Introduction

Poly- and perfluoro alkyl substances (PFASs), also known as “forever chemicals”, are persistent in the environment and are challenging to eliminate. There is a growing concern over their widespread presence in the environment and potential adverse effects on human health and ecosystems. Most of the current studies on PFAS pollution are related to aqueous and soil matrices while less emphasis has been given to their relevance to air quality. Several recent studies reported presence of PFASs in atmosphere; however, their atmospheric sources, especially for restricted for more than a decade perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), are not well understood (e.g. Kourtchev et al., 2022; Zhou et al., 2021). Wastewater treatment (WWT) plants are repositories of 1000s of pollutants including PFASs (Barisci & Suri, 2021). Aerosolisation/volatilisation during WWT processes (e.g., aeration, trickling filtration) is suggested as one of the potential sources of PFASs in the atmosphere. However, to the best of our knowledge, aerosolisation potential of PFASs was conducted on a very small number of molecules from that class and under relevant to other than WWT processes conditions e.g., seaspray. 

The aim of this work is to investigate, for the first time, the aerosolisation potential of the extensive number of PFASs from contaminated waters under relevant to WWT plant conditions.

Method and results

Aerosolisation potential of PFASs, covering short-, medium- and long-chain compounds and including legacy PFOA, PFOS and perfluorononanoic acid (PFNA), was examined by aerating PFAS-fortified aqueous solutions at relevant to wastewater effluent concentrations and pHs in an aeration chamber. The generated PFAS-enriched aerosol was collected onto a prebaked glass fiber filter and methanolic solution using a filter pack, and an impinger. The samples were extracted and analysed using an on-line solid phase extraction (SPE) liquid chromatography (LC)-Orbitrap-Mass spectrometry (MS). The PFAS decay from the fortified aqueous solutions were also monitored to understand the extent of PFAS partitioning onto aerosol.

Our study indicates that a significant fraction of PFASs can be aerosolised from the contaminated water. This effect was more pronounced for long-chain PFASs irrespective of the pH of the contaminated water. Perfluorocarboxylic acids showed an increase in aerosol phase enrichment with increasing carbon chain length. Short chain PFASs showed lowest aerosol phase enrichment and losses from the contaminated water.

Conclusions

This study, for the first time, establishes the liquid-to-air transfer potential of 15 persistent semi-volatile PFASs including new generation replacements for legacy PFASs such as 4:2 fluorotelomer sulfonate (4:2 FTS) and 8:2 fluorotelomer sulfonate (8:2 FTS) via aerosolisation. The aerosolisation tendency of PFASs was found to increase with increasing carbon chain length. Legacy PFOS and PFOA were detected in the aerosol phase at alarming concentrations suggesting that the contaminated with PFAS waters exposed to aeration can be responsible for  observation of “forever chemicals” in the atmosphere.

 Reference:

Barisci and Suri, Water Sci.Technol., 84(12), 3442-3468. https://doi.org/10.2166/wst.2021.484

Kourtchev et al.  Sci. Total Environ., 835, 155496. https://doi.org/10.1016/j.scitotenv.2022.155496

Zhou et al. Environ.Sci.: Processes Impacts, 23(4), 580-587. https://doi.org/10.1039/D0EM00497A

How to cite: Pandamkulangara Kizhakkethil, J., Shi, Z., Bogush, A., and Kourtchev, I.: Aerosolisation of “forever chemicals” from contaminated water , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-301, https://doi.org/10.5194/egusphere-egu24-301, 2024.

No other group of anthropogenic chemicals has been intentionally released on such a large scale as pesticides. Once in the environment, they can spread through various pathways (surface runoff, surface water, infiltration), which are already being analyzed in detail by a broad monitoring system and research projects. An often overlooked and inadequately quantified process is airborne transport. Through this transport route, pesticides can be transported over large distances and end up far away from the original emission source.

To investigate pesticide concentrations, particulate matter filter samples (PM_2.5) were collected continuously at the Taunus Observatory using a high-volume sampler. The measurement station is situated in the Taunus mountain range at an elevation of 826°m. The location is classified as a rural background station with no nearby urban or agricultural areas. The collected filters underwent extraction, enrichment, and analysis using a high-performance liquid chromatography system coupled to an ultra-high resolution (Orbitrap) mass spectrometer. Samples from April 2021 to May 2022 were analyzed in two-week increments. For a more detailed examination of diurnal cycles, two-week periods were analyzed with day and night resolution Additionally, backward trajectories were analyzed to identify potential sources.

By applying this technique, we successfully identified and quantified two fungicides (Pyrimethanil, Dimetomorph) and six different herbicides (e.g., Terbuthylazine, Prosulfocarb). The year-long data collection allowed the observation of seasonal variations in pesticide concentrations. The highest occurrences of pesticides were measured during spring, particularly in May. Pesticides used for winter crops showed highest concentrations in late autumn. The identified substances also included the herbicide Atrazine, which has been prohibited in Germany since 1991 and in the EU since 2002. Atrazine is typically used for corn and showed the typical patterns in its seasonality.

By applying this method, we were able to demonstrate that certain pesticides can be detected even at significant distances from potential sources. This makes it challenging to limit their occurrence and deposition to a specific area. Outstanding is the detection of Atrazine in aerosols, which has not been reported in Germany before.

How to cite: Saur, F. and Vogel, A. L.: Pesticides in Particulate Matter (PM2.5) at the Rural Background Station Taunus Observatory, Germany , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6180, https://doi.org/10.5194/egusphere-egu24-6180, 2024.

In tropical forests, organic material accounts for a large fraction of particulate matter and the contribution can be as high as 90 % at the submicrometer scale, mainly through the formation of secondary organic aerosols (SOA) from the oxidation of biogenically released volatile organic compounds (VOCs). Despite the abundance of organic material and the important role these particles play in the rainforest boundary layer, the composition of submicrometer organic aerosols is poorly understood (Andreae et al., 2015; Hallquist et al., 2009).

Several different biogenic VOCs are released in tropical regions, but it is undisputed that isoprene is emitted in such large global quantities (600 Tg year^-1) that the formation of SOA results in significant production of atmospheric particulate matter even at small yields (Chen et al., 2015; Liu et al., 2016).  NOx concentrations have a strong influence on SOA production, but SO₂ also affects SOA composition.  Reactions of acidic sulphate aerosol with Isoprene derived oxidation products leads to the formation of organosulphates (OS) that provide information about mixtures of biogenic gases and anthropogenic pollutants. Due to the large variety of formation processes, the composition of SOA is very complex and varies constantly. To understand the formation and transformation processes, specific molecular marker compounds must be identified and quantified. Methyltetrol sulphates and methyltetrols are isoprene SOA markers that are formed from isoprene-derived epoxydiols (IEPOX). However, organosulphates have proved analytically challenging to quantify, due to lack of authentic standards and the complex sample matrix in which they are observed.

This study provides a suitable analytical tool for chemical characterisation of such isoprene derived organosulphates by combining high performance liquid chromatography (HPLC) with electrospray ionisation ultra-high resolution orbitrap mass spectrometry (ESI-UHR-Orbitrap-MS). Chamber simulation experiments  were performed to investigate isoprene OS formation by comparing different atmospheric reaction pathways and authentic standards were synthesised to enable complete identification of individual OS compounds. Marker compounds for aged isoprene derived organic aerosols could be assigned and quantified in ambient aerosol samples of the Amazon rainforest. Moreover, it could be shown that the lack of authentic standards has led to significant underestimation of isoprene derived OS concentrations in the past.

