This session invites contributions about tropospheric organics on local, regional and global scales, from theoretical studies, laboratory experiments, field measurements, modeling studies, satellite studies, and including measurement technique development. The emphasis of this session is on gas-phase organics, including aerosol precursors and semi-volatile species.
Orals: Mon, 4 May, 08:30–15:45 | Room F2
Isoprene is the dominant non-methane volatile organic compound (VOC) emitted into the atmosphere globally. Within urban areas, there can be significant emissions of isoprene due to urban green spaces and planting, which can have important atmospheric chemistry impacts on ozone and secondary organic aerosol. The main loss route of isoprene is reaction with OH radicals, which leads to the formation of a hydroxyperoxy radical intermediate (ISOPO2). In clean or “low NO” environments, ISOPO2 predominantly reacts with HO2 radicals to form isoprene hydroxyhydroperoxides (ISOPOOH), which can be further oxidized by OH radicals to produce isoprene epoxydiols (IEPOX), accompanied by OH recycling. In more polluted “high NO” environments, ISOPO2 can react with NO to form MACR and MVK as the main reaction products and isoprene hydroxynitrates (IHN) with a yield of 0.04-0.15.
During a period of field observations during summer 2017 in Beijing, China, we observed in-situ formation of gas- and aerosol-phase oxidation products that are usually associated with low-NO “rainforest-like” atmospheric oxidation pathways. IEPOX and ISOPOOH concentrations measured by I-CIMS peaked during the afternoon, with an associated increase in particulate methyltetrol organosulfates via heterogenous reaction of IEPOX with sulfate aerosol. High levels of ozone scavenged NO, with concentrations decreasing to less than 1 ppb in the afternoon, and less than 0.1 ppb on some days. Box model simulations, using the Master Chemical Mechanism, suggest that during the morning high-NO chemistry predominates (95 %) but in the afternoon low-NO chemistry plays a greater role (30 %) in VOC oxidation in Beijing, with implications for the formation of highly oxidised molecules and SOA. Additional measurements in other urban areas (Manchester, Guangzhou) indicate that low-NO isoprene oxidation products are often observed in more polluted environments.
In addition, we combined quantum calculations and box model simulations, to determine that the oxidation of isoprene hydroxynitrates (IHN) can be an alternative, NO-driven pathway leading to the formation of IEPOX in urban areas. Theoretical calculations indicated that the currently acknowledged yield of IEPOX from the IHN reaction with OH might be underestimated. The updated chemistry was incorporated into a box model using the full isoprene oxidation scheme from the MCMv3.3.1. For a steady state concentration of 1 ppb isoprene, the cross-over point at which the IEPOX production from IHN equals that from ISOPOOH, occurs at NO ~1 ppb using the IEPOX yields from this work (varies with [HO2]). The model was then constrained to the measurements from Beijing to demonstrate the relative contributions of the IHN and ISOPOOH pathways to IEPOX formation. We show that the oxidation of IHN contributed to more than 50 % of IEPOX formation in the morning and early afternoon.
Our observations show that classifying specific isoprene oxidation products in both gas and particle phase as tracers for the NO regime needs to be carefully considered. The results improve our understanding of the NOx dependence of isoprene oxidation chemistry in polluted areas, where anthropogenic emissions can significantly impact biogenic SOA formation.
How to cite: Hamilton, J., Newland, M., Wang, S., Lui, P., Bryant, D., Bannan, T., Percival, C., Squires, F., Wang, X., Ding, X., and Rickard, A.: New insights into urban isoprene oxidation chemistry and impacts on air quality, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20268, https://doi.org/10.5194/egusphere-egu26-20268, 2026.
Isoprene is the most abundant non-methane volatile organic compound (VOC) emitted by terrestrial vegetation. Owing to its high reactivity, isoprene is rapidly removed through oxidation by the hydroxyl radical (OH), thereby playing a key role in modulating atmospheric composition, including secondary organic aerosol formation, tropospheric ozone production, and the lifetime of methane. However, due to sparse in-situ measurements in remote tropical regions and the limited early-afternoon overpass (~13:30 local time) of the Cross-track Infrared Sounder (CrIS), the diurnal variability of isoprene emissions is still poorly constrained. Fengyun-3E (FY-3E) is the world’s first civilian meteorological satellite operating in a dawn-dusk orbit and is equipped with the second-generation Hyperspectral Infrared Atmospheric Sounder (HIRAS-II). It enables retrievals of isoprene by capturing isoprene spectral signal and provides unique late-afternoon (~17:30 local time) overpass data, complementing existing early-afternoon measurement capabilities. Using spectral data from FY-3E/HIRAS-II and CrIS, this study employed a full-physics retrieval algorithm based on the optimal estimation method to derive isoprene column abundances over Amazon from 2023 to 2025. The resulting isoprene retrievals exhibit consistent spatiotemporal patterns between HIRAS-II and CrIS observations, and are further validated against previous CrIS retrievals, in situ measurements, and GEOS-Chem model. Sensitivity tests using model simulations were conducted to evaluate the roles of emission and chemical processes in controlling isoprene variability. Our results provide the first direct satellite-based characterization of daytime isoprene variations, offering new insights into the biosphere-atmosphere interactions and their implications for atmospheric chemistry-climate coupling in the Amazon region.
How to cite: Sheng, M., Zeng, Z.-C., Shen, L., and Chen, Z.: Observing atmospheric isoprene over Amazon from hyperspectral infrared sounders onboard China’s FengYun-3 satellites, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18268, https://doi.org/10.5194/egusphere-egu26-18268, 2026.
The majority of atmospheric fine particulate matter (PM₂.₅) by mass is typically organic, predominantly composed of secondary organic aerosol (SOA). SOA forms through the gas-phase oxidation of volatile organic compounds (VOCs), followed by the gas-to-particle conversion of oxidized products. Among these precursors, biogenic VOCs (BVOCs), such as isoprene and monoterpenes, are the most abundant, particularly in regions with dense vegetation. For instance, in boreal forests, α-pinene significantly contributes to SOA formation, primarily through the generation of highly oxygenated molecules (HOMs). These low-volatility compounds play a critical role in atmospheric new particle formation. Chirality, a fundamental molecular property, holds profound implications across chemistry, biology, and environmental sciences. While enantiomers exhibit identical physical and chemical properties under most conditions, they can interact distinctly with biological systems—a phenomenon known as enantioselectivity. In atmospheric chemistry, chirality introduces an additional layer of complexity, influencing VOC emissions, oxidation pathways, and the formation and composition of SOA. Despite the ubiquity of chiral VOCs in the atmosphere, their role in aerosol formation and potential health impacts remains poorly understood. This gap is partly due to the analytical challenges of distinguishing enantiomers in both gas and particle phases. Most monoterpenes have been studied without considering the impact of their specific enantiomeric structures. However, certain sources, such as anthropogenic emissions (e.g., limonene) or drought-stressed vegetation (e.g., α-pinene), release specific enantiomers into the atmosphere. Consequently, the formation of SOA from the oxidation of (+)- and (–)-enantiomers has been largely overlooked in experimental studies and atmospheric models. In this study, we investigated the O₃/OH-initiated oxidation of two common chiral monoterpenes ((+)- and (–)-limonene and (+)- and (–)-α-pinene) using a flow tube reactor and an atmospheric simulation chamber. We characterized gaseous and particle-phase products using online chemical ionization mass spectrometry. Our findings reveal that the chirality of the precursors (+)- vs. (–)-enantiomers significantly influences HOM formation, particle formation, and subsequent SOA aging. Overall, this work highlights the distinct particle formation potentials arising from the oxidation of chiral monoterpenes, offering novel insights into the formation of biogenic SOA.
How to cite: Riva, M., Gao, L., Perrier, S., Iyer, S., Vanoye, L., Fache, F., Claflin, M., and Kurtén, T.: Impact of the chirality on the formation of organic condensable vapors and particle formation from monoterpenes oxidation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22903, https://doi.org/10.5194/egusphere-egu26-22903, 2026.
Secondary organic aerosol (SOA) is ubiquitous in the atmosphere and has been widely studied due to its effects on both climate and human health. SOA formation is attributed to the gas-particle transfer of various oxidized products, especially highly oxygenated organic molecules (HOMs), which are formed through autoxidation following the reaction of volatile organic compounds (VOCs) with atmospheric oxidants. Monoterpenes (MTs) are among the most important biogenic VOCs. While their oxidation by ozone and hydroxyl radicals has been extensively studied, the role of nitrate radicals (NO3) remains less understood, despite it being a crucial nighttime oxidant with non-negligible daytime contributions.
This study utilized a newly built free-jet flow-tube system (at effective reaction time of 8.8 s) and an Eisele-type chemical ionization mass spectrometer (in amine and nitrate modes), to directly investigate the NO3-initated oxidation of five MTs: α-pinene (AP), Δ-3-carene, limonene, β-pinene (BP), and β-myrcene. We successfully observed a wide range of peroxy radicals and closed-shell products from all five MTs. Product closure was reasonably reached for AP, limonene, and myrcene (estimated to 50%–70%), but the incomplete closure for carene and BP (20%–40%) suggests substantial formation of one-oxygen-containing products that are undetectable by our methods. We found that among the three MTs with an endocyclic double bond, AP and limonene had the dominant product C10H16O2 with molar yields exceeding 50%, while carene produced much less C10H16O2. For carene, we instead observed considerably higher amounts of the peroxy radical C10H16NO8, suggesting that ring-opening processes favoring autoxidation are more common for this MT. For BP, the major species was C20H32N2O8, following a quadratic trend with increasing NO3, suggesting very fast dimer-forming bimolecular reactions of the primary peroxy radical C10H16NO5. The acyclic structure and three double bonds of myrcene make ring closures (forming C–O–O–C groups) more efficient than in other MTs, resulting in the highest HOM yield out of the studied MTs. The distinct HOM yields further emphasize highly structure-dependent oxidation pathways: 6.5% (myrcene), 6.1% (carene), 1.8% (BP), 1.1% (limonene), and 0.8% (AP). Though the HOM yield from reaction with NO3 can differ significantly from the ozonolysis HOM yield for a given MT, the overall HOM yields of NO3 oxidation are comparable in magnitude to ozonolysis, falling in the range of 0–10%. Overall, benefiting from the short reaction times and near-wall-free conditions of the flow-tube, this study provides comprehensive and quantitative distributions of NO3 oxidation products for the five common MTs, providing important knowledge of their fast (aut)oxidation pathways.
How to cite: Zhang, J., Zhang, Y., Koskenvaara, H., Zhao, J., and Ehn, M.: Gas-phase products from nitrate radical oxidation of five monoterpenes: insights from free-jet flow-tube experiments, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16128, https://doi.org/10.5194/egusphere-egu26-16128, 2026.
Seasonal variations of VOC emissions and concentrations in a mixed temperate forest consisting of beech and Douglas fir
X. Shi1, H. Li1, Y. Li1, M. Menon1, A. Orphal1, U. Ezenobi1, T. Leisner1, H. Saathoff1
1Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
Biogenic volatile organic compounds (BVOCs) play a dominating role in the formation of secondary pollution due to their large emissions and high reactivity (Carslaw et al., 2010, Emanuelsson et al., 2013). Secondary organic aerosol (SOA) generated from oxidation of monoterpenes results in the formation of oxygenated volatile organic compounds (OVOC) with a wide range of volatility. Highly oxygenated organic molecules (HOMs) are a subset of OVOCs, which play an important role in new particle formation and the growth of newly formed particles to cloud condensation nuclei (CCN). Although forest vegetation is known to be a significant source of BVOCs, the role of soil and especially seasonal variations remains uncertain due to limited observations (Vermeul et al., 2023).
Therefore, we studied VOC levels and emissions in a healthy mixed temperate forest consisting of beech and Douglas fir on the slopes of the upper Rhine valley (476 m a.s.l.) in southwest Germany at two different seasons. The study in autumn lasted from September 6th to October 16th, 2024 and the study in summer from July 5th to August 29th 2025. VOC emissions were observed with a time resolution of 1.5h in autumn and 3 h in summer at 10 different individual beech leaves or bundles of fir needles within the canopy. Furthermore, VOC concentrations were measured at different heights between ground level and 46 m, which is about 18 m above the canopy top. The VOC were measured by proton-transfer-reaction mass spectrometry (PTR-MS 4000, IONICON) including also a fast GC to separate individual monoterpenes.
The primary objective of this experiment is to understand VOC emission seasonal patterns depending on tree species and environmental parameters. For example, we will show diurnal cycles of monoterpene emission at different seasons and for different tree types and positions. Overall, the monoterpene emission rates from Douglas fir needles were higher than those from beech leaves in summer but not in autumn. The monoterpene emission rates of Douglas fir in summer were much higher than those in autumn but this wasn’t the case for the beech. This indicates that the monoterpene emissions of Douglas fir show a higher temperature dependence.
In this contribution we will discuss the influence of tree type and environmental parameters on VOC emissions at individual leaves and the resulting vertical gradients.
This work was supported by the China Scholarship Council.
Carslaw et al., Atmos. Chem. Phys.,10(4): 1701-1737, 2010
Emanuelsson et al., Atmos. Chem. Phys., 13(5): 2837-2855, 2013
Vermeuel et al., Atmos. Chem. Phys., 23, 4123–4148, 2023
How to cite: Shi, X. and Saathoff, H.: Seasonal variations of VOC emissions and concentrations in a mixed temperate forest consisting of beech and Douglas fir , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18101, https://doi.org/10.5194/egusphere-egu26-18101, 2026.
Terpenoids are volatile organic compounds (VOCs) with chemical structures of C5nH8n. Models estimate that the biosphere directly emits approximately 600 Tg terpenoids into atmosphere annually.1 Once released, these compounds undergo oxidation reactions with O3 and OH; leading to the formation of secondary organic aerosols (SOA), which can impact cloud formation and Earth’s albedo.2
Whilst observations show that modelled future increases in atmospheric CO2 will suppress isoprene (C5H8) emissions, the impact on the emission of larger terpenoids such as monoterpenes (C10H16) and sesquiterpenes (C15H24) vary between studies.3 Furthermore, not only do larger compounds (particularly sesquiterpenes), often go unidentified in forest VOC studies,4 these compounds also have limited measurements for their reaction rate coefficients with OH and O3, adding uncertainty to the impact of these emissions on atmospheric oxidative capacity.5
We present a study carried out at a forested Free Air Carbon Dioxide Enrichment (FACE) site at the Birmingham Institute for Forest Research. Here, mature 150-year-old Quercus robur (pedunculate oak) trees have been exposed to elevated CO2 treatment at 150 ppm above ambient for a prolonged 8 year period. We deployed a Proton-Transfer-Reaction Mass-Spectrometer (PTR-MS) to quantify biogenic VOCs emitted under both ambient and elevated CO2 (410 ± 10 and 560 ± 20 ppm CO2 respectively). Measurements of ozone reactivity (kO3) were also carried out using the homebuilt Total Ozone Reactivity System (TORS).6 Our results show a decrease in the emission of C5H8 under elevated CO2, but an increase in the emission of larger, more reactive C15H24 compounds; which drive a doubling in the kO3 measured. This is in contrast to some model assumptions that elevated CO2 will decrease all reactive VOC emissions.
How to cite: Dunn, L., Acton, W. J., Sommariva, R., Walker, S., Bloss, W., and Lehman, J. H.: Impact of Prolonged Elevated CO2 on the Emission of Reactive BVOCs from Mature Forest., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18548, https://doi.org/10.5194/egusphere-egu26-18548, 2026.
Secondary organic aerosol (SOA) constitutes the most important type of ambient particles and strongly affects tropospheric chemistry and air quality. SOA also affects climate, directly by scattering light and indirectly by acting as cloud condensation nuclei (CCN). SOA mostly forms within the atmosphere by oxidation of volatile organic compounds (VOCs) with tropospheric oxidants, such as ozone (O3) and nitrate radicals (NO3). The most important classes of VOCs in the troposphere are monoterpenes and sesquiterpenes. Many previous studies have focused on SOA generated from oxidation of monoterpenes, such as α-pinene, and investigated SOA properties. In contrast, much less is known about SOA formed from oxidation of sesquiterpenes, denoting the second most important class of tropospheric VOCs. In addition, these previous studies were mostly performed at room temperature (T) and there have been very few studies at T < 293 K, despite tropospheric temperature typically ranging from 220 K to 300 K. Studies with realistic SOA formed at T < 293 K are urgently needed to confirm conclusions from previous work and to better understand SOA’s impact on tropospheric chemistry and climate.
Here, we studied SOA generated from oxidation of β-caryophyllene, the most abundant sesquiterpene in the troposphere. SOA was formed in the Aarhus University Research on Aerosol (AURA) atmospheric simulation chamber via dark ozonolysis of β-caryophyllene. Experiments were performed as a function of temperature between ~258 K to 297 K, covering common tropospheric conditions. Gas- and particle-phase chemical composition was monitored online, using high-resolution mass spectrometry, while simultaneously determining SOA’s phase state and CCN activity, using a printed optical particle and cloud condensation nuclei counter, respectively.
Our results demonstrate that the reaction of β-caryophyllene with O3 and the properties of the resulting aerosols are sensitive to the temperature at which SOA was formed. Temperature impacts the SOA composition and phase state. Interestingly, β-caryophyllene SOA formed at room T showed CCN-activity, while SOA formed at low T showed no CCN activity. We attribute this, at least in parts, to changes in SOA composition. However, changes in the phase state, observed during the experiments, of the SOA formed at different temperatures may help explain the observed changes in CCN activity. Overall, our results suggest that parameterizations based on room temperature SOA measurements frequently used to estimate SOA’s CCN ability in atmospheric models could be more uncertain than previously assumed, with possibly important implications for climate.
How to cite: Angelaki, M., Dubois, C., Horchler, E. J., Møller Åbom, K. O., Rasmussen, M., Iversen, E. M., Bilde, M., and Mahrt, F.: Temperature Affects Composition and Cloud Formation Activity of Secondary Organic Aerosol from β-Caryophyllene Ozonolysis, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9235, https://doi.org/10.5194/egusphere-egu26-9235, 2026.
