Surfactant OM

The air-sea interface mediates the exchange of materials between the atmosphere and ocean thereby profoundly impacting ocean-atmosphere biogeochemical cycles and global climate. Surfactant organic matter accumulates at this interface, in the surface microlayer (SML), influencing both the chemistry of materials available for exchange and the physical environment (e.g., surface tension, turbulence) for gas and particle transfers between air and sea. Biological and photochemical production and degradation processes represent surfactant sources and sinks, but the relative importance of those processes for determining surfactant quantities and molecular composition remains unclear. Similarly, the exact relationships between surfactant molecular classes and SML surface tension have not been established. As a result, the spatiotemporal variability of SML properties cannot currently be predicted. This project addresses these knowledge gaps through a logical set of field collections and lab experiments paired with high resolution chemical, biological, and physical analyses. SML and subsurface waters will be collected from estuarine, coastal ocean, and open ocean sites during high and low productivity conditions to establish surfactant molecular characteristics over a range of space, time, and ocean biological activity. The effects of irradiation will be assessed via diurnal sampling efforts and laboratory photochemical irradiations. Samples will be analyzed for their chemical (via colorimetry and UV-vis spectroscopy; Fourier transform ion cyclotron resonance mass spectrometry; high resolution liquid chromatograph mass spectrometry), biological (via next-generation DNA sequencing), and physical (via dynamic and equilibrium surface tension) characteristics.