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.

海-气界面（air-sea interface）层厚度仅为数微米，却在诸多与气候相关的过程中发挥关键作用，涵盖气体与热量的海-气交换，以及一次有机气溶胶（primary organic aerosols, POA）的排放。近期研究表明，北冰洋上空的低层云形成过程，或与海洋微生物产生的有机聚合物存在关联。海冰内部蕴含大量由海冰卤水（sea-ice brine）中生长的微生物细胞合成的聚合物质。本研究基于2012年北冰洋中部科考航次展开，结果显示海冰融化时，微生物聚合物会在海-气界面处积聚。蛋白质类化合物是构成该凝胶状界面微层（gelatinous interface microlayer）的主要聚合物组分，同时也是此前未被认知的海洋一次有机气溶胶潜在来源。本研究揭示了海冰-海洋与大气之间的一种新型关联，该关联或对气候变化敏感。