Gas-phase polar compounds, including water-soluble nitrogen (WSNg), and water-soluble organic carbon (WSOCg) contribute to ambient fine particulate matter through partitioning into atmospheric waters and forming aqueous secondary organic aerosol (aqSOA), a substantial contributor to fine particulate matter (PM2.5). In this work, we make continuous gas-phase measurements of WSNg, WSOCg, and ammonia (NH3) at the Flax Pond Marine Laboratory, a Photochemical Air Monitoring Station (PAMS) on Long Island, during the Greater New York Oxidant Trace Gas Halogen and Aerosol Airborne Mission (GOTHAAM) field campaign from 14 July to 20 August, 2025. To the best of our knowledge, these are the first continuous atmospheric measurements of WSNg. We pair measurements with predictions from the U.S. EPA’s Community Multiscale Air Quality (CMAQ). Measured WSNg concentrations vary ranging from below detection limits to 33.4 ppb, averaging 5.71 ppb (n = 757, ±5.80 𝜎), and exhibit a distinct diurnal pattern with afternoon enhancements out of phase with oxides of nitrogen. The WSOCg average diurnal profile exhibit afternoon maxima consistent with secondary photochemistry from volatile organic compound (VOC) oxidation. CMAQ accurately reproduces average diurnal profiles of criteria pollutants O3 (r=0.97) and NO2 (r=0.86) but is out of phase for both WSNg or WSOCg. These findings suggest that CMAQ cannot accurately describe key aqSOA precursors.
How to cite: Carlton, A., Landi, M., Gharehbagh, A., and Hennigan, C.: Where Urban and Marine Air Masses Converge: Water-Soluble Gas-Phase Carbon and Nitrogen in the NYC Region, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13050, https://doi.org/10.5194/egusphere-egu26-13050, 2026.
Urban air quality is affected by a complex mix of volatile organic compound (VOC) sources, including fossil-fuel combustion, volatile chemical products (VCPs), cooking, and vegetation. Prior studies have identified gaps in emissions inventories and a need to better understand the seasonal mechanisms controlling these sources. Here, we combine high-resolution proton-transfer reaction mass spectrometry (PTRMS) with the eddy covariance method to directly quantify VOC fluxes at an urban/suburban site in New York during summer and winter. The emissions are strongly seasonal: over twice as many individual VOCs undergo surface-atmosphere exchange during summer, and the resulting mass-based and OH reactivity-weighted fluxes are 2-3.5x higher at this time. We find that temperature-dependent processes predominate during summer, with VCPs accounting for ~50% of the emitted VOC-C mass flux and ~30% of the emitted OH reactivity. Ethanol alone accounts for ~25% of the total mass fluxes. Biogenic and residential sources are also substantial, contributing 28% of the emitted OH reactivity. During winter, temperature-dependent emissions are reduced and traffic becomes the largest VOC source. An updated inventory agrees with summer observations to within 25%, but overestimates winter fluxes by >2×. The winter discrepancy arises from overestimated VCP and cooking emissions and from missing temperature-dependent volatilization in the inventory framework. Results highlight the need to account for seasonal and temperature-dependent urban VOC emissions to support air quality and mitigation assessment in the context of global change.
How to cite: Millet, D., Vermeuel, M., Commane, R., Griffis, T., Maddaleno, T., Franklin, E., Richard, K., Rossell, R., Peischl, J., and Farmer, D.: Surface temperatures drive strong seasonality in urban reactive carbon emissions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2246, https://doi.org/10.5194/egusphere-egu26-2246, 2026.
Volatile Organic Compounds (VOCs), emitted by both biogenic and anthropogenic sources, play a crucial role in atmospheric processes and significantly affect air quality. Despite their importance, routine monitoring of VOCs poses challenges due to limitations in time-resolution, labor intensity, long-term stability, and compound-specific identification capabilities. Proton-transfer-reaction mass-spectrometry (PTR-MS) is widely used for detecting VOCs with high time-resolution and stability. However, as a soft chemical ionization method, it primarily identifies chemical compositions rather than specific compounds. Urban environments are especially challenging due to the release of thousands of VOCs from numerous sources, which can also necessitate additional corrections for possible interferences (Coggon et al., 2024; Peron et al., 2024). Acquiring additional chemical information through alternative ionization methods remains labor-intensive, making it impractical for long-term VOC monitoring.
The recently introduced VOCentinel (IONICON Analytik) leverages Selective-Reagent-Ion (SRI) PTR-MS combined with Automatic Measurement and Evaluation (AME), integrating recent technological advancements in PTR-MS, such as fast switching of reagent ions, extended volatility range (EVR, Piel et al., 2021) surface treatment, dynamic humidity control (Winkler et al., 2024), alongside IONICON's extensive experience in robust industrial monitoring. Essentially, five ionization modes sequentially ionize specific atmospheric VOCs within one minute, and the resulting mass spectra are immediately analyzed for chemical composition using a pattern matching algorithm.
The Innsbruck Atmospheric Observatory (IAO, Austria) is a well characterized urban field site (Karl et al., 2020) and hosts measurements within the Interreg Italy–Austria Breathing project, a collaboration between University of Innsbruck, ARPA Veneto, Ca’ Foscari University of Venice, and the Free University of Bolzano. A VOCentinel was installed in Summer 2025 at the Innsbruck Atmospheric Observatory (IAO, Austria) and has since then been monitoring urban VOC concentrations. In this presentation we will share first results from these multi-seasonal VOC measurements.
Coggon et al. (2024) Identifying and correcting interferences to PTR-ToF-MS measurements of isoprene and other urban volatile organic compounds, Atmos. Meas. Tech., 17, 801–825
Peron et al. (2024) Deciphering anthropogenic and biogenic contributions to selected non-methane volatile organic compound emissions in an urban area, Atmos. Chem. Phys., 24, 7063–7083
Piel et al. (2021) Introducing the extended volatility range proton-transfer-reaction mass spectrometer (EVR PTR-MS), Atmos. Meas. Tech., 14, 1355–1363.
Winkler et al. (2024) 100% humidity independent PTR-MS: Novel method and proof-of-concept, Phys. Scr. 99 121502
Karl et al. (2020) Studying Urban Climate and Air Quality in the Alps: The Innsbruck Atmospheric Observatory. Bull. Amer. Meteor. Soc., 101, E488–E507
How to cite: Peron, A., Graus, M., Winkler, K., Müller, M., Leiminger, M., Reinecke, T., and Karl, T.: Urban VOC monitoring by VOCentinel at the Innsbruck Atmospheric Observatory (IAO), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9861, https://doi.org/10.5194/egusphere-egu26-9861, 2026.
Contributions of non-exhaust sources to urban particulate matter (PM) pollution now often exceed those from vehicle exhaust in many high-income countries. Brake wear is one major source of such non-exhaust emissions. Particulate brake wear emissions have therefore come under increasing scrutiny, and are now for the first time being regulated within the EU through the recently established Euro 7 emission regulations. In contrast, there is only limited information regarding any potential gaseous emissions from the braking process. However, several recent studies indicate that these gaseous emissions should not be neglected.
In this study, we employed a proton transfer reaction time-of-flight mass spectrometer (PTR-MS) in combination with a chemical ionization mass spectrometer (CIMS) with iodide as the reagent ion to characterize the emission of volatile and semi-volatile organic compounds from brake wear. In total, four different brake materials were studied: two for heavy duty vehicles (bus and truck), and two for light duty vehicles. All brake wear emissions were generated in the laboratory using a pin-on-disc tribometer under different user case scenarios.
The PTR-MS results show that all four brake materials emitted a variety of organic compounds, including nitrogen- and sulphur-containing organics, oxygenated hydrocarbons, siloxanes as well as pure hydrocarbons. Out of these different groups, the oxygenated hydrocarbons contributed most to the overall concentrations. The emitted concentrations varied with the harshness of braking and type of brake pad. As expected, total emissions increased with increasing harshness of braking. As a novel result, we found that light duty brake pads emitted higher concentrations than heavy duty brake pads under the same braking conditions. Determination of emission ratios and evaluation of the CIMS data are currently ongoing.
How to cite: Steimer, S., Kisimbiri, W., Couval, R., Elihn, K., Haslett, S., and Olofsson, U.: Volatile organic compounds emitted from the brakes of heavy and light duty vehicles, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20043, https://doi.org/10.5194/egusphere-egu26-20043, 2026.
Amines are important alkaline gases in the atmosphere besides ammonia, profoundly influencing air quality, climate and human health through complex physicochemical processes. They facilitate new particle formation through acid-base nucleation process, with the resulting particles further growing into cloud condensation nuclei or contributing to secondary particulate pollution. They also participate in atmospheric oxidation process, yielding toxic gaseous pollutants such as aldehydes, nitramines, and nitrosamines. An increase in atmospheric amine abundance could lead to adverse effects to the environment. Vocus Proton-Transfer-Reaction Mass Spectrometry (Vocus-PTR) is an effective technique in volatile organic compounds (VOCs) detection. In this study, we optimized the condition of focusing ion-molecule reactor (FIMR) of Vocus-PTR to measure a wider variety of amines with lower concentrations, achieving good performance in the detection of both atmospheric amines and VOCs. Using the optimized Vocus-PTR, we conducted field measurement at a typical urban site in Beijing, China. C2-6-alkylamines, C1-6-amides and several emerging amines were identified and quantified. Their concentrations, atmospheric variations and potential sources are further investigated.
How to cite: Zhao, Y., An, Z., Li, Y., Yin, R., Li, D., Wang, D., Zheng, J., and Jiang, J.: Atmospheric amines in urban Beijing: measurements, characteristics and potential sources, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8564, https://doi.org/10.5194/egusphere-egu26-8564, 2026.
Ethanol is an abundant volatile organic compound with important atmospheric chemical implications, both through its direct oxidation (as a major contributor to urban OH reactivity) and as a precursor of acetaldehyde and in turn peroxyacetyl nitrate (PAN), by which it contributes to long-range transport of NOx and increased tropospheric ozone production. It is emitted both by plants and from anthropogenic activity (including industry, solvent use, fuel, and agriculture), but is chronically underestimated in atmospheric chemistry models. Here, we seek to mitigate this underestimate in GEOS-Chem, a global chemical transport model, by incorporating novel sources of ethanol and constraining their emissions using field observations collected across the United States in various recent field campaigns. We correlate measured ethanol concentrations to those of tracers with known emission profiles (e.g. nonanal from cooking, D5 siloxane from personal care products, etc.) using multivariate regression analysis to apportion ethanol to each tracer's individual source. We show that urban summertime ethanol has different dominant sources in the major US cities sampled across field campaigns -- e.g., agriculture in Chicago, volatile chemical products (VCPs) in Los Angeles, cooking in Las Vegas and Salt Lake City, and traffic in New York. These ethanol sources are poorly represented in the current version of GEOS-Chem, in which biogenic emissions dominate the global ethanol budget and VCP and cooking sources are omitted entirely. Based on our source apportionment from field data, we add ethanol emissions from agriculture, traffic, VCPs, and cooking to GEOS-Chem, along with additional species from each source (including updated mechanisms for newly added cooking and VCP tracers), and perform new simulations to compare with the field datasets. Incorporating these emissions into GEOS-Chem eliminates the model ethanol bias in US cities and improves model performance in simulating formaldehyde and PAN, though it results in overestimations of acetaldehyde. Finally, we assess the importance of ethanol to global budgets of PAN, ozone, and OH, and we extend our hybrid field/modeling analysis to other oxygenated volatile organic compounds typically underestimated by models, including methanol, acrolein, and ethylene glycol, and make recommendations for inclusion of their emissions and chemistry in GEOS-Chem.
How to cite: Bates, K., Odai, R., and Amiri, N.: Constraining anthropogenic emissions and impacts of ethanol and other oxygenated VOCs: a combined modeling and field observational approach, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16066, https://doi.org/10.5194/egusphere-egu26-16066, 2026.
Oxygenated organic compounds are key reactive pollutants that significant impact air quality and human health. They play critical roles in tropospheric photochemistry and oxidation capacity, profoundly influencing radical cycling and O3 formation. Despite their importance, the precise quantification of these compounds remain a significant challenging. Here we present a comprehensive study of oxygenated volatile organic compounds (OVOCs) in coastal and urban air, employing a combination of real-time online mass spectrometry and offline sampling methods. The measurements revealed the substantial abundance of OVOCs and their significant contributions (~50%) to photochemical reactivity and O3 formation potential. Observation-based modeling analysis were performed to quantify the impacts of these reactive organic species on photochemistry and the formation of secondary pollutants. The results demonstrated that the OVOCs related reactions can contribute to 30-65% of peroxy radical formation and recycling, thereby enhancing daytime O3 formation. Model simulations without comprehensive consideration of OVOCs would significantly underestimate daytime production rates of O3 and ROx radicals by 41 %–48 %, and shift the diagnosis of O3 formation from a transition regime to a VOC-limited regime, leading to biased policy recommendations and potentially ineffective control strategies. These findings underscore the critical role of OVOCs in atmospheric photochemistry and highlight the urgent need for comprehensive OVOC quantification to accurately characterize O3-precursor relationships and for developing effective and sustainable strategies to mitigate regional photochemical air pollution.
How to cite: Wang, Z., Hui, L., Xu, Y., Chen, Y., Chen, Y., and Feng, X.: Atmospheric oxygenated organic compounds and their impacts on photochemical air pollution, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13063, https://doi.org/10.5194/egusphere-egu26-13063, 2026.
Atmospheric formaldehyde is an air pollutant and a crucial component of the methane and hydrogen chemical budgets. Using simulations representative of the atmosphere between 2010 and 2019, we have analysed the global budget for formaldehyde and investigated the cause of changes during this period. Methane and hydrogen are both intricately coupled to the future energy pathway the global community takes. Currently, the anthropogenic emissions of methane and the emissions of hydrogen from production are rising, although efforts such as the Global Methane Pledge aim to counteract this. The complex balance of how these species evolve over the coming decades will influence formaldehyde. Sensitivity simulations using perturbations of methane and hydrogen have allowed the influence of these species on the budget of formaldehyde to be assessed. These simulations aim to elucidate these relationships, by unpicking how the fluxes of the reactions which control formaldehyde are changed when methane or hydrogen are perturbed. This will allow better prediction of the future evolution of formaldehyde. These simulations have been run using the atmosphere-only version of UKESM1.0, a global Earth System Model with the StratTrop chemical mechanism. This research contributes to both the “HYway: Climate Impacts of a Hydrogen Economy” project, and “VOCMIP: Volatile Organic Compound Model Intercomparison Project”.
How to cite: Bryant, H. and Stevenson, D.: The atmospheric formaldehyde budget and its modulation by methane and hydrogen, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7531, https://doi.org/10.5194/egusphere-egu26-7531, 2026.
Aromatic volatile organic compounds are major anthropogenic precursors driving new particle growth in urban atmospheres. However, the influence of temperature on aromatic oxidation pathways and product condensation remains poorly understood. While colder winter temperatures reduce product volatility, they are also associated with lower OH levels, potentially suppressing multi-generation oxidation that forms low-volatility species. Moreover, temperature-dependent changes in following reaction branching ratios remain largely unknown. Here, we present a series of controlled chamber experiments at the CERN CLOUD facility examining the temperature dependence of aromatic oxidation and its contribution to particle growth. A representative aromatic mixture—toluene, 1,2,4-trimethylbenzene (TMB), and naphthalene—was oxidized at 5 and 20 °C, under varying NO and OH levels to simulate urban boundary-layer conditions. We find that lower temperatures enhance multi-generation OH oxidation, increasing the yield of highly oxygenated organic molecules (HOM) by ~60%. At the same time, the branching ratio of organonitrate formation from aromatic RO2 + NO reactions rise at low temperatures, leading to a ~20% greater fraction of organonitrates among HOM. Despite organonitrate typically higher volatility, the overall particle growth rates increased due to enhanced HOM production and a decrease in products volatility. These results reconcile the elevated wintertime organonitrate fractions observed in urban and highlight the pivotal role of temperature in controlling multi-generation aromatic oxidation and particle growth under anthropogenic environments.
How to cite: Yang, B., Xiao, M., Wang, M., Mentler, B., Simon, M., Stolzenburg, D., Dada, L., Kirkby, J., Baltensperger, U., Donahue, N., Dommen, J., and El Haddad, I.: Enhanced Aromatic HOM Production at Low Temperatures Accelerates Particle Growth, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21320, https://doi.org/10.5194/egusphere-egu26-21320, 2026.
Wildland fires, including both wildfires and prescribed burns, emit large quantities of smoke containing hazardous air pollutants such as polycyclic aromatic hydrocarbons (PAHs). Understanding PAHs concentrations in these smoke-filled environments is key to developing effective mitigation strategies to protect public health and safety. However, conventional measurement strategies are not always feasible in the highly dynamic and logistically complex settings of wildfire events. As a result, alternative approaches are needed, such as the use of silicone wristbands (SWBs) as passive air samplers. PAHs were analyzed in SWBs worn by fire fighters with different occupational tasks during wildland fires. After deployment, extraction, and GC-MS/MS analysis, PAH air concentrations were calculated using a compound-specific a kinetic uptake model. Personal exposure to PAHs was task-specific and in relation to the distance of fire smoke exposure. PAH air concentrations measured in SWBs were compared with those obtained from PM filter of personal Black Carbon samplers, and with results from brain cell exposure samples.
Reference:
Gili et al. Passive sampling of atmospheric polycyclic aromatic hydrocarbons by silicone wristbands during wildland fires. Atmospheric Environment 362 (2025) 121564
How to cite: van Drooge, B. L., Bedia, C., Sevilla, A., Gili, J., and Viana, M.: Exposure concentrations of PAHs in firefighters during wildland fires, and neurotoxic effects in brain cells models, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22491, https://doi.org/10.5194/egusphere-egu26-22491, 2026.
Anthropogenic biomass burning (ABB) is a major yet least understood source of atmospheric pollution, with significant implications for air quality, visibility, atmospheric chemistry, the Earth’s radiation budget and biogeochemical cycling. This study examines the chemical composition of aerosols during biomass burning (BB) and non-biomass burning (NBB) periods to assess their impact on aerosol composition and their contribution in generating oxidative stress. Sampling of PM₂.₅ and PM₁₀ was carried out at two contrasting sites one of the highly polluted cities of Indo-Gangetic Plain (IGP), Agra: Dayalbagh (suburban) and Rambagh (urban), from December, 2022 to November, 2024. The samples were analyzed for dicarboxylic acids (DCAs), sugars, organic and elemental carbon (OC/EC), water-soluble inorganic ions (WSIIs), metals and polycyclic aromatic hydrocarbons (PAHs). Moderate Resolution Imaging Spectroradiometer (MODIS) and Fire Information for Resource Management System (FIRMS) data identified intense fire hotspots over northwestern India (Punjab–Haryana) during BB, coinciding with elevated particulate concentrations. The mean concentration of PM₂.₅ and PM₁₀ increased considerably during BB (PM₂.₅: 101.1 ± 74.4 µg m⁻³ at Dayalbagh, 120.0 ± 57.5 µg m⁻³ at Rambagh; PM₁₀: 161.2 ± 67.3 and 184.4 ± 61.7 µg m⁻³, respectively) compared to NBB. The Pearson correlation analysis showed that carbonaceous species and biomass tracers (DCAs, K⁺, levoglucosan) showed strong positive correlations (r > 0.8), confirming the influence of agricultural residue and biofuel combustion. Secondary ions (SO₄²⁻, NO₃⁻, NH₄⁺) displayed enhanced interrelationships (r = 0.75–0.77) during NBB, indicating increased secondary aerosol formation. The oxidative potential, assessed using the dithiothreitol (DTT) assay, exhibited markedly higher activity in fine particles (r2 = 0.70 and 0.79) and during BB (DTTv: 18.2 ± 10.1 pmol min⁻¹ m⁻³ at Dayalbagh, 17.1 ± 15.0 pmol min⁻¹ m⁻³ at Rambagh) compared to NBB (7.0 ± 4.0 and 10.0 ± 2.4 pmol min⁻¹ m⁻³, respectively). The correlation between DTTv and biomass tracers (oxalic acid (C2), malonic acid (C3), adipic acid (C6), levoglucosan (Lev), arabitol (Arab); r = 0.50-0.83), OC/EC (r = 0.52-0.70), metals (Fe, Mn, K, Na, Ni, Mn, Cr; r = 0.52-0.64) during BB period suggest higher redox activity during this period. Positive Matrix Factorization (PMF) identified four dominant sources: biomass burning (31–35%), vehicular emissions (26–30%), industrial activities (18–22%), and crustal dust (10–13%). Thus, BB emissions significantly enhanced PM loadings and oxidative potential, posing elevated health risks. The findings highlight the synergistic role of biomass combustion and urban emissions in amplifying aerosol toxicity and degrading air quality over the IGP.