Andreae, M., Acevedo, O., et al. (2015), Atmos. Chem. Phys., 15(18), 10723-10776.

Chen, Q., et al. (2015), Atmos. Chem. Phys. 15(7), 3687-3701.

Hallquist, M., Wenger, J. C., et. al. (2009), Atmos. Chem. Phys., 9(14), 5155–5236.

Liu, Y., et al. (2016), PNAS, 113(22), 6125-6130.

How to cite: Hildmann, S., Wasserzier, D., Hopson, L., Kremper, L., Pöhlker, C., and Hoffmann, T.: Chemical characterisation and comparison of Isoprene Organosulphates in simulation chamber experiments and ambient aerosol samples in the Amazon rainforest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16372, https://doi.org/10.5194/egusphere-egu24-16372, 2024.

Organic aerosols (OA) are of great concern because they contribute to haze pollution, threaten human health and affect the radiation balance. However, tracking OA evolution in real time at the molecular level is still limited, hindering a comprehensive understanding of their origins and behaviors. In this study, we investigated wintertime OA in a megacity in East China by combining simultaneous measurements from an extractive electrospray time-of-flight mass spectrometer (EESI-TOF) and a high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS). AMS results show that the OA mass concentration account for about 27% of non-refractory submicron particulate matters (NR-PM₁) on average during the measurement. Speciated-organic data from EESI-TOF further reveals that C_xH_yO_z and C_xH_yN_1-2O_z are the predominant components of OA, contributing over 70% and 20%, respectively. By performing factorization analysis of data obtained from both instruments, we found that traffic, cooking and biomass burning are major primary sources of OA, but most of OA (>70% for EESI-TOF, >55% for AMS) come from secondary production. Compared to AMS, EESI-TOF misses hydrocarbon-like OA but owns advances in providing molecular information on oxygenated OA, revealing that aromatics and aliphatics are important precursors. Specifically, EESI-TOF further splits the less oxidized secondary organic aerosols (SOA) into two factors with distinct molecular compositions, possibly resulted from diverse source regions. Importantly, EESI-TOF additionally identifies two factors based on the tracer molecules, one possibly related to plasticizers and the other representing the SOA formation from the oxidation of monoterpenes by NO₃ radicals. In conclusion, our findings suggest that EESI-TOF is highly complementary to the widely used AMS, providing valuable molecular information that aids in uncovering chemical processes underlying the formation of OA, especially in the highly complex urban environment.

How to cite: Ge, D., Nie, W., Liu, Y., Huang, D., Yan, C., Wang, J., Li, Y., Liu, C., Wang, L., Wang, J., Chi, X., and Ding, A.: New insights into the sources of atmospheric organic aerosols in East China: a comparison of online molecule-level and bulk measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4246, https://doi.org/10.5194/egusphere-egu24-4246, 2024.

Organosulfates (OSs) are ubiquitous compounds in ambient aerosols, being formed by multiphase chemistry.^1,2 However, accurate quantification of unknown and suspected OSs remains difficult. One of the main reasons for this is the limited availability of authentic standards. Furthermore, a large amount of unknown and not yet identified OSs might remain undetected in ambient samples.

To overcome the two main difficulties, we developed a new solid phase extraction (SPE) method to enrich and fractionate OSs compounds. Preliminary result shows that with this approach the majority of the OSs fraction was separated from the native sample matrix. Furthermore, we can easily enrich the native extract by a factor of ~300 and get good recovery of those targeted OS-compounds. Following this SPE-method, a charged aerosol detector (CAD) was employed for the quantification of the OSs fraction extracts after chromatographic separation. CAD, which has universal response as a prominent feature, is advantageous to the quantification of non-volatile species without the necessity for the preparation of authentic or surrogate standards.³ 

The sample preparation by SPE greatly reduced the complexity of both chromatograms detected with a mass spectrometer and the CAD, thereby increasing our confidence for the peak identification and quantification. Although, CAD has a sub-nanogram sensitivity, our classical extraction method for ambient filter samples most OSs are below the limit of detection. Therefore, the SPE enrichment of an ambient filter extraction is necessary for CAD detection.

Moreover, the volatility for majority OSs compounds is very low, which perfectly match the CAD feature. With this method we can identify and quantify ~40 OSs compounds and nitrooxy-OSs in an ambient Chinese PM_2.5 sample. This work emphasizes the potential of the SPE approach in combination with CAD to quantify the unknown and suspected OSs precisely in ambient air. The presented method is able to quantify the individual OS compounds without authentic or surrogate standards.

References

1. Brüggemann, M. et al. Organosulfates in Ambient Aerosol: State of Knowledge and Future Research Directions on Formation, Abundance, Fate, and Importance. Environ. Sci. Technol. 54, 3767–3782 (2020).

2. Gao, K. & Zhu, T. Analytical methods for organosulfate detection in aerosol particles: Current status and future perspectives. Sci. Total Environ. 784, 1–10 (2021).

3. Vehovec, T. & Obreza, A. Review of operating principle and applications of the charged aerosol detector. J. Chromatogr. A 1217, 1549–1556 (2010).

How to cite: Ma, J., Zhao, C., Reininger, N., and Vogel, A.: A universal method to isolate, enrich, and quantify atmospheric organosulfates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3189, https://doi.org/10.5194/egusphere-egu24-3189, 2024.

Phenolic compounds are largely emitted from biomass burning (BB) and have significant potential to form SOA (Phc-SOA). However, the toxicological properties of Phc-SOA remain unclear. In this study, phenol and guaiacol were chosen as two representative phenolic gases in BB plumes, and the toxicological properties of their SOA generated under different photochemical ages and NO_x levels were investigated. Across explored aging conditions, oxidative potentials (OP) of Phc-SOA measured by the dithiothreitol (DTT) assay were 41.3-83.9 pmol min^-1 μg^-1. OH-adducts of guaiacol (e.g., 2-methoxyhydroquinone) were identified as components of guaiacol SOA (GSOA) with high OP. The addition of nitro groups to 2,5-dimethyl-1,4-benzoquinone, a surrogate quinone compound in Phc-SOA, increased its OP. In pure water, H₂O₂ presented the main reactive oxygen species produced by Phc-SOA. The toxicity of both phenol SOA (PSOA) and GSOA in vitro in human alveolar epithelial cells decreased with aging in terms of both cell death and cellular ROS, possibly due to more ring-opening products with relatively low toxicity. The influence of NO_x was consistent between cell death and cellular ROS for GSOA, but not for PSOA, indicating that cellular ROS production does not necessarily represent all processes contributing to cell death caused by PSOA.

How to cite: Fang, Z., Lai, A., Cai, D., Li, C., Carmieli, R., Chen, J., Wang, X., and Rudich, Y.: Secondary Organic Aerosol Generated from Biomass Burning Emitted Phenolic Compounds: Oxidative Potential, Reactive Oxygen Species and Cytotoxicity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12439, https://doi.org/10.5194/egusphere-egu24-12439, 2024.

Atmospheric aerosols play an important role not only due to the effect on climate but especially because of the adverse effects on human health, which studies consistently link to the exposure to particulate matter. Here, especially fine particles below a diameter of 2.5 μm can enter deep into the lungs, causing inflammation or translocate into the bloodstream and eventually lead to further disease.

