[pam-users] Deegan et al., ACS ES&T Air, 2025; Penland et al., ACS ES&T Air, 2025; El Mais et al., Environmental Research, 2025; David et al., AMT, 2025

[pam-users]

Deegan, Ariana M, Glenn, Chase K., El Hajj, Omar, Anosike, Anita, Kumar, Kruthika, Abdurrahman, Muhammad, Bai, Bin, Liu, Pengfei, O’Brien, Joseph, Saleh, Rawad, and Frossard, Amanda A. Properties of Surface-Active Organics in Aerosol Particles Produced from Combustion of Biomass Fuels under Simulated Prescribed-Fire and Wildfire Conditions, ACS ES&T Air, 2(2), 264-276, https://doi.org/10.1021/acsestair.4c00243, 2025.

Abstract. The interfacial properties of the organic fraction of biomass burning aerosols (BBA), such as the critical micelle concentration (CMC) and surfactant composition, may vary based on the origin and moisture content of the fuel and the resulting combustion conditions. Surfactant composition, fraction of total particle mass, surface tension minimums, and CMC values of organics extracted from fresh and aged BBA produced using fuel beds from Georgia ecoregions (Piedmont, Coastal Plain, and Blue Ridge) and with fuel moisture contents representative of prescribed fires or drought-induced wildfires were measured using high resolution mass spectrometry, UV–vis spectroscopy, and pendant drop tensiometry. Surface tension minimums of organics extracted from all BBA were low (<45 mN m–1), and surfactants were ∼2% of the total particle mass. The surfactant fraction was tied to combustion conditions, with the highest fractions present in BBA produced from the most efficient (highest temperature) combustion. Aging of BBA using a potential aerosol mass oxidative flow reactor resulted in an increase in the surfactant fractions of total BBA mass. The dependence of the surfactant fraction on combustion conditions may have implications for the microphysics of BBA from wildfires and prescribed fires.



Penland, Robert, Flanagan, Steven, Ellison, Luke, Abdurrahman, Muhammad, Glenn, Chase K., El Hajj, Omar, Anosike, Anita, Kumar, Kruthika, Callaham, Mac A.,  Loudermilk, E. Louise, Karle, Nakul N., Sakai, Ricardo K., Flores, Adrian, Hewagam, Tilak, Ichoku, Charles, O’Brien, Joseph, and Saleh, Rawad. The Effect of Combustion Conditions on Emissions of Elemental Carbon and Organic Carbon and Formation of Secondary Organic Carbon in Simulated Wildland Fires, ACS ES&T Air, https://doi.org/10.1021/acsestair.4c00300, 2025.

Abstract. We investigated the influence of combustion conditions on emissions of elemental carbon (EC) and organic carbon (OC) and the formation of secondary organic carbon (SOC) in wildland fires. We performed combustion experiments using fuel beds representative of three ecoregions in the Southeastern U.S. and varied the fuel-bed moisture content to simulate either prescribed fires (Rx) or drought-induced wildfires (Wild). We used fire radiative energy normalized by fuel-bed mass (FREnorm) as a proxy for combustion conditions. For fuel beds that contained surface fuels only, the higher moisture content in Rx led to lower FREnorm compared to Wild and consequently led to lower EC emissions, but higher OC emissions and SOC formation. For fuel beds that contained duff in addition to surface fuels, duff did not ignite in Rx because of the high moisture content. However, duff ignited in Wild, leading to prolonged smoldering and substantially lower FREnorm in Wild compared to Rx. Consequently, OC emissions and SOC formation were an order of magnitude higher in Wild compared to Rx for the duff-containing fuel beds. These findings indicate that characterizing fuel availability and variability in combustion conditions, which emerges from variability in fuel-bed composition and environmental conditions, is crucial for determining carbonaceous aerosol formation in wildland fires.


Abd El Rahman El Mais, Barbara D'Anna, Alexandre Albinet, Selim Aït-Aïssa, In vitro assessment of aryl hydrocarbon, estrogen, and androgen receptor-mediated activities of secondary organic aerosols formed from the oxidation of polycyclic aromatic hydrocarbons and furans, Environmental Research, 273, 121220, https://doi.org/10.1016/j.envres.2025.121220, 2025.