How to cite: Agarwal, M. and Lakhani, A.: Unveiling the chemical composition and sources in PM2.5 at an urban and sub-urban site in Indo-Gangetic Plain: Insights from Biomass Markers, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-187, https://doi.org/10.5194/egusphere-egu26-187, 2026.
Despite global shifts toward clean energy, traditional biomass remains the primary source of household energy for millions of people in Northeast India. This study presents a comprehensive assessment of residential fuel chemistry using a large-scale, uniform grid-based survey covering 522 grids and 8,577 households, complemented by rigorous laboratory characterization. Physicochemical analyses categorized the fuels into three distinct groups: hardwoods, softwoods, and grasses.
To capture real-world fuel-use conditions, over 312 solid residential fuel samples were collected directly from households and subjected to proximate and ultimate analyses to evaluate their combustion efficiency and energy potential. The results revealed that volatile matter was the dominant component across all samples (>92%), indicating high reactivity and suitability for energy applications. Regionally, samples from Nagaland exhibited the lowest moisture (1.77%) and ash content (1.78%). Among biomass types, softwood (pine) demonstrated the most favourable characteristics, with the highest volatile matter content (96.9%), whereas bamboo (grass) showed the highest ash content (4.97%), significantly exceeding the average for hardwood (3.57%). These findings highlight the importance of considering both regional origin and biomass type when predicting combustion behaviour.
Furthermore, fourteen dominant biomass species were comprehensively analysed using Fourier Transform Infrared Spectroscopy (FTIR; non-destructive) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS; destructive) to elucidate their molecular-scale thermal degradation behaviour and correlate it with energy performance. High-acidity species such as Artocarpus heterophyllus (jackfruit) and Quercus spp. (oak) exhibited elevated acetic acid yields (up to 14.20%), indicating a high acetylated hemicellulose content and increased bio-oil corrosivity. Nitrogen-rich feedstocks, including Hevea brasiliensis (rubberwood) and Syzygium cumini (jamun), produced higher levels of nitrogenous compounds such as dimethylamine (11.05%) and ammonium salts (9.93%), suggesting enhanced NOₓ emission potential. In contrast, bamboo (Bambusoideae) was characterized by a high abundance of 4-vinylphenol (~7.39%).
These findings, supported by thermogravimetric analysis (TGA) and FTIR results, provide critical insights into the combustion and pyrolytic behaviour of regional biomass resources and will be used to develop an energy–economic model for predicting the energy potential of solid residential fuels in Northeast India.
Keywords: Solid residential fuel, Energy economic model, thermochemical properties, pyrolytic characteristics
How to cite: Yadav, L., Mandal, T. K., Choudhary, S., Patra, A., Saini, P., Kaur, M., Singh, S. P., Mondal, S., Ghosh, P., Upadhyay, S., Chandel, S., and Charlier, D.: Physicochemical Characterization of Solid Residential Fuels in Northeast India, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3057, https://doi.org/10.5194/egusphere-egu26-3057, 2026.
Urban air pollution in Central Asia remains a critical challenge, with volatile organic compounds (VOCs) posing significant threats to public health and regional climate stability. This research integrates studies conducted in Almaty, Kazakhstan, between 2015-2023 to characterize VOC concentrations, identify emission sources, and quantify human health risks [1-4].
In Almaty, the COVID-19 lockdown period in 2020 provided a unique opportunity to observe air quality under traffic-free conditions. While traffic-related pollutants (CO and NO2) decreased by 49% and 35%, benzene and toluene levels remained 2–3 times higher than in the same seasons of 2015-2019. These results indicate that VOC pollution is dominated by non-traffic sources, such as coal-fired combined heat and power plants (CHPs) and residential heating systems. During the lockdown, people remained at home, potentially increasing coal combustion for private heating and public bathhouses (saunas) [1].
Throughout 2020, VOC concentrations in Almaty displayed significant seasonal and spatial variability. In total, 9 of 19 VOCs showed significant seasonal fluctuations, peaking during the winter heating season. Total VOC (TVOC) concentrations in January (233-420 µg/m3) weresubstantially higher than in summer. Spatially, TVOC levels correlated with Almaty’s northward-declining topography, increasing from southern upper to northern lower districts, closer to CHPs and characterized by stagnant conditions and persistent temperature inversions [2].
Consequently, a stochastic human health risk assessment for Almaty residents revealed concerning long-term implications. Median non-carcinogenic Hazard Indices (HI-s) were generally within acceptable limits (<1.0), but 95th percentile HIs exceeded 3–5 in winter, indicating exceeded exposure margins for a non-negligible population fraction. More critically, lifetime carcinogenic risk exceeded the 10-6 threshold in all scenarios. Median risks ranged from 10-5 to 10-4, while worst-case winter scenarios reached 10-3, indicating significant cancer risk primarily driven by benzene [3].
Following these assessments, a year-long study (2022–2023) utilized sorbent tubes for active 24-hour air sampling to characterize Almaty’s air quality. An annual average benzene concentration (8.25 µg/m3) exceeded European Union and Canadian standards by factors of 4.9 and 13.8. HYSPLIT backward trajectory modeling identified that stagnant winter conditions facilitate local VOC accumulation, while additional transboundary contributions from Kyrgyzstan and Uzbekistan. Reactivity analysis showed that xylenes, toluene, and pseudocumene contribute over 80% of ozone formation potential, highlighting their role in urban smog [4]. These findings highlight an urgent need for targeted regulatory interventions, including annual benzene limits, CHP infrastructure modernization, and transitioning to cleaner fuels to mitigate the air quality crisis in Central Asia.
Acknowledgments
This research was funded by the Science Committee of the Ministry of Higher Education and Science of the Republic of Kazakhstan (Grant No.AP22785481,2024-2026).
References
[1]A.Kerimray et al. Assessing air quality changes in large cities during COVID-19 lockdowns: The impacts of traffic-free urban conditions in Almaty, Kazakhstan. STOTEN (2020),730,139179.
[2]O.P.Ibragimova et al. Seasonal and Spatial Variation of VOCs in Ambient Air of Almaty City, Kazakhstan. Atmosphere, (2021),12(12),1592.
[3]A.Alibekov et al. Severe health risks from ambient VOCs in a Central Asian city: Source attribution and probabilistic risk assessment. Atmos.Environ.X (2025),28,100378.
[4]O.P.Ibragimova et al. Urban atmospheric volatile organic compounds pollution in Kazakhstan: Trends, sources identification, and health risk assessment. Atmos.Pollut.Res. (2025),102761.
How to cite: Ibragimova, O. P., Baimatova, N., Omarova, A., Tursun, K., and Bukenov, B.: Spatiotemporal Dynamics, Source Apportionment, and Stochastic Health Risk Assessment of Volatile Organic Compounds in Almaty, Kazakhstan, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7677, https://doi.org/10.5194/egusphere-egu26-7677, 2026.
Wastewater treatment plants (WWTPs) are increasingly recognized as significant, yet potentially underestimated, sources of emerging contaminants (ECs) released into the atmosphere.1-3 The activated sludge process is one of the most widely used technologies in WWTPs, where continuous aeration generates rising and bursting bubbles. This dynamic can lead to substantial particulate emissions through similar mechanisms to sea-spray aerosol formation. Recent field studies have reported the presence of pharmaceuticals and persistent organic pollutants in the air surrounding WWTPs at pg/m3 to ng/m3 levels.4-6 Theseemissions are attributed to both aerosolization and volatilization processes. This work aimed to experimentally characterize water-to-air transfer processes under controlled laboratory conditions using a bubbling-bursting setup.
The setup consisted of a glass reactor containing synthetic wastewater spiked with eleven ECs. Synthetic air was injected through a sintered filter to simulate aeration, with flow rates ranging from 0.5 to 4 L/min. A dual analytical strategy was employed: offline sampling using glass filters and polyurethane foams for targeted High-Performance Liquid Chromatography – High-Resolution Mass Spectrometry (HPLC-HRMS) analysis, and online monitoring for real-time aerosol characterization. Specifically, a Scanning Mobility Particle Sizer (SMPS) monitored aerosol size distributions, while a Bromine Chemical Ionization Mass Spectrometer (Br-CIMS) equipped with a thermal desorber provided high-frequency chemical analysis of the particulate phase. This setup enabled the evaluation of the effects of contaminant concentration, temperature, dissolved organic matter (DOM), surfactants, and aeration flow rate on emission dynamics.
The study demonstrated the emissions of both semi-volatile and low-volatility compounds. Clear and reproducible releases were observed for venlafaxine, the macrolide antibiotics erythromycin and clarithromycin, carbamazepine, and irbesartan. Macrolides showed the highest airborne concentrations , reaching 28–53 ng/m³ at a water concentration of 1 µg/L in water. Even compounds with extremely low vapour pressures were emitted, confirming that aeration-driven aerosolization can transfer substances unlikely to volatilize. Emission intensities increased with aqueous concentration and aeration flow rate and were significantly influenced by temperature, DOM, and surfactant content. No homogeneous emission pattern was observed across all compounds, highlighting the influence of their intrinsic physicochemical properties. Aerosols were predominantly in the ultrafine range, with a mean diameter of approximately 44 nm, while DOM and surfactants significantly enhanced both particle size and aerosol mass. For the first time, erythromycin, clarithromycin, and irbesartan were successfully detected in real-time using online Br-CIMS
These results demonstrated that aeration-driven aerosolization in WWTPs enabled the atmospheric emission of low-volatility ECs, as confirmed by both offline and real-time particulate-phase measurements. Ongoing work extends this approach to real wastewater matrices, with combined online monitoring of particulate and gas phases using non-target screening strategies.
Acknowledgement - The authors thank the ANR – FRANCE (French National Research Agency) for its financial support of the WECARE project n°ANR-23-CE01-0007.
(1) Wang et al., 2024 - The Innovation https://doi.org/10.1016/j.xinn.2024.100612.
(2) Barroso et al,. 2019 - Environmental Science and Technology.https://doi.org/10.1080/10643389.2018.1540761.
(3) Ferrey et al,. 2018 - Science of The Total Environment https://doi.org/10.1016/j.scitotenv.2017.06.201.
(4) Lin et al,. 2020 - Water Research. https://doi.org/10.1016/j.watres.2020.115495.
(5) Shoeib et al,. 2016 - Environmental Pollution https://doi.org/10.1016/j.envpol.2016.07.043.
(6) Sanli et al,. 2025 - Chemosphere https://doi.org/10.1016/j.chemosphere.2024.144038.
How to cite: Moinard, E., Riva, M., Perrier, S., Fenet, H., and Duporté, G.: Atmospheric transfer of emerging contaminants from wastewater aeration: real-time and offline characterization using a laboratory bubbling-bursting setup, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7819, https://doi.org/10.5194/egusphere-egu26-7819, 2026.
Understanding biomass burning emissions is critical because they represent a major source of atmospheric particulate matter, influencing air quality, climate, and public health. The chemical complexity and dynamic evolution of these particles during atmospheric aging pose significant challenges for predicting their environmental and health impacts. A key knowledge gap concerns the evolution of particle-bound reactive oxygen species (ROS) during aging, particularly short-lived ROS that are difficult to quantify using conventional offline methods.
In this study, we investigate the formation and transformation of particle-bound ROS in smoke generated from eucalyptus leaves under controlled photochemical aging. Atmospheric oxidation was simulated using a Rapid Aerosol Aging Device (RAAD), which enabled real-time monitoring of aerosol compositional changes and oxidative potential. A suite of instruments—including two Particle Into Nitroxide Quencher (PINQ) systems, a Scanning Mobility Particle Sizer (SMPS), gas monitors, Selected Ion Flow Tube mass spectrometry (SIFT), and a High-Resolution Aerosol Mass Spectrometer (HR-AMS)—was employed to characterize both physical and chemical transformations during aging. Relative humidity was maintained using an integrated humidification system, as it can significantly influence oxidation reactions and ROS formation.
Fresh smoke was first analyzed under dark, low-oxidant conditions to establish baseline properties. The aerosol was then subjected to RAAD-driven photochemical aging equivalent to 1–6 days of atmospheric OH exposure. The first PINQ measured initial particle-bound ROS levels, while the second PINQ quantified ROS after aging. SIFT provided measurements of key gas-phase species associated with oxidation chemistry, and HR-AMS supplied real-time information on chemical composition and mass-based size distribution. This integrated approach enabled continuous evaluation of ROS formation and transformation during simulated atmospheric aging, offering new insight into how biomass burning emissions develop enhanced oxidative potential over timescales of several days.
Dual-PINQ measurements revealed clear differences in particle-bound ROS before and after photochemical aging, demonstrating that aging processes substantially modify ROS levels compared to those measured immediately after burning. These findings highlight the importance of real-time techniques for detecting short-lived species that cannot be preserved through offline sampling. Overall, photochemical aging significantly increases the oxidative potential of biomass burning aerosols over short timescales, with implications for air quality assessment and human exposure during fire events.
How to cite: Ristovski, Z., Elkaee, S., Li, Z., Miljevic, B., Okuljar, M., Xiao, Y., Han, S., and Wang, H.: Evolution of Particle-Bound Reactive Oxygen Species (ROS) During Photochemical Aging of Biomass Burning Emissions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8496, https://doi.org/10.5194/egusphere-egu26-8496, 2026.
Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals widely used in electronics manufacturing. PFAS monitoring in aquatic systems and soil surrounding electronic-waste (e-waste) recycling plants has gained significant attention due to their toxicological effects on human health and the environment. While previous studies have demonstrated the aqueous-to-air transport of PFAS (predominantly perfluorooctanoic acid) at low pH while measuring acid-dissociation constants, atmospheric PFAS emissions remain understudied and the combined effect of low pH and temperature, and the role of PFAS physicochemical properties in governing atmospheric transfer of neutral PFAS have not been systematically investigated. Therefore, the key conditions (pH and temperature) controlling the airborne release of ionic PFAS (including new generation and legacy substances) from acidic aqueous solutions were investigated by focusing on the representative e-waste leaching conditions. Additionally, airborne PFAS emissions were characterised during the hydrometallurgical leaching of shredded e-waste materials.
Airborne PFAS releases were quantified from acidified aqueous solutions (pH < 1) spiked with EPA 533PAR native PFAS standard mixture, containing 25 ionic PFAS compounds. Subsequently, the studies were extended to leaching experiments using the shredded e-waste materials. All the leaching experiments were conducted in an enclosed chamber, with air drawn through the chamber at a low flow rate to capture airborne PFAS on sorbent tubes. Post-sampling analysis was performed using online solid-phase extraction coupled with high-resolution LC-MS, following the workflow reported by Kourtchev et al., (2022).
Up to 50% by mass of airborne PFAS transfer from acidic solutions was observed for selected compounds with an initial PFAS load of 2500 pg. It was found that pH, temperature, and solution composition influenced the amount of PFAS transfer. Additionally, airborne PFAS transfer was found to be related to its physicochemical properties (e.g., functional group). In summary, the work demonstrated aqueous to air transport of PFAS under acidic conditions, which is governed by pH and PFAS molecular structure (e.g., PFAS headgroup). The work also confirmed that airborne PFAS emissions can occur during the leaching of shredded e-waste materials, signifying the need for routine PFAS monitoring and appropriate control measures to avoid potential human exposure.
Reference:
Kourtchev, I., Hellebust, S., Heffernan, E., Wenger, J., Towers, S., Diapouli, E., & Eleftheriadis, K. (2022). A new on-line SPE LC-HRMS method for the analysis of Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) in PM2.5 and its application for screening atmospheric particulates from Dublin and Enniscorthy, Ireland. Science of The Total Environment, 835, 155496. doi:https://doi.org/10.1016/j.scitotenv.2022.155496
How to cite: Eluri, A., Gates, W., Charlesworth, S., Callahan, D. L., and Kourtchev, I.: Airborne transfer of per-and polyfluoroalkyl substances (PFAS) during hydrometallurgical leaching of electronic waste., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11507, https://doi.org/10.5194/egusphere-egu26-11507, 2026.
Per- and polyfluoroalkyl substances (PFASs) are a large class of synthetic chemicals that are globally distributed due to extensive industrial use, exceptional chemical stability, and long-range atmospheric transport. Many PFASs have been linked to adverse toxicological effects, including developmental, immunological, and endocrine disruption, raising concerns regarding chronic human and environmental exposure. Despite increasing regulatory attention, substantial knowledge gaps remain regarding the atmospheric occurrence, composition, and source influences of both legacy and emerging PFASs, highlighting the need for continuous monitoring.
This study investigates the atmospheric occurrence, distribution, and source-related characteristics of PFASs in the urban environment of Seoul, Korea, by integrating targeted quantification with non-targeted screening. A total of 21 ambient air samples were collected between February and June 2024 on the rooftop of the Korea Institute of Science and Technology (KIST) and analyzed using high-resolution Orbitrap mass spectrometry. Thirty-two ionic and neutral PFASs were quantified, with total concentrations ranging from 17.0 to 348 pg m⁻³. Short-chain perfluoroalkyl carboxylates and sulfonates, including perfluorobutanoic acid (PFBA) and perfluorobutanesulfonic acid (PFBS), were identified as dominant contributors, consistent with the increasing use of short-chain alternatives.