To investigate and describe the potential toxicity of atmospheric particles, the oxidative potential (OP) can be measured. Since particles can be formed by many reaction paths and therefore be a mixture of many compounds, a deeper understanding of the composition is needed in order to understand the main chemical drivers for OP. It is known, that especially metals and secondary organic aerosols (SOA) lead to OP, but in order to attribute sources, a
further chemical characterization of SOA, linked to OP, is needed.

In this study, 42 samples from different locations in Frankfurt, Germany and Beijing, China have been measured by inductively coupled plasma - mass spectrometry (ICP-MS), in order to obtain the metal content and by high pressure liquid chromatography - high resolution mass spectrometry (HPLC-HRMS) to determine organic compounds and their composition groups via non target analysis. The OP then was determined by extracting the filters and either measuring directly or treating with Chelex^® 100 to remove the metals and carry out the measurement afterward. By employing this technique, the contribution of metals and organics can be investigated separately to gain a better understanding of the OP caused by SOA. In order to examine the contribution of different compound groups to OP, a hierarchical cluster analysis and several Pearson correlations have been carried out. By this approach, similarities between samples can be observed, which then might give an indication about relevant compounds. Moreover, correlations between the variability of the OP throughout the sample and the variability of compounds point to certain OP-effective compounds.

First results show that the metal containing extracts have a higher volume-normalized OP (OP_V ) compared to the non-metal ones, with 0.2 to 5 nmol DTT min^-1m^-3, which is mainly due to manganese and copper. After the Chelex^® 100 treatment, there is still a OP_V of 0.1 up to 4 nmol DTT min^-1m^-3, indicating the significance of organic matter, causing the oxidative potential. Comparing the different locations, the samples from Beijing show an OP up to four
times higher than samples from Frankfurt. Looking deeper into the chemical composition, especially chemical groups containing phosphor and nitrogen, such as CHOP and CHNO, correlate with high OP.

How to cite: Breuninger, A., Vogel, A., and Steimer, S.: Investigating the Chemical Composition of Organic Aerosols and their Contribution to the Oxidative Potential, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5583, https://doi.org/10.5194/egusphere-egu24-5583, 2024.

It is important to investigate formation, composition and properties of secondary organic aerosol (SOA) from monoterpenes in order to develop an accurate understanding of their atmospheric chemistry, impact on the aerosol budget and the effects of climate change. Δ³-Carene is one of the monoterpenes emitted in highest amounts in the boreal forest, yet only few studies have investigated the atmospheric chemistry and aerosol formation of Δ³-carene.

In this work, we have investigated aerosol formation and composition of SOA from ozonolysis of Δ³-carene at different concentration levels in the AURA atmospheric simulation chamber at Aarhus University, Denmark. At low concentrations of Δ³-carene (about 10 ppb), SOA formation shows minimal temperature dependence under dry conditions. This contrasts with results from studies of Δ³-carene at higher concentrations (about 50 ppb) and studies of the structurally quite similar monoterpene a-pinene. Furthermore, we observed increased particle nucleation at higher relative humidity (about 80% RH, 10°C). Chemical analysis of the SOA found a series of carboxylic acids, in line with previous studies, with different concentration profiles over time, depending on experiment temperature. In experiments with ozonolysis of mixtures of Δ³-carene and a-pinene, we were able to identify a mixed dimer composed of molecular units from each of the precursors.

How to cite: Glasius, M., Thomsen, D., Björgvinsdóttir, Þ. N., Thomsen, L. D., Iversen, E. M., Skønager, J. T., Luo, Y., Li, L., Priestley, M., Pedersen, H. B., Roldin, P., Elm, J., Hallquist, M., Ehn, M., and Bilde, M.: Recent advances in understanding secondary organic aerosol formation from ozonolysis of Δ3-carene and other monoterpenes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19375, https://doi.org/10.5194/egusphere-egu24-19375, 2024.

Atmospheric secondary organic aerosols (SOA) can significantly affect air quality, climate, and human health. The formation of SOA is attributable to the vapour phase oxidation of biogenic or anthropogenic organic compounds and subsequent partitioning to the particulate phase. The oxidation of biogenic volatile organic compounds (bVOCs), such as monoterpenes, has received extensive attention owing to their larger global emissions compared with anthropogenic volatile organic compounds (aVOCs). α-Pinene, constituting nearly 50% of the global monoterpene emissions and with a high SOA forming efficiency is thereby considered one of the most important SOA precursors in the atmosphere.

The essential characteristics of α-pinene SOA, such as the oxidation pathways, molecular constitutions, volatility, and yields, have been widely studied in chamber experiments. However, most of them focused on single precursor systems. In the real atmosphere, SOA formation is influenced by the interactions of other molecules. Human emissions, such as the aVOCs, NOx, and CO, are likely to affect α-pinene SOA formation processes. Thus, the chamber investigation on SOA formation should be considered more realistically. Establishing a framework to understand the interactions of mixed SOA precursors in the presence of NOx and CO is needed.

Diesel vehicular emission is an important anthropogenic source for SOA precursors in urban areas. n-Dodecane (C₁₂H₂₆) represents a reasonable proxy for intermediate volatility organic compounds (IVOC) in diesel exhaust. In this study, we plan to investigate the SOA formation from (i) α-pinene and n-dodecane system and (ii) α-pinene and diesel exhaust system, under controlled NOx and CO conditions.

The experiments are conducted at the Manchester Aerosol Chamber (MAC) facility, which is an 18 m³ fluorinated ethylene propylene bag. A combination of gas-phase and particle-phase analytical instruments are employed for the experiments: High-Resolution Time-of-Flight Chemical Ionization Mass Spectrometer with a Filter Inlet for Gases and Aerosols (FIGAERO-CIMS) equipped with iodide reagent, Proton-transfer-reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS), Differential Mobility Particle Sizer (DMPS), Compact Time-of-Flight Aerosol Mass Spectrometer (C-ToF-AMS), and Gas Analysers.

This work reports the changes in SOA compositions, SOA particle volatility, and yields in the mixtures of α-pinene and n-dodecane/diesel exhaust under controlled NOx and CO conditions. The results provide new insights into SOA formation in mixtures.

How to cite: Xie, G., Voliotis, A., Bannan, T., Coe, H., and McFiggans, G.: Effects of Anthropogenic Emissions on Secondary Organic Aerosol Formation from Biogenic Volatile Organic Compound, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5942, https://doi.org/10.5194/egusphere-egu24-5942, 2024.

The environmental and health-damaging effects of “high aerosol concentration” periods often represent an issue in Hungary, which is mainly due to the country's location (basin is within the Carpathians). The main sources of carbonaceous aerosol are already more or less known, but the numerical extent and temporal distribution of the contributions are still the subject of numerous investigations in the region. In these researches, isotopic analytical procedures are increasingly involved, which, in addition to traditional analytical methods, enable us to make more and more accurate source apportionment analyses. By means of the radiocarbon method, the modern and fossil fuel sources can unambiguously be separated, while levoglucosan can be used as tracer to distinguish the two largest modern sources i.e. biological emissions and anthropogenic wood burning. In the first half of 2015, a comprehensive PM10 collection campaign in five big cities (Budapest, Debrecen, Miskolc, Pécs, Nyíregyháza) was completed, financed by the Hungarian state. Its purpose was to identify the most relevant emission sources and quantify their contributions as accurately as possible. In the course of the analyses, mass concentration of the total, organic and elemental carbon (TC, OC, EC, respectively) of the collected samples were determined, in addition, the specific ¹⁴C activity and levoglucosan concentration of TC were also measured. Our studies clearly revealed the predominance of the anthropogenic wood burning source in the winter/heating period, but the contribution of biological sources ranged in a broader scale during the observation period. Contrarily, the contributions from fossil sources were relatively balanced for the same period.

