Photosensitized Formation of Secondary Organic Aerosols above the Air/Water Interface

Environmental Science & Technology, Год журнала: 2016, Номер 50(16), С. 8678 - 8686

Опубликована: Июль 19, 2016

In this study, we evaluated photosensitized chemistry at the air-sea interface as a source of secondary organic aerosols (SOA). Our results show that, in addition to biogenic emissions, abiotic processes could also be important marine boundary layer. Photosensitized production aerosol was studied custom-built multiphase atmospheric simulation chamber. The experimental chamber contained water, humic acid (1-10 mg L(-1)) proxy for dissolved matter, and nonanoic (0.1-10 mM), fatty which formed an film air-water interface. Dark reaction with ozone after illumination resulted SOA particle concentrations excess 1000 cm(-3), illustrating unsaturated compounds by chemical reactions numbers via photosensitization alone absence did not exceed background levels. From these results, derived dependence on surface coverage matter concentration. We present discussion potential role from origins.

Язык: Английский

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Mechanistic Insights on the Photosensitized Chemistry of a Fatty Acid at the Air/Water Interface

Environmental Science & Technology, Год журнала: 2016, Номер 50(20), С. 11041 - 11048

Опубликована: Сен. 9, 2016

Interfaces are ubiquitous in the environment and many atmospheric key processes, such as gas deposition, aerosol, cloud formation are, at one stage or another, strongly impacted by physical chemical processes occurring interfaces. Here, photoinduced chemistry of an air/water interface coated with nonanoic acid—a fatty acid surfactant we use a proxy for chemically complex natural aqueous surface microlayers—was investigated source volatile semivolatile reactive organic species. The carboxylic coating significantly increased propensity photosensitizers, chosen to mimic those observed real environmental waters, partition enhance reactivity there. Photochemical functionalized unsaturated compounds was systematically upon irradiation these surfaces. role appears be critical providing concentrated medium allowing radical–radical reactions occur parallel molecular oxygen additions. Mechanistic insights provided from extensive analysis products both phases online switchable reagent ion-time flight-mass spectrometry off-line ultraperformance liquid chromatography coupled Q Exactive high resolution mass spectrometer through heated electrospray ionization, respectively.

Язык: Английский

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Reactive VOC Production from Photochemical and Heterogeneous Reactions Occurring at the Air–Ocean Interface

Accounts of Chemical Research, Год журнала: 2020, Номер 53(5), С. 1014 - 1023

Опубликована: Май 5, 2020

The ocean surface serves as a source and sink for diverse set of reactive trace gases in the atmosphere, including volatile organic compounds (VOCs), halogens, oxidized reduced nitrogen compounds. exchange between atmosphere has been shown to alter atmospheric oxidant concentrations drive particle nucleation growth. Uncertainties cloud radiative forcing aerosol-cloud interactions are among largest uncertainties current global climate models. Climate models particularly sensitive cover over remote due large changes albedo tops. Oceanic emissions contribute condensation nuclei concentrations, either through direct emission particles during wave breaking or formation secondary aerosol following gas-phase Despite generally small diffuse oceanic rates gases, it that number acutely air-sea gas chemical composition emitted species. To date, field measurements have focused primarily on biological origin, such dimethyl sulfide (DMS). While DMS relatively well constrained, oxidation connects sulfate is less understood. Recent laboratory suggest heterogeneous photochemical reactions occurring at interface can also lead production wide array VOC. When laboratory-based used derive scale emissions, calculated sea-to-air fluxes VOC generated from processes comparable larger magnitude flux DMS. It not yet clear how mechanisms proposed these experiments translate conditions. abiotic potential regions low activity, which carries important implications regional modeling.This Account reviews recent biotic with specific focus exploring open questions related impact large, oxidants particles. typically included transport discussed here significant understanding chemistry marine if present magnitudes suggested by studies. In order validate their significance, coordinated laboratory, field, modeling studies under ocean-relevant conditions necessary.

Язык: Английский

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pH Dependence of the Aqueous Photochemistry of α-Keto Acids

The Journal of Physical Chemistry A, Год журнала: 2017, Номер 121(44), С. 8368 - 8379

Опубликована: Окт. 14, 2017

α-Keto acids are important, atmospherically relevant species, and their photochemistry has been considered in the formation processing of aerosols. Despite atmospheric relevance, these species primarily studied under extremely low pH conditions. Using a variety analytical techniques, we characterize extent hydration deprotonation for solutions two α-keto acids, pyruvic acid 2-oxooctanoic acid, as function pH. We find that changes initial solution composition govern accessibility different photochemical pathways, resulting slowed photolysis high conditions shift photoproducts can be predicted mechanistically.

Язык: Английский

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Atmospheric oxidation of phenanthrene initiated by OH radicals in the presence of O2 and NOx — A theoretical study

The Science of The Total Environment, Год журнала: 2016, Номер 563-564, С. 1008 - 1015

Опубликована: Май 8, 2016

Язык: Английский

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