Gas–particle partitioning of PFASs was dominated by temperature effects. Across the campaign, TSP-normalized log Kp values spanned several orders of magnitude, indicating large compound-to-compound differences in aerosol affinity. For most measured PFASs. For most measured PFASs, log Kp was positively correlated with 1/T, indicating that increasing air temperature shifted gas–particle partitioning toward the gas phase. This temperature dependence was most evident for short- to mid-chain PFCAs (perfluoroalkyl carboxylic acids) and for several PFSAs (perfluoroalkyl sulfonic acids) and precursor compounds. By contrast, longer-chain homologues exhibited weak or nonsignificant temperature dependence, consistent with stronger particulate association. Relative humidity showed no statistically significant influence for most compounds; notably, perfluoroethoxyethanesulfonic acid (PFEESA) was the sole species with a strong positive association with humidity, indicating increased particle-phase partitioning at higher humidity. These results highlight temperature as the key meteorological variable to consider when interpreting and modeling PFAS phase partitioning in urban air.
Non-target screening conducted using the FluoroMatch Modular workflow revealed 43 additional PFAS-like features with annotation confidence levels of D - or higher, indicating the presence of a diverse set of previously uncharacterized compounds. To evaluate potential source influences, air-mass back trajectories were clustered into five distinct groups and further examined using partial least-squares discriminant analysis (PLS-DA). Each cluster exhibited a characteristic PFAS profile, reflecting differences in transport pathways and regional influences. Air masses associated with transport over the Yellow Sea (Clusters 2 and 3) showed the highest numbers of unidentified PFAS features (5 and 34, respectively), suggesting enhanced regional contamination or complex source contributions. Selected formulas, including C₃HF₅O₃ (Cluster 2, B–) and C₇H₈F₆N₂O₂ (Cluster 3, D), were identified as indicative features based on cluster specificity and annotation confidence rather than definitive source markers.
Overall, this trajectory-informed analytical framework improves the understanding of PFAS behavior in urban air and demonstrates the value of combining targeted and non-targeted approaches for identifying emerging PFASs and assessing their potential source regions.
How to cite: Do, M.-N., Sardar, S. W., and Kim, J.-T.: Atmospheric PFAS Partitioning and Source Attribution Using a Trajectory-Informed Targeted and Non-Targeted Approach: Insights from Seoul, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17005, https://doi.org/10.5194/egusphere-egu26-17005, 2026.
The detection and screening of pesticide residues remain analytically challenging due to the wide chemical diversity of active substances and their occurrence in complex matrices. This study evaluates the performance of an ambient-pressure Multischeme Chemical Ionization inlet (MION) coupled to high-resolution Orbitrap mass spectrometry for comprehensive pesticide detection. The MION inlet enables rapid switching between multiple reagent ion chemistries and polarities, allowing complementary ionization pathways to be exploited within a single analytical platform.
Pesticide detection was investigated using four ionization schemes: bromide (Br⁻) and superoxide (O₂⁻) in negative polarity, and hydronium (H₃O⁺) and protonated acetone (C₃H₆OH⁺) in positive polarity. Measurements were performed using a thermal desorption unit coupled to the MION inlet (TD-MION-MS), enabling direct analysis of liquid samples without chromatographic separation. A total of 651 pesticide standards were analyzed across a range of concentrations, along with ten real fruit and vegetable extracts, and results were compared to validated reference methods.
The results demonstrate reagent-dependent selectivity, with individual ionization schemes detecting distinct subsets of pesticides. No single reagent ion could detect all compounds; however, combining results from multiple ionization schemes substantially increased detection coverage. At a concentration of 100 ng/mL, 447 pesticides were detected, while 218 and 136 compounds were detected at 20 ng/mL and 10 ng/mL, respectively. Protonated acetone ionization yielded the highest overall number of detections, while bromide ionization provided robust detection for compounds forming stable adducts. Measurements of fruit extracts showed detection performance comparable to conventional GC-MS/MS and LC-MS/MS methods.
Overall, this study highlights the versatility and effectiveness of multischeme chemical ionization combined with high-resolution mass spectrometry for rapid pesticide screening. The ability to seamlessly switch between reagent ions and polarities enables broader chemical coverage than single-ionization approaches, demonstrating the potential of the MION-Orbitrap methodology for comprehensive pesticide analysis in food and environmental applications. In the subsequent study, the TD-MION inlet was coupled to a high-resolution Orbitrap Exploris 120 mass spectrometer, representing an advancement compared to the LTQ Velos Pro used in earlier work. A systematic comparison of three reagent ion schemes, bromide (Br⁻), uronium ([(NH₂)₂COH]H⁺), and nitrate (NO₃⁻), was performed using X-ray ionization. The performance of these schemes was evaluated using five individual pesticides and comprehensive pesticide solutions comprising 651 compounds from the previous study. The expanded instrumental capability and additional ionization modes enabled a broader assessment of reagent-dependent pesticide detection.
How to cite: Partovi, F., Mikkilä, J., Iyer, S., Kontro, J., Ojanperä, S., Shcherbinin, A., Vinkvist, N., and Rissanen, M.: Multischeme Chemical Ionization Orbitrap Mass Spectrometry for Comprehensive Pesticide Detection, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20530, https://doi.org/10.5194/egusphere-egu26-20530, 2026.
Per- and polyfluorinated alkyl substances (PFAS) are a group of more than 10,000 synthetic compounds that have been widely used in industrial and consumer products for decades. Due to their water-, oil-, and dirt-repellent properties, they are of particular interest to many manufacturers, especially in industries such as textiles, food packaging, and firefighting foams. However, there is growing concern about their environmental persistence and toxicity. According to the Forever Pollution Project, there are at least 22,934 contamination sites across Europe, with 2,032 of these located in Germany alone. The extensive presence of PFAS underscores the urgent need for effective regulation and remediation efforts to address this growing environmental concern. One of the hotspots for PFAS contamination is Rastatt, Germany. Due to the contaminated agricultural soil, the ambient air in Rastatt was analyzed to determine the spread of PFAS in the air.
How to cite: Borkowska, K. I.: Determination of the spread of PFAS in the atmosphere at contaminated sites using adsorptive preconcentration and GC-Orbitrap-MS, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3073, https://doi.org/10.5194/egusphere-egu26-3073, 2026.
This study examined how particulate nitrosamines and nitramines form in the urban atmosphere during spring over Seoul. These organic nitrogen compounds are recognized carcinogens and necessitate systematic investigation in metropolitan areas characterized by high population density and elevated exposure risks. We collected 17 daily particulate matter with an aerodynamic diameter equal or less than 2.5 μm (PM₂.₅) samples from May to June 2019 and analyzed them using gas chromatography-mass spectrometry to determine concentrations and formation mechanisms. Measurements showed total nitroso compound levels of 17.51 ± 16.74 ng/m³, markedly higher than previous spring observations, with nitroso-dibutylamine dominating at 7.86 ± 8.59 ng/m³. This represents a notable shift from prior seasonal patterns where nitrosodimethylamine typically predominated, suggesting changes in either emission sources or secondary formation processes. Correlation analysis revealed positive associations with both primary emission markers such as carbon monoxide and polycyclic aromatic hydrocarbons, as well as factors indicative of secondary formation including liquid water content, indicating multiple pathways contribute to ambient concentrations. Box model simulations incorporating comprehensive gas-phase and aqueous-phase reaction mechanisms revealed that secondary atmospheric reactions contributed substantially to measured concentrations, accounting for approximately 24% of nitrosodimethylamine and 55% of N-nitrodimethylamine formation. Examining compound responses to nitrogen oxide variations revealed distinct patterns: nitrogen dioxide increases enhanced both compounds through elevated N₂O₃ and N₂O₄ production, whereas nitrogen monoxide selectively promoted only nitrosodimethylamine formation via the formation of dimethylamino radicals. Our findings demonstrate the complex NOx chemistry governing carcinogenic nitro(so) compound formation in urban environments and suggest that effective mitigation requires coordinated strategies targeting both NOx emissions and precursor amine sources rather than singular approaches.
How to cite: Choi, N. R., Kim, Y. P., Lee, J. Y., Lee, E., and Kim, S.: NOx Dependent Formation Pathways of Particulate Organic Nitrogen Compounds in Urban Seoul, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3249, https://doi.org/10.5194/egusphere-egu26-3249, 2026.
Waste treatment processes emit complex mixtures of volatile organic compounds (VOCs) that frequently cause odor nuisance, public complaints, and growing concerns regarding human exposure and well-being. Persistent exposure to odors has been widely associated with psychological stress, annoyance, and a reduced quality of life, making odor pollution an increasingly relevant public health issue. However, conventional concentration-based indicators, such as total VOCs (TVOC), often fail to represent odor perception and exposure relevance, indicating that sensory response is dominated by a limited number of odor-active compounds rather than by overall chemical abundance.
In this study, VOC emission characteristics during typical waste treatment processes were systematically investigated to identify sensory-relevant organic pollutants and evaluate their implications for exposure-oriented assessment. VOC compositions were characterized using 2D gas chromatography–mass spectrometry (GC×GC–MS), enabling comprehensive profiling of both abundant compounds and low-concentration species with high odor activity. Odor concentration was determined by dynamic olfactometry, providing an independent sensory reference to confirm key odorants and to define control-relevant compounds based on their sensory contribution.
The results demonstrate that odor perception was governed by a small subset of sensory-active VOCs, mainly aldehydes and mercaptans, whose concentrations were relatively low but whose sensory impacts were disproportionately high. This reveals a pronounced mismatch between chemical abundance and sensory relevance, highlighting the limitations of concentration-based metrics for exposure characterization of organic air pollutants. Based on sensory evaluation, priority odor-active compounds were identified, offering a robust basis for targeted control strategies during waste treatment operations.
Furthermore, electronic nose measurements were applied to explore rapid, sensor-based prediction of odor concentration. Multivariate models linking electronic nose responses to olfactometric odor concentration showed good predictive performance, indicating that electronic noses can effectively capture sensory-relevant emission dynamics and support real-time exposure-oriented monitoring.
Overall, this study demonstrates that integrating chemical characterization, sensory assessment, and sensor-based prediction provides a more exposure-relevant framework for evaluating organic air pollutants from waste treatment processes, with implications for health-oriented air pollution assessment.
How to cite: Gong, H., Han, S., Zhuo, Y., Dong, Q., Li, X., and Lee, S.: Sensory-relevant organic pollutants and exposure-oriented odor assessment during waste treatment processes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4807, https://doi.org/10.5194/egusphere-egu26-4807, 2026.
Secondary organic aerosol (SOA) impacts climate by interactions with radiation and clouds. A globally important source of SOA is the oxidation of biogenic volatile organic compounds (BVOCs) emitted from terrestrial plants. Climate change is intensifying the frequency and severity of heat waves, subjecting plants to unprecedented stress from elevated temperatures and atmospheric pollutants, particularly ozone. However, the consequences of such abiotic stress on forest-derived SOA formation remain poorly understood, as stress conditions can significantly alter BVOC emission composition.
Current research gaps include limited studies examining SOA formation from authentic, complex plant emissions under realistic multi-stressor conditions that reflect actual environmental scenarios. To address this, we conducted controlled experiments using the atmospheric simulation chamber SAPHIR coupled with a plant chamber system (PLUS). Six European oak trees (Quercus robur) were exposed to: (1) no stressor, (2) ozone stress alone, and (3) combined heat and ozone stress conditions. The oak emissions were transferred into SAPHIR for oxidation. Here, we present how environmental stress altered emitted BVOC mixtures, their atmospheric reactivity, and resulting SOA yields.
How to cite: Pfannerstill, E. Y., Dey, B., Sjøgren, T. D., He, Q., Färber, M., Wu, Y., Gkatzelis, G. I., Rinnan, R., Fuchs, H., Novelli, A., and Hohaus, T.: Combined heat and ozone stress impacts on SOA formation and OH reactivity from oak emissions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5473, https://doi.org/10.5194/egusphere-egu26-5473, 2026.
Organosulfates (OSs) are ubiquitous in atmospheric particulate matter and serve as key tracers for secondary organic aerosols. Traditionally, OSs have been primarily linked to the particle phase, with their presence in the gas phase remaining largely undetected. This study provides compelling observational evidence of a continuously present gas-phase OS, glycolic acid sulfate (GAS), in the urban atmosphere using advanced mass spectrometry techniques. GAS concentrations exhibited distinct seasonal and diurnal patterns, peaking in summer with maximum levels of 4.6 × 104 cm-3 observed around midday, indicating a photochemical origin. Thermal desorption profile analysis revealed GAS as an extremely low-volatility organic compound, suggesting preferential aerosol partitioning. Remarkably, the observed gas-phase fraction of GAS exceeded predictions based on gas-particle equilibrium theory by 5~7 orders of magnitude, strongly suggesting the existence of a distinct source from gas-phase chemistry. We propose a potential formation mechanism involving the reaction between SO3 radical and glycolic acid, which correlates nearly linearly with GAS production rates, suggesting a near-collision-limited rate constant (kfield ≈ 2.2 × 10-10 cm3 s-1). This study fundamentally reshapes our understanding of OSs sources and underscores the potential involvement of SO3 in the formation of low-volatility organic compounds in the atmosphere.
How to cite: Sun, H., Liu, Y., Nie, W., Li, Y., Ge, D., Xu, T., Yin, J., Liu, C., Fu, Z., Qi, X., Liu, T., Zha, Q., Yan, C., Wang, Z., Chi, X., and Ding, A.: Unexpected Gas-Phase Formation of Glycolic Acid Sulfate in the Atmosphere, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6234, https://doi.org/10.5194/egusphere-egu26-6234, 2026.
Recent studies suggest that terpenes in urban air may have substantial anthropogenic sources, yet distinguishing these from biogenic emissions remains challenging. In this study, we measured terpene concentrations in a street canyon in Helsinki during cold winter months (mean temperature < 0 °C), when biogenic emissions were expected to be minimal. Monoterpenes were observed at mean concentrations of ~160 ng m⁻³, more than an order of magnitude lower than the mixing ratios of aromatic hydrocarbons. Nevertheless, their high reactivity with hydroxyl radicals, nitrate radicals, and ozone led to a disproportionately large contribution to local atmospheric oxidation processes. This pronounced reactivity, combined with their high secondary organic aerosol (SOA) formation potential, indicated the important potential role of anthropogenic terpene emissions even in wintertime SOA formation.
How to cite: Hellén, H., Tykkä, T., Suhonen, E., Teinilä, K., Niemi, J., Rönkkö, T., Timonen, H., and Praplan, A. P.: Contribution of low-abundance terpenes to wintertime VOC reactivity in urban air in Helsinki, Finland, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7430, https://doi.org/10.5194/egusphere-egu26-7430, 2026.
Particulate N-nitrosamines and nitramines are potent organic carcinogens with significant public health implications. They are formed in the atmosphere through primary emissions from sources such as rubber and plastic combustion, and tobacco smoke, as well as secondary formation of gaseous and aqueous phase amine. This study quantifies seven nitrosamines and two nitramines in PM2.5 collected from summer 2024 to spring 2025 at Ansan (industrial) and Baengnyeong Island (background). The mean total concentration at Ansan (2.67 ± 1.87 ng m-3) was comparable at Baengnyeong (2.23 ± 1.45 ng m-3). Among the quantified species, N-nitrosodi-n-butylamine (NDBA) was generally the most abundant at both sites across most seasons. At Ansan, NDBA showed positive correlations with elemental carbon (EC) during autumn (r = 0.517, p < 0.01) and with SO₂ during summer (r = 0.488, p < 0.01); however, these correlations alone could not resolve the relative contributions of primary emissions versus secondary formation.
To better understand the role of aqueous-phase chemistry in NDBA formation, we conducted controlled batch reactor experiments simulating atmospheric aqueous aerosol reactions. The experiments systematically varied precursor (dibutylamine and nitrite) concentrations, pH, temperature, and reaction time to quantify NDBA formation rates in the homogeneous aqueous phase. Experimental results were integrated with field-based observations to investigate possible connections between environmental conditions such as pH levels and precursor availability and observed variations in ambient NDBA concentrations across different sites and seasons.
How to cite: Jeong, S., Song, M., Lee, T., Shin, H. J., Heo, G.-Y., and Choi, N. R.: Characterization of Particulate Nitrosamines and Nitramines at Industrial and Background Sites in Korea: Field Observations and Laboratory Experiments, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9003, https://doi.org/10.5194/egusphere-egu26-9003, 2026.
Non-methane volatile organic compounds (NMVOCs) emissions are dominated by biogenic VOC (BVOC) primarily from vegetation emissions. Main compounds are isoprene and monoterpenes which are precursors to tropospheric ozone and secondary organic aerosols, leading to impacts on air quality, human health, visibility and climate change both directly and indirectly.
Camphene is an abundant monoterpene which has been understudied, particularly in terms of its kinetics, secondary organic aerosol (SOA) yields and molecular composition (Gaona-Colmán et al., 2017; Afreh et al., 2021; Li et al., 2022). Here, we present a systematic study of SOA formation from Camphene over a wider temperature range (243 K – 313K) by dedicated simulation chamber experiments. We used ozone concentrations of 2.18–3.72 ppm for camphene oxidation, representing a substantial excess of ozone, to a allow a significant chemical conversion at relative low reaction rates.
Based on PTR-MS (PTR-MS 4000, Ionicon Analytik GmbH) measurements of camphene and acetone concentrations as well as ozone measurements (Environment 0341M), the rate coefficients of the reaction of camphene with ozone and OH radicals were determined by fitting the results of a kinetic model to the observations. Particle size distributions and number concentrations were measured by a scanning mobility particle sizer (SMPS) utilizing a differential mobility analyser (DMA; 3071, TSI Inc.) coupled to a CPC (3772, TSI Inc.). Particle number concentrations were measured by two condensation particle counters (3022A and 3776, TSI Inc.). The particle number size distributions of the SMPS were corrected for the total number concentration measured by a calibrated CPC and used to calculate the SOA mass concentration by applying an effective particle density of 1.3 (Li et al., 2022). SOA mass concentrations were also measured with a HR-ToF-AMS (Aerodyne Inc.) SOA yields (YSOA) were calculated as YSOA = ΔMorg/ΔVOC, where ΔMorg is the SOA mass formed from the reacted mass of camphene (ΔVOC).
A chemical ionization mass spectrometer coupled with a filter inlet for gases and aerosols (FIGAERO-CIMS, Aerodyne Inc) was used to measure both gas-phase and particle phase chemical composition employing iodide as reagent ion. Particles were collected on prebaked Teflon filters (1 µm, SKC Inc.) using a stainless-steel filter holder for offline analysis.
Major secondary organic aerosol products and different chemical components of the gas and particle phase present at all temperatures were resolved. The variation in the abundance of individual organic molecules during ozonolysis and OH radical initiated oxidation were resolved at four different temperatures: 243, 273, 298, 313 K. This presentation will discuss the main findings in the context of previous studies as well as its implications for the role of camphene in atmospheric aerosol chemistry.
