Formation of In‐Cloud Aqueous‐Phase Secondary Organic Matter and Related Characteristic Molecules

Journal of Geophysical Research Atmospheres, Journal Year: 2024, Volume and Issue: 129(7)

Published: March 28, 2024

Abstract The formation process of in‐cloud aqueous‐phase secondary organic matter (aqSOM) and its characteristics are unclear. Herein, water‐soluble inorganic ions, oxalate, carbon (WSOC) were determined in cloud water aerosol (PM 2.5 ) samples simultaneously collected at a remote mountain site southern China during spring 2018 winter 2020. molecular compositions (WSOM) aerosols analyzed by Fourier transform ion cyclotron resonance mass spectrometer negative electrospray ionization (ESI‐) mode. results showed that the mean concentration WSOC was 6.27–8.54 mg C L −1 0.60–1.37 μg m −3 aerosols. strong correlation observed between WSOM aqueous (e.g., NO 3 − oxalate), positive matrix factorization results, elevated WSOM/K + ratios suggested enhanced aqSOM water. According to random forest analysis, factors related variation mainly included K , pH, atmospheric x . Additionally, 37 characteristic molecules, classified as ‐O ‐NO ‐N 2 O 1‐2 S, consisting dicarboxylic acids, nitrophenols, dinitrophenols, identified using linear discriminant analysis effect size (LefSe). N‐ S‐containing molecules with numbers >10 had low or extremely volatility; therefore, they might contribute after droplet evaporation. revealed modifying effects processes on composition level could improve our understanding aerosol–cloud interactions.

Language: Английский

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Seasonal Trends and Site Differences of Nitroaromatic Compounds in PM2.5 in Sichuan Basin and Their Effects on Light Absorption of Brown Carbon

Toxics, Journal Year: 2025, Volume and Issue: 13(2), P. 124 - 124

Published: Feb. 6, 2025

Nitroaromatic compounds (NACs) have adverse effects on human health and climate. Daily PM2.5 samples were collected in winter summer of 2022 two cities, Chengdu (CD) Mianyang (MY), located Sichuan Basin southwestern China. Four types NACs PM2.5, containing nitrophenols, nitrocatechols, nitrosalicylic acids, nitronaphthol, analyzed. The mean concentration a total 10 (ΣNACs) at the suburban MY site (71.7 ± 35.6 ng m−3) was higher than that urban CD (29.5 16.2 m−3), while summer, concentrations ΣNACs cities similar, around 2.2 m−3. much attributed to impact biomass burning. 4-Nitrocatechol (4NC) most abundant species during sampling period, accounting for 35–56% mass. In winter, light absorption coefficient methanol-soluble brown carbon (Abs365,M) 10.5 3.4 13.6 4.3 Mm−1 MY, respectively, which about 4–7 times summer. contributions 365 nm Abs365,M 1.6–3.6% 0.5–0.7% with 4NC contributing among all NACs. geographical origins potential sources both sites mainly distributed within basin.

Language: Английский

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Non-negligible emissions of amines from vehicle and ship exhausts in China

Atmospheric Environment, Journal Year: 2025, Volume and Issue: unknown, P. 121220 - 121220

Published: April 1, 2025

Language: Английский

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Different formation pathways of nitrogen-containing organic compounds in aerosols and fog water in northern China

Atmospheric chemistry and physics, Journal Year: 2024, Volume and Issue: 24(12), P. 6987 - 6999

Published: June 18, 2024

Abstract. While aqueous-phase processing is known to contribute the formation of nitrogen-containing organic compounds (NOCs), specific pathways involved remain poorly understood. In this study, we aimed characterize NOCs present in both pre-fog aerosols and fog water collected at a suburban site northern China. Fourier-transform ion cyclotron resonance mass spectrometry was utilized analyze molecular composition negative positive modes electrospray ionization (ESI− ESI+). samples, constituted significant portion, accounting for over 60 % all assigned formulas ESI− more than 80 ESI+. By comparing originating from biomass burning, coal combustion, vehicle emissions, identified that 72.3 were attributed primary anthropogenic sources (pNOCs), while remaining categorized as secondary formed within (saNOCs). Unique found classified (sfNOCs). Through comprehensive “precursor–product pair” screening involving 39 reaction pathways, observed nitration reaction, amine pathway, intramolecular N-heterocycle pathway NH3 addition reactions contributed 43.6 %, 22.1 11.6 saNOCs, respectively. contrast, these 26.8 28.4 29.7 sfNOCs, This disparity likely influenced by diverse precursors, aqueous acidity, gas-phase species partitioning. Correspondingly, saNOCs contain higher abundance carbohydrate-like highly oxygenated with two nitrogen atoms compared pNOCs. Conversely, sfNOCs exhibited content lipid-like fewer oxygen atoms. These results underscore distinct processes contributing diversity water, which may lead their different climate effects.

