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Biogenic volatile organic compounds (BVOCs) are a highly complex and diverse set of chemicals emitted into the atmosphere by the Earth's biosphere [1]. Atmospheric oxidation of BVOCs affects atmospheric mixing ratios of CH4, CO, and tropospheric O3, and leads to the formation of Secondary Organic Aerosol (SOA) (i.e., submicron particulate matter). Atmospheric aerosol plays a crucial role in defining Earth's radiative balance and impacts air-quality [2]. Climate models project a further increase in the average global temperature for the next decades. Warm winters appear to lead to earlier leaf-out which may put trees at higher risks of late frost in spring and summer droughts are increasing in frequency and extent. The probability that a late frost and an extreme summer drought occurs in the same year is expected to increase and thus, how trees respond to and recover from the (double) stress will be important in determining changes in BVOC emissions composition and quantities. Climate warming may thus lead to changes in atmospheric chemistry, including SOA properties [3]. During 2022, we studied the impact of spring frost and summer drought on BVOC emissions from broadleaf seedlings. We exposed 2-year-old seedlings of 3 species (Quercus petraea, Quercus robur, Fagus sylvatica) to an artificial spring frost by keeping seedlings with leaves that were fully out at -5.5℃ for 3 hours at the beginning of May 2022. Subsequently we simulated a summer drought from early July through the end of August (50% water reduction). The BVOC emissions of QP, QR, and FS, were measured deploying a PTR-ToF-MS alongside a newly developed plant chamber system [4] in August 2022. We address the following research questions in our conference contribution: How do BVOC emissions composition and quantities of broadleaf control trees (QP, QR, FS) compare to coniferous ones (studied during AccliMemo 2022 [4])? How are the BVOC emissions of QP and FS modulated in response to a) late spring frost, b) summer drought, and c) double stress? References: [1] Sindelarova et al. Global data set of biogenic VOC emissions calculated by the MEGAN model over the last 30 years, ACP, 14, 9317–9341, https://doi.org/10.5194/acp-14-9317-2014, 2014 [2] Seinfeld, John H. and Pandis, Spyros N.: Atmospheric Chemistry and Physics: From Air Pollution to Climate Change, 3rd Edition., Wiley, 1152 pp., 2016 [3] Smith, N. R. et al.: Viscosity and liquid–liquid phase separation in healthy and stressed plant SOA, Environ. Atmospheres, 1, 140–153, https://doi.org/10.1039/D0EA00020E, 2021 [4] Molteni, U. et al., 2023, EGU23 GA Abstract Nr. EGU23-14587 Acknowledgements: SMP acknowledges funding by the Swiss National Science Foundation (SNSF) grant no. P400P2_194390.

We present air quality and trace gas observations at the regional Global Atmosphere Watch (GAW) station Pha Din (PDI) in rural Northwestern Vietnam. PDI is located in a sparsely populated area on the top of a hill (1466 m a.s.l.) [1], and frequently receives pollution plumes from large-scale fires on the Indochinese Peninsula [1]. We previously analyzed carbonaceous PM2.5 chemical composition in an intensive campaign conducted during 3 weeks in March-April 2015. The study included measurements of elemental and organic carbon (EC/OC) and more than 50 organic markers, such as sugars, PAHs, fatty acids and nitro-aromatics [2]. For this intensive campaign, we linked trace gas mixing ratios of CO, CO2, CH4 and O3 to a statistical classification of large-scale fires, which was based on organic aerosol composition. We found increased CO and O3 levels during medium and high biomass burning influence during March-April 2015. A backward trajectory analysis confirmed different source regions for the identified periods based on the organic aerosol cluster. The more polluted periods were characterized by trajectories from southwest, with more continental recirculation of the medium cluster, and more westerly advection for the high cluster. Cleaner air masses instead arrived from northeast, i.e., mainland China and Yellow sea during this period. These findings highlighted that biomass burning in Northern Southeast Asia significantly enhances the regional organic aerosol loading, chemical PM2.5 composition and the trace gases in northwestern Vietnam [2]. For our contribution to EGU22, we extend this analysis to a multi-year period and present continuous trace gas observations of CO2, CH4, CO, and O3 conducted at PDI since 2014. The data are interpreted with atmospheric transport simulations, and add valuable insight on air quality and trace gas mixing ratios in a region of scarce data availability.REFERENCES: [1] Bukowiecki, N. et al. Effect of Large-scale Biomass Burning on Aerosol Optical Properties at the GAW Regional Station Pha Din, Vietnam. AAQR 19, 1172–1187 (2019). [2] Nguyen, D. L, et al. Carbonaceous aerosol composition in air masses influenced by large-scale biomass burning: a case-study in Northwestern Vietnam. Atmos. Chem. Phys., 21, 8293–8312 (2021) https://doi.org/10.5194/acp-21-8293-2021FUNDING AND ACKNOWLEDGMENTS: Capacity Building and Twinning for Climate Observing Systems (CATCOS), GAW Quality Assurance/Science Activity Centre Switzerland (QA/SAC-CH), Swiss National Science Foundation (SNSF) (194390), German Academic Exchange Service (DAAD), Vietnam Academy of Science and Technology (VAST).