Afreh et al., Atmos. Chem. Phys., 21, 11467–11487, 2021.
Gaona-Colmán et al., RSC Adv., 7, 2733-2744, 2017.
Li et al., Atmos. Chem. Phys., 22(5), 3131–3147, 2022
How to cite: Ezenobi, U. V., Saathoff, H., Li, Y., and Leisner, T.: Secondary organic aerosol from oxidation of camphene with ozone and OH radicals – kinetics, yields and molecular composition at 313 – 243K, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9753, https://doi.org/10.5194/egusphere-egu26-9753, 2026.
Herein we introduce the fully automated Ionicon Laminar-flow Oxidation reactor (ILOx) for rapid photochemical oxidation of atmospheric organics, as a useful tool to mimic atmospheric processes of days within minutes. ILOx consists of a 110 cm long quartz glass tube with a total internal volume of 8 l that is irradiated by UVA and UVC LEDs. Oxidants can be introduced through multiple customizable inlet ports. To achieve laminar flow conditions, sample injection is CFD optimized to suppress any formation of injection jets. The outlet of ILOx allows for sampling both particles and VOCs simultaneously. A characterization of the particle transmission through the reactor with dried ammonium sulfate particles showed no significant change in the particle distribution before and after the reactor, proving the highly efficient particle transmission of the system. VOCs are coresampled to reduce wall interactions and potential formations of artifacts. In addition, all wetted surfaces are optimized for purest experiments providing fast response, even for reduced volatility gas-phase organics.
To experimentally confirm the oxidation potential of the reactor, air containing 2 ppbV of toluene is sampled through ILOx while VOCs are monitored by FUSION PTR-TOF 10 (IONICON Analytik, Austria). Just minutes after starting the UVA irradiation, 50% of toluene is oxidized, mimicking atmospheric aging in the range of 2 days. In addition, known toluene oxidation products like methyl glyoxal, cresols or dihydroxymethyl benzene are increasing. MCM 3.3.1 simulations of this experiment result in average OH concentrations of 3x108 cm-3, which equals to an OH exposure OHexp of 1011 cm-3s.
To characterize the overall efficiency of the system, we study the secondary organic aerosol (SOA) mass-yield of two aerosol precursors, xylene and limonene, respectively. For these experiments, humidified zero air (50% RH, 25°C) containing ~2 ppmV of ozone from an external 185 nm UVC source is used as the carrier gas. ILOx’s integrated 275 nm UVC LED is activated to photolyze O3 to O2 and O(1D) to consequently form OH together with the carrier gas’ humidity. By adding xylene and limonene at atmospherically relevant concentrations of single-digit ppbVs we are able to identify a SOA mass-yield of 25.2 ± 2.7% for xylene and 36 ± 6.4% for limonene.
Ultimately, we demonstrate the rapid oxidation of ambient air during a summer-time rush-hour event within ILOx. By intercomparison of FUSION PTR-TOF 10 mass spectra pre- and post-ILOx, with and without oxidation, we can quantitatively characterize the chemical compositions of ambient air and identify reacted and formed compounds. We can observe a clear change of chemical composition with a dominant reduction of aromatic and non-aromatic hydrocarbons (e.g. terpenoids) of higher volatility to a production of oxidized species of lower volatility.
How to cite: Leiminger, M. S., Reinecke, T., Klinger, A., Graus, M., and Müller, M.: A versatile laminar-flow oxidation reactor for studying multiple-day oxidation of atmospheric organics, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9889, https://doi.org/10.5194/egusphere-egu26-9889, 2026.
Benzene, toluene, ethylbenzene, and xylene (BTEX) are hazardous air pollutants with high toxicity and a strong potential for secondary pollutant formation. However, their occurrence and behavior in the Arctic remain poorly understood. During the Alaskan Layered Pollution and Chemical Analysis (ALPACA) field campaign in Fairbanks, Alaska in January-February 2022. Surface observations in downtown Fairbanks revealed two major pollution periods, with extremely cold (down to -35°C) and warmer temperatures (around 0°C), respectively. BTEX concentrations reached 4–12 times higher than those reported in the US and European countries under dark, cold Arctic winter conditions at breathing level, posing a significant health risk.
We simulated BTEX atmospheric distributions in the Fairbanks region using the FLEXible PARTicle-Weather Research and Forecasting (FLEXPART-WRF) Lagrangian particle dispersion model and anthropogenic emissions at the surface and aloft. Due to limited photochemical loss in to the dark polar winter conditions, we treat BTEX as an unreactive tracer in the model. The control run with the emission inventory developed by Alaska Department of Environmental Conservation (ADEC) substantially underestimates BTEX concentrations compared to observations during both polluted periods, indicating deficiencies in winter emissions and near-surface mixing. Enhancing cold-start gasoline vehicle emissions by a factor of 2 during very low-temperatures substantially improved model results during the cold polluted period, while introducing a relative humidity dependence for mobile emissions improved simulated BTEX during the warm, humid pollution period. Addition of emissions of residential heating oil aromatics, not taken into account in the ADEC inventory, also reduced normalized mean biases by 5-10%.
The improved model simulation was used to investigate contributing source sectors. While mobile traffic emissions were identified as the dominant source of BTEX across the Fairbanks North Star Borough, residential heating and non-point sources contributed substantially in downtown Fairbanks. Replacing residential wood burning in the inventory with oil heating during severe pollution periods, in line with air quality control guidelines, was found to effectively reduce BTEX concentrations, particularly benzene by up to 30%. While persistent surface-based temperature inversions largely confined BTEX below ~20 m, upward transport, induced by wind shear, during severe episodes, sometimes lofted near-surface pollutants to higher altitudes, potentially contributing to regional pollution and background Arctic haze.
The findings of this study emphasise the need to accurately account for temperature and humidity dependent vehicle emissions, residential oil heating emissions, and winter boundary-layer dynamics for improved simulations of air quality in cold wintertime environments, not only in the Arctic but also in mid-latitudes.
How to cite: Zhang, W., Brett, N., Law, K. S., Temime-Roussel, B., D'Anna, B., Raut, J.-C., Bekki, S., Barret, B., Arnold, S. R., Savarino, J., Ketcherside, D. T., Yokelson, R. J., Hu, L., Huff, D., Mao, J., Campbell, J., Desecari, S., Pappaccogli, G., Pohorsky, R., and Schmale, J.: Simulation of aromatics in Fairbanks, Alaska during the wintertime ALPACA-2022 campaign, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10449, https://doi.org/10.5194/egusphere-egu26-10449, 2026.
While proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) is widely used for ambient volatile organic compounds (VOCs) quantification, its accuracy is limited by isobaric interferences, fragmentation, and ionization byproducts. Here, a thermal desorption preconcentration gas chromatography (GC) coupled with Vocus PTR-ToF-MS was deployed at a suburban site in Hong Kong to resolve isomers and quantify interferences for ambient VOCs measurement. We identified and quantified 48 compounds using GC-PTR measurements and resolved their isomer profiles in real-time PTR data based on GC-derived fractions. Our analysis revealed that real-time (RT) PTR measurements substantially underestimate long-chain aldehydes (e.g., C5–C8 aldehydes) due to extensive fragmentation, while overestimating isoprene, benzene, styrene, and phenol by 14-60% because of interference from other species. These biases propagate into photochemical modeling, leading to overestimation of daytime ozone production by ~40% and of biogenic VOCs’ OH reactivity. Correcting isomer distributions and interference effects reduces modeled ozone production rates and alters precursor sensitivities, revealing a larger role for oxygenated VOCs in ozone formation than previously recognized. Our results highlight the necessity for isomer-resolved measurements and interference-aware calibration to improve VOC-based assessments of photochemical air pollution.
How to cite: Feng, X., Hui, L., Chen, Y., Zheng, P., Chen, Y., Zhong, J., Xu, Y., Clafin, M., Lerner, B., and Wang, Z.: Resolving Isomer and Interference Biases in PTR-ToF-MS Measurements of Atmospheric VOCs and Photochemical Impacts, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11269, https://doi.org/10.5194/egusphere-egu26-11269, 2026.
The bimolecular reaction of Criegee intermediates (CIs) with esters of varying chain length and α-substitution have been investigated under atmospherically relevant conditions using laser flash photolysis combined with cavity ring-down spectroscopy (CRDS). The bimolecular rate coefficient for propyl formate reaction with the simplest CI (formaldehyde oxide) is about 300 times larger than those for methyl formate, ethyl formate, methyl acetate, and propyl acetate. The only structural difference between propyl formate and the other formates is the length of the alkyl chain, implicating the propyl group as a key factor in the observed rate enhancement.
The enhanced reactivity of propyl formate suggests that its extended chain facilitates a more favorable transition state via hydrogen bonding. In contrast, α-substitution with a methyl group in propyl acetate leads to a marked decrease in reactivity, indicating steric hindrance limits the reactive pathway. Interestingly, methyl trifluoroacetate bearing an electron-withdrawing CF3 group exhibits a rate similar to propyl formate (~10-12 cm3 s-1), likely due to stabilization of the transition state through enhanced charge separation.1 Smaller esters such as methyl formate react more slowly (~10-15 cm3 s-1). These results reveal a subtle interplay of hydrogen-bonding and steric effects in the 1,3 cycloaddition reaction of CIs and underscore the potential role of such reactions in secondary organic aerosol (SOA) formation and growth,2 expanding our understanding of CI-driven oxidation processes in the troposphere.
Figure 1. Laboratory generation and detection of CIs for bimolecular reaction rate measurements.
References
1 R. Chhantyal-Pun, M. A. H. Khan, C. A. Taatjes, C. J. Percival, A. J. Orr-Ewing and D. E. Shallcross, Int. Rev. Phys. Chem., 2020, 39 (3), 385-424.
2 R. Chhantyal-Pun, B. Rotavera, M. R. McGillen, M. A. H. Khan, A. J. Eskola, R. L. Caravan, L. Blacker, D. P. Tew, D. L. Osborn, C. J. Percival, C. A. Taatjes, D. E. Shallcross and A. J. Orr-Ewing, ACS Earth Space Chem., 2018, 2 (8), 833-842.
How to cite: Khodia, S., Garavagno, M. D. L. A., Klippenstein, S. J., and Orr-Ewing, A. J.: Role of H-bonding in Modulating Reactivity with Criegee Intermediates, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11380, https://doi.org/10.5194/egusphere-egu26-11380, 2026.
Volatile organic compounds (VOCs) play a central role in atmospheric chemistry and air quality yet their long-term, high time resolution measurements remain challenging to deploy at scale due to instrument complexity, maintenance requirements, and the need for expert-driven data processing. As monitoring networks continue to expand their observational capability across Europe, new instrumentation strategies are required. Here, we introduce the Airtox monitor, a new proton-transfer-reaction (PTR)-based instrument specifically designed for autonomous, long-term VOC monitoring in both stationary and mobile applications. The system features a vacuum ultraviolet (VUV) ionization source coupled to a high-resolution time-of-flight mass spectrometer, delivering broad chemical coverage with unprecedent stability. Integrated automation - including real-time background correction, online mass calibration, and scheduled gas-phase calibrations, enables fully unattended operation while providing continuous stream of reliable quantitative concentration data. We evaluate Airtox performance during month-long deployments at two ACTRIS sites: the Deutscher Wetterdienst (DWD) station in Germany and the high-altitude Jungfraujoch (JFJ) observatory in Switzerland. In both campaigns, the instrument operated continuously without human intervention, demonstrating exceptional robustness under varying environmental and logistical constraints. Automated workflows maintained stable instrument response and calibration, while real-time quality control verified proper system operation and ensuring reliability of the delivered concentration data. We compare these real-time concentration outputs to post processed datasets to assess the accuracy, identify where postprocessing remains beneficial and outline the remaining challenges for true real- time VOC monitoring. We show how the same system also supports mobile monitoring with rapid time response, enabling spatially resolved VOC mapping during on-road or near-source surveys. This versatility allows the same system to be deployed at a monitoring station for long-term observations or to be transferred into a mobile laboratory for targeted field campaigns, extending its utility across diverse research and regulatory applications. We demonstrate that Airtox provides a robust, autonomous VOC monitoring solution that lowers operational barriers and supports reliable, decision-ready data delivery.
How to cite: Pospisilova, V., Jorga, S., Abou-Ghanem, M., and Koss, A.: Airtox: A Next-Generation PTR-Based Instrument for Autonomous Long-Term VOC Monitoring, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11712, https://doi.org/10.5194/egusphere-egu26-11712, 2026.
Wastewater treatment plant (WWTP) influents and effluents are known to contain contaminants of emerging concerns (CECs), including surfactants, industrial chemicals, and pharmaceuticals (Freeling et al., 2019; Lenka et al., 2021). WWTP involve numerous steps, e.g., aeration, that may facilitate the transfer of these compounds to the atmosphere through aerosolisation or volatilisation. Understanding the fate of these pollutants during wastewater treatment is important, as it could inform emission pathways, atmospheric exposure, and potential environmental and human health impacts.
In this study, particulate matter (PM, total suspended particles) samples collected from the grit chamber, secondary settler, and a staff building at a WWTP in Brazil were analysed using high-resolution mass spectrometry (HRMS)-based targeted and non-targeted approaches. Targeted analysis demonstrated both legacy and new generation per and polyfluoroalkyl substances (PFAS) in PM samples, with perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) dominating the PFAS profiles, indicating continued inputs of these compounds into wastewater cycles years after regulatory restrictions.
Non-targeted analysis (NTA) revealed the presence of a broad range of CECs, including nitroaromatics, insecticides, personal care products, and industrial intermediates. Semi-targeted analysis of the PM samples identified the highest abundance of 4-nitrophenol (a nitroaromatic compound with known adverse effects on climate and health) in the grit-chamber samples.
Overall, our results emphasise that WWT processes may represent a potential source of PFAS and other CECs to the atmosphere.
Reference:
Lenka, S. P., Kah, M., & Padhye, L. P. (2021). A review of the occurrence, transformation, and removal of poly- and perfluoroalkyl substances (PFAS) in wastewater treatment plants. Water Research, 199, 117187. https://doi.org/10.1016/j.watres.2021.117187
Freeling, F., Alygizakis, N. A., von der Ohe, P. C., Slobodnik, J., Oswald, P., Aalizadeh, R., Cirka, L., Thomaidis, N. S., & Scheurer, M. (2019). Occurrence and potential environmental risk of surfactants and their transformation products discharged by wastewater treatment plants. Science of The Total Environment, 681, 475-487. https://doi.org/10.1016/j.scitotenv.2019.04.445
How to cite: Pandamkulangara Kizhakkethil, J., Baglioli, F., Zanicotti Leite, B., Rafael Collere Possetti, G., H. M. Godoi, R., and Kourtchev, I.: Emission of airborne contaminants of emerging concern from wastewater treatment processes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12680, https://doi.org/10.5194/egusphere-egu26-12680, 2026.
Chlorine radicals (Cl) formed from reactive chlorine compounds are highly efficient oxidants for volatile organic compounds (VOCs) in the atmosphere, both in marine influenced regions and polluted urban environments, owing to their exceptionally high reactivity. While the reaction kinetics of Cl with VOCs have been extensively investigated in laboratory studies, and several modeling and chamber studies have explored the impacts of Cl-initiated oxidation on secondary organic aerosol (SOA) formation and atmospheric composition, direct ambient observations of chlorine-containing oxygenated organic molecules (Cl-OOMs) remain extremely limited. In this study, we report comprehensive field observations of Cl-OOMs in the urban atmosphere of Nanjing during summer, using an ultrahigh-resolution Orbitrap mass spectrometer coupled with a nitrate (NO3-) chemical ionization source. More than 40 distinct Cl-OOMs were unambiguously identified, among which, chlorinated nitrophenol-related compounds exhibited the highest concentrations. The majority of Cl-OOMs showed pronounced daytime maxima, consistent with enhanced photochemical activity, although several species displayed elevated nighttime concentrations. These compounds are likely formed through atmospheric oxidation of VOCs involving Cl radicals, frequently in combination with other oxidants such as OH and NO3 radicals. In addition, regional transport and the oxidation of chlorinated VOC precursors by other oxidants may also contribute to the observed Cl-OOMs. This work provides rare ambient evidence for the existence and diversity of Cl-OOMs, bridging the gap between laboratory studies and real atmospheric conditions. The results offer new constraints for understanding Cl-initiated VOC oxidation pathways and their potential role in urban atmospheric chemistry.
How to cite: Zhang, Y., Nie, W., Liu, Y., Yan, C., Sun, H., Yin, J., Wang, Z., Xia, M., and Zhu, C.: Ambient observations of chlorine-containing oxygenated organic molecules in summer Nanjing using ultrahigh-resolution Orbitrap mass spectrometry, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13507, https://doi.org/10.5194/egusphere-egu26-13507, 2026.
Acyl peroxy radicals (RC(=O)O2) are a particular class of organic peroxy radicals formed in the troposphere predominantly by OH-initiated oxidation of aldehydes or the photolysis of ketones. One of the key features is the formation of acyl peroxy nitrates by reaction with NO2 which act as reservoir species for nitrogen oxides (NOx = NO + NO2) and enable the long-range transport of NOx. When NOx concentrations fall below critical levels, acyl peroxy radical chemistry exhibits substantially an increased complexity. Reactions with HO2 were shown to produce OH. Particularly for larger acyl peroxy radicals (> C4) unimolecular H shift reactions are rapid and yield the formation of highly oxygenated organic molecules (HOMs). More recently, it has been proposed that reactions of acyl peroxy radicals with unsaturated organics such as terpenes finally result in the formation of low-volatility vapours that act as aerosol precursors.
To further elucidate acyl peroxy radical chemistry at conditions where the peroxy radical loss is no longer dominated by reactions with NO we performed experiments in the QUAREC atmospheric simulation chamber (University of Wuppertal) using α,β-dicarbonyl photolysis as clean acyl peroxy radical sources. Based on the results of two methods (FTIR spectroscopy, NH4+-CIMS) we provide evidence for the formation of accretion products from acyl peroxy radical self- and cross-reactions.
How to cite: Illmann, N., Arnold, N., Rösgen, V., and Patroescu-Klotz, I.: Accretion product formation from acyl peroxy radicals, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14008, https://doi.org/10.5194/egusphere-egu26-14008, 2026.