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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Machine Learning Approach for the Estimation of Henry’s Law Constant Based on Molecular Descriptors

Atmosphere, Journal Year: 2024, Volume and Issue: 15(6), P. 706 - 706

Published: June 13, 2024

In atmospheric chemistry, the Henry’s law constant (HLC) is crucial for understanding distribution of organic compounds across gas, particle, and aqueous phases. Quantitative structure–property relationship (QSPR) models described in scientific research are generally tailored to specific groups or categories substances often developed using a limited set experimental data. This study machine learning model an extensive dataset HLCs approximately 1100 compounds. Molecular descriptors calculated alvaDesc software (v 2.0) were used train models. A hybrid approach was adopted feature selection, ensuring alignment with domain knowledge. Based on root mean squared error (RMSE) training test data after cross-validation, Gradient Boosting (GB) selected as predicting HLC. The hyperparameters optimized automated hyperparameter optimization framework Optuna. impact features target variable assessed SHapley Additive exPlanations (SHAP). demonstrated strong performance training, evaluation, datasets, achieving coefficients determination (R2) 0.96, 0.78, 0.74, respectively. estimate HLC associated carbon capture storage (CCS) emissions secondary aerosols.

Language: Английский

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Mixing state and influence factors controlling diurnal variation of particulate nitrophenol compounds at a suburban area in northern China

Environmental Pollution, Journal Year: 2024, Volume and Issue: 344, P. 123368 - 123368

Published: Jan. 19, 2024

Language: Английский

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Different Formation Pathways of Nitrogen-containing Organic Compounds in Aerosols and Fog Water in Northern China

Published: Feb. 5, 2024

Abstract. While aqueous-phase processing contributes to the formation of nitrogen-containing organic compounds (NOCs), detailed pathways are not well understood. In this study, molecular composition NOCs in both pre-fog aerosols and fog water collected at a suburban site northern China was characterized using Fourier-transform ion cyclotron resonance mass spectrometry negative positive modes electrospray ionization (ESI- ESI+). water, account for number fractions more than 60 % all assigned formulas ESI- mode 80 ESI+ mode. By comparing biomass burning, coal combustion, vehicle emissions, 72.3 were as originating from these primary anthropogenic sources (pNOCs), while remaining regarded secondary formed aerosol (saNOCs). On other hand, unique (sfNOCs). According “precursor-product pair” screening involving 39 reaction pathways, we found that nitration reaction, amine pathway intramolecular N-heterocycle NH3 addition reactions contribute 43.6 %, 22.1 11.6 saNOCs, but 26.8 28.4 29.7 sfNOCs, respectively. Such distinct most likely attributed diverse precursors aqueous acidity. Correspondingly, saNOCs contain abundant carbohydrates-like highly oxygenated with two nitrogen atoms compared pNOCs, whereas sfNOCs lipids-like fewer oxygen atoms. The results reveal disparity processes richness water. findings valuable understanding control pollution.

Language: Английский

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Characterization of atmospheric nitroaromatic compounds in Southwest China by direct injection liquid chromatography-tandem mass spectrometry analysis of aerosol extracts

Chemosphere, Journal Year: 2024, Volume and Issue: 363, P. 142845 - 142845

Published: July 14, 2024

Language: Английский

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Efficient Nitrate Formation in Fog Events Implicates Fog Interstitial Aerosols as Significant Drivers of Atmospheric Chemistry

Environmental Science & Technology, Journal Year: 2024, Volume and Issue: unknown

Published: Nov. 21, 2024

Clouds and fogs, consisting of tiny water droplets formed by the condensation in supersaturated air, are vital atmospheric chemistry, as they facilitate multiphase reactions. While measuring high-altitude cloud is challenging, fog ground-level clouds offer a unique opportunity for direct observation. In this study, we explored radiation fogs North China Plain using an advanced aerosol-fog sampling system to measure chemical physical properties both inactivated interstitial aerosols activated droplet residues. Our findings revealed that efficient nitrate formation primarily occurred on rather than within droplets, with observed aerosol net production rates reaching up 3.6 μg m

Language: Английский

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