Photosensitized production of functionalized and unsaturated organic compounds at the air-sea interface

Ciuraru, Raluca; Fine, L.; Pinxteren, Manuela van; D’Anna, Barbara; Herrmann, Hartmut; George, Christian

doi:10.1038/srep12741

Cited by 91 publications

(181 citation statements)

References 39 publications

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“…This relatively simple environment allowed us to detect OVOCs that were emitted not by wind-driven fluxes or gas-phase chemistry but by chemistry at the air-sea interface. Our field observations combined with previous laboratory experiments (17,(26)(27)(28)(29) provide a compelling reason to consider this chemistry as a source of OVOCs in the MBL globally.…”

Section: Resultsmentioning

confidence: 91%

“…Although SML chemical composition is complex and not fully understood, it contains both saturated and unsaturated fatty acids (32,34,35). Gas-phase production of smaller and more oxygenated molecules from these model SML constituents can occur via three different mechanisms: direct photooxidation (17,26), photosensitized oxidation (27,28,31), or heterogeneous oxidation (29). Thus, OVOCs can be produced from the SML in the presence of light with or without the action of photosensitizers, or in the presence of gas-phase oxidants such as ozone or the hydroxyl radical.…”

Section: Significancementioning

confidence: 99%

“…Recent laboratory studies (17,(26)(27)(28)(29)(30)(31) have uncovered novel mechanisms for the emission of OVOCs to the MBL involving chemistry at the interface between the ocean and atmosphere, where the sea surface microlayer (SML) can be enriched in organic matter. The thickness of the SML is typically about 50 μm (32), and substantial SML enrichments (relative to underlying bulk seawater) in surfactants, saccharides, and plankton exudates have been observed globally in both eutrophic and oligotrophic waters (e.g., ref.…”

Section: Significancementioning

confidence: 99%

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Microlayer source of oxygenated volatile organic compounds in the summertime marine Arctic boundary layer

Mungall

Abbatt

Wentzell

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

121

142

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Summertime Arctic shipboard observations of oxygenated volatile organic compounds (OVOCs) such as organic acids, key precursors of climatically active secondary organic aerosol (SOA), are consistent with a novel source of OVOCs to the marine boundary layer via chemistry at the sea surface microlayer. Although this source has been studied in a laboratory setting, organic acid emissions from the sea surface microlayer have not previously been observed in ambient marine environments. Correlations between measurements of OVOCs, including high levels of formic acid, in the atmosphere (measured by an online highresolution time-of-flight mass spectrometer) and dissolved organic matter in the ocean point to a marine source for the measured OVOCs. That this source is photomediated is indicated by correlations between the diurnal cycles of the OVOC measurements and solar radiation. In contrast, the OVOCs do not correlate with levels of isoprene, monoterpenes, or dimethyl sulfide. Results from box model calculations are consistent with heterogeneous chemistry as the source of the measured OVOCs. As sea ice retreats and dissolved organic carbon inputs to the Arctic increase, the impact of this source on the summer Arctic atmosphere is likely to increase. Globally, this source should be assessed in other marine environments to quantify its impact on OVOC and SOA burdens in the atmosphere, and ultimately on climate.Arctic | chemical ionization mass spectrometry | oxygenated volatile organic compounds | sea surface microlayer | marine boundary layer

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Section: Resultsmentioning

confidence: 91%

Section: Significancementioning

confidence: 99%

Section: Significancementioning

confidence: 99%

See 1 more Smart Citation

Microlayer source of oxygenated volatile organic compounds in the summertime marine Arctic boundary layer

Mungall

Abbatt

Wentzell

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

121

142

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“…50, 51 Moreover, fatty acids are also known components of the EPS matrix 15 surrounding the cells in biofilms. 18,52,53 In contrast to the other fatty acid classes, oxo-fatty acids have been observed previously to be produced also by photo-oxidation, 51 besides enzymatic digestion. 54 Moreover, similar oxidation products have been found earlier from irradiation of a microlayer of a saturated fatty acid and were attributed to photo-induced peroxy-radical chemistry.…”