How to cite: Major, I., Kertész, Z., Angyal, A., Furu, E., Papp, E., Vasanits, A., Bán, S., Molnár, A., Gergely, V., and Molnár, M.: Source apportionment of PM10 carbonaceous aerosol collected in Hungarian cities, using tracer analytical methods, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11190, https://doi.org/10.5194/egusphere-egu24-11190, 2024.

The analysis of filter samples of atmospheric organic aerosols provides information about atmospheric processes and the origin of aerosol particles. However, limiting analysis to a few target compounds ignores a large proportion of the compounds present on the filters. Since the availability of high-resolution mass spectrometers, non-target analysis addresses parts of this problem. However, such an analysis can be very time-consuming. Since it is hardly possible to analyze all individual compounds manually, an automated or semi-automated evaluation of the data is required.

This poster presents a method for the non-target analysis of atmospheric organic aerosol filter samples using UHPLC-Orbitrap-MS. The extracted filter samples are analyzed in a two-step process that provides maximum information. In the first step, a full-scan high resolution mass spectrum is measured, which is then analyzed with MZmine, capturing all compounds with their respective retention time and exact mass. Using this data, a second experiment is designed in which an isolated MS/MS spectrum (with stepped fragmentation energy) of all detected compounds is measured. With the MS/MS data of the measured compounds and a local database in combination with in-silico fragmentation, a reliable prediction of the chemical composition, functional groups and/or parts of the molecular structure is possible. The combination of these steps drastically improves the reliability of the prediction, as not only the exact mass of the molecule is considered, but also additional information about the fragmentation of the molecule is included. Python scripts automate the processes and create a comprehensible summary for each detected compound, minimizing the manual workload.

For this contribution, filters of the ACROSS campaign 2022 (Rambouillet Forest, France), where urban and biogenically influenced air masses are present, were analyzed in the manner described above and a brief summary of the results is given.

How to cite: Karbach, N., Pouyes, P., Perraudin, E., Villenave, E., Vogel, A., and Hoffmann, T.: Development of a non-targeted LC-UHRMS approach for organic aerosol analysis: first application to urban and biogenically influenced air masses, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17155, https://doi.org/10.5194/egusphere-egu24-17155, 2024.

Brown Carbon (BrC) is a wide class of aerosol species whose optical properties span from near dark Black Carbon (BC) to transparent/reflective and Organic Carbon (OC), are potent in their impact on Earth's climate radiative forcing (RF) and air quality. To date, the uncertainties about their contributions are larger compared to that of BC/OC, trace gases and other factors  (IPCC, 2021, Chapter 6). This is to a considerable extent due to current Earth System Models (ESMs) lacking sufficient representation of BrC, whilst no consistent unified classification and framework for BrC implementation in ESMs has been developed yet. Here, we review such implementation options and offer an advanced implementation of the BrC in the atmospheric chemistry general circulation model EMAC (Pozzer et al., 2021).

EMAC includes all relevant processes (detailed aerosol physicochemistry, optical radiation calculation, online emission, etc.) for the comprehensive simulation of organic aerosol (OA). Our BrC intermediate-complexity implementation includes primary (e.g. biomass- or fossil-fuel burning) and secondary (e.g. oxidation of phenolic precursors) formation processes and includes “fresh” and “aged” mixture states defining final optical properties. Because most of available ambient measurements do not allow such differentiation, BrC categories are assigned refractive properties obtained chiefly in controlled lab experiments. The optical properties of OC and BC were adjusted to account for BrC presence and updated to recent recommendations. Ultimately, the new parameterization aims at more accurate reproduction of primary (POA) and secondary (SOA) organic aerosol optical properties and/under their atmospheric aging.

Our preliminary simulations with EMAC indicate that POA and SOA optical properties are sensitive to representation of the newly implemented BrC-contributed and updated OC/BC parts, compared at selected AERONET observational stations. Further sensitivities are associated with the primary/secondary BrC emission proportion varying with the source sector. The overall refractive index (RI) of BrC results in an intensified absorption of the C-inclusive aerosol than the simulated with the former OC/BC-only speciation. On a global scale, changes to the top-of-atmosphere global RF may reach non-negligible extra 0.45 W/m² (upper limit of POA absorption efficiency), whereas up to 50% larger negative RF changes are obtained at the surface. Due to BC and selected BrC species intense absorption in the UV range, we also quantify the effects of using the new parameterisation on ozone photolytic formation and loss. In summary, our findings suggest that an improved representation of BrC indicates a prior underestimation of its contribution to th e OA light-absorbing efficiency, consequently affecting the simulated RF in EMAC. A wavelength-resolved analysis of refractive indices against observational data is planned for subsequent in-depth analyses.

This work was funded by the European Commission Horizon Europe project FOCI, Non-CO2 Forcers and Their Climate, Weather, Air Quality and Health Impacts (No. 101056783, see https://www.project-foci.eu).

References

Intergovernmental Panel on Climate Change (IPCC). (2023). Short-lived Climate Forcers. In: Climate Change 2021 – The Physical Science Basis, Cambridge UP, 817-922. doi:10.1017/9781009157896.008

Pozzer, A., Reifenberg, S. F., Kumar, V., et al. (2022). Simulation of organics in the atmosphere: evaluation of EMACv2.54 with the Mainz Organic Mechanism (MOM) coupled to the ORACLE (v1.0) submodel, Geosci. Model Dev. 15, 2673–2710. doi:10.5194/gmd-15-2673-2022

How to cite: Gromov, S., Taraborrelli, D., and Pozzer, A.: Sensitivity of organic aerosol optical properties to improved representation of brown carbon in the EMAC model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18402, https://doi.org/10.5194/egusphere-egu24-18402, 2024.

Biomass burning (BB) is an increasingly important contributor to air pollution on global, regional and local scales affecting air quality, public health and climate. Anhydrosugars (e.g., levoglucosan) and methoxyphenols (guaiacol, vanillin, etc.) are key tracer compounds emitted through biomass burning. Once emitted, they can undergo complex multiphase chemical processing in tropospheric aerosol particles and fog/cloud droplets. Their multiphase chemistry contributes to the formation and modification of the secondary organic aerosol (SOA) composition. However, the chemical multiphase processing of levoglucosan and methoxyphenols is not yet well understood and investigated by atmospheric chemistry models. A detailed multiphase oxidation mechanism has not been developed so far.
The present work aimed at a better understanding of the multiphase chemistry of BB tracers, such as levoglucosan and vanillin, by detailed process model studies with a new developed CAPRAM biomass burning module (CAPRAM-BBM1.0). This module was developed based on the kinetic data from measurements in our lab at TROPOS-ACD [1,2] and other literature studies as well as evaluated estimation methods [3]. CAPRAM-BBM1.0 includes 2881 processes (10 phase transfers and 2871 aqueous-phase reactions) and was coupled with the multiphase chemistry mechanism MCMv3.3.1/CAPRAM4.0 [3,4] and the extended CAPRAM aromatics module (CAPRAM-AM1.0) [5,6]. Afterwards, CAPRAM-BBM1.0 was applied in a multiphase chemistry process model for a winter/spring residential wood burning scenario in Europe [7,8].
The model results show that levoglucosan and vanillin are effectively oxidized under cloud conditions leading to concentration reductions of 75%/40% and 97%/94% after the third model day under spring/winter conditions. The chemistry of BB tracers contributes to the formation of BB-SOA and affects also the aqueous-phase budgets of key radical oxidants such as OH and NO3. Aqueous-phase oxidation of BB compounds contributes significantly to the aqSOA formation and aging. For example, a 38% higher organic mass is modelled for the spring case when CAPRAM-BBM1.0 is coupled to the core mechanism. Particularly, the formation of functionalized mono- and dicarboxylic acids is enhanced by a factor of 6.5 and 1.2 in the spring cases when chemistry of BB tracers is considered. Detailed chemical rate analyses show that the daytime oxidation by OH acts as the most important sink for BB tracers. Furthermore, the simulations reveal that in-cloud oxidations represent the main loss for methoxyphenols but their importance strongly depends on the respective Henry’s Law solubilities of the phenolic compounds. All in all, the present studies illustrated the potential role of the chemistry of BB compounds for the formation and processing of SOA.