Here we present recent results from coupling the Filter Inlet for Gases and AEROsols (FIGAERO) to a Bipolar Time-of-Flight (BTOF) Chemical Ionization Mass Spectrometer. Fast switching-between positive and negative reagent ions addresses the need for instruments that can simultaneously characterize both precursors and oxidation products in ambient measurements. The FIGAERO inlet allows for measurements of gas and particle phase composition as well as thermal desorption profiles of particulate species. FIGAERO-BTOF measurements of laboratory standards and complex chamber mixtures are discussed. FIGAERO-BTOF thermal desorption profiles of inorganic and organic salts such as ammonium nitrate, ammonium sulfate and ammonium oxalate, show that the appearance of simultaneous high temperature desorption peaks in both acidic and basic moieties can be used to distinguish between reactive and non-reactive condensation processes. These observations indicate that previous unipolar (I- only) FIGAERO desorption measurements that assigned high temperature desorptions of small organic acids to thermal decomposition may underestimate the formation of low volatility species from reactions of small organic acids and bases in the atmosphere. Ambient measurements with the FIGAERO-BTOF are also discussed and compared/contrasted with the laboratory observations. The temporal evolution of the particle phase composition and comparisons with the gas phase measurements obtained over the same time periods are investigated.
How to cite: Canagaratna, M., Devivo, J., Alton, M., Stinchfield, A., Lopez-Hilfiker, F., Worsnop, D., and Donahue, N.: Distinguishing Between Reactive and Non-reactive Condensation with a Fast-Switching Bipolar Mass Spectrometer, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15150, https://doi.org/10.5194/egusphere-egu26-15150, 2026.
Organosulfur compounds are important constituents of atmospheric aerosols and have been extensively studied in previous field, laboratory, and modeling investigations. However, current mechanisms cannot fully account for their atmospheric abundance. Ubiquitous in the atmosphere, micrometer-sized droplets serve as distinctive microreactors and may provide an important medium for organosulfur formation. Here, we demonstrate that reaction of inorganic sulfur with oxygenated volatile organic compounds in microdroplets can spontaneously and rapidly produce sulfonates (C-SO3) and organosulfates (C-OSO3) within hundreds of microseconds (~220 μs), without any catalyst, external potential, or radiation. Furthermore, some organosulfur species identified in laboratory work were detected in ambient aerosols at an urban site and a high-altitude mountain station, confirming the environmental relevance of this pathway. This transformation is driven by the strong interfacial electric field of microdroplets, which promotes the loss of one electron from SO32- to form SO3-•. SO3-• subsequently undergoes nucleophilic addition and radical coupling with unsaturated oxygenated volatile organic compounds to generate organosulfur. Our findings offer a new perspective on atmospheric organosulfur formation and highlight the critical, yet previously overlooked, role of microdroplet interfaces in the formation of secondary organic aerosols.
How to cite: Fu, P., Han, H., and Zhang, D.: Rapid Spontaneous Generation of Organosulfur from Inorganic Sulfur in Atmospheric Microdroplets, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15276, https://doi.org/10.5194/egusphere-egu26-15276, 2026.
The Guangdong-Hong Kong-Macao Greater Bay Area (GBA), particularly Hong Kong, faces severe challenges regarding ozone (O3) pollution. As volatile organic compounds (VOCs) are primary precursors driving near-surface O3 formation, accurately assessing their contribution is essential for developing effective synergistic control strategies. In this study, high-resolution online observations of O3-sensitive VOCs were conducted at a coastal site in Hong Kong using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS). We investigated emission characteristics, photochemical transformations, and the evolution of VOCs during regional transport.
Results indicate that Oxygenated VOCs (OVOCs) consistently exhibited higher concentrations during daytime. Methanol was the most abundant species (average 3.73 ppb), while concentrations of isoprene and methyl ethyl ketone (MEK) exceeded levels previously reported in coastal regions. Crucially, the Empirical Kinetic Modeling Approach (EKMA) confirmed a nonlinear relationship between O3, nitrogen oxides (NOX), and VOCs. The photochemical regime shifted from VOC-limited in the morning to a transition regime in the afternoon. Notably, by accounting for chemical loss, the calculated Photochemical Initial Concentration (PIC-VOC) was found to be 8.2 ppb higher than the observed concentration (OBS-VOC). This discrepancy highlights that neglecting photochemical consumption significantly leads to an underestimation of the local Ozone Formation Potential (OFP).
Source apportionment via Positive Matrix Factorization (PMF) revealed that the site was significantly influenced by urban plumes transported from the GBA (contributing 63.7%) and oceanic emissions (13.5%). During three identified high-O3 episodes (with a maximum peak of 382.65 µg/m3), backward trajectory analysis attributed the pollution to long-range transport (52%), short-range transport (28%), and local sources (20%). These findings demonstrate that elevated ozone levels in Hong Kong result from the synergistic effects of local photochemical production and regional pollutant transport, providing a critical scientific basis for refining regional air quality assessments.
How to cite: Tan, Y.: Synergistic Effects of Local Photochemistry and Regional Transport on Ozone Formation in Hong Kong, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15501, https://doi.org/10.5194/egusphere-egu26-15501, 2026.
Nitrophenols are important contributors to light absorption and toxicity in atmospheric aerosols, yet their sources and formation pathways remain poorly constrained. In this study, we investigate the occurrence and formation mechanisms of 2-nitrophenol (2-NP) in PM2.5 at an urban site in Mumbai, India, using ultra-high performance liquid chromatography mass spectrometry coupled with Orbitrap detector (UHPLC–MS-O). The mean concentration of 2-NP was 22.03 ± 13.45 ng m-3. Concurrent measurements of major water-soluble inorganic ions, organic and elemental carbon fractions, and water-soluble organic carbon (WSOC) were employed to examine sources and atmospheric processing. 2-NP exhibited strong positive correlations with WSOC (r = 0.92), K+ (r = 0.73), organic carbon (r = 0.62), and NO3- (r = 0.61), while negative correlations were observed with Cl-. Principal component analysis indicates that 2-NP is predominantly associated with secondary organic aerosol formation under nitrate-rich conditions, with additional influence from biomass-burning emissions. The co-variation of 2-NP with WSOC, carbon fractions, NH4+, and SO42- further suggests that photochemical aging and multiphase processing of phenolic precursors under elevated oxidant and NOx levels are key drivers of its formation in fine particles. Together, these results provide molecular-level evidence that NOx-driven secondary processing is a dominant pathway for ambient nitrophenol formation in a humid, polluted urban environment. Our findings show that controlling NOx emissions can directly suppress the formation of toxic, light-absorbing nitro-aromatic aerosols, offering a targeted strategy for improving air quality and climate-relevant aerosol properties.
How to cite: Pakki, J. and Chakraborty, A.: Drivers of Ambient Nitrophenol Formation and evolution in fine particulates: Influence of NOx, pH, and Relative Humidity, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16460, https://doi.org/10.5194/egusphere-egu26-16460, 2026.
Comprehensive detection of atmospheric organic compounds remains a key analytical challenge, particularly for highly oxygenated organic molecules (HOMs), semi-volatile species, and amines. These compounds play central roles in secondary aerosol formation and atmospheric reactivity, yet are often underrepresented in long-term datasets due to limitations in sensitivity, resolution, or chemical coverage.
We present a high-resolution multi-pressure chemical ionization mass spectrometry (HR-MPCIMS) system, integrating novel ionization schemes with a high resolution accurate mass analyzer (>120,000 resolving power). Ionization is carried out at both ambient and low pressures using interchangeable solid-state reagent sources (nitrate, urea, and fluoranthene), enabling detection of a wide range of organics without the need for pressurized gas cylinders or vapor delivery of toxic substances.
The system allows rapid switching between ion chemistries and has demonstrated stable performance in both laboratory oxidation experiments and ambient air campaigns. Observations include VOCs, OVOCs, peroxides, HOMs, and amines, with sensitivities reaching the ppqv range. Time series of ambient amines highlight its applicability to nitrogen-containing organics. During a three-month deployment at the CLOUD experiment at CERN, the instrument achieved >99.9% uptime.
These results demonstrate the potential of HR-MPCIMS for wide coverage, high-resolution monitoring of gas-phase organics in both laboratory and field settings.
How to cite: Jost, H., Shcherbinin, A., Finkenzeller, H., Partovi, F., Vinkvist, N., Kontro, J., Boyer, M., Mikkilä, J., Iyer, S., Mikkilä, J., Juuti, P., Sarnela, N., Kangasluoma, J., and Rissanen, M.: A High-Resolution Multi-Pressure Chemical Ionization Platform for Comprehensive Monitoring of Atmospheric Organics, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16805, https://doi.org/10.5194/egusphere-egu26-16805, 2026.
Per- and polyfluoroalkyl substances (PFAS) are a diverse group of anthropogenic chemicals that have attracted increasing attention due to their environmental persistence, long-range transport potential, and adverse effects on ecosystems and human health. While PFAS have been extensively studied in surface waters, precipitation, and aerosols, their occurrence and behaviour in cloud water remain poorly investigated. Clouds play a critical role in atmospheric chemistry and pollutant distribution, making them a potentially important but underexplored compartment for PFAS cycling in the atmosphere.
This study includes two cloud water sampling campaigns conducted at the Sonnblick Observatory (3106 m a.s.l.) in the Austrian Alps, an ideal site for investigating the remote atmosphere. Active cloud water sampling was carried out in August 2024 and May 2025, resulting in a total of 130 samples, with sampling times from 15 min to 10 h. All samples were analysed for 20 PFAS as well as additional contaminants. The analysis of PFAS in cloud water is of particular interest, as previous studies on PFAS in the atmosphere have mainly been focused on aerosols, the gas phase, and precipitation. Analyses were performed by High Performance Liquid Chromatography Tandem Mass Spectrometry (HPLC-MS/MS).
A total of 20 PFAS were identified as target analytes, including 10 perfluorocarboxylic acids and 10 perfluorosulfonic acids, as also mentioned in the EU Drinking Water Directive (EU) 2020/2184. The most abundant compounds were PFBA and PFPeA, followed by PFHxA and PFBS. Total concentrations (Σ20 PFAS) ranged from the LOD to 10 ngL⁻¹ in May and from 0.13 to 34 ngL⁻¹ in August. Data will be evaluated regarding the seasonal differences, meteorological conditions and the overall composition of cloud water samples. Additional analytes comprised selected carbohydrates, inorganic ions, and organic acids. During the two sampling campaigns, meteorological conditions were recorded and are compared with the obtained data, i.e. warm and mixed-phase clouds and a mineral dust event showed as an episode at the end of the August campaign
How to cite: Porkert, M., Riedelberger, T., Scherzer, N., Hochwartner, C., Happenhofer, F., Gregori, M., Maier, C., and Kasper-Giebl, A.: PFAS in Cloud Water, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16972, https://doi.org/10.5194/egusphere-egu26-16972, 2026.
Particulate matter (PM2.5) has significant impacts on air quality, climate, and human health. Exposure to PM2.5 can induce oxidative stress either by transferring oxidants to the lungs or via catalytic production of reactive oxygen species (ROS), leading to various respiratory and cardiovascular diseases. In this study, we quantified the oxidative potential (OP) using the DTT assay in surrogate lung fluid (SLF) for aerosol collected in the northwestern Himalayas, examined its sources and chemical drives, and its potential links with aerosol optical properties. The annual mean volume-normalized DTT (OPv) was 0.30 ± 0.15 nmol min-1m-3 while the absorption coefficient (babs_aq_365) was 7.9 ± 7.8 Mm-1. OPv showed a strong seasonality, with the highest value in the winter season (0.35±0.17 nmol min-1m-3), followed by the post-monsoon and summer. BrC absorption showed a similar trend with the highest levels in winter (babs_aq_365: 16.1 ± 7.6 Mm-1), which was 6 and 4.4 times higher than the summer and post-monsoon seasons, respectively (p<0.05). The mass absorption efficiency (MAE) for BrC also peaked in the winter at 1.85 ± 0.44 m2 g-1 with lower E2/E3 values (5.8 ± 0.6) as compared to the summer (0.8 ± 0.3 m2 g-1, 9.0 ± 2.6) and post-monsoon (1.0 ± 0.4 m2 g-1, 7.1 ± 1.2). This indicated the presence of more aromatic, higher molecular weight chromophores in the winter, which were more resistant to photobleaching. Moderate but significant positive correlations were observed for babs_aq_365 and MAE with OPv (r=0.40, p<0.01, and r=0.25, p<0.05, respectively), signifying the potential role of light absorbing chromophores in inducing oxidative stress. Also, a significant negative correlation of OPv with E2/E3 (r=-0.28, p<0.05) was observed, indicating that aromatic, high-molecular-weight BrC chromophores possibly enhanced redox activity. Atmospheric aging/SOA formation from fossil fuel and biomass burning emissions played a dominant role in driving both OPᵥ and babs_aq_365. Random forest (RF) coupled with regression analysis identified Cu, K+, and NO3- as dominant drivers of OPᵥ, followed by OC, EC, and Mn. Positive matrix factorization (PMF) resolved seven sources, with industrial emissions and secondary formation contributing ~83% of OPv. These findings emphasize the potential linkages between the light absorbing and stress-inducing roles of aged aerosol in the Himalayan region.
Keywords: DTT assay, Mass absorption efficiency (MAE), Surrogate lung fluid (SLF), Positive matrix factorization (PMF), Random forest (RF).
How to cite: Rana, A., Prabhakaran, P., Yadav, R. K., Singh, R., Phuleria, H. C., and Sarkar, S.: Association between oxidative potential and optical properties of PM2.5 over the northwestern Himalayan region , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17855, https://doi.org/10.5194/egusphere-egu26-17855, 2026.
Ambient oxidation of volatile organic compounds (VOCs) is the route to condensable oxygenated molecules that form ambient secondary organic aerosol (SOA). It is generally accepted that NOx (=NO and NO2) considerably hinders, even prevents, the formation of highly condensable products, and thus cuts short the SOA production. However, in certain chemical systems the involvement of NOx, or rather NO, can increase the yield of condensable chemicals by converting relatively unreactive peroxy radicals (RO2) into much more reactive alkoxy radicals (RO) that contrary to previous reports can propagate the oxidation sequence through mechanistic bottlenecks. In select oxidation systems this leads to remarkably enhanced generation of highly condensable matter, an observation which carries an important message to polluted air chemistry.
In this work we studied three aromatic carbonyl oxidation systems benzaldehyde, acetophenone and phenylacetaldehyde by a joint experimental-computational approach. In the lab the reactions were studied in flow reactor setups under variable short reaction times and NOx additions, and the products were quantified utilizing nitrate ion based chemical ionization mass spectrometry. Computations and kinetic modelling were performed to strengthen the hypotheses originating from the experimental work. We find significant differences between the systems, with 2/3 studied aromatics showing much pronounced condensable product generation upon addition of NO, and the remaining 1/3 channeling the yield into a single nitro hydroxy product channel. Importantly the results show that even unrealistically large NO addition of 1 ppm does not shut down the highly efficient oxidation cascade but instead leads to several condensable products in higher yields than in absence of NO. This is in stark contrast to insights from the frequent monoterpene chamber oxidation experiments, in which practically invariably NO has been implied to severely hinder SOA generation.
How to cite: Rissanen, M., Barua, S., Kumar, A., Seal, P., Bezaatpour, M., Jha, S., Myllys, N., and Iyer, S.: NO increases direct aerosol precursor yields from aromatic carbonyl compounds, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17885, https://doi.org/10.5194/egusphere-egu26-17885, 2026.
Nitroaromatics are an incredibly toxic group of volatile compounds. They are both primary emissions from industrial sources [1] and biomass burning [2], as well as secondary emissions forming from the reactions between phenols and NOx. Due to their toxicity and presence in the atmosphere, it is important to know their atmospheric fate. Nitrogen containing compounds have also been found to be abundant in organic aerosol [3], and thus nitroaromatics likely play a role in aerosol formation. However, no mechanistic studies have been conducted on its gas-phase reactions under atmospheric conditions.
Most aromatics react in the atmosphere with the hydroxyl radical (OH) creating an alkyl radical that reacts with molecular oxygen producing a peroxy radical. This peroxy radical then undergoes subsequent unimolecular isomerization reactions and O2 addition reactions in an autoxidation chain. Similar reactions have been shown to happen to a multitude of substituted aromatics, but not for nitro-substituted aromatics.
In this study, the reactions between the hydroxyl radical and three simple nitroaromatics (nitrobenzene, nitrophenol and nitrocatechol), as well as further possible reactions leading to termination and autoxidation are studied computationally. The three chosen compounds are among the simplest nitroaromatics and offer a range in both the toxicity of the reactant as well as atmospheric abundance. This study offers new insights into the atmospheric processes of nitroaromatics and elucidates their possible gaseous reaction mechanisms, which in turn gives insight on the effects of nitroaromatics in aerosol formation.
[1] Ahmed, M., Rappenglueck, B., Ganranoo, L., & Dasgupta, P. K. (2023). Source apportionment of gaseous Nitrophenols and their contribution to HONO formation in an urban area. Chemosphere, 338, 139499.
[2] Wang, H., Gao, Y., Wang, S., Wu, X., Liu, Y., Li, X., ... & Zhang, X. (2020). Atmospheric processing of nitrophenols and nitrocresols from biomass burning emissions. Journal of Geophysical Research: Atmospheres, 125(22), e2020JD033401.
[3] Wang, X., Hayeck, N., Brüggemann, M., Yao, L., Chen, H., Zhang, C., ... & Wang, L. (2017). Chemical characteristics of organic aerosols in Shanghai: A study by ultrahigh‐performance liquid chromatography coupled with Orbitrap mass spectrometry. Journal of Geophysical Research: Atmospheres, 122(21), 11-703.
How to cite: Savolainen, A. and Iyer, S.: OH-initiated oxidation reactions of nitroaromatics, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18768, https://doi.org/10.5194/egusphere-egu26-18768, 2026.
Volatile organic compounds (VOC) have significant impact on air quality as they oxidize and form condensable vapors, which are important sources of secondary organic aerosol (SOA). As vehicle emissions are becoming increasingly regulated, other sources of VOC are increasing in relevance. One of these sources are volatile chemical compounds (VCPs), which include cleaning agents, personal care products, pesticides and adhesives (McDonald et al., 2018). However, quantifying the SOA yields from VCP emissions is challenging as the atmospheric chemistry of many of the compounds is still unclear.
In this work, we use quantum chemical calculations to study the multigenerational atmospheric oxidation of benzyl alcohol, an aromatic hydrocarbon often found in VCPs. Its sources include cosmetics, inks and dyes, pharmaceuticals and flowers. The atmospheric oxidation of benzyl alcohol produces SOA in high yields (Charan et al. 2020), but the formation mechanisms are largely unknown. Fast intra-molecular reactions are needed for condensable vapor formation, but the double-ringed intermediates, bicyclic peroxy radicals (BPRs), in aromatic oxidation make these reactions slow. However, recently ipso-BPR, where the OH radical has added to a substituted carbon, have been shown to be unstable, leading to ring-open products that rapidly form condensable vapors through intra-molecular reactions (Iyer et al., 2023). Furthermore, geminal diol BPRs, where OH has added to an OH substituted carbon, have been shown to be highly unstable as well, leading to condensable vapors (Ojala et al., 2025).
