Quality over Quantity: Organic Compounds Altering the Antarctic Sea Spray Aerosol Concentrations

The Antarctic coastal zones are among the most biologically productive areas on Earth. The effect of marine microbiota on the emissions of sea spray particles, a critical factor for global climate and clouds, remains an open and actively researched question. Here, by means of in situ ship-borne bubble-bursting SSA production experiments at multiple locations around the Antarctic Peninsula, we show a 2-fold variability in the 10-500 nm size-resolved SSA number concentrations. We observed that the organic chemical composition of seawater (SW) and surface microlayers (SML) clearly impacts SSA number concentrations. SW and SML samples with saccharides, proteins, and N-osmolytes were less efficient at emitting SSA compared with waters rich in biotic material originating from lipids, such as fatty acids and polyols. We found that the dissolved organic carbon (DOC) fraction containing lipid degradation products and polyols indicates higher SSA production. Our results indicate that low concentration organic components, rather than the most abundant classes of biomolecules, influence the ability to be aerosolized, with strong chemical selectivity affecting SSA production.