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The presence of organic compounds on the particulate matter (PM) or aerosols can arise from the condensation of gaseous organic compounds on the existing aerosols, or from organic precursors to form secondary organic aerosols (SOA) through photochemistry. The objective of this study is to characterize organic constituents on aerosols relevant to their emission sources and the key compounds revealing the evolution of aerosols with the use of a novel analytical technique. A time-of-flight mass spectrometry (TOFMS) coupled with comprehensive two-dimensional gas chromatography (GC×GC) was developed using a flow type of modulator instead of a thermal type as a prelude to field applications without the need for cryogen. The methodology of GC×GC-TOFMS is discussed in this study in detail. Since the coarse PM (PM 10-2.5) may exhibit with a relatively high OC content compared to PM 2.5 , the GC×GC results have been obtained by analyzing PM 10 samples collected in parallel with OC/EC analysis of PM 2.5 samples at the Lulin Atmospheric Background Station (LABS, 23.47°N, 120.87°E, 2862 m ASL) as the high-mountain background site in East Asia. We found that the organic analytes were in a majority in the range of 12–30 carbon numbers falling in the category of semi-volatile organic compounds (SVOCs) with 43 compounds of alcohol, aldehyde, ketone, and ester varieties if excluding alkanes. Intriguingly, trace amounts of plasticizers and phosphorus flame retardants such as phthalates (PAEs) and triphenyl phosphate (TPP) were also found, likely originating from regions involved in open burning of household solid waste in Southeast Asia or e-waste recycling in southern China and along the long-range transport route. Compounds such as these are unique to the specific sources, demonstrating the wide spread of these hazardous compounds in the environment. [Display omitted] • A GC×GC-TOFMS method is developed for aerosols using flow type modulation. • The PM organic constituents at a high-mountain site in March 2015 were analyzed. • PAEs and TPP were detected presumably from transboundary sources. [ABSTRACT FROM AUTHOR]

Atmospheric aerosol optical, physical, and chemical properties play a fundamental role in the Earth's climate system. A better understanding of the processes involved in their formation, evolution, and interaction with radiation and the water cycle is critical. We report the analysis of atmospheric molecules/particles collected with a new sampling system that flew under regular weather balloons for the first time. The flight took place on January 18, 2022 from Reims (France). The samples were subsequently analyzed by high-resolution mass spectrometry (Orbitrap) to specifically infer hundreds of organic components present in 4 different layers from the troposphere to the stratosphere (up to 20 km). Additional measurements of O 3 , CO, and aerosol concentrations a few hours before this flight took place to contextualize the sampling. After separating common species found on each filter that might be common to atmospheric layers or residuals for contaminations, we found that each sample yields significant differences in the number and size of organic species detected that should reflect the unique composition of atmospheric layers. While tropospheric samples yield significantly oxidized and saturated components, with carbon numbers below 30 that might be explained by complex organics chemistry from local and distant source emissions, the upper tropospheric and stratospheric samples were associated with increased carbon numbers (C > 30), with a significantly reduced unsaturation number for the stratosphere, that might be induced by strong UV radiations. The multimodal distributions of carbon numbers in chemical formulas observed between 15 and 20 km suggest that oligomerization and growth of organic molecules may take place in aged air masses of tropical origin that are known to carry organic compounds even several km above the tropopause where their lifetime significantly increases. In addition, the presence of organics may also reflect the extended influence of wildfires smoke injected during the spring and summer in the NH hemisphere before the in situ observations and their long-lifetime in the upper troposphere and stratosphere. Photographic credit: Marc Fourmentin - Laboratoire de PhysicoChimie de l'Atmosphère. [Display omitted] • Unique launching infrastructure in Europe (Reims/France) to operate state-of-the art atmospheric instruments • New balloon-borne sampling device to characterize the chemical composition of organics (troposphere to stratosphere) • Offline analysis reveals the growth of organics aerosol in the stratosphere • Organics aerosol could derive from oligomerization processes along transport from the tropics and/or influenced by wildfires [ABSTRACT FROM AUTHOR]