Based on our calculations, the high SOA yield measured from benzyl alcohol oxidation is likely in part due to the ipso-BPR of benzyl alcohol and geminal diol BPR from hydroxybenzyl alcohol, which is a first-generation phenolic product of benzyl alcohol. The oxidation products phenol and catechol also likely to contribute to the total SOA yield. Our results provide key insights into the multigenerational atmospheric oxidation of benzyl alcohol, showing the potential pathways to condensable vapors.
References
Charan, S. M. et al. (2020) Secondary organic aerosol yields from the oxidation of benzyl alcohol. Atmospheric chemistry and physics. 20 (21), 13167–13190.
Iyer, S. et al. (2023) Molecular rearrangement of bicyclic peroxy radicals is a key route to aerosol from aromatics. Nature communications. 14 (1), 4984.
McDonald, B. C. et al. (2018) Volatile chemical products emerging as largest petrochemical source of urban organic emissions. Science. 359 (6377), 760–764.
Ojala, A. et al. (2025) Secondary organic aerosol formation from sequential oxidation of toluene and cresols. [Preprint] Available from: https://doi.org/10.21203/rs.3.rs-7621262/v1
How to cite: Kervinen, A. and Iyer, S.: Multigenerational oxidation of benzyl alcohol in the atmosphere, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18796, https://doi.org/10.5194/egusphere-egu26-18796, 2026.
Volatile organic compounds (VOCs) can be processed in the atmosphere through chemical reactions which generates organic aerosols (OAs). These aerosols have a direct influence on climate and public health. Therefore, understanding the chemical composition of OAs and VOCs is essential for the identification of transformations and the sources of these components. (Leppla et al. 2026; Xie and Laskin 2024)
To achieve a measurement regarding the chemical composition of the organic aerosol fraction as well as the semi volatile fraction, an adequate sampler is needed. A piston pump is used to generate sufficient airflow through a filter onto which the aerosols are deposited. The sampler is self-developed to ensure an ideal flow as well as adequate weight. Therefore, a 3D-printed sampler was developed which is ideally suited for our requirements. On a second airstream a thermal adsorption tube is used to sample the volatile organics. The requirements for the sampling system are low weight and high performance due to the desired application on a weather balloon as well as on a drone which requires both low weight and high performance due to shorter sampling periods and limited carrying capabilities. For a possible weather balloon application. The aim is also to employ a variety of sensors to automate the sampling procedure based on pressure, temperature and height of the balloon or drone.
First field tests were performed to evaluate the capability of the sampling methods. The filters were extracted and analysed using high-performance liquid chromatography coupled with high-resolution mass spectrometry (HPLC-HRMS). The adsorption tubes were analysed using a thermal desorption gas chromatography high resolution mass spectrometer (TD-GC-HRMS). The Orbitrap as a HRMS is used to detect and characterise a wide range of organic compounds using a non-targeted approach. This study aims to achieve a detailed chemical profile of the organic aerosols as well as semi volatile organic species present.
This poster aims to provide an overview of the development process of this novel, lightweight, high-performance sampler, which is suitable for weather balloon measurements to enable sampling under the different and harsh conditions in the stratosphere.
Literaturverzeichnis
Leppla, Denis; Hildmann, Stefanie; Zannoni, Nora; Kremper, Leslie A.; Holanda, Bruna A.; Williams, Jonathan et al. (2026): Comprehensive non-targeted molecular characterization of organic aerosols in the Amazon rainforest. In: Atmos. Chem. Phys. 26 (1), S. 365–390. DOI: 10.5194/acp-26-365-2026.
Xie, Qiaorong; Laskin, Alexander (2024): Molecular characterization of atmospheric organic aerosols: Contemporary applications of high-resolution mass spectrometry. In: TrAC Trends in Analytical Chemistry 181, S. 117986. DOI: 10.1016/j.trac.2024.117986.
How to cite: Wasserzier, D. and Hoffmann, T.: Development of a sampling system for organic aerosols (OAs) and volatile organic compounds (VOCs) in the stratosphere, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18874, https://doi.org/10.5194/egusphere-egu26-18874, 2026.
Monoterpenes emitted by vegetation, among other biogenic volatile organic compounds (BVOC), can play an important role in the formation of secondary organic aerosol (SOA). In reactions with atmospheric oxidants, monoterpenes can form products that condense into SOA. As the emissions of monoterpenes are temperature-dependent, a climate feedback is formed where rising temperatures increase biogenic SOA formation, which then cools the climate through aerosol-radiation interactions.
The accurate representation of this feedback mechanism would be important when modeling future climate. This necessitates a model of the underlying monoterpene oxidation chemistry to account for the volatilities of the oxidation products in varying conditions. Such models have been developed in recent years, one of which is the chamber chemistry model ADCHAM. ADCHAM is extended by the Peroxy Radical Autoxidation Mechanism to include monoterpene oxidation pathways, particularly for α-pinene. For climate applications, ADCHAM remains too complex without heavy simplification.
Our study aims to produce a parametrization of ADCHAM capable of predicting the volatility distribution of α-pinene oxidation products in simulations of the global atmosphere. To this end, we have trained a neural network (NN) to model the error between the current parametrization in the SALSA aerosol model and the more accurate ADCHAM in various conditions. We represent these conditions by eight input variables, including temperature and oxidant concentrations. The training data was generated by sampling points from the atmospheric ranges of the input variables in global reanalysis and climate model datasets, a subset of which were reserved for testing. For each point, ADCHAM was run for 7.5 minutes, corresponding to the timestep of our targeted climate model. The resulting compounds were aggregated into three bins based on their volatilities, according to the volatility basis set (VBS) representation used in SALSA. The differences between the VBS bin production rates (1/cm3s) from SALSA and ADCHAM constitute the training targets of the NN. For comparison, a linear regression model was also fitted.
We have tested the NN and linear model on the holdout set and found both to be successful in correcting the VBS concentrations produced by SALSA to match those from ADCHAM. Without correction, the SALSA representation generally resulted in higher production rates of the VBS bins compared to ADCHAM, in some cases by more than ten orders of magnitude (RMSE=5.03, i.e., five orders of magnitude). While the linear model corrects the overestimation and improves the fit (RMSE=1.97), errors as large as five orders of magnitude remain. Using the NN, such errors are eliminated – the NN-augmented SALSA corresponds remarkably well to ADCHAM (RMSE=0.28; R2=0.995). Additionally, the NN improved the modeled dependences between input variables and VBS bin production. The results are encouraging, suggesting that the dependence of condensable vapor production on ambient conditions in global models could be represented by augmenting simplified VBS schemes already in use with NNs. While our NN is relatively small, further pruning seems possible without significantly affecting its accuracy. Before implementing the correction scheme into a global model, we will evaluate its ability to reproduce SOA yields in chamber simulations.
How to cite: Vartiainen, A., Roldin, P., Irfan, M., Thomasson, A., Kokkola, H., and Yli-Juuti, T.: Improving the monoterpene oxidation scheme in a global-scale model through neural network-based bias correction, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19598, https://doi.org/10.5194/egusphere-egu26-19598, 2026.
Organic compounds are key components to tropospheric reactivity, secondary pollutant formation, and air-climate interactions. Yet their sources and transformation pathways remain incompletely constrained, especially under warm, stagnant conditions such as polluted summers. In this work, a regional dataset over (Western) Europe combining background, urban, suburban, and forest locations is used to characterize the variability of organic and inorganic species during summer 2022, a hot dry summer which is considered as a proxy of future climate over Western Europe. A large number of datasets from 2 major campaigns Atmospheric ChemistRy Of the Suburban forest (ACROSS) and European Monitoring and Evaluation Programme (EMEP) Intensive Measurement Campaign (EIMP) have been utilized for this work. ACROSS (13 June - 25 July 2022) is a comprehensive, multi-platform field measurement campaign mainly focused on the understanding of the interactions of urban air and biogenic organic compounds (Cantrell and Michoud, 2022). EIMP campaign for VOC was carried out linked to a European heat wave during 12- 19 July 2022 involving 27 European Sites (EMEP sites) (Solberg et al., 2024). A large suite of offline and online sampling methods have been incorporated during these two campaigns, yielding more than 100 different compounds. To interpret these observations, a set of zero-dimensional simulations was created and a highly detailed gas-phase chemical mechanism generated with the GECKO-A tool. A set of primary organic compounds including around 200 anthropogenic and 150 biogenic species have been input into GECKO-A. Then GECKO-A generates the explicit mechanism of about 2.5 millions of secondary organic species from the experimental kinetic laboratory data and structure activity relationships. The generated mechanism and the inorganic mechanism together goes as a input into the box model with the meteorological parameters, boundary conditions and emissions to represent daily mean scenarios of the species during the ACROSS and EIMP campaigns. Thus, the box model framework allows exploration of emission speciation from anthropogenic and biogenic sources and their major oxidation pathways at the molecular scale. Comparisons between explicit simulations and observations are used to identify systematic discrepancies in daily profiles and magnitudes of more than 100 organic and inorganic species concentrations. The results indicate differences between observed and modelled behavior of organic carbon and associated secondary pollutants. These results will be interpreted in order to improve emission representations and chemical schemes.
Keywords: Organic Compounds, ACROSS campaign, EIMP campaign, GECKO-A tool, explicit modeling
References:
Cantrell, C., Michoud, V., 2022. An Experiment to Study Atmospheric Oxidation Chemistry and Physics of Mixed Anthropogenic–Biogenic Air Masses in the Greater Paris Area. Bull. Am. Meteorol. Soc. 103, 599–603. https://doi.org/10.1175/BAMS-D-21-0115.1
Sverre Solberg, Anja Claude, Stefan Reimann. EMEP_CCC Report_4_2024_VOC_measurements_2022.pdf. https://emep-ccc.nilu.no/static/reports/EMEP_CCC
How to cite: Sreenivas, S., Camredon, M., Beekmann, M., Dusanter, S., Siour, G., Valorso, R., Aumont, B., and Scientific Team, T. A.: Evaluation of Our Understanding of Organic Carbon Evolution: Insights from Intensive Observations and Explicit Chemical Modelling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20415, https://doi.org/10.5194/egusphere-egu26-20415, 2026.
Volatile organic compounds (VOCs) play a central role in atmospheric chemistry, yet their vertical distribution and transformation in the lower troposphere remain insufficiently characterized. VOCs originate from diverse natural and anthropogenic sources, and their accumulation, dispersion, and photo‑oxidation are strongly influenced by meteorological conditions and boundary‑layer dynamics. Some VOCs are carcinogenic (e.g., benzene) and others are neurotoxic (e.g., toluene). In addition to their toxicological relevance, many VOCs act as key precursors of tropospheric ozone and secondary organic aerosol (SOA).
For organic contaminants, the air above the daytime mixing layer and within the nocturnal residual layer remain poorly characterized. The photolysis of VOCs can release radicals that promote ozone formation aloft, while their photooxidation and transformation into lower-volatility products may contribute to SOA. The accumulation of these secondary pollutants in the nocturnal residual layer can increase its oxidative capacity, and once vertical mixing resumes, they may contribute to photochemical reactions and to the secondary pollutant burden at the surface. Beyond evaluating the oxidative state of air aloft, an important question is whether oxidized compounds result from local emissions undergoing rapid transformations.
This work investigated the origins, composition, and vertical distribution of VOCs and its oxidized products across rural, suburban, and industrial environments in the Western Mediterranean. Active offline sampling of VOCs and total suspended particles was conducted using multiple sorbent cartridges and quartz filters, followed by GC‑MS and HPLC analysis. To resolve vertical gradients, ground‑level observations were complemented with tethered‑balloon measurements reaching 350 meters above ground level, which allowed sampling both within the surface layer and above the nocturnal residual layer.
The results obtained from the vertical profiles showed a consistent decrease in VOC concentrations with altitude due to dilution and oxidation. Primary VOCs concentration declined by roughly 30% at balloon height, while secondary VOCs showed a smaller decrease, and even some carbonyl species exhibited nearly uniform vertical distributions. Air masses aloft were found consistently more oxidized than those near the surface, particularly in winter under strong stratification, and they contained higher levels of long‑lived VOCs and secondary products, including SOA. Diagnostic ratios, such as benzene to toluene or SOA tracers to isoprene and α-pinene, confirmed that aged compounds predominated at higher altitudes. Multivariate analysis showed that local photooxidation of freshly emitted compounds contributed substantially to this ageing and accounted for up to 41% of aged VOCs aloft.
Overall, these findings highlight the importance of incorporating vertical pollutant gradients and source apportionment analysis to better understand the origin of compounds accumulated in the residual layer and tackle their influence on surface photochemical pollution the following day.
How to cite: Díez-Palet, I., Jaén, C., Marco, E., Van Drooge, B. L., Fernández, P., and O. Grimalt, J.: Sources and vertical distribution of VOCs and their oxidized products across rural, suburban and industrial environments in the Western Mediterranean, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20561, https://doi.org/10.5194/egusphere-egu26-20561, 2026.
Chemical ionization mass spectrometry (CIMS) is a powerful analytical technique for the detection of trace gases in the atmosphere. It is uniquely suited for measuring temporal variations of trace volatile organic compounds (VOCs) as well as atmospheric oxidation products including extremely low volatility organic compounds that play a key role in secondary organic aerosol formation.
By choosing an appropriate reagent ion, CIMS enables highly sensitive, online detection of a broad range of chemical species. However, the combination of multiple reagent ions within a single measurement can be technically challenging, especially when both positive and negative ion chemistries are required. Here, we present a versatile fast polarity switching CI-TOFMS platform featuring millisecond transition times between positive and negative ions. This capability enables quasi-simultaneous measurements of diverse molecular families, making the system uniquely suited for comprehensive studies of atmospheric composition. In particular, we present how our novel VUV driven PTR reactor featuring traditional positive ion chemistries such as H3O+ and O2+ can be combined with negative ion chemistries, for example iodide or bromide adducts on a single high resolution instrument platform. We present the characterization of the new system in terms of sensitivities, dynamic range, time response, humidity dependence, as well as reagent ion switching timescales. We also present the first results from test ambient measurements performed in Thun, Switzerland.
How to cite: Yatsyna, V., Rohner, U., Bansal, P., Riva, M., Kamrath, M., and Lopez-Hilfiker, F.: A versatile fast polarity switching CIMS platform for studies of atmospheric composition, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20587, https://doi.org/10.5194/egusphere-egu26-20587, 2026.
Organic acids are, besides inorganic constituents, important components of cloud water samples. Typical analytes include monocarboxylic, dicarboxylic, tricarboxylic, and aromatic carboxylic acids. They are either scavenged from the gas and aerosol phase or formed within cloud droplets via chemical reactions in the aqueous phase. Concentrations in cloud water depend on meteorological conditions, air mass origin, and cloud properties, including cloud type and liquid water content. Organic acids influence cloud chemistry, facilitate cloud droplet formation, and increasingly contribute to the acidity of cloud water.
We present the results of two cloud water sampling campaigns conducted in August 2024 and May 2025 at Sonnblick Observatory (3106 m a.s.l.) in the Austrian Alps. The sampling campaigns were conducted within the framework of ACTRIS activities. Depending on the season, sampling comprised warm clouds as well as mixed-phase clouds, including periods coinciding with mineral dust events. Chemical analyses of organic acids were performed using ion chromatography with conductivity and mass spectrometry detection. Further analyses included inorganic ions, pH, conductivity, and selected carbohydrates.
One part of the evaluations focuses on methodological topics, such as the comparison of different analytical set-ups used for the analysis of organic acids. The advantage of mass spectrometry detection is demonstrated by the analysis of several coeluting substances that cannot be resolved by routine gradient ion chromatography. Additionally, the ion concentrations of organic acids observed during the two sampling campaigns are shown and discussed with respect to the overall chemical composition and meteorological conditions. Finally, the contribution of organic acids to the overall acidity of cloud water is discussed and evaluated in comparison with earlier measurements from the 1990s conducted at Sonnblick Observatory.
How to cite: Riedelberger, T., Scherzer, N., Hochwartner, C., Porkert, M., Maier, C., Schittmayer, M., and Kasper-Giebl, A.: Cloud Water Chemistry at Sonnblick Observatory with a Focus on Organic Acids, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20809, https://doi.org/10.5194/egusphere-egu26-20809, 2026.
Volatile organic compounds (VOCs) play a central role in atmospheric oxidation chemistry and the formation of secondary air pollution. Through complex oxidation processes, VOCs generate secondary products with reduced volatility and enhanced toxicity, contributing to secondary organic aerosol (SOA) formation and chemical health risks. In recent years, increasingly stringent regulations on fossil fuel combustion from transportation and industry have substantially altered the composition of anthropogenic VOC emissions in urban atmospheres across the European Union. As traditional sources decline, volatile chemical products (VCPs)—including personal care products, coatings, rubber materials, adhesives, and pesticides—have emerged as a dominant and rapidly growing source of urban VOC emissions.
Despite their importance, VCPs have long been underrepresented in emission inventories, leading to significant uncertainties in current air quality models and an incomplete understanding of their atmospheric oxidation chemistry. In particular, the oxidation mechanisms and kinetics of high-emission VCP species remain poorly constrained, limiting robust assessment of their contributions to secondary pollution and chemical risk.
In recent studies, we investigate the molecular-level oxidation chemistry and environmental impacts of representative high-emission VCPs relevant to urban environments, such as (A) volatile methyl siloxanes (Fu, Z., et al., Environ. Sci. Technol., 2020, 54, 7136-7145), (B) organophosphate esters (Fu, Z., et al., Environ. Sci. Technol., 2022, 56, 6944-6955), (C) linalool (Fu, Z., et al., Environ. Health, 2024, 2, 486-498), and (D) limonene (Fu, Z., et al., Environ. Sci. Technol., 2024, 58, 19762-19773). Focusing on compounds from personal care, coating, and rubber-related products, we combine quantum chemical calculations, detailed kinetic and chemical mechanism modeling, and environmental chamber experiments. This integrated approach aims to (1) elucidate previously unexplored autoxidation and radical-driven reaction pathways, (2) quantify the formation potential of SOA precursors, and (3) assess the yields of toxic secondary oxidation products.
The results will improve mechanistic understanding of VCP atmospheric oxidation, reduce uncertainties in SOA and toxicity predictions, and support the refinement of chemical transport models. Ultimately, these works contribute to improved air quality assessment and chemical risk evaluation, aligning with EU priorities on clean air, chemical safety, and sustainable innovation.
How to cite: Fu, Z., Guo, S., and Boy, M.: Molecular-level oxidation mechanisms and secondary pollution impact of volatile chemical products (VCPs), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21132, https://doi.org/10.5194/egusphere-egu26-21132, 2026.
