engleski

Interfacial photochemistry of marine diatom lipids: Abiotic production of volatile organic compounds and new particle formation

The sea surface microlayer (SML) represents the widest environmental interface with a major environmental importance. It is enriched with surface active organic matter (OM) accumulating at the air–water interface and forming surface films. Also present in the SML OM pool, although in a low degree, are biogenic lipids, known to play a significant role in formation and stabilization of the SML, as well as in the physico-chemical, and morphological properties of the marine surface films. When irradiated, biogenic surface films may undergo unique photochemical reactions leading to abiotic production of unsaturated and functionalized volatile organic compounds (VOCs) acting as precursors for the secondary organic aerosol (SOA). Although previous studies demonstrated photoinduced VOCs production from artificial surfactants in laboratory grade water, saline solutions, and biofilm-containing solutions comprising a mixture of different microorganisms, these experiments were typically conducted under far from ambient conditions or for a very limited number of authentic samples. To investigate the potentially underestimated VOCs sources under more realistic conditions, the analyzed biogenic OM was produced by an authentic diatom culture. Additionally, lipid material was isolated to further investigate phytoplankton lipid material as the main driver of surfactant release and, thus, abiotic photochemical VOCs production. Experiments were conducted in a photochemical reactor and an atmospheric simulation chamber, to study VOCs formation upon irradiation and their implications for aerosol formation and growth, respectively. An improved chemical characterization of the biogenic surfactants and their interfacial photochemical processing is highly desirable to better understand the abiotic VOCs sources, and to improve our understanding of their subsequent impact on the climate. This research was financed by the European Union’s Horizon 2020 research and innovation programme - EUROCHAMP-2020 Infrastructure Activity under grant agreement No 730997, COGITO project and Croatian Science Foundation project BiREADI IP-2018-01- 3105.

volatile organic compounds, phytoplankton, organic matter, lipids

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