[1] Hoffmann, D. et al. (2010), Environmental Science & Technology, 44(2), 694-699.,
[2] He, L. et al. (2019), The Journal of Physical Chemistry A, 123(36), 7828-7838.
[3] Bräuer P. et al. (2019), Atmospheric Chemistry and Physics, 19, 9209–9239.
[4] MCM, http://mcm.york.ac.uk/home.htt.
[5] Hoffmann, E. H. et al. (2018), Physical Chemistry Chemical Physics, 20(16), 10960-10977.
[6] Hoffmann, E. H. et al. (2019), ACS Earth and Space Chemistry, 3, 2452–2471.
[7] Poulain, L. et al. (2011), Atmospheric Chemistry and Physics, 11(24), 12697-12713.
[8] Wolke, R. et al. (2005), Atmospheric Environment, 39(23), 4375-4388

How to cite: Tilgner, A., He, L., Hoffmann, E. H., Nibert, P., and Herrmann, H.: Modelling the Multiphase Chemistry of Biomass Burning Compounds with CAPRAM-BBM1.0, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22330, https://doi.org/10.5194/egusphere-egu24-22330, 2024.

Organic carbon is a significant constituent of PM_2.5. The organic carbon percentage in indoor microenvironments is higher than in the ambient environment. Water soluble organic carbon (WSOC) is responsible for altering hygroscopicity, hence determining the ability of particles to act as cloud condensation nuclei (CCN). In this study, quartz fiber filters were collected from two restaurants (R1 and R2 ) using an Airmetrix low-volume sampler at a 5 lpm flow rate. R1 was a closed restaurant where dining tables and the cooking locations were adjacent to each other. R2 was a semi-indoor environment; two sides of the dining place were open with adjoining dining tables, and cooking locations. Organic carbon (OC), elemental carbon (EC), and water-soluble organic carbon (WSOC) were estimated using DRI thermal optical analyzer and total organic carbon analyzer instruments. All these constituents can exfiltrate outdoors and alter the climate. Absorption coefficient (b_abs)  and Mass Absorption Efficiency (MAE) were calculated for Water-soluble carbon at 365 nm. Average OC and EC concentrations were very high in R1, i.e. 160.31 µg/m³ and 14.99 µg/m^3,respectively. It was lower in R2, i.e., 29.61 µg/m³ and 4.88 µg/m^3,respectively. As there was a direct biomass burning source, i.e., cooking, the major portion of the OC was POC. In R1, the average POC was ~67%, and in R2, ~60% of the total OC. The average WSOC percentages in the R1 and R2 were 8.01% and 25.21%, respectively. MAE values were comparable, i.e., 0.04 and 0.03 in R1 and R2, as the nature of the source was similar. Brown Carbon (BrC) absorption peaks at 365 nm were observed in both locations, confirming its presence. A negative correlation was observed between b_abs and WSOC, indicating BrC as the main absorption component of the WSOC. The effective carbon ratio (ECR= SOC/[POC+EC]) was calculated to estimate the impact of the particles on the local radiative energy balance. The values were 0.42 in R1 and 0.51 in R2. Aerosol generated from both locations was more absorbing in nature than scattering. In the R1, the aerosol had more absorption capability than in R2 . This study did not quantify the amount of  WSOC and BrC from different food and cooking fuels. But, from this study, it was noticed that cooking-related aerosols are absorbing in nature and can exfiltrate outdoors and alter the local climate.

Keywords: Water Soluble Organic Carbon, Mass Absorption Effiency , Effective Carbon Ratio, Brown Carbon

How to cite: Mandal, D., Chakraborty, A., and Tripathi, S.: Carbonaceous aerosols in restaurants: optical properties and possible impact on climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1071, https://doi.org/10.5194/egusphere-egu24-1071, 2024.

Various studies identified airports as a major source of ultrafine particles (UFPs – aerodynamic diameter <100 nm), whereby little is known about their chemical composition and formation processes ^{[1] [2] [3] [4] [5]}. In a previous work, we determined the organic chemical composition of aviation-related UFPs and identified jet engine oils as a major contributor ^[6].

Here, we show the nucleation and particle formation potential of jet oil vapors, supported by a quantitative analysis of the full spectrum of jet engine oil components in particles with diameters <56 nm. We used a common synthetic lubrication oil to analyse the jet oils gas-to-particle partitioning behavior using laboratory based thermodenuder-experiments and quantified the oil contribution to ambient UFPs originating from Frankfurt International Airport.

We sampled UFPs on aluminium-filters at an air quality monitoring station 4 km north of the Frankfurt Airport using a 13-stage cascade impactor system (Nano-MOUDI). Quantitative characterization of UFPs in the size ranges 10–18 nm, 18–32 nm and 32–56 nm was performed by standard addition combined with liquid chromatography (UHPLC), followed by heated electrospray ionization (HESI) and mass analysis using a high-resolution Orbitrap mass spectrometer (HRMS). In parallel to filter sampling, the particle size distribution was monitored to determine the size-resolved total particle mass.

Thermodenuder-experiments enable the monitoring of the gas-to-particle partitioning behavior of jet engine oils at different temperatures. We observed a fivefold increase in total particle number at 300 °C, with a significant increase in the number of particles with a mean diameter of ~12 nm compared to the same experiments performed at 20 °C.

Particle diameters of UFPs from other directions (e.g. winds originating from the city centre) are larger compared to the UFPs downwind of large airports ^[4].They are rather in the same size region as the newly formed oil particles in our laboratory experiment. Quantification of the jet oil compounds in ambient samples was achieved by standard-addition of purchased original standards to the native sample extracts. Besides two ester base materials, additives were also quantified, including two amines serving as stabilizers and an organophosphate used as wear inhibitor/metal deactivator. The two homologous ester series were quantified using one ester compound and cross-calibration. We characterized the Nano-MOUDI to determine loss factors and corrected the ambient jet oil contribution to the total particle mass for each UFP size stage accordingly.

Results indicate that aircraft emissions have a strong influence on the total mass of the 10-18 nm particles. The aircraft fraction decreases with larger particles (e.g. 18-56 nm), implying that jet oils form new particles in the cooling exhaust of aircraft engines.

[1] Habre, R., et al. (2018) Environ. Int., 118, 48–59.

[2] Ditas, F., Rose, D. & Jacobi, S. (2022) Hessian Agency for Nature Conservation, Environment and Geology.

[3] Fushimi, A., et al. (2019) Atmos. Chem. Phys., 19, 6389–6399.

[4] Stacey, B., (2019) Atmos. Environ., 198, 463–477.

[5] Rivas, I., et al. (2020) Environ. Int., 135, 105345.

