George Christian - Viernes 1 de Junio 11:00 hs

Emissions of aerosols and gases in the marine boundary layer: abiotic vs biotic processes

The sea-surface microlayer (SML) chemical composition, driven by biogeochemical and physical processes in the ocean, influences not only the organic fraction of marine aerosol produced by sea spray processes but also controls trace gas deposition to the ocean and may be involved in secondary organic aerosol formation in the marine boundary layer. Hence, a better chemical characterization and understanding of the oceanic microlayer and its processes is highly desirable. The SML, covering up to 70% of the ocean’s surfacehas different physical, chemical and biological properties compared to the subsurface water, with an enrichment of organic matter i.e., dissolved organic matter including UV absorbing humic substances, fatty acids, amino acids, proteins, lipids, phenolic compounds, as well as trace metals, particulate matter and microorganisms.
Here we will show that the existence of organic films on the ocean surface due to biological activities influences air/sea exchanges in an unexpected significant manner, as interfacial photosensitized chemistry is demonstrated to be a significant source of various gases, in the absence of any biological source.
Here we suggest that this suggests a new paradigm for describing emissions of gases and aerosols in the marine boundary layer, where abiotic processes might be more important than previously thought.