Workplace aggression, including workplace bullying and mobbing, can have tremendous impacts on both the professional and the personal well-being of the target. The experience is an immense source of distress and can lead to physical health issues such as high blood pressure and increased risk for strokes, and to mental health issues, such as anxiety, depression and suicidal tendencies. The negative effects of workplace aggression go beyond those on the target. For instance potential bystanders and the overall work performance of teams and collaborations may suffer, leading to failed projects, loss of research funding and prematurely terminated careers. The latter also adds to the continued loss of a diverse workforce in the Geosciences, since historically marginalised groups are more affected by workplace discrimination than the current majority of geoscientists in senior positions. Creating healthy and safe working environments should therefore be the top priority of academic institutions, and thus also the Geosciences community. To raise awareness and provide clarity around some terminology and dynamics, we previously shared the blog post "Mind your Head - An introduction to workplace bullying in academia" (1). It includes references to other resources, such as a 10-step practical guideline (2) which scientists can follow to counteract the detrimental effects of abusive academic work environments. The blog post also served as a stimulus for "Great Debate 5" (GDB5) during vEGU21, which allowed early career scientists in the Geosciences to engage in a discussion on "Bullying in Academia – towards creating healthy and safe working environments" (3). During GDB5, 86% of the participants confirmed to have witnessed a bullying or harassment situation at work and ~65% of the session attendees estimated that the academic community is unaware of or uninformed about bullying and harassment. GDB5 participants stated that, amongst others, they a) would like to learn how to become better allies/bystanders, b) would like to know what to do as an ally/bystander, c) want to find systematic and structural solutions on an institutional level for safe working environments, d) would like to learn how to deal with bullying and harassment on a personal level and e) would like to create more awareness about bullying and harassment. The Great Debate helped people to feel supported and trusted, become aware of the problems at an institutional level, and to connect and talk about appropriate and not-appropriate behaviour.Following the GDB5, we created a list of bottom up, lateral and top down actions to foster safe and healthy work environments within the Geosciences, which serves as a basis for our current work to tackle workplace bullying and mobbing in the Geosciences. This includes, for instance, an in-depth survey around this topic to obtain more quantitative information and data. By creating visibility for our efforts during EGU22, we hope to broaden our initiative and receive new input from the scientific community. References:(1) Pieber, van Rijsingen, Gürer, Beniest (2021) https://blogs.egu.eu/divisions/ts/2021/03/24/mind-your-head-an-introduction-to-workplace-bullying-in-academia/(2) Popp, Hall, Yılmaz (2020) https://doi.org/10.1029/2020EO151914.(3) Beniest, Gürer, Pieber, van Rijsingen (2021) https://meetingorganizer.copernicus.org/EGU21/session/39992

Understanding of regional greenhouse gas emissions into the atmosphere is a prerequisite to mitigate climate change. In this study, we investigated the regional contributions of carbon dioxide (CO2) at the location of the high Alpine observatory Jungfraujoch ("JFJ", Switzerland, 3580 m a.s.l.). To this purpose, we combined receptor-oriented atmospheric transport simulations for CO2 concentration in the period of 2009–2017 with stable carbon isotope (δ13C-CO2) information. We applied two Lagrangian particle dispersion models driven by output from two different numerical weather prediction systems (FLEXPART-COSMO and STILT-ECMWF) in order to simulate CO2 concentration at JFJ based on regional CO2 fluxes, to estimate atmospheric δ13C-CO2, and to obtain model-based estimates of the mixed source signatures (δ13Cm). Anthropogenic fluxes were taken from a fuel type-specific version of the EDGAR v4.3 inventory and ecosystem fluxes were based on the Vegetation Photosynthesis and Respiration Model (VPRM). The simulations of CO2, δ13C-CO2 and δ13Cm were then compared to observations performed by quantum cascade laser absorption spectroscopy. Around 40 % of the regional CO2 variability above or below the large-scale background was captured by the models, and up to 35 % of the regional variability in δ13C-CO2. This is remarkable considering the complex Alpine topography, the low intensity of regional signals at JFJ, and the challenging measurements. Best agreement between simulations and observations in terms of short-term variability and intensity of the signals for CO2 and δ13C-CO2 was found between late autumn and early spring. The agreement was inferior in the early autumn periods and during summer. This may be associated with the atmospheric transport representation in the models. In addition, the net ecosystem exchange fluxes are a possible source of error, either through inaccuracies in their representation in VPRM for the (Alpine) vegetation or through a day (uptake) vs. night (respiration) transport discrimination to JFJ. Furthermore, the simulations suggest that JFJ is subject to relatively small regional anthropogenic contributions, due to its remote location (elevated and far from major anthropogenic sources), and the limited planetary boundary layer-influence during winter. Instead, the station is primarily exposed to summer-time ecosystem CO2 contributions, which are dominated by rather nearby sources (within 100 km). Even during winter, simulated gross ecosystem respiration accounted for approximately 50 % of all contributions to the CO2 concentrations above the largescale background. The model-based monthly mean δ13Cm ranged from −22 ‰ in winter to −28 ‰ in summer and reached the most depleted values of −35 ‰ at higher fractions of natural gas combustion, and the most enriched values of −17 to −12 ‰ when impacted by cement production emissions. Observation-based δ13Cm values derived by a moving Keeling-plot approach were in good agreement with the model-based estimates. They exhibited a larger scatter, while model-based estimates spread in a more narrow range. Overall, observation-based δ13Cm were limited to a smaller number of data points compared to model-based estimates owing to the stringent analysis prerequisites in combination with the low regional signal at JFJ.