Accelerator mass spectrometry (AMS) was shown to be applicable for studying the penetration of organic aerosols, inhaled by laboratory mice at ultra-low concentration ca. 10 3 cm −3 . We synthesized polystyrene (PS) beads, composed of radiocarbon-labeled styrene, for testing them as model organic aerosols. As a source of radiocarbon we used methyl alcohol with radioactivity. Radiolabeled polystyrene beads were obtained by emulsifier-free emulsion polymerization of synthesized 14 C-styrene initiated by K 2 S 2 O 8 in aqueous media. Aerosol particles were produced by pneumatic spraying of diluted 14 C-PS latex. Mice inhaled 14 C-PS aerosol consisting of the mix of 10 3 225-nm particles per 1 cm 3 and 5·10 3 25-nm particles per 1 cm 3 for 30 min every day during five days. Several millions of 225-nm particles deposited in the lungs and slowly excreted from them during two weeks of postexposure. Penetration of particles matter was also observed for liver, kidneys and brain, but not for a heart. [ABSTRACT FROM AUTHOR]

Seventy three individual organic compounds in the atmospheric particulate matter with an aerodynamic diameter of less than or equal to a nominal 10 μm (PM 10 ) over Seoul were identified and quantified from April 2010 to April 2011 using gas chromatography/mass spectrometry (GC/MS). These organic compounds were classified into five groups, n-alkanes, polycyclic aromatic hydrocarbons (PAHs), mono-carboxylic acids, di-carboxylic acids (DCAs), and sugars based on their chemical structures and properties. The organic compounds showed higher seasonal average concentrations from fall to winter than from spring to summer due to source strength, except some organic compounds among mono-carboxylic acids, DCAs, sugars such as undecanoic acid, methylmalonic acid, and fructose. Through qualitative data analysis using seasonal concentration variations and relevant diagnostic parameters, it was found that (1) anthropogenic sources such as combustion of fossil fuel and biomass burning attributed more to the formation of the organic aerosols than biogenic sources, and (2) the ambient level of n-alkanes, PAHs, and some compounds of DCAs and sugars was elevated in winter due to the increased primary emissions and larger transport from outside of the organic compounds in winter. [ABSTRACT FROM AUTHOR]

Organic aerosols (OA) play significant roles in several atmospheric processes and adversely impact human health. This study examines the key structural units present in water- and methanol-soluble organic carbon (WSOC, MSOC) fraction of OA from emission sources (traffic and biomass cooking) and an urban background location in India. Proton nuclear magnetic resonance (1H NMR) spectroscopy was employed to assess the distribution of non-exchangeable proton structural groups of the OAs. Organic carbon, elemental carbon, black carbon, and water-soluble organic carbon (WSOC) analyses were also conducted. The 1H NMR analysis corroborated that the WSOC and MSOC fractions hold similar 1H structural groups; however, they differ in their relative distribution and absolute concentrations across the ambient locations and source emissions. The relative contribution of the proton structural groups to OA was in the order C-H > H–C–C=> H–C–O > Ar–H. The aliphatic concentration was lower in the morning tunnel entry aerosols when compared to other tunnel aerosols, whereas the unsaturated structures (H–C–C=) were present in all the tunnel aerosols within a range of 47.2–62.3 μmol/m3. The aromatic groups were the maximum in the firewood aerosols, about 1.4 and 3.7 times higher than the crop residue and the mixed fuel aerosols, respectively. The total functional groups, i.e., the sum of all the observed groups, significantly correlated with C–H (r = 0.96) and WSOC (r = 0.7), suggesting the higher contribution of aliphatic groups in the WSOC fraction. WSOC examined in this study fits well in the established 1H NMR source identification fingerprints of urban aerosols. However, biomass cooking aerosols do not fit the established biomass burning organic aerosols (BBOAs) boundaries, exhibiting a smaller relative contribution of carbon-oxygen double bonds and a less oxidised character than open-field burning. Our results provide essential insights into the nature of urban atmospheric, near-traffic and biomass cooking OAs in India. [Display omitted] • Aerosols of traffic exhaust origin show more hydrophobic nature functional groups. • Ar–H largely primary in origin and correlates positively with EC, WSOC and H–C at urban sites. • WSOC fraction fits the established 1H NMR source apportionment regions of urban aerosols. • Biomass cooking aerosols depict distinct character and with new source boundaries. [ABSTRACT FROM AUTHOR]

