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SSCI-VIDE+CARE+NHY:MBM:SPR:CGO; International audience; Surfaces coated with biogenic surfactants exposed to the atmosphere are ubiquitous and are commonly present on aerosol particles, cloud droplets, buildings, plants, and oceans. As shown in the past, photochemical reactions taking places at these air/water interfaces lead to unique chemical pathways, producing volatile organic compounds (VOCs) and leading to secondary organic aerosol formation. Here, photochemical processes at the air/water interface of biofilm-containing solutions were studied, demonstrating abiotic VOC production from authentic biogenic surfactants under ambient conditions [1]. Using a combination of online-APCI-HRMS and PTR-ToF-MS, unsaturated and functionalized VOCs were identified and quantified, giving emission fluxes comparable to previous field and laboratory observations. Interestingly, VOC fluxes increased with the decay of microbial cells in the samples, indicating that cell lysis due to cell death was the main source for surfactants, and VOC production. In agreement with our previous studies, LC-MS measurements of the liquid phase suggested the presence of fatty acids and known photosensitizers, possibly inducing the observed VOC production via peroxy-radical chemistry. Up to now, such VOC emissions were directly attributed to high biological activity in surface water. However, our results suggest that abiotic photochemistry can lead to similar atmospheric emissions, especially in low biologically-active regions. Furthermore, chamber experiments suggested that oxidation (O3 /OH-radicals) of the photochemically-produced VOCs leads to aerosol formation and growth, possibly affecting atmospheric chemistry and climate-related processes, such as cloud formation or the Earth’s radiation budget.[1] M. Brüggemann et al., Faraday Discussions, 2017, in press.

SSCI-VIDE+CARE+NHY:ABO:SPR:CGO; International audience; Surfaces coated with biogenic surfactants exposed to the atmosphere are ubiquitous and are commonly present on aerosol particles, cloud droplets, buildings, plants, and oceans. As shown in the past, photochemical reactions taking places at these air/water interfaces lead to unique chemical pathways, producing volatile organic compounds (VOCs) and leading to secondary organic aerosol formation.Here, photochemical processes at the air/water interface of biofilm-containing solutions were studied, demonstrating abiotic VOC production from authentic biogenic surfactants under ambient conditions [1]. Using a combination of online-APCI-HRMS and PTR-ToF-MS, unsaturated and functionalized VOCs were identified and quantified, giving emission fluxes comparable to previous field and laboratory observations. Interestingly, VOC fluxes increased with the decay of microbial cells in the samples, indicating that cell lysis due to cell death was the main source for surfactants, and VOC production. In agreement with our previous studies, LC-MS measurements of the liquid phase suggested the presence of fatty acids and known photosensitizers, possibly inducing the observed VOC production via peroxy-radical chemistry. Up to now, such VOC emissions were directly attributed to high biological activity in surface water. However, our results suggest that abiotic photochemistry can lead to similar atmospheric emissions, especially in low biologically-active regions. Furthermore, chamber experiments suggested that oxidation (O3/OH-radicals) of the photochemically-produced VOCs leads to aerosol formation and growth, possibly affecting atmospheric chemistry and climate-related processes, such as cloud formation or the Earth's radiation budget.[1] M. Brüggemann and N. Hayeck et al., Faraday Discussions, 2017, DOI: 10.1039/c7fd00022g