Smog chamber experiments were conducted to characterize the light absorption of brown carbon (BrC) from primary and photochemically aged coal combustion emissions. Light absorption was measured by the UV-visible spectrophotometric analysis of water and methanol extracts of filter samples. The single-scattering albedo at 450 nm was 0.73 ± 0.10 for primary emissions and 0.75 ± 0.13 for aged emissions. The light absorption coefficient at 365 nm of methanol extracts was higher than that of water extracts by a factor of 10 for primary emissions and a factor of 7 for aged emissions. This suggests that the majority of BrC is water-insoluble even after aging. The mass absorption efficiency of this BrC (MAE365) for primary OA (POA) was dependent on combustion conditions, with an average of 0.84 ± 0.54 m2 g-1, which was significantly higher than that for aged OA (0.24 ± 0.18 m2 g-1). Secondary OA (SOA) dominated aged OA and the decreased MAE365 after aging indicates that SOA is less light absorbing than POA and/or that BrC is bleached (oxidized) with aging. The estimated MAE365 of SOA (0.14 ± 0.08 m2 g-1) was much lower than that of POA. A comparison of MAE365 of residential coal combustion with other anthropogenic sources suggests that residential coal combustion emissions are among the strongest absorbing BrC organics.

Open biomass burning (BB) is a globally widespread phenomenon. The fires release pollutants, which are harmful for human and ecosystem health and alter the Earth's radiative balance. Yet, the impact of various types of BB on the global radiative forcing remains poorly constrained concerning greenhouse gas emissions, BB organic aerosol (OA) chemical composition and related light absorbing properties. Fire emissions composition is influenced by multiple factors (e.g., fuel and thereby vegetation-type, fuel moisture, fire temperature, available oxygen). Due to regional variations in these parameters, studies in different world regions are needed. Here we investigate the influence of seasonally recurring BB on trace gas concentration and air quality at the regional Global Atmosphere Watch (GAW) station Pha Din (PDI) in rural Northwestern Vietnam. PDI is located in a sparsely populated area on the top of a hill (1466 m a.s.l.) and is well suited to study the large-scale fires on the Indochinese Peninsula, whose pollution plumes are frequently transported towards the site [1]. We present continuous trace gas observations of CO2, CH4, CO, and O3 conducted at PDI since 2014 and interpret the data with atmospheric transport simulations. Annually recurrent large scale BB leads to hourly time-scale peaks CO mixing ratios at PDI of 1000 to 1500 ppb around every April since the start of data collection in 2014. We complement this analysis with carbonaceous PM2.5 chemical composition analyzed during an intensive campaign in March-April 2015. This includes measurements of elemental and organic carbon (EC/OC) and more than 50 organic markers, such as sugars, PAHs, fatty acids and nitro-aromatics [2]. For the intensive campaign, we linked CO, CO2, CH4 and O3 mixing ratios to a statistical classification of BB events, which is based on OA composition. We found increased CO and O3 levels during medium and high BB influence during the intensive campaign. A backward trajectory analysis confirmed different source regions for the identified periods based on the OA cluster. Typically, cleaner air masses arrived from northeast, i.e., mainland China and Yellow sea during the intensive campaign. The more polluted periods were characterized by trajectories from southwest, with more continental recirculation of the medium cluster, and more westerly advection for the high cluster. These findings highlight that BB activities in Northern Southeast Asia significantly enhances the regional OA loading, chemical PM2.5 composition and the trace gases in northwestern Vietnam. The presented analysis adds valuable data on air quality in a region of scarce data availability. REFERENCES[1] Bukowiecki, N. et al. Effect of Large-scale Biomass Burning on Aerosol Optical Properties at the GAW Regional Station Pha Din, Vietnam. AAQR. 19, 1172–1187 (2019).[2] Nguyen, D. L, et al. Carbonaceous aerosol composition in air masses influenced by large-scale biomass burning: a case-study in Northwestern Vietnam. ACPD., https://doi.org/10.5194/acp-2020-1027, in review, 2020.

We investigated concentrations of organic carbon (OC), elemental carbon (EC) and a wide range of particle-bound organic compounds in daily sampled PM2.5 at the remote Pha Din (PDI) – Global Atmosphere Watch (GAW) monitoring station in Northwestern Vietnam during an intense 3-week sampling campaign from 23rd March to 12th April 2015. The site is known to receive trans-regional air masses during large-scale biomass burning episodes, but OC composition studies are missing in the scientific literature. We quantified 51 organic compounds simultaneously by in-situ derivatization thermal desorption gas chromatography time-of-flight mass spectrometry (IDTD-GC-TOFMS). Anhydrosugars, methoxyphenols, n-alkanes, fatty acids, polycyclic aromatic hydrocarbons, oxygenated polycyclic aromatic hydrocarbons, nitrophenols as well as OC were used in a hierarchical cluster analysis highlighting distinctive patterns for periods under low, medium and high biomass burning (BB) influence. The highest particle phase concentration of the typical primary organic aerosol (POA) and possible secondary organic aerosol (SOA) constituents, especially nitrophenols, were found on 5th and 6th April. We linked the trace gases CH4, CO2, CO, O3 mixing ratios to the statistical classification of BB events based on OA composition and found increased CO and O3 levels during medium and high BB influence. Likewise, a backward trajectory analysis indicates different source regions for the identified periods based on the OA cluster, with cleaner air masses arriving from northeast, i.e., mainland China and Yellow sea. The more polluted periods are characterized by trajectories from southwest, with more continental recirculation of the medium cluster, and more westerly advection for the high cluster. These findings highlight that BB activities in Northern Southeast Asia cannot only significantly enhance the regional organic aerosol loading, but also affect the carbonaceous PM2.5 constituents and the trace gases in northwestern Vietnam. The presented analysis adds valuable data on the carbonaceous and in particular OC chemical composition of PM2.5 in a region of scarce data availability.

