Sulfate formation via aerosol-phase SO₂ oxidation by model biomass burning photosensitizers: 3,4-dimethoxybenzaldehyde, vanillin and syringaldehyde using single-particle mixing-state analysis

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(9), P. 5251 - 5261

Published: May 10, 2023

Abstract. Atmospheric oxidation of sulfur dioxide (SO2) to sulfate has been widely investigated by means gas-phase and in-cloud chemistry studies. Recent field measurements have shown significant formation in cloud-free environments with high aerosol loadings. As an important fraction biomass burning components, particulate phenolic non-phenolic aromatic carbonyls may initiate photosensitized multiphase SO2 aerosols, which our knowledge however is still its nascent stage. In this study, on the basis single-particle mass spectrometry (SPAMS) measurements, we find evident biomass-burning-derived photosensitizer particles under UV exposure, attributable S(IV), while almost no was observed dark conditions. The efficiency production irradiation, represented number percentage sulfate-containing (99 %–43 %) relative peak area (RPA) (0.67–0.12) spectra, descending order, were 3,4-dimethoxybenzaldehyde (DMB), vanillin (VL) syringaldehyde (SyrAld). Internal mixtures VL potassium nitrate (KNO3) gave a slightly lower RPA than alone. externally mixed KNO3 particles, predominantly formed former, confirming that via photosensitization prevails over photolysis. Our results suggest S(IV) could make contribution formation, especially areas influenced burning.

Language: Английский

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Aqueous-Phase Photoreactions of Mixed Aromatic Carbonyl Photosensitizers Yield More Oxygenated, Oxidized, and less Light-Absorbing Secondary Organic Aerosol (SOA) than Single Systems

Environmental Science & Technology, Journal Year: 2024, Volume and Issue: 58(18), P. 7924 - 7936

Published: April 23, 2024

Aromatic carbonyls have been mainly probed as photosensitizers for aqueous secondary organic aerosol (aqSOA) and light-absorbing (i.e., brown carbon or BrC) formation, but due to their nature, they can also undergo oxidation form aqSOA BrC. However, photochemical transformations of aromatic carbonyl photosensitizers, particularly in multicomponent systems, are understudied. This study explored formation from the irradiation mixed single systems under cloud/fog conditions. Mixed consisting phenolic only (VL + ActSyr SyrAld: vanillin [VL] acetosyringone [ActSyr] syringaldehyde [SyrAld]) another composed both nonphenolic (DMB 3,4-dimethoxybenzaldehyde [DMB], a carbonyl, SyrAld) were compared VL (VL*) DMB (DMB*), respectively. In shorter lifetimes indicate diminished capacity trigger other compounds (e.g., guaiacol [GUA], noncarbonyl phenol). contrast slow decay minimal photoenhancement DMB*, rapid photodegradation significant VL* efficient direct photosensitized self-photosensitization). Relative increased oxidant availability promoted functionalization SyrAld accelerated conversion early generation SyrAld. Moreover, oxidizable substrates countered by stronger oxidative limited contribution light absorption. suggests weaker radiative effect BrC photosensitizer than systems. Furthermore, more oxygenated oxidized was observed with increasing complexity reaction < GUA). work offers new insights into emphasizing dual role sources substrates.

Language: Английский

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Contribution of Carbonyl Chromophores in Secondary Brown Carbon from Nighttime Oxidation of Unsaturated Heterocyclic Volatile Organic Compounds

Environmental Science & Technology, Journal Year: 2023, Volume and Issue: 57(48), P. 20085 - 20096

Published: Nov. 20, 2023

The light absorption properties of brown carbon (BrC), which are linked to molecular chromophores, may play a significant role in the Earth's energy budget. While nitroaromatic compounds have been identified as strong chromophores wildfire-driven BrC, other types remain be investigated. Given electron-withdrawing nature carbonyls ubiquitous atmosphere, we characterized carbonyl BrC samples from nighttime oxidation furan and pyrrole derivatives, important but understudied precursors secondary organic aerosols primarily found wildfire emissions. Various were quantified samples, their ultraviolet-visible spectra simulated by using time-dependent density functional theory. Our findings suggest that with bonded nitrogen (i.e., imides amides) derived N-containing heterocyclic substantially contribute absorption. contributed over 40% total at wavelengths below 350 nm above 430 BrC. contributions differed significantly wavelength, highlighting divergent importance different wavelength ranges. Overall, our highlight significance underscore need for further investigation.