[6] Ungeheuer, F., et al. (2021) Atmos. Chem. Phys., 21, 3763–3775.

How to cite: Ungeheuer, F., Caudillo, L., Ditas, F., Simon, M., van Pinxteren, D., Kilic, D., Rose, D., Jacobi, S., Kürten, A., Curtius, J., and Vogel, A. L.: Nucleation of jet engine oil vapours is a large source of aviation-related ultrafine particles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10369, https://doi.org/10.5194/egusphere-egu24-10369, 2024.

    Secondary organic aerosols (SOAs) account for a large fraction of atmospheric aerosol mass and play significant roles in visibility impairment by scattering solar radiation. However, comprehensive evaluations of SOA scattering abilities under ambient relative humidity (RH) conditions on the basis of field measurements are still lacking due to the difficulty of simultaneously direct quantifications of SOA scattering efficiency in dry state and SOA water uptake abilities. In this study, field measurements of aerosol chemical and physical properties were conducted in winter in Guangzhou using a humidified nephelometer system and aerosol chemical speciation monitor. A modified multilinear regression model was proposed to retrieve dry-state mass scattering efficiencies (MSE, defined as scattering coefficient per unit aerosol mass) of aerosol components. The more oxidized oxygenated organic aerosol (MOOA) with O/C ratio of 1.17 was identified as the most efficient light scattering aerosol component. On average, 34% mass contribution of MOOA to total submicron organic aerosol mass contributed 51% of dry-state organic aerosol scattering. The overall organic aerosol hygroscopicity parameter κ_OA was quantified directly through hygroscopicity closure, and hygroscopicity parameters of SOA components were further retrieved using multilinear regression model by assuming hydrophobic properties of primary organic aerosols. The highest water uptake ability of MOOA among organic aerosol factors was revealed with κ_MOOA reaching 0.23, thus further enhancing the fractional contribution of MOOA in ambient organic aerosol scattering. In particular, the scattering abilities of MOOA was found to be even higher than those of ammonium nitrate under RH of <70% which was identified as the most efficient inorganic scattering aerosol component, demonstrating that MOOA had the strongest scattering abilities in ambient air (average RH of 57%) during winter in Guangzhou. During the observation period, secondary aerosols contributed dominantly to visibility degradation (~70%) with substantial contributions from MOOA (16% on average), demonstrating significant impacts of MOOA on visibility degradations. The findings of this study demonstrate that more attention needs to be paid to SOA property changes in future visibility improvement investigations. Also, more comprehensive studies on MOOA physical properties and chemical formation are needed to better parameterize its radiative effects in models and implement targeted control strategies on MOOA precursors for visibility improvement.

How to cite: Liu, L.: Strong light scattering of highly oxygenated organic aerosols impacts significantly on visibility degradation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2324, https://doi.org/10.5194/egusphere-egu24-2324, 2024.

Photochemical aging of redox-active transition metals in organic aerosol (OA) particles contributes
to an increase in oxidative potential and changes their atmospheric fate. We evaluated the
poorly characterized role of copper as a highly emitted transition metal in a well-established iron-
containing proxy for SOA material (citric acid with iron citrate). Here, we computationally
model photochemical aging experiments from a coated-wall flow-tube to derive an iron-copper cy-
cling mechanism that explains the enhanced aging with copper found in scanning transition X-ray
microscope measurements. Aging was carried out under UV light irradiation (λ = 365 nm) at at-
mospherically relevant residence times as a function of relative humidity. We measure volatilized
CO₂as the first decarboxylation product of iron citrate to quantify the rate of photochemical iron
redox cycling. For kinetic modeling, we utilized the kinetic multilayer model of aerosol surface and
bulk chemistry (KM-SUB) for films, in which we incorporated chemical reaction mechanisms
built on previous work. The model explicitly treats photo- and redox chemistry along with the
mass transfer of reactants and products between the condensed and gas phase, and is used to
describe CO₂production in the flow reactor. The model was applied to data from experiments
using iron citrate alone and to mixed iron and copper citrate experiments. We tested chemical
mechanisms for iron-copper cycling found in the literature and a newly developed mecha-
nism [3]. Inverse modeling and global optimization techniques were used to constrain kinetic
parameters and optimize the chemical reaction mechanism. In addition, some physical para-
meters were quantified anew by measuring the viscosity of aged and non-aged iron-copper citric
acid particles. This supports the KM-SUB modeling, including exact microphysical properties un-
der different humidity and/or aging conditions. The new model uniquely includes redox reactions
between iron and copper complexes in a multiphase system, which may elucidate the role of photo-
chemically active OA in the atmosphere. In future work, the model will also be used for similar
aging processes with SOA such as α-pinene and OA particles containing nitrate and/or iodine
species.

How to cite: Kilchhofer, K., Mishra, A., Alpert, P. A., Iezzi, L., Bertram, A. K., Berkemeier, T., and Ammann, M.: Modeling Iron-Copper Cycling in Photochemically Aged Organic Aerosol Particles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3353, https://doi.org/10.5194/egusphere-egu24-3353, 2024.

This work is part of the project ‘TRACE’: Transport and transformation of atmospheric aerosol across Central Europe with emphasis on anthropogenic sources. Synergic measurement methods and state-of-the art modelling tools are combined to obtain a comprehensive picture of the contribution of transported anthropogenic aerosol compared to local emissions.

Measurement data are available for three sites which are located in an important transition area between highly polluted and less polluted regions in Central Europe for winter 2021. This study focuses on the application of a simplified labelling approach within the COSMO-MUSCAT model (Wolke et al., 2012) for the identification of particulate matter sources. For this purpose, emissions of organic matter (OM) and black carbon were tracked by emission class and source country with a spatial resolution of about 2 km.

The modelled source attribution shows a high contribution of residential heating to organic matter sources. While the model reproduces the OM values at two of our measuring stations quite well, the measured data are strongly underestimated at one station near Prague. Since we can reproduce the black carbon concentrations for this station reasonably well, we are confident that we are capturing the primary aerosols correctly.

We assume an underestimation of anthropogenic volatile organic compound (AVOC) emissions from residential wood and coal burning, leading to an underestimation of secondary organic aerosols (SOA) produced by these precursors. Although biogenic sources account for the majority of VOCs, in urban environments light aromatic hydrocarbons emitted during combustion processes can contribute up to 30% of VOCs (Srivastava et al., 2022). Due to the low temperature dependence of these AVOCs, SOA formation occurs even in winter at lower temperatures (Bruns et al., 2016). This indicates that AVOC precursors could account for a considerable proportion of our SOA budget.

So far, only the contribution of biogenic VOCs to SOA formation has been evaluated and improved in COSMO-MUSCAT. First results of the implementation of a new emission factor for anthropogenic VOCs from combustion sources and a corresponding SOA yield in COSMO-MUSCAT will be presented.

E. A. Bruns et al., “Identification of significant precursor gases of secondary organic aerosols from residential wood combustion,” Scientific Reports, vol. 6, no. 1, Jun. 2016, doi: DOI: 10.1038/srep27881.

D. Srivastava, T. V. Vu, S. Tong, Z. Shi, and R. M. Harrison, “Formation of secondary organic aerosols from anthropogenic precursors in laboratory studies,” npj Climate and Atmospheric Science, vol. 5, no. 1, Mar. 2022, doi: https://doi.org/10.1038/s41612-022-00238-6.