Evaluating atmospheric transport simulations against observations helps refining bottom-up estimates of greenhouse gas fluxes and identifying gaps in our understanding of regional and category-specific contributions to atmospheric mole fractions. This insight is critical in the efforts to mitigate anthropogenic environmental impact. Beside total mole fractions, stable isotope ratios provide further constraints on source-sink processes [1-3].Here, we present two receptor-oriented model simulations for carbon dioxide (CO2) mole fraction and δ13C-CO2 stable isotope ratios for a nine year period (2009-2017) at the High Altitude Research Station Jungfraujoch (Switzerland, 3580 m asl). The model simulations of CO2 were performed on a 3-hourly time-resolution with two backward Lagrangian particle dispersion models driven by two different numerical weather forecast fields: FLEXPART-COSMO and STILT-ECMWF. Anthropogenic CO2 fluxes were based on the EDGAR v4.3 emissions inventory aggregated into 14 source categories representing fossil and biogenic fuel uses as well as emissions from cement production. Biospheric CO2 fluxes representing the photosynthetic uptake and respiration of 8 plant functional types were based on the Vegetation Photosynthesis and Respiration Model (VPRM). The simulated CO2 emissions per source and sink category were weighted with category-specific δ13C-CO2 signatures from published experimental studies. Background CO2 values at the boundaries of both model domains were taken from global model simulations and the corresponding δ13C-CO2 values were constructed as suggested in Ref. [3]. We compare the simulations to a unique data set of continuous in-situ observations of CO2 mole fractions and δ13C-CO2 stable isotope ratios by quantum cascade laser absorption spectroscopy as described in previous work [1, 4-5], available for the whole nine year period at the site.The simulated atmospheric CO2 and δ13C-CO2 time-series are in good agreement with the observations and capture the observed variability at the models' 3-hourly time-resolution. This allows for an in-depth evaluation of the contribution of different CO2 emission sources and for an allocation of source regions when Jungfraujoch is influenced by air masses from the planetary boundary layer. In brief, the receptor-oriented model simulations suggest that anthropogenic CO2 contributions are primarily of fossil origin (90%). Anthropogenic emissions contribute between 60% in February, and 20% in July/August, to the CO2 enhancements observed at Jungfraujoch. The remaining fraction is due to biosphere respiration, which thus largely dominates emissions during the summer season. However, intense photosynthetic CO2 uptake during June, July and August roughly outweighs CO2 contributions from anthropogenic activities and biosphere respiration at JFJ. REFERENCES[1] Tuzson et al., 2011. ACP, 11, 1685[2] Röckmann et al., 2016. ACP, 16, 10469[3] Vardag et al., 2016. Biogeosciences, 13, 4237[4] Tuzson et al., 2008. Appl. Phys. B, 92, 451[5] Sturm et al., 2013. AMT 6, 1659

Log wood burning is a significant source of volatile organic compounds including aromatic hydrocarbons (ArHC). ArHC are harmful, are reactive in the ambient atmosphere, and are important secondary organic aerosol (SOA) precursors. Consequently, SOA represents a major fraction of the sub-micron organic aerosol pollution from log wood burning. ArHC reduction is thus critical in the mitigation of adverse health and environmental effects of log wood burning. In this study, two Pt-based catalytic converters were prepared and tested for the mitigation of real-world log wood burning emissions, including ArHC and SOA formation, as well as toxic carbon monoxide and methane, a greenhouse gas. Substantial removal of mono- and polycyclic ArHC and phenolic compounds was achieved with both catalysts operated at realistic chimney temperatures (50% conversion was achieved at 200 and 300 °C for non-methane hydrocarbons in our experiments for Pt/Al2O3 and Pt/CeO2-Al2O3, respectively). The catalytically cleaned emissions ex...

Gasoline direct injection (GDI) vehicles have recently been identified as a significant source of carbonaceous aerosol, of both primary and secondary origin. Here we investigated primary emissions and secondary organic aerosol (SOA) from four GDI vehicles, two of which were also retrofitted with a prototype gasoline particulate filter (GPF). We studied two driving test cycles under cold- and hot-engine conditions. Emissions were characterized by proton transfer reaction time-of-flight mass spectrometry (gaseous non-methane organic compounds, NMOCs), aerosol mass spectrometry (sub-micron non-refractory particles) and light attenuation measurements (equivalent black carbon (eBC) determination using Aethalometers) together with supporting instrumentation. Atmospheric processing was simulated using the PSI mobile smog chamber (SC) and the potential aerosol mass oxidation flow reactor (OFR). Overall, primary and secondary particulate matter (PM) and NMOC emissions were dominated by the engine cold start, i.e., before thermal activation of the catalytic after-treatment system. Trends in the SOA oxygen to carbon ratio (O : C) for OFR and SC were related to different OH exposures, but divergences in the H : C remained unexplained. SOA yields agreed within experimental variability between the two systems, with a tendency for higher values in the OFR than in the SC (or, vice versa, lower values in the SC). A few aromatic compounds dominated the NMOC emissions, primarily benzene, toluene, xylene isomers/ethylbenzene and C3-benzene. A significant fraction of the SOA was explained by those compounds, based on comparison of effective SOA yield curves with those of toluene, o-xylene and 1,2,4-trimethylbenzene determined in our OFR, as well as others from literature. Remaining discrepancies, which were smaller in the SC and larger in the OFR, were up to a factor of 2 and may have resulted from diverse reasons including unaccounted precursors and matrix effects. GPF retrofitting significantly reduced primary PM through removal of refractory eBC and partially removed the minor POA fraction. At cold-started conditions it did not affect hydrocarbon emission factors, relative chemical composition of NMOCs or SOA formation, and likewise SOA yields and bulk composition remained unaffected. GPF-induced effects at hot-engine conditions deserve attention in further studies.