Language: Английский

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Enhanced HONO Formation from Aqueous Nitrate Photochemistry in the Presence of Marine Relevant Organics: Impact of Marine-Dissolved Organic Matter (m-DOM) Concentration on HONO Yields and Potential Synergistic Effects of Compounds within m-DOM

ACS ES&T Air, Journal Year: 2024, Volume and Issue: 1(6), P. 525 - 535

Published: April 30, 2024

Nitrous acid (HONO) is a key molecule in the reactive nitrogen cycle. However, sources and sinks for HONO are not fully understood. Particulate nitrate photochemistry has been suggested to play role formation of marine boundary layer (MBL). Here we investigate impact relevant organic compounds on from aqueous photochemistry. In particular, steady-state, gas-phase yields were measured irradiated solutions at low pH containing marine-dissolved matter (m-DOM). m-DOM induces nonlinear increase yield across all concentrations compared that pure solutions, with rates increasing by up 3-fold when present. Furthermore, understand potential synergistic effects may occur within complex samples such as m-DOM, mixtures chromophoric (light-absorbing) aliphatic (non-light-absorbing) molecular proxies utilized. 4-benzoylbenzoic (4-BBA) ethylene glycol (EG) acidic showed more upon irradiation only one proxies. This suggests can samples. Atmospheric implications results presented here discussed.

Language: Английский

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Enhanced sulfate formation in mixed biomass burning and sea-salt interactions mediated by photosensitization: effects of chloride, nitrogen-containing compounds, and atmospheric aging

Atmospheric chemistry and physics, Journal Year: 2025, Volume and Issue: 25(1), P. 425 - 439

Published: Jan. 13, 2025

Abstract. Discrepancies persist between modeled simulations and measured sulfate concentrations in the marine boundary layer, especially when air is influenced by biomass burning plumes. However, there has been a notable dearth of research conducted on interactions sea-salt aerosol plumes, impeding comprehensive understanding formation. This work studied formation mixing real (BB) extracts NaCl, mimicking internal mixtures BB particles. BB–NaCl particles had significantly higher rate than incense (IS)–NaCl For fresh particles, followed trend corn straw (CS)–NaCl > rice (RS)–NaCl wheat (WS)–NaCl IS–NaCl. The filter sample aging was achieved exposure to OH• generated from UV irradiation. After aging, RS–NaCl exhibited highest enhancement rates among all due RS NaCl. Bulk aqueous experiments spiked with NaCl using model photosensitizers (PSs) nitrogen-containing organic compounds (NOCs), pyrazine (CHN), 4-nitrocatechol (CHON) revealed positive effects chloride PS–CHON system negative PS–CHN Our suggests that reaching or near coastal areas can affect via photosensitizer-mediated reactions, potentially exacerbating pollution.

Language: Английский

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Intermolecular Interactions Enhance the Light Absorption of a Methoxyphenol Constituent of Biomass Burning Emissions

ACS ES&T Air, Journal Year: 2025, Volume and Issue: 2(3), P. 406 - 415

Published: Feb. 27, 2025

Brown carbon (BrC) components of biomass burning organic aerosol (BBOA) absorb sunlight at visible wavelengths. However, it is not clear whether the total light absorption this BrC simply sum contributions individual or can bind noncovalently to give additional through charge transfer. Here, intermolecular interactions between guaiacol and quinones (1,4-benzoquinone 1,4-naphthoquinone) were identified in proxies nonpolar, water-insoluble phase BBOA, using UV-vis spectroscopy. Guaiacol its derivatives are some most abundant emissions smoldering coniferous species. Enhanced occurred instantaneously upon mixing colorless with either quinone n-heptane did increase time, contrast absorbance changes that would be expected for a covalent product. This enhancement decreased by about 25% as temperature increased from 303 323 K, consistent exothermic association complexes, yielding enthalpies complexation -13.3 ± 0.6 -12.3 0.4 kJ mol-1 benzoquinone naphthoquinone, respectively. Enhancement was also observed gas-liquid partitioning into thin films guaiacol, example, thickness 20 μm. multiphase processing, mimicking liquid produced comparable moderately absorbing other sources, suggestive atmospheric relevance these interactions.

Language: Английский

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Photolytic Mass Loss of Secondary Organic Aerosol Derived from Photooxidation of Biomass Burning Furan Precursors

ACS ES&T Air, Journal Year: 2025, Volume and Issue: 2(4), P. 476 - 485

Published: March 11, 2025

Direct photolysis as a potentially important chemical loss pathway for atmospheric organic aerosol (OA) is increasingly recognized but remains highly uncertain, particularly secondary (SOA) derived from biomass burning (BB) precursors. We present the measurements of photolytic mass change SOA photooxidation three furan precursors, 3-methylfuran, 2-methylfuran, and furfural, in an environmental chamber under both dry humid conditions. Each type was collected on crystal sensors, losses by 300 or 340 nm light were continuously monitored using quartz microbalance (QCM). By incorporation modeling, 10-40% masses can be lost direct solar radiation over their typical lifetime. The fraction well correlated with nitrogen-containing compounds (NOC) SOA, possibly because these species largely enhance absorption cross section readily undergo photodissociation UV light.

