engleski

Sea surface microlayers : a unified physicochemical and biological view of the air-ocean interface

The sea surface microlayer (SML) covers more than 70% of the Earth’s surface and is the boundary layer interface between the ocean and the atmosphere. This important biogeochemical and ecological system is critical to a diverse range of Earth system processes, including the synthesis, transformation and cycling of organic material, and the air-sea exchange of gases, particles and aerosols. In this review we discuss a new paradigm of the SML that takes account of those physicochemical and biological characteristics that define SML structure and function. These include enrichments in biogenic molecules such as carbohydrates, lipids and proteinaceous material that contribute to organic carbon cycling, distinct microbial assemblages that may participate in air-sea gas exchange, the generation of climate-active aerosols and the accumulation of anthropogenic pollutants with potentially serious implications for the health of the ocean. Characteristically large physical, chemical and biological gradients thus separate the SML from the underlying water and the available evidence implies that the SML retains its integrity over wide ranging environmental conditions. In support of this we present previously unpublished time series of bacterioneuston composition and SML surfactant activity immediately following physical SML disruption ; these imply timescales of the order of minutes for SML reestablishment. A progressive approach to understanding the SML and hence its role in global biogeochemistry can only be achieved by considering as an integrated whole, all the key components of this complex environment.

sea surface microlayer ; transparent exopolymer particles ; microbial communities ; air-sea gas transfer ; aerosols ; pollution

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