Heavy fuel oil (HFO) particulate matter (PM) emitted by marine engines is known to contain toxic heavy metals, including vanadium (V) and nickel (Ni). The toxicity of such metals will depend on the their chemical state, size distribution, and mixing state. Using online soot-particle aerosol mass spectrometry (SP-AMS), we quantified the mass of five metals (V, Ni, Fe, Na, and Ba) in HFO-PM soot particles produced by a marine diesel research engine. The in-soot metal concentrations were compared to in-PM2.5 measurements by inductively coupled plasma-optical emission spectroscopy (ICP-OES). We found that, Environmental Science & Technology, 52 (11), ISSN:0013-936X, ISSN:1520-5851

To reduce the influence of biomass burning on air quality, consumers are encouraged to replace their old woodstove with new and cleaner appliances. While their primary emissions have been extensively investigated, the impact of atmospheric aging on these emissions, including secondary organic aerosol (SOA) formation, remains unknown. Here, using an atmospheric smog chamber, we aim at understanding the chemical nature and quantify the emission factors of the primary organic aerosols (POA) from three types of appliances for residential heating, and to assess the influence of aging thereon. Two, old and modern, logwood stoves and one pellet burner were operated under typical conditions. Emissions from an entire burning cycle (past the start-up operation) were injected, including the smoldering and flaming phases, resulting in highly variable emission factors. The stoves emitted a significant fraction of POA (up to 80%) and black carbon. After ageing, the total mass concentration of organic aerosol (OA) increased on average by a factor of 5. For the pellet stove, flaming conditions were maintained throughout the combustion. The aerosol was dominated by black carbon (over 90% of the primary emission) and amounted to the same quantity of primary aerosol emitted by the old logwood stove. However, after ageing, the OA mass was increased by a factor of 1.7 only, thus rendering OA emissions by the pellet stove almost negligible compared to the other two stoves tested. Therefore, the pellet stove was the most reliable and least polluting appliance out of the three stoves tested. The spectral signatures of the POA and aged emissions by a High Resolution – Time of Flight – Aerosol Mass Spectrometer (Electron Ionization (EI) at 70 eV) were also investigated. The m/z 44 (CO2+) and high molecular weight fragments (m/z 115 (C9H7+), 137 (C8H9O2+), 167 (C9H11O3+) and 181 (C9H9O4+, C14H13+)) correlate with the modified combustion efficiency (MCE) allowing us to discriminate further between emissions generated from smoldering vs flaming conditions.

Secondary organic aerosol (SOA) is formed from the atmospheric oxidation of gas-phase organic compounds leading to the formation of particle mass. Gasoline- and diesel-powered motor vehicles, both on/off-road, are important sources of SOA precursors. They emit complex mixtures of gas-phase organic compounds that vary in volatility and molecular structure-factors that influence their contributions to urban SOA. However, the relative importance of each vehicle type with respect to SOA formation remains unclear due to conflicting evidence from recent laboratory, field, and modeling studies. Both are likely important, with evolving contributions that vary with location and over short time scales. This review summarizes evidence, research needs, and discrepancies between top-down and bottom-up approaches used to estimate SOA from motor vehicles, focusing on inconsistencies between molecular-level understanding and regional observations. The effect of emission controls (e.g., exhaust aftertreatment technologies, fuel formulation) on SOA precursor emissions needs comprehensive evaluation, especially with international perspective given heterogeneity in regulations and technology penetration. Novel studies are needed to identify and quantify "missing" emissions that appear to contribute substantially to SOA production, especially in gasoline vehicles with the most advanced aftertreatment. Initial evidence suggests catalyzed diesel particulate filters greatly reduce emissions of SOA precursors along with primary aerosol.

Aerodyne aerosol mass spectrometer (AMS) and Aerodyne aerosol chemical speciation monitor (ACSM) mass spectra are widely used to quantify organic aerosol (OA) elemental composition, oxidation state, and major environmental sources. The OA CO2+ fragment is among the most important measurements for such analyses. Here, we show that a non-OA CO2+ signal can arise from reactions on the particle vaporizer, ion chamber, or both, induced by thermal decomposition products of inorganic salts. In our tests (eight instruments, n = 29), ammonium nitrate (NH4NO3) causes a median CO2+ interference signal of +3.4% relative to nitrate. This interference is highly variable between instruments and with measurement history (percentiles P10–90 = +0.4 to +10.2%). Other semi-refractory nitrate salts showed 2–10 times enhanced interference compared to that of NH4NO3, while the ammonium sulfate ((NH4)2SO4) induced interference was 3–10 times lower. Propagation of the CO2+ interference to other ions during standard AMS and ACSM d...