Language: Английский

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Seasonal variations in the production of singlet oxygen and organic triplet excited states in aqueous PM_2.5 in Hong Kong SAR, South China

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(16), P. 9245 - 9263

Published: Aug. 22, 2023

Abstract. Photooxidants drive many atmospheric chemical processes. The photoexcitation of light-absorbing organic compounds (i.e., brown carbon, BrC) in waters can lead to the generation reactive triplet excited states (3C∗), which undergo further reactions produce other photooxidants such as singlet oxygen (1O2∗). To determine importance these aqueous secondary aerosol (SOA) formation and transformation, we must know their steady-state concentrations quantum yields. However, there have been limited measurements 3C∗ 1O2∗ samples outside North America Europe. In this work, report first yields produced aerosols South China. We quantified production illuminated extracts PM2.5 collected different seasons at two urban sites one coastal semi-rural site during a year-round study conducted Hong Kong SAR, mass absorption coefficients 300 nm for BrC ranged from 0.49 2.01 m2 g-C−1 three sites. Both were year-round. ([1O2∗]ss) 1.56×10-14 1.35×10-12 M, with average (4.02±3.52)×10-13 M. At nearly 2 orders magnitude lower than [1O2∗]ss, ([3C∗]ss) 2.93×10-16 8.08×10-14 (1.09±1.39)×10-14 also spanned wide ranges across samples, range 1.19 % 13.74 an (5.19±2.63) 0.05 3.24 (0.56±0.66) 3C∗. [1O2∗]ss [3C∗]ss correlated concentration absorbance BrC, thus implying that amount drives photooxidants. locations (urban vs. semi-rural) did not significant effect on indicated local sources influence production. found be highest winter lowest summer all observed seasonal trends could attributed variations long-range air transport. Our analysis highlighted key role regional play influencing composition water-soluble contributed current results will useful modeling photochemistry China region.

Language: Английский

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Photoaging of phenolic secondary organic aerosol in the aqueous phase: evolution of chemical and optical properties and effects of oxidants

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(12), P. 7103 - 7120

Published: June 28, 2023

Abstract. While gas-phase reactions are well established to have significant impacts on the mass concentration, chemical composition, and optical properties of secondary organic aerosol (SOA), aqueous-phase aging SOA remains poorly understood. In this study, we performed a series long-duration photochemical experiments investigate evolution composition light absorption aqueous (aqSOA) from guaiacyl acetone (GA), semivolatile phenolic carbonyl that is common in biomass burning smoke. The aqSOA was produced GA with hydroxyl radical (•OH-aqSOA) or triplet excited state carbon (3C∗-aqSOA) then photoaged water under conditions simulate sunlight exposure northern California for up 48 h. effects increasing •OH 3C∗ concentration photoaging were also studied. High-resolution spectrometry (HR-AMS) UV–Vis spectroscopy utilized characterize absorptivity track their changes during aging. Compared •OH-aqSOA, 3C∗-aqSOA more rapidly shows less oxidation, greater abundance oligomers, higher absorption. Prolonged promotes fragmentation formation volatile light-absorbing products. More than half initial lost, substantial photobleaching occurs after 10.5 h prolonged simulated illumination •OH-aqSOA. By performing positive matrix factorization (PMF) analysis combined HR-AMS spectral data, resolved three generations distinctly different properties. first-generation oligomer enhanced at 340–400 nm. second-generation enriched functionalized species has highest coefficients 300–500 nm, while third-generation contains fragmented products least absorbing. These results suggest intermediately aged absorbing other generations, competition between brown (BrC) photobleaching, which dependent time. Although generally increases oxidation aqSOA, slightly decreased O/C •OH-aqSOA observed additional exposure. This likely due evaporation highly oxidized compounds. Increased oxidant accelerates transformation decay BrC chromophores, leading faster reduction photobleaching. addition, compared •OH, by produces low-volatility products, counterbalances part loss evaporation.

Language: Английский

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Aqueous Photosensitization of Syringaldehyde: Reactivity, Effects of Environmental Factors, and Formation of Brown Carbon Products

ACS Earth and Space Chemistry, Journal Year: 2024, Volume and Issue: 8(6), P. 1193 - 1203

Published: May 18, 2024

Phenolic aldehydes as brown carbon (BrC) chromophores may contribute to the mass of aqueous secondary organic aerosol (aqSOA) due their potential atmospheric photosensitizers. However, there is still a lack knowledge about sensitizing ability and impact environmental factors. In this work, we studied photosensitized behavior phenolic aldehyde, syringaldehyde (SyrAld), in solutions. Under illumination, influences factors such precursor concentration, solution pH, codissolved inorganic constituents (NaCl Na2SO4), matter (vanillyl alcohol, VAL, methoxyphenol produced during biomass burning) were investigated. Our results show that increasing pH salt concentration causes strong red shift absorption peak SyrAld, chloride salts sulfate exert different effects on photochemical reactivity SyrAld. Interestingly, opposite SyrAld VAL oxidation observed at wavelengths light. UV-B irradiation, inhibited degradation by light shielding effect, while under UV-A photosensitization promoted degradation. The major photooxidation products identified hydroxylated induced reactive oxygen species (OH radicals) dimerized direct triplet excited state (3SyrAld*) using UPLC-Q-TOF-MS. This work suggests play significant roles determining fate waters.

Language: Английский

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