Section: Resultsmentioning

confidence: 98%

Interfacial photochemistry of biogenic surfactants: a major source of abiotic volatile organic compounds

et al. 2017

Self Cite

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15Films of biogenic compounds exposed to the atmosphere are ubiquitously found on surfaces of cloud droplets, aerosol particles, buildings, plants, soils, and the ocean. These air/water interfaces host countless amphiphilic compounds concentrated there with respect to bulk water, leading to a unique chemical environment. Here, photochemical processes at the air/water interface of biofilmcontaining solutions were studied, demonstrating abiotic VOC production from authentic biogenic 20 surfactants under ambient conditions. 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 particular, irradiation of samples containing solely 25 biofilm cells without matrix components exhibited the strongest VOC production upon irradiation. In agreement with 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 accounted to high biological activity in surface waters. However, the obtained results suggest that abiotic photochemistry can 30 lead to similar emissions into the atmosphere, especially in less biologically-active regions.Furthermore, chamber experiments suggested that oxidation (O 3 /OH-radicals) of the photochemically-produced VOCs leads to aerosol formation and growth, possibly affecting 2 atmospheric chemistry and climate-related processes, such as cloud formation or the Earth's radiation budget. 3 IntroductionAir/water interfaces are omnipresent in the ambient atmosphere, reaching from the nm-scale for single aerosol particles to the surface of the ocean, which covers more than 70% of the Earth's surface. In the past, it was shown that unique photochemical reactions with significant implications for atmospheric processes can occur at such interfaces, leading to the formation of volatile organic 5 compounds (VOCs) 1-5 and secondary organic aerosols, 6 or acting as sinks for reactive species, such as NO 2 or ozone. [7][8][9][10] This interfacial photochemistry is exclusively due to the presence of surfactants which tend to concentrate in surface layers with respect to the underlying bulk water. Additionally, such surfactants also increase the propensity of less surface-active compounds to enrich there as well, creating a unique chemical environment, affecting not only chemistry but also trace-gas 10 exchange. 5,[10][11][12][13][14][15][16] A major source of biogenic surfactants in the ambient environment are so-called biofilms, loosely defined as a population of microorganisms (i.e., fungi, algae, archaea) that accumulate at an interface. In addition, such microorganisms can also form cel...

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“…Nonanoic acid (NA) forms from the oxidation of oleic acid [ King et al ., ] and has been used as a proxy for SML carboxylic acid chemistry more generally. Photosensitized interfacial chemistry of NA is a source of nonenal and other OVOC [ Ciuraru et al ., ], but it is unclear which nonenal isomer forms, and whether it acts as a precursor for glyoxal. Here we present a series of laboratory experiments investigating whether the irradiation of carboxylic acids at a simulated ocean surface is a source of glyoxal, in the presence and absence of a photosensitizer.…”

Section: Introductionmentioning

confidence: 99%

UV photochemistry of carboxylic acids at the air‐sea boundary: A relevant source of glyoxal and other oxygenated VOC in the marine atmosphere

Chiu

Tinel

González

et al. 2017

Geophysical Research Letters

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Photochemistry plays an important role in marine dissolved organic carbon (DOC) degradation, but the mechanisms that convert DOC into volatile organic compounds (VOCs) remain poorly understood. We irradiated carboxylic acids (C7–C9) on a simulated ocean surface with UV light (<320 nm) in a photochemical flow reactor and transferred the VOC products into a dark ozone reactor. Glyoxal was detected as a secondary product from heptanoic, octanoic, and nonanoic acid (NA) films, but not from octanol. Primary glyoxal emissions were not observed, nor was glyoxal formed in the absence of ozone. Addition of a photosensitizer had no noticeable effect. The concurrent detection of heptanal in the NA system suggests that the ozonolysis of 2‐nonenal is the primary chemical mechanism that produces glyoxal. This source can potentially sustain tens of parts per trillion by volume (pptv) glyoxal over oceans, and helps to explain why glyoxal fluxes in marine air are directed from the atmosphere into the ocean.

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Photosensitized production of functionalized and unsaturated organic compounds at the air-sea interface

Cited by 91 publications

References 39 publications

Microlayer source of oxygenated volatile organic compounds in the summertime marine Arctic boundary layer

Microlayer source of oxygenated volatile organic compounds in the summertime marine Arctic boundary layer

Interfacial photochemistry of biogenic surfactants: a major source of abiotic volatile organic compounds

UV photochemistry of carboxylic acids at the air‐sea boundary: A relevant source of glyoxal and other oxygenated VOC in the marine atmosphere

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