International audience; Residential coal combustion is a significant contributor to particulate urban air pollution in Chinese mega cities and some regions in Europe. While the particulate emission factors and the chemical characteristics of the organic and inorganic aerosol from coal combustion is extensively studied, the chemical composition and non methane organic gas (NMOG) emission factors from residential coal combustion are mostly unknown. We conducted 23 individual burns in a traditional Chinese stove used for heating and cooking using five different coals with Chinese origins, characterizing the NMOG emissions using a proton transfer reaction time-of-fight mass spectrometer. The measured emission factors range from 1−15 g/kgcoal for bituminous coals and are below 0.1 g/kgcoal for anthracite coals. The emission factors from the bituminous coals are mostly influenced by the time until the coal is fully ignited. The emissions from the bituminous coals are dominated by aromatic and oxygenated aromatic compounds with a significant contribution of hydrocarbons. The results of this study can help to improve urban air pollution modeling in China and eastern Europe and can be used to constrain a coal burning factor in ambient gas phase positive matrix factorization studies.

A Thermal Desorption Aerosol Gas Chromatograph coupled to a High Resolution – Time of Flight – Aerosol Mass Spectrometer (TAG-AMS) was connected to an atmospheric chamber for the molecular characterization of the evolution organic aerosol (OA) emitted by woodstoves appliances for residential heating. Two logwood stoves (old and modern) and one pellet stove were operated under typical conditions. Emissions were aged during a time equivalent to 5 hours of atmospheric aging. 5 to 7 samples were collected and analyzed with TAG-AMS during each experiment. We detect and quantify over 70 compounds, including levoglucosan and nitrocatechols. We calculate the emission emissions factor (EF) of these tracers in the primary emissions and highlight the influence of the combustion efficiency on these emissions. Smoldering combustion contribute to higher EF and a more complex composition. We also demonstrate the effect of the atmospheric aging on the chemical fingerprint. The tracers are sorted into 3 categories according to the evolution of their concentration: primary compounds, non-conventional primary compounds, and secondary compounds. For each we provide a quantitative overview of their contribution to the OA mass at different times of the photo-oxidative process.

Vapor wall loss has only recently been shown a potentially significant bias in atmospheric chamber studies. Yet, previous works aimed at the determination of the degradation rate of semi-volatile organic compounds (SVOCs) often did not account for this process. Here we evaluate the influence of vapor wall loss on the determination of the gas phase reaction rate kOH of several biomass burning markers (levoglucosan, mannosan, coniferyl aldehyde, 3-guaiacyl propanol, and acetosyringone) with hydroxyl radicals (OH). Emissions from the combustion of beech wood were injected into a 5.5 m3 Teflon atmospheric chamber, and aged for 4 hours (equivalent to 5–8 hours in the atmosphere). The particle phase compound concentrations were monitored using a Thermal Desorption Aerosol Gas Chromatograph coupled to a High-Resolution – Time of Flight – Mass Spectrometer (TAG-AMS). The observed depletion of the concentration was later modeled using two different approaches: the previously published approach which does not take into consideration partitioning and vapor wall loss, and an approach with a more complex theoretical framework which integrates all the processes likely influencing the particle phase concentration. We find that with the first approach one fails to predict the measured markers concentration time evolution. With the second approach, we determine that partitioning and vapor wall loss play a predominant role in the particle phase concentration depletion of all the compounds, while the reactivity with OH has a non-significative effect. Furthermore we show that kOH cannot be determined precisely without a strong constraint of the whole set of physical parameters necessary to formally describe the various processes involved. It was found that the knowledge of the saturation mass concentration C* is especially crucial. Therefore previously published rate constants of levoglucosan and more generally SVOCs with hydroxyl radicals inferred from atmospheric chamber experiments must be, at least, considered with caution.

We characterized the chemical composition and optical properties of particulate matter (PM) emitted by a marine diesel engine operated on heavy fuel oil (HFO), marine gas oil (MGO), and diesel fuel (DF). For all three fuels, ∼80% of submicron PM was organic (and sulfate, for HFO at higher engine loads). Emission factors varied only slightly with engine load. Refractory black carbon (rBC) particles were not thickly coated for any fuel; rBC was therefore externally mixed from organic and sulfate PM. For MGO and DF PM, rBC particles were lognormally distributed in size (mode at drBC≈120 nm). For HFO, much larger rBC particles were present. Combining the rBC mass concentrations with in situ absorption measurements yielded an rBC mass absorption coefficient MACBC,780nm of 7.8 ± 1.8 m2/g at 780 nm for all three fuels. Using positive deviations of the absorption Ångström exponent (AAE) from unity to define brown carbon (brC), we found that brC absorption was negligible for MGO or DF PM (AAE(370,880 nm)≈1.0 ± 0.1) but typically 50% of total 370‐nm absorption for HFO PM. Even at 590 nm, ∼20 of the total absorption was due to brC. Using absorption at 880 nm as a reference for BC absorption and normalizing to organic PM mass, we obtained a MACOM,370nm of 0.4 m2/g at typical operating conditions. Furthermore, we calculated an imaginary refractive index of (0.045 ± 0.025)(λ/370nm)−3 for HFO PM at 370 nm>λ > 660 nm, more than twofold greater than previous recommendations. Climate models should account for this substantial brC absorption in HFO PM., Journal of Geophysical Research: Atmospheres, 123 (11), ISSN:0148-0227, ISSN:2169-897X