R. Wolke, W. Schröder, R. Schrödner, and E. Renner, “Influence of grid resolution and meteorological forcing on simulated European air quality: A sensitivity study with the modeling system COSMO–MUSCAT,” Atmospheric Environment, vol. 53, pp. 110–130, Jun. 2012, doi: doi:10.1016/j.atmosenv.2012.02.085.

How to cite: Wiedenhaus, H., Schroedner, R., Wolke, R., Arora, S., Poulain, L., Lhotka, R., and Schwarz, J.: Sources of organic aerosols in Central Europe identified with labelled species in a chemical transport model and a complementary measurement campaign., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5771, https://doi.org/10.5194/egusphere-egu24-5771, 2024.

A fast and cost-efficient off-line methodology was developed to analyze organic molecular tracer compounds in atmospheric particulate matter collected on quartz filter after high- or low-volume sampling in outdoor ambient air. The method allows the processing of 20 samples/h, and another hour per sample for analyze by GC-MS of more than 30 tracer compounds that are related to air pollution and major emission sources, such as biomass burning, plastics, personal care products, food cooking, soil dust, traffic, and secondary organic aerosol formation processes. These compounds can be used independently for source apportionment analysis, or by analyzed in combination with data from air quality, meteorology, or toxicity.

Overall, the developed methodology provides fast acquisition of data; saving time (85%) and consumables (99% solvents) in the analysis respect to conventional methods, which is very relevant for long term air pollution monitoring and large sample sets. Moreover, only a very small fraction of the whole HiVol-filter sample (<1 m³ eq.sample volume) is used for analysis, which offers the possibility of further analyses in these filters, such as toxicity tests.

Here present examples from several source apportionment studies in rural, background and urban traffic sites, relating results to toxicity.

References

van Drooge, et al. (2023). Determination of subpicogram levels of airborne polycyclic aromatic hydrocarbons for personal exposure monitoring assessment. Journal of Environmental Monitoring and Assessment, 195:368, https://doi.org/10.1007/s10661-023-10953-z

Jaén et al. (2021). Source apportionment and toxicity of PM in urban, sub-urban, and rural air quality network stations in Catalonia. Atmosphere 2021, 12, 744. https://doi.org/10.3390/atmos12060744

How to cite: van Drooge, B. L., Jaén, C., and Bedia, C.: Fast and cost efficient analysis of organic molecular tracer compounds in PM for source apportionment studies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9871, https://doi.org/10.5194/egusphere-egu24-9871, 2024.

Aerosol particles are complex mixtures of organic and inorganic compounds suspended in the atmosphere that significantly impact the climate, human health, and the environment. Understanding their composition and sources is crucial for developing effective air pollution control policies. Although some studies have been conducted on the chemical composition of PM and the sources of PM in Moroccan urban areas, a knowledge gap exists regarding the organic composition and chemical processes across different-sized bins. A detailed study was conducted in September and October 2019 at two distinct sites in Morocco: Atlas Mohammed V (AMV) and the urban city of FEZ. Size-resolved aerosol samples were collected using a 5-stage Berner impactor. Analyses included PM mass, organic carbon (OC)/elemental carbon (EC), trace metals, water-soluble ionic species, and a broad range of organic species. The results show strong regional variations in PM mass, with FEZ (32 µg m^-3) showing approximately three times the PM level of AMV (11 g m^-3). Coarse particles within the 3.5-10 µm size range made up 35% of the PM mass at AMV and 32% at FEZ. The PM_3.5/PM₁₀ ratio at both sites was comparable, with an average of 0.65±0.037. However, the chemical composition analysis revealed a strong urban-remote contrast. FEZ showed higher concentrations of fine-mode pollutants such as OC, EC, and sulfates. At the same time, the remote AMV site exhibited higher coarse-mode OC and nitrates, suggesting different sources and formation processes influenced the PM composition at both sites. The organic compound profiling identified a dominance of alkanes (12±6.8 ng m^-³) and PAHs (1.9±2.5 ng m^-³), such as Benz(a)pyrene, Benzo(k)fluoranthene, Phenanthrene, and Retene, with the urban FEZ site revealing significantly higher concentrations, particularly in the 0.42-1.2 µm size range. In contrast, at AMV, these compounds were more evenly distributed across all particle sizes, reflecting the influence of both natural and anthropogenic sources on their abundances. According to the Positive Matrix Factorization (PMF) model, we identified four and six particle emission sources at AMV and FEZ, respectively. Mineral dust (36-55%) was the predominant component in the coarse mode at both sites, while road dust mixed with local pollutants was significant (up to 44%) in smaller particles (1.2-3.5 µm) in FEZ. At AMV, mixed anthropogenic emissions (21-45%) and secondary aerosols (26-61%) significantly impacted the ultra-fine and acceptable modes, while in FEZ, traffic exhaust (18-34%) and biomass burning (17-41%) dominated the fine mode. Diagnostic ratios of polycyclic aromatic hydrocarbons (PAHs) indicated a blend of fresh and aged particles at AMV, predominantly from petroleum and combustion sources with long-range anthropogenic influence. In contrast, FEZ showed a predominance of fresh emissions from traffic-related sources affecting all particle sizes. These results explore the chemical composition and source apportionment, highlighting the need to control anthropogenic traffic-related emissions to improve urban air quality in North Africa.

How to cite: Deabji, N., Fomba, K. W., and Herrmann, H.: Size-resolved aerosol composition and source apportionment in Morocco: Contrasting urban and remote sites , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11833, https://doi.org/10.5194/egusphere-egu24-11833, 2024.

    The fluorescence characteristics of atmospheric aerosols are related to their chemical characteristics including the oxygenation state; hence they show differences based on their types and sources. Excitation-emission matrix (EEM) fluorescence spectroscopy is becoming an important method for analyzing the chromophores of water-soluble organic aerosols. Although a number of studies have reported the fluorescence characteristics of chromophores in atmospheric aerosols, the relationship betweentheir fluorescence characteristics and types is still unclear. In this study, the fluorescence characteristics of water-soluble components of atmospheric aerosols in different environments in Japan were studied as a means to understand their changes in characteristics and their relationship with aerosol types. The fluorescence was also analyzed for urban rainwater for comparison with aerosol.

    Atmospheric aerosol samples collected at urban (Nagoya), forest (Wakayama), remote (Okinawa)sites and rainwater samples collected at the urban site were subjected to the analysis of EEM for water-soluble extracts. The EEM of water-soluble organic matter from forest aerosol samples showed that the relative contribution of protein-like substances (PRLIS) to total analyzed fluorescence was on average higher than that of other samples. For marine aerosol samples, the intensity of fluorescence originated from humic-like substances (HULIS) containing highly oxygenated compounds (HOS) was on average 4.5 times higher than that originated from HULIS containing less oxygenated compounds (LOS), according to our definition of the quantification of the fluorescence intensity. In the case of forest aerosol samples, the difference in the intensity was smaller (3.4 times on average). This result suggests that the studiedremote aerosols were more aged, while forest aerosols were fresher. For forest aerosol samples, the temporal variation of the fluorescence within a day was obtained. The fluorescence index (FI), humidity index (HIX), and biological index (BIX) were also compared. The HIX-BIX plots showed different patterns for forest, remote and urban aerosol samples, which suggests that they had different degrees of aging and/ordifferent source types, and that this method is useful for the analysis of the characteristics of atmospheric organic aerosols. A parallel factor (PARAFAC) analysis was applied to EEMs, and it identified three different components including two different types of HULIS and one PRLIS. In Nagoya,the contribution by HOS was on average largest among three components in the case of both rainwater and aerosol samples, and the proportion of HOS component for aerosol samples was on average slightly higherthan that for rainwater samples. Although the difference may be affected by the presence ofcoexisting inorganic substances, further comparison may provide a clue to understand the relationship between aerosol and rain chromophores.