Abstract: Biomass burning constitutes a significant source of fine particulate matter (PM2.5) in the atmosphere, particularly during winter due to residential wood heating. This source also emits substantial quantities of volatile and semi-volatile organic compounds, leading through (photo-chemical and physical processes, to the formation of secondary organic aerosols (SOAs), accounting for a significant fraction of PM2.5. The current understanding of the biological effects of SOA resulting from the oxidation of major gaseous precursors emitted by biomass burning (e.g., polycyclic aromatic hydrocarbons (PAHs), phenols, furans) is still limited. Mechanism-based in vitro cellular bioassays targeting toxicologically relevant modes of action have proven valuable in assessing and quantifying the overall biological activity of complex mixtures like SOA, thereby revealing the presence of toxicologically relevant compounds. The main objective of this study was to investigate, using a battery of in vitro mechanism-based cellular bioassays, the aryl hydrocarbon (AhR), estrogen (ER), and androgen receptor (AR)-mediated activities of laboratory-generated SOA resulting from the oxidation of four PAHs and three furans. SOA was produced using an oxidation flow reactor (OFR) under either daytime (OH radicals) or nighttime (NO3 radicals) conditions. Furan-derived SOA did not exhibit any biological activity with the targeted endpoints. PAH-derived SOA, formed from AhR weakly or inactive PAHs, showed significant AhR-mediated activities. Notably, SOA resulting from naphthalene and acenaphthylene + acenaphthene demonstrated the highest AhR activation potency, with greater activities observed for SOA formed through NO3 radical oxidation. No endocrine-disrupting activity was observed for the PAH-derived SOA, similar to the individual parent PAHs (with the exception of fluorene and phenanthrene PAHs which were weekly anti-androgenic). These findings underscore the substantial contribution of PAH-derived SOA to the AhR-mediated activities of PM.


David, J., D'Angelo, L., Simon, M., and Vogel, A. L.: Real-time organic aerosol characterization via Orbitrap mass spectrometry in urban and agricultural environments, Atmos. Meas. Tech., 18, 4573–4591, https://doi.org/10.5194/amt-18-4573-2025, 2025.

Abstract. Mass spectrometry techniques traditionally deployed in the field often operate at low mass resolution, making it hard to unambiguously identify and attribute organic molecules. In this regard, in-situ, accurate and precise online mass-spectrometric measurements of organic molecules in atmospheric organic aerosol (OA) are essential for understanding its sources, formation and chemical composition. In this study, we demonstrate the field applicability of a high-resolution (Orbitrap) mass spectrometer with Atmospheric Pressure Chemical Ionization (APCI-Orbitrap-MS) for real-time ambient OA measurements, achieving online, molecular resolution at atmospherically relevant concentrations with a high temporal resolution of 1 s, mass resolution of R = 120 000 at  200, and mass accuracy of ±1.5 ppm. These features enable chemically reliable measurements in environments that are exhibiting chemically complex aerosol composition, through molecular-level detection and identification of anthropogenic pollutants, biogenic and biomass burning tracers. As proof of principle, we deployed the APCI-Orbitrap-MS for in-situ measurements in a mobile laboratory container at an urban background station at Campus Riedberg (CR, Frankfurt am Main, Germany) and an agricultural field site in Schivenoglia (SKI, Italy) in the heavily polluted Po Valley. The APCI-Orbitrap-MS showed good agreement with the organic aerosol mass of an aerosol chemical speciation monitor (ACSM), with Pearson's R values of 0.91 and 0.70 for the urban and agricultural sites, respectively. In SKI, we resolved distinct diurnal variations in compounds such as MBTCA (C8H12O6), a biogenic marker of photochemical aging, and C8H13O8N, an organic nitrate indicative of nighttime chemistry. Additionally, nighttime biomass burning events were detected frequently, with durations ranging from 10 to 40 min, emphasizing the importance of high temporal resolution. During these events we found up to 30 isobaric peaks per unit mass that are baseline-resolved. For the first time, the hydroxypinonyl ester of cis-pinic acid (C19H28O7) could be measured and confirmed with MS2 experiments in ambient aerosol by an in-situ method at CR. In addition, laboratory experiments were performed to confirm the broad applicability of the APCI-Orbitrap-MS for the real-time detection of biogenic and biomass burning tracers, as well as specific anthropogenic pollutants, such as pesticides, organophosphates or organic esters from aircraft lubrication oil.


PAM Wiki - Publications Using the PAM Oxidation Flow Reactor<https://sites.google.com/site/pamwiki/publications-using-the-pam-oxidation-flow-reactor?authuser=0>

Andrew Lambe
Principal Scientist
Aerodyne Research, Inc.

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