A variety of tools are used to simulate atmospheric aging, including smog chambers and flow reactors. Traditional, large-scale smog chambers age emissions over the course of hours to days, whereas flow reactors rapidly age emissions using high oxidant concentrations to reach higher degrees of oxygenation than typically attained in smog chamber experiments. The atmospheric relevance of the products generated under such rapid oxidation warrants further study. However, no previously published studies have compared the yields and chemical composition of products generated in flow reactors and smog chambers from the same starting mixture. The yields and composition of the organic aerosol formed from the photo-oxidation of α-pinene and of wood-combustion emissions in a smog chamber (SC) and two flow reactors: a potential aerosol mass reactor (PAM) and a micro-smog chamber (MSC), were determined using aerosol mass spectrometry. Reactants were sampled from the SC and aged in the MSC and the PAM using a range of hydroxyl radical (OH) concentrations and then photo-chemically aged in the SC. The chemical composition, as well as the maximum yields and emission factors, of the products in both the α-pinene and wood-combustion systems determined with the PAM and the SC agreed reasonably well. High OH exposures have been shown previously to lower yields by breaking carbon–carbon bonds and forming higher volatility species, which reside largely in the gas phase; however, fragmentation in the PAM was not observed. The yields determined using the PAM for the α-pinene system were slightly lower than in the SC, possibly from increased wall losses of gas phase species due to the higher surface area to volume ratios in the PAM, even when offset with better isolation of the sampled flow from the walls. The α-pinene SOA results for the MSC were not directly comparable, as particles were smaller than the optimal AMS transmission range. The higher supersaturation in the flow reactors resulted in more nucleation than in the SC. For the wood-combustion system, emission factors measured from the MSC were typically lower than those measured from the SC. Lower emission factors in the MSC may have been due to considerable nucleation mode particles formed in the MSC which were not detected by the AMS or due to condensational loss of gases to the walls inside or after the MSC. More comprehensive coverage of the potential particle size range is needed in future SOA measurements to improve our understanding of the differences in yields when comparing the MSC to the SC. The PAM and the SC agreed within measurement uncertainties in terms of yields and composition for the systems and conditions studied here and this agreement supports the continued use of the PAM to study atmospheric aging.

Oxidative processing of aircraft turbine-engine exhausts was studied using a potential aerosol mass (PAM) chamber at different engine loads corresponding to typical flight operations. Measurements were conducted at an engine test cell. Organic gases (OGs) and particle emissions pre- and post-PAM were measured. A suite of instruments, including a proton-transfer-reaction mass spectrometer (PTR-MS) for OGs, a multigas analyzer for CO, CO2, NOx, and an aerosol mass spectrometer (AMS) for nonrefractory particulate matter (NR-PM1) were used. Total aerosol mass was dominated by secondary aerosol formation, which was approximately 2 orders of magnitude higher than the primary aerosol. The chemical composition of both gaseous and particle emissions were also monitored at different engine loads and were thrust-dependent. At idling load (thrust 2.5–7 %), more than 90 % of the secondary particle mass was organic and could mostly be explained by the oxidation of gaseous aromatic species, e.g., benzene; toluene; xylenes; tri-, tetra-, and pentamethyl-benzene; and naphthalene. The oxygenated-aromatics, e.g., phenol, furans, were also included in this aromatic fraction and their oxidation could alone explain up to 25 % of the secondary organic particle mass at idling loads. The organic fraction decreased with thrust level, while the inorganic fraction increased. At an approximated cruise load sulfates comprised 85 % of the total secondary particle mass., Atmospheric Chemistry and Physics, 18 (10), ISSN:1680-7375, ISSN:1680-7367

Gasoline direct injection (GDI) vehicles have recently been identified as a significant source of carbonaceous aerosol, of both primary and secondary origin. Here we investigated primary emissions and secondary organic aerosol (SOA) formation from GDI vehicle exhaust for multiple vehicles and driving test cycles, and novel GDI after-treatment systems. Emissions were characterized by proton transfer reaction time-of-flight mass spectrometry (gaseous non-methane organic compounds, NMOCs), aerosol mass spectrometry (sub-micron non-refractory particles), and light attenuation measurements (equivalent black carbon (eBC) determination using Aethalometer measurements) together with supporting instrumentation. We evaluated the effect of retrofitted prototype gasoline particle filters (GPFs) on primary eBC, organic aerosol (OA), NMOCs, as well as SOA formation. Two regulatory driving test cycles were investigated, and the importance of distinct phases within these cycles (e.g. cold engine start, hot engine start, high speed driving) to primary emissions and secondary products was evaluated. Atmospheric processing was simulated using both the PSI mobile smog chamber (SC) and the potential aerosol mass oxidation flow reactor (OFR). GPF retrofitting was found to greatly decrease primary particulate matter (PM) through removal of eBC, but showed limited partial removal of the minor POA fraction, and had no detectable effect on either NMOC emissions (absolute emission factors or relative composition) or SOA production. In all tests, overall primary and secondary PM and NMOC emissions were dominated by the engine cold start, i.e. before thermal activation of the catalytic after-treatment system. Differences were found in the bulk compositional properties of SOA produced by the OFR and the SC (O : C and H : C ratios), while the SOA yields agree within our uncertainties, with a tendency for lower SOA yields in SC experiments. A few aromatic compounds are found to dominate the NMOC emissions (primarily benzene, toluene, xylene isomers and C3-benzenes). A large fraction (> 0.5) of the SOA production was explained by those compounds, based on investigation of reacted NMOC mass and comparison with SOA yield curves of toluene, o-xylene and 1,2,4-trimethylbenzene determined in our OFR within this study. Remaining differences in the obtained SOA yields may result from diverse reasons including aging conditions, unaccounted-for precursors and differences in SOA yields of aromatic hydrocarbons with different degrees of substitution, as well as experimental uncertainties in the assessment of particle and vapor wall losses.