The gas-phase reaction of trans-2-pentenal (T2P) with Cl atoms was studied at atmospheric pressure and room temperature. A rate coefficient of (2.56 ± 0.83) × 10-10 cm3 molecule-1 s-1 was obtained using the relative rate method and isoprene, cyclohexane and ethanol as reference compounds. The kinetic study was carried out using a 300-L Teflon bag simulation chamber (IMT Lille Douai-France) and a 16-L Pyrex cell (UCLM-Ciudad Real-Spain), both coupled to the Fourier transform infrared (FTIR) technique. Gas-phase products and secondary organic aerosol (SOA) formation were studied at UCLM using a 16-L Pyrex cell and a 264-L quartz simulation chamber coupled to the FTIR and gas-chromatography-mass spectrometry (GC-MS) techniques. HCl, CO, and propanal were identified as products formed from the studied reaction and quantified by FTIR, the molar yield of the latter being (5.2 ± 0.2)%. Formic acid was identified as a secondary product and was quantified by FTIR with a yield of (6.2 ± 0.4)%. In addition, 2-chlorobutanal and 2–pentenoic acid were identified, but not quantified, by GC-MS as products. The SOA formation was investigated using a fast mobility particle sizer spectrometer. The observed SOA yields reached maximum values of around 7% at high particle mass concentrations. This work provides the first study of the formation of gaseous and particulate products for the reaction of Cl with T2P. A reaction mechanism is suggested to explain the formation of the observed gaseous products. The results are discussed in terms of structure-reactivity relationship, and the atmospheric implications derived from this study are commented as well. • A rate coefficient of (2.56 ± 0.83) × 10−10 cm3 molecule−1 s−1 was obtained for the reaction of T2P with Cl. • This work is the first study of the gas-phase products and the SOA formation from the reaction of T2P with Cl. • The T2P + Cl reaction may contribute to the acidity of marine atmospheres. • The T2P + Cl reaction proceeds mainly by H-abstraction of the aldehydic group and by β-addition of Cl atoms to the double bond. • Atmospheric lifetimes of T2P toward chemical removals are of few hours. [ABSTRACT FROM AUTHOR]

Levoglucosan, a product from thermal decomposition of cellulose, is widely known as an organic tracer of biomass burning, but has also been reported from coal smoke particulate matter (PM) including lignites. This study provides direct evidence that levoglucosan is generated not only during low-temperature burning/smoldering of xylite, but also from other lignite types including detritic and detroxylitic brown coals from Poland. Moreover, only trace amounts of mannosan and galactosan have been detected in PM of lignite smoke. The hopanes in lignite smoke PM comprise the thermodynamically unstable ββ -hopanes and hopenes, with values of the homohopane index 22S/(22S + 22R) ranging from 0.02 to 0.12. This is characteristic for immature organic matter, and combined with the presence of anhydrosaccharides can be used as tracers for lignite combustion in ambient air. Furthermore, almost all Miocene lignite smoke PM samples contain α-, β-, γ-, and δ-tocopherols, and prist-1-ene. This is the first report of the occurrence of all four tocopherol isomers in the geological record (in lignite extracts) and in lignite smoke PM samples. Lower α-tocopherol is observed for the lignite burn-test samples than in the corresponding lignite extracts, probably due to partial chain degradation to prist-1-ene during combustion. • Low-temperature combustion of lignite produces significant amounts of levoglucosan. • Mannosan and galactosan are present in trace concentrations mainly in xylite smoke PM. • All lignite smoke PM samples contain thermodynamically less stable hopanes. • Hopanes are lignite burning tracers in samples with high levoglucosan concentrations. • First report of all four tocopherol isomers in lignite extracts and their smoke PM. [ABSTRACT FROM AUTHOR]