Polycyclic Aromatic Hydrocarbons (PAHs) and Nitro-PAHs are ubiquitous semi-volatile organic pollutants. Their high concentration in the ambient air is a severe cause for concern because they are carcinogenic, mutagenic, and teratogenic to humans. This study elucidates the atmospheric chemistry and gas-particle partitioning mechanisms of PAHs and Nitro-PAHs, as well as their role in the formation of secondary aerosols. 16 priority PAHs and two nitro-PAHs were analysed using gas chromatograph-mass spectrometry (GC-MS) from dual-phase (gas and particle) aerosol samples that were simultaneously collected in a rural and traffic-dominated region of Agra. At the traffic and rural sites, the overall concentration of PAHs (gas + particulate) was 2481 and 1011 ng m-3, respectively, while the total concentration of nitro-PAHs was 90 and 28 ng m-3. The dual model governs the gas-particle partitioning of PAHs in Agra's ambient air, demonstrating how the concentration of PAHs is affected by the concentrations of OC and EC in the environment. Regression statistics (R2 > p<0.01) of the dual model, along with a statistically significant negative correlation between 1-NPyr (R2= 0.73, p<0.01)and 3-NFla (R2= 0.78, p<0.01)and their parent compounds, i.e., Pyr and Fla, confirm the formation of nitro-PAHs in the ambient air of Agra. A statistically significant correlation (R2 > 0.75, p<0.01) for Clausius–Clapeyron plots was obtained, indicating the temperature dependency of gas-phase PAHs at both sites. Source analysis of PAHs and Nitro-PAHs reveals that the PAH concentration at the traffic site is primarily attributed to traffic and combustion sources, whereas at the rural site, the PAH concentration is largely due to biomass combustion and pyrogenic sources. However, the Nitro-PAHs concentration at the traffic site is due to both primary and secondary sources. ILCR values of PAHs and Nitro-PAHs show that humans are prone to cancer risk from the dermal exposure pathway, followed by ingestion and inhalation.
How to cite: Verma, P. K., kumari, K. M., and Lakhani, A.: Atmospheric chemistry of Polycyclic Aromatic Hydrocarbons (PAHs) and role of gas-partitioning in the formation of secondary Nitro-PAHs, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-959, https://doi.org/10.5194/egusphere-egu26-959, 2026.
We report long-term, vertically resolved measurements of biogenic volatile organic compounds (BVOCs) above pristine Amazon rainforest. Since March 2018, air from 80, 150, and 325 m on the 325 m Amazon Tall Tower Observatory (ATTO; ~150 km NE of Manaus) has been sequentially sampled (5 min per level, ~4 cycles per hour per height) via insulated Teflon lines to a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) at ground level. The site sits on a plateau within terra firme rainforest, with prevailing NE–E winds transporting air over >1000 km of intact forest to the site. The system quantifies a multitude of BVOCs at sub-ppb levels. The dataset allows to investigate the variability of these BVOCs as a function of height (80-325m), time (0-24h) and season (wet, dry, transition). The extreme drought in 2023, due to an El Nino event, left a clear mark in some BVOCs. This unique record enables analysis of long-term trends and interannual variability and provides a baseline for assessing future atmospheric change.
How to cite: Edtbauer, A., Ringsdorf, A., Pfannerstill, E., Quaresma Dias Júnior, C., and Williams, J.: BVOC measurements in the Amazon rainforest: Results from vertically resolved long term measurements, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13937, https://doi.org/10.5194/egusphere-egu26-13937, 2026.
Many polycyclic aromatic hydrocarbons (PAHs), along with their nitrated and oxygenated derivatives (NPAHs and OPAHs), are known for their toxicity and ecotoxicity (Bandowe et al., 2014; Rengajaran et al., 2015; IARC, 2019; Nováková et al., 2020). These compounds are co-emitted with PAHs during fossil fuel and biomass combustion, or they form through photochemical and microbiological reactions involving PAHs in the atmosphere and soil (Tsapakis and Stephanou, 2007; Keyte et al., 2013; Bandowe et al., 2017; Wilcke et al., 2021).
While laboratory and field studies have explored the sources, photochemistry, and atmospheric occurrence of these pollutants, their large-scale atmospheric lifetimes and environmental fate remain poorly understood. As semivolatile compounds resistant to biodegradation in soils and surface waters, their potential for long-range transport is further amplified by the "grasshopper effect" (Keyte et al., 2013; Mulder et al., 2014).
We determined the concentration of 25 parent PAHs, 10 OPAHs and 17 NPAHs during summer in air and soils at a rural and near-coastal north European site (Birkenes, southern Norway), a north European forest site (Hyytiälä, southern Finland), a central European rural background site (Košetice, Czech Republic), and in air and surface seawater at two off-shore sites in the Aegean Sea and along transects across the Mediterranean Sea. Directions of diffusive air-soil and air-sea exchanges were derived from the fugacities.
In the source area (central Europe), the diffusive vertical fluxes of most 2-4 ring PAHs, 2-nitronaphthalene and a number of 3-4 ring OPAHs were upward and the carcinogen 1-nitropyrene was found close to phase equilibrium. In the receptor area (northern Europe), acenaphthylene, acenaphthene, benzo(a)anthracene, two 3-4 ring OPAHs, dibenzofuran and 6H-benzo(c)chromen-6-one, were found to volatilise, and 2-nitrofluoranthene close to phase equilibrium (Mwangi et al., 2024). In the Mediterranean Sea, phenanthrene, fluoranthene, pyrene, 2-nitronaphthalene and few 3-4 ring OPAHs were found to volatilise from the sea surface or being close to equilibrium. These findings suggest that land and sea areas even far from the primary sources may indeed act as secondary sources for PAHs, NPAHs and OPAHs in the atmosphere and enable global transport by multihopping.
Secondary emissions may include toxic species, such as e.g., the carcinogenic 1-nitropyrene. Because of neglected re-emissions (secondary sources), PAH emission inventories may be underestimated, in particular in receptor areas.
Acknowledgements: Czech Science Foundation (GAČR, grants 07117S, 17534S), the Max Planck Society, the European Commission – H2020, JERICO-S3 (871153), ACTRIS-CZ (LM2023030), RECETOX (LM2023069) financed by the Czech Ministry of Education, Youth and Sports (MŠMT).
References:
Bandowe, B.A.M. et al. (2017) Sci. Total Environ. 581-582, 237-257.
IARC (2019) IARC Monographs Eval. Carcinogenic Risks to Humans 92, 1–852
Keyte, I.J. et al., Chem. Soc. Rev. 42 (2013) 9333-9391.
Lammel, G. et al. (2025) Atmos. Poll. Res. 16, 102460.
Mulder, M.D. et al. (2914) Atmos. Chem. Phys. 14, 8905-8915.
Mwangi, J.K. et al. (2024) Sci. Total Environ. 921, 170495.
Nováková, J. et al. (2020) Environ. Int. 139, 105634.
Rengarajan, T. et al. (2015) Asian Pac. J. Trop. Biomed. 5, 182–189.
Tsapakis, M. and Stephanou, E.G. (2007) Environ. Sci. Technol., 41 (23), 8011-8017.
Wilcke, W. et al. (2021) J. Environ. Qual. 50, 717-729.
How to cite: Lammel, G., Bezdeková, D., Bohlin-Nizzetto, P., Halse, A. K., Iakovides, M., Kukučka, P., Letocha, O., Martiník, J., Mayer, L., Mwangi, J. K., Palátová Nežiková, B., Přibylová, P., Prokeš, R., Stephanou, E. G., Tsapakis, M., Wietzoreck, M., and Vrana, B.: Re-emissions of polycyclic aromatic compounds from land and sea surfaces in source and receptor areas, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14923, https://doi.org/10.5194/egusphere-egu26-14923, 2026.
Atmospheric trace gases is a very wide term, which involves tens to hundreds of thousands of distinct chemical compounds. Not only does this pose significant challenges when attempting to measure these compounds but inferring the interconnections between individual species from such data is a monumental task. This is especially true for analyzing ambient data from a chemical ionization mass spectrometer from an entire year. Often some factorization method is applied to reduce the dimensions that must be considered when analyzing either gas or particle phase data and especially PMF has become a very popular tool for source apportionment of atmospheric mass spectral datasets. However, the computations required for PMF take a significant amount of time, and running the factorization for a full year of data would require a lot of time and resources. Therefore, this work focuses on using the faster Non-Negative Matrix Factorization (NNMF) algorithm to accomplish what PMF does, but in a fraction of the time. Specifically, bin-NNMF, a method analogous to the one described by Zhang et al. (2019), was used in this work. The key distinction between PMF and NNMF is that NNMF does not accept an error matrix, denoting the uncertainty of each separate data point in the input matrix. To still account for uncertainties, the rows and columns of the input matrix were instead weighted. Using this approach, which allows for faster experimenting with factorization outcomes and can handle the whole dataset without issue, the NO3-CIMS data for the entire year of 2024 was analyzed.
While work is still ongoing to further investigate the dataset, the analysis so far shows that the instrument has operated stably during the studied time-period. Several sets of NNMF runs with different weighting schemes, and between one and twelve output factors have been conducted. This would be extremely time consuming, or even impossible, using the PMF algorithm. The output factors all seem useful for further interpretation of the data, with slight variations based on the chosen weighting scheme. In general, the factors present distinct temporal patterns, and the spectral chemistry seems to make sense. Looking at the factors in connection to wind direction, many factors also exhibit clear directionality, as one might expect from a successful factor analysis. Especially for a coastal site the directional separation may be crucial for further data interpretation. For example, factors corresponding to organics from land or sea respectively were identified along with factors for sulfuric acid, iodic acid, and methanesulfonic acid, mostly originating from the sea. Therefore, NNMF seems to offer a viable alternative to the commonly used PMF analysis and provides a powerful tool for understanding long term mass spectral data.
How to cite: Mickwitz, V., Thakur, R., Peltola, M., Spence, K., Graeffe, F., Luo, Y., Norkko, J., Norkko, A., Kulmala, M., and Ehn, M.: Factor analysis of long-term NO3- chemical ionization mass spectrometer (CIMS) dataset from Tvärminne coastal station, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18053, https://doi.org/10.5194/egusphere-egu26-18053, 2026.
Posters virtual: Tue, 5 May, 14:00–18:00 | vPoster spot 5
EGU26-17672 | ECS | Posters virtual | VPS3
Numerical modeling of tropospheric chemistry in an Earth System ModelTue, 05 May, 14:06–14:09 (CEST) vPoster spot 5
Abstract. This work presents the incorporation of a tropospheric isoprene oxidation scheme into an Earth System Model to enhance the simulation of tropospheric ozone levels. Numerical experiments were performed using two distinct model setups: one accounting for isoprene oxidation and another in which this chemical pathway was not considered.
Keywords: Isoprene, tropospheric ozone, atmospheric chemistry, MIM1 mechanism
Understanding the processes of tropospheric ozone formation is of key importance both for the development of air quality control measures and for climate prediction, especially under conditions of changing anthropogenic and biogenic emissions. While on the global scale the production of tropospheric ozone is primarily governed by the oxidation of carbon monoxide and methane, in densely populated and industrial regions non-methane volatile organic compounds (NMVOCs) become the dominant contributors. Among these NMVOCs, isoprene plays a particularly important role, with the majority of its atmospheric emissions originating from vegetation.
The aim of this study is to further develop the INM RAS–RSHU chemical–climate model [1], which is a component of the Earth System Model (ESM), with an emphasis on a more accurate representation of tropospheric chemical processes. The primary focus is on the implementation of an improved chemical mechanism designed to enhance the accuracy of simulated concentrations of key atmospheric gaseous components. One of the main criteria in selecting the mechanism is achieving an optimal balance between the level of chemical detail and the computational efficiency of the model.
As part of the model development, a comparative analysis of several widely used chemical mechanisms was performed, including the Mainz Isoprene Mechanism (MIM1) [2], comprising 16 species and 44 reactions; MIM2, with 69 species and 178 reactions [3]; the Model for Ozone and Related Chemical Tracers (MOZART), including 151 species and 287 reactions [4]; and the Regional Atmospheric Chemistry Mechanism (RACM), which includes more than 100 species and 363 reactions [5]. Based on the results of this analysis, the MIM1 mechanism was considered the most appropriate for initial implementation in the ESM, as it was decided to begin with the most compact option while still providing sufficient accuracy in representing key tropospheric chemical processes.
To assess the impact of the MIM1 mechanism, two numerical experiments were conducted using identical model settings and boundary conditions. In the control simulation, a basic tropospheric chemistry scheme without isoprene was applied, whereas the MIM1 experiment implemented the full isoprene oxidation mechanism, including 44 chemical reactions.
The study and the set of numerical experiments are aimed at optimizing the chemical component of the INM RAS–RSHU chemical–climate model in order to improve the accuracy of representing tropospheric processes while maintaining high computational efficiency. The obtained results provide a solid basis for further investigation of the interactions between chemical and dynamical processes in the atmosphere and will contribute to the development of approaches for forecasting atmospheric composition and its impact on regional and global climate change.
How to cite: Okulicheva, A., Tkachenko, M., and Smyshlyaev, S.: Numerical modeling of tropospheric chemistry in an Earth System Model, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17672, https://doi.org/10.5194/egusphere-egu26-17672, 2026.
EGU26-186 | ECS | Posters virtual | VPS3
3D-Printed Electrochemical Sensor for Rapid Detection of Phenolic Oxidation Products Relevant to Organic Aerosol FormationTue, 05 May, 14:09–14:12 (CEST) vPoster spot 5
Phenolic compounds are key precursors and intermediates in the formation and aging of secondary organic aerosols (SOA), particularly in biomass-burning plumes and urban atmospheres. However, their detection typically requires laboratory-based chromatographic or mass-spectrometric techniques, limiting rapid or on-site characterization. The current research present a fully 3D-printed electrode (3D-PE) platform produced via hybrid material extrusion additive manufacturing, providing a compact, low-cost, and field-deployable tool for electrochemical quantification of atmospheric phenolics. The device integrates PLA-based structural components with graphene and silver conductive layers deposited in a single manufacturing step. Cyclic voltammetry measurements demonstrate clear and distinct redox signatures for representative phenolic structures, with oxidation potentials of 0.48–0.68 V and well-resolved reduction peaks. These redox behaviors correspond to functional groups commonly found in lignin-derived and anthropogenically emitted aromatic species.
The 3D-PE operates with sample volumes as low as 50 µL, suitable for extracts from aerosol filters, cloud water, or fog samples. Its electroactive surface area (5.8–6.7 mm²) and high electron-transfer efficiency from the graphene electrode enable sensitive detection of trace phenolic compounds. The platform’s portability and rapid response offer new opportunities for quantifying oxidation intermediates during field campaigns, studying heterogeneous oxidation pathways, and investigating Secondary Organic Aerosol (SOA) formation dynamics.
This work demonstrates that additive manufacturing provides a promising route for developing next-generation, customizable atmospheric chemistry sensors. The 3D-printed electrochemical platform can complement established mass-spectrometric techniques by enabling low-cost, high-frequency measurements of reactive organic compounds that play central roles in SOA formation and atmospheric oxidative chemistry.
How to cite: Raj, A., Yadav, P., Sahai, A., and Sharma, R. S.: 3D-Printed Electrochemical Sensor for Rapid Detection of Phenolic Oxidation Products Relevant to Organic Aerosol Formation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-186, https://doi.org/10.5194/egusphere-egu26-186, 2026.
EGU26-8822 | ECS | Posters virtual | VPS3
Seasonal variation of organic sources during the post-monsoon and spring seasons across multiple urban sites of the Indo-Gangetic Plain using a mobile lab platformTue, 05 May, 14:12–14:15 (CEST) vPoster spot 5
The Indo-Gangetic Plain (IGP) experiences strong seasonal and spatial heterogeneity in aerosol composition, driven by variations in emissions, meteorology, and regional transport. Capturing these variations requires measurement approaches that extend beyond conventional fixed-site monitoring. In this study, we deployed a mobile lab platform equipped with aerosol instrumentation, including a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), to investigate seasonal variability in organic aerosol (OA) sources during the post-monsoon and spring seasons across distinct urban environments in Lucknow, located in the central Indo-Gangetic Plain.
Field campaigns were conducted during the post-monsoon and spring seasons at Babasaheb Bhimrao Ambedkar University (BBAU), a site influenced by traffic near major highways, and at the Council of Scientific & Industrial Research–Central Institute of Medicinal and Aromatic Plants (CSIR-CIMAP), located adjacent to a forested area. Additional measurements were conducted during the spring season at the Uttar Pradesh Pollution Control Board (UPPCB) site, which represents a residential–commercial environment.
At each location, the mobile laboratory was operated for approximately 10–15 days, enabling continuous, near real-time characterization of fine particulate matter and associated co-pollutants. Measurements of non-refractory PM2.5 (NR-PM2.5) chemical composition (measured using HR-ToF-AMS) were supported by simultaneous observations of trace elements, black carbon, gaseous species, total PM2.5 mass, and meteorological parameters. This integrated, multi-instrument framework allowed for a consistent comparison of aerosol chemical signatures across sites and seasons, while capturing short-term variability linked to local emissions, atmospheric processing, and regional transport.
Organic aerosol dominated the mass of NR-PM2.5 across all sites and seasons, contributing more than 50% of the total NR-PM2.5. Source apportionment using Positive Matrix Factorization (PMF) with the multilinear engine (ME-2) resolved hydrocarbon-like OA (HOA), biomass-burning OA (BBOA), oxidized biomass-burning OA (O-BBOA), and secondary oxygenated OA components (SVOOA and LVOOA). During the post-monsoon period, BBOA accounted for approximately 28–40% of total OA across the sites, indicating a strong combustion influence under shallow boundary-layer conditions. Traffic-related HOA contributed about 8–13% of OA, with enhanced fractions at the highway-influenced BBAU site, reflecting local vehicular emissions. In contrast, springtime conditions showed enhanced secondary OA contributions (70-60%), with trajectory-based analyses highlighting the role of long-range transport in shaping aerosol composition.
The use of a mobile laboratory enabled rapid deployment across diverse land-use environments while maintaining consistent instrumentation and methodology, allowing robust inter-site and inter-seasonal comparisons. This approach emphasises the significance of high-resolution mobile observations for elucidating the fine-scale spatial variability and seasonal evolution of organic aerosol sources in the complex urban regions of the IGP.
How to cite: Lakra, A., Tripathi, S. N., Sethi, D., Kumar, A., Bhowmik, H. S., and Shukla, A. K.: Seasonal variation of organic sources during the post-monsoon and spring seasons across multiple urban sites of the Indo-Gangetic Plain using a mobile lab platform, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8822, https://doi.org/10.5194/egusphere-egu26-8822, 2026.