How to cite: Wei, C., Afsana, S., Deng, Y., Yai, H., Fujinari, H., and Mochida, M.: Characteristics of the Fluorescence of Water-Soluble Organic Matter in Atmospheric Aerosols under Different Environments in Japan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14154, https://doi.org/10.5194/egusphere-egu24-14154, 2024.

Fine particulate matter fraction (PM_2.5) is a hazardous risk to human health due to its small size, complex chemical composition, and high specific surface area. Different carbonaceous compounds of which some have mutagenic and cancerogenic properties could bind to the PM_2.5 surface and by inhalation penetrate the human body which further leads to the development of severe respiratory and cardiovascular illnesses, even premature death. According to the World Health Organization (WHO)  lower air quality due to elevated PM_2.5 levels in rural and urban areas worldwide caused around 4.2 million premature deaths in 2019, while the European Environment Agency (EEA) reported around 238 000 of premature deaths in Europe in 2020. The goal of EEA's long-term action plans on zero air pollution considering PM_2.5 levels until 2030 is to further lower these numbers by 55%. Due to its high specific surface area, PM_2.5 is subjected to aerosol aging processes which can change the PM_2.5 properties and further amplify its negative impact on the environment due to eutrophication and acidification.

Ambient PM_2.5 could be directly emitted from its source as primary or could be produced as secondary from its gaseous pollutants. In an urban environment, anthropogenic sources such as vehicular emissions, industry processes, and fossil fuel combustion are considered predominant to elevate PM_2.5 levels while the contribution of natural sources like dust resuspension and lightning as well as the long-range transport should not be neglected. The chemical composition of PM_2.5 is mostly related to source characteristics e.g. its type, intensity, temporal, spatial, and/or seasonal distribution, while meteorological parameters such as relative humidity, temperature, wind velocity, and solar radiation index could contribute to PM_2.5 gas-phase and aqueous-phase transformation processes.

This study aimed to assess the air pollution sources regarding PM_2.5 chemical content due to its diverse impact on the environment and human health. Mass concentrations of PM_2.5,  as well as, the mass concentrations of water-soluble inorganic and organic ions (Cl^-, NO₃^-, SO₄^2-, Na⁺, NH₄⁺, K⁺, Mg²⁺, Ca²⁺, acetic (AA), formic (FA), oxalic (OX)) in its content were determined at five measuring sites in different part of Zagreb, capital of Croatia. Daily PM_2.5 concentrations were measured by gravimetry and ion chromatography was used to determine water-soluble inorganic and organic ions. Results show that in urban environments mobile and stationary sources as well as primary and secondary sources show the same temporal distribution depending on the day of the week. The mobile and stationary sources both contribute to the overall air pollution in Zagreb at each location, regardless of the station classification. At all measuring sites the higher contribution of primary sources was obtained. Additionally, results indicated  that on certain days, secondary sources were found to be dominant in the northern and western parts of the city. This information highlights the importance of monitoring and regulating both primary and secondary sources of emissions to ensure a healthier environment for all.

How to cite: Gluščić, V., Bešlić, I., Pehnec, G., and Godec, R.: Insights into air pollution sources in urban enviroments during winter , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19928, https://doi.org/10.5194/egusphere-egu24-19928, 2024.

Nitrosamines, organic compounds featuring the nitroso functional group (N-NO), are found in both gas and particle phases in the ambient air, known for their carcinogenic properties. The International Agency for Research on Cancer (IARC) has classified most nitrosamines as likely carcinogenic to humans. Given their carcinogenic nature, it is crucial to manage ambient concentrations of nitrosamines. Nevertheless, the concentrations of nitrosamines in Seoul, South Korea, surpass the recommended level of 10 ng/m³ set by the Norwegian Institute of Public Health (NIPH).

In the previous study, the contributions of primary emissions and atmospheric reactions were investigated using field measurement data from Seoul, Korea, along with a kinetic box. It was estimated that there was a mixed contribution of the atmospheric reaction and primary emission. In addition, the model estimation result showed that nitrosamine formation was enhanced by nitrosation under higher concentrations of NO_x in Seoul. However, there was a large discrepancy between the measured and estimated concentrations of particulate nitrosamines in Seoul. Therefore, further identification of the hidden reaction forming nitrosamines was necessary.

This study aimed to identify whether ozonation could be an unknown reaction forming particulate nitrosodi-methylamine (NDMA) to reduce the discrepancy between the measured and estimated concentration of NDMA in the previous study. Ozonation of dimethylamine (DMA) can form dimethylhydrazine (UDMH), subsequently, UDMH reaction with O₃ and O₂ can produce NDMA in the ambient air. In order to quantify the contribution of ozonation, the ozonation mechanism was added to the kinetic box model developed in the previous study. The model simulation results showed that (1) the ozonation contributed to the ambient concentration of NDMA (7.9 ± 3.8% (winter); 1.9 ± 3.0% (spring); 10.0 ± 0.77% (summer); 3.6 ± 7.3% (autumn)), (2) the relatively higher O₃/NO_x ratio in summer (1.63 ± 0.69; 0.64 ± 0.52 (winter); 1.14 ± 0.92 (spring); 0.52 ± 0.54 (autumn)) could enhance ozonation, and (3) relatively lower pH in summer (2.2 ± 0.4; 5.3 ± 1.2 (winter); 3.9 ± 1.2 (spring); 3.9 ± 0.7 (autumn)) could hinder nitrosation compared to that in other seasons.

How to cite: Choi, N. R., Kim, Y. P., Lee, J. Y., Kim, E., Kim, S., and Shin, H. J.: Contribution of ozonation forming the particulate nitrosodi-methylamine (NDMA) in the ambient air , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-211, https://doi.org/10.5194/egusphere-egu24-211, 2024.

Polycyclic aromatic hydrocarbons (PAHs) generally form an integral component of air pollutants in the ambient atmosphere. This study focuses on how proximity to roadways affects the ambient concentration of PAHs. Spatial and seasonal distribution of sixteen PAHs, and collectively represented as Σ₁₆ PAHs were determined in the ambient atmosphere of Delhi, the National Capital Region (NCR) of India. The results showed that the average mass concentration of Σ₁₆ PAHs near the roadway (67.8 ± 40.2 ng m^-3) is significantly higher as compared to the urban background site (56 ± 30 ng m^-3). Moreover, a source apportionment study indicated that major PAH-emission sources in Delhi NCR are traffic and coal combustion. Health risks associated with inhalation of particulate PAHs were assessed using benzo(a)pyrene equivalent concentration (BaPeq) and incremental lifetime cancer risk (ILCR) approach. ILCR values at both sites fall in the range of 10^-2 to 10^-4 which corresponds to the priority risk level (10^-3) and not the acceptable risk level (10^-6). Thus, the present study concludes that the concentration of ambient PAHs is significantly higher at a site with busy traffic than at an urban background site, thereby indicating a significantly higher health risk to the population of Delhi.

How to cite: Sonwani, S. and Saxena, P.: Atmospheric Polycyclic Aromatic Hydrocarbon Inhalation Exposure and Human Health Risk Assessment at Traffic Site in Delhi, India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-474, https://doi.org/10.5194/egusphere-egu24-474, 2024.