Biopolymers form a gelatinous microlayer at the air-sea interface when Arctic sea ice melts

The interface layer between ocean and atmosphere is only a couple of micrometers thick but plays
a critical role in climate relevant processes, including the air-sea exchange of gas and heat and the
emission of primary organic aerosols (POA). Recent findings suggest that low-level cloud formation
above the Arctic Ocean may be linked to organic polymers produced by marine microorganisms. Sea
ice harbors high amounts of polymeric substances that are produced by cells growing within the seaice
brine. Here, we report from a research cruise to the central Arctic Ocean in 2012. Our study shows
that microbial polymers accumulate at the air-sea interface when the sea ice melts. Proteinaceous
compounds represented the major fraction of polymers supporting the formation of a gelatinous
interface microlayer and providing a hitherto unrecognized potential source of marine POA. Our study
indicates a novel link between sea ice-ocean and atmosphere that may be sensitive to climate change.