML covers app. 70 % of the Earth’s surface and forms a unique habitat for various microorganisms thanks to specific physical, chemical and biological properties.

In order to understand how exchange processes across the SML may be related to changes in the composition of the SML, a variety of chemical and biological data were obtained during two cruises to the Peruvian upwelling region in 2012 (M91) and 2015 (SO243). Here, we will present data on the biogenic composition of the SML including dissolved organic matter, gel particles such as the polysaccharidic Transparent Exopolymer Particles (TEP) and the proteinaceous Coomassie Stainable Particles (CSP) as well as microbial abundances. We will discuss the potential role of the organic SML components on gas exchange processes across the SML.