Carbonaceous particulate matter (PM), comprising black carbon (BC), primary organic aerosol (POA) and secondary organic aerosol (SOA, from atmospheric aging of precursors), is a highly toxic vehicle exhaust component. Therefore, understanding vehicle pollution requires knowledge of both primary emissions, and how these emissions age in the atmosphere. We provide a systematic examination of carbonaceous PM emissions and parameterisation of SOA formation from modern diesel and gasoline cars at different temperatures (22, −7 °C) during controlled laboratory experiments. Carbonaceous PM emission and SOA formation is markedly higher from gasoline than diesel particle filter (DPF) and catalyst-equipped diesel cars, more so at −7 °C, contrasting with nitrogen oxides (NOX). Higher SOA formation from gasoline cars and primary emission reductions for diesels implies gasoline cars will increasingly dominate vehicular total carbonaceous PM, though older non-DPF-equipped diesels will continue to dominate the primary fraction for some time. Supported by state-of-the-art source apportionment of ambient fossil fuel derived PM, our results show that whether gasoline or diesel cars are more polluting depends on the pollutant in question, i.e. that diesel cars are not necessarily worse polluters than gasoline cars.

Small-scale pellet boilers and stoves became popular as a wood combustion appliance for domestic heating in Europe, North America and Asia due to economic and environmental aspects. Therefore, an increasing contribution of pellet boilers to air pollution is expected despite their general high combustion efficiency. As emissions of primary organic aerosol (POA) and permanent gases of pellet boilers are well investigated, the scope of this study was to investigate the volatile organic emissions and the formation potential of secondary aerosols for this type of appliance. Fresh and aged emissions were analysed by a soot-particle aerosol time-of-flight mass spectrometry (SP-AMS) and the molecular composition of the volatile precursors with single-photon ionisation time-of-flight mass spectrometry (SPI-TOFMS) at different pellet boiler operation conditions. Organic emissions in the gas phase were dominated by unsaturated hydrocarbons while wood-specific VOCs, e.g. phenolic species or substituted furans, were only detected during the starting phase. Furthermore, organic emissions in the gas phase were found to correlate with fuel grade and combustion technology in terms of secondary air supply. Secondary organic aerosols of optimised pellet boiler conditions (OPT, state-of-the-art combustion appliance) and reduced secondary air supply (RSA, used as a proxy for pellet boilers of older type) were studied by simulating atmospheric ageing in a Potential Aerosol Mass (PAM) flow reactor. Different increases in OA mass (55% for OPT, 102% for RSA), associated with higher average carbon oxidation state and O:C, could be observed in a PAM chamber experiment. Finally, it was found that derived SOA yields and emission factors were distinctly lower than reported for log wood stoves., final draft, peerReviewed

The review highlights the correlation between removal of various eco-toxins by micro algae and the production of high-value products thereof. It appraises established and novel strategies for micro algal cultivation, downstream processing methods for product recovery, and recent progress in algal generation of the green energy carriers biogas and biohydrogen micro algae. The suitability of selected micro algal species for various final products, and the potential of different strains for abating environmental problems are discussed. Due to the fact that low cell densities and moderate growth rates are known as the major obstacles towards a broad market penetration of micro algal products, the article shows how high cell densities and reasonable volumetric productivities can be obtained. Here, the article deals with the improvements of process design and nutrient supply regimes that are needed to achieve these goals. As demonstrated by an integrated case study, mixotrophic cultivation results in increased biomass concentration in a first cultivation step for some micro algal strains like Nannochloropsis oculata . In a second step, the fresh active algal biomass accumulates desired products via CO 2 fixation, e.g. from industrial effluent gases, as the sole carbon source. This can be realized by a novel, two-stage, continuously operated closed photo-bioreactor system. After cell harvest and optimized product recovery, the value-added conversion of residual algal biomass for generation of green energy carriers, e.g. in biogas plants, constitutes another focal point of the ongoing research.

Microalgae are the primary producers of economically valuable polyunsaturated fatty acids (PUFAs) and can be used as a resource for biorefining. In this respect, these high-value products may support the economical viable energy recovery from microalgae. The extraction of PUFA-containing lipids from Nannochloropsis oculata , a marine species rich in eicosapentaenoic acid (EPA), was tested with a commercially available pressurized fluid extraction technique (PFE, traded as Accelerated Solvent Extraction (ASE ® )) in our study. Solvents, which are suitable for an application in the food and pharmaceuticals industry, were used ( n -hexane, n -hexane/propan-2-ol (2:1 vol.%), ethanol 96 vol.%) to test the quantitative effect of solvent polarity on the gravimetric extraction yield, total fatty acid and EPA yield. The highest extraction yield resulted from ethanol extraction (36 ± 4 mass%), compared to low yields from n -hexane extraction (6.1 ± 0.3 mass%). A maximum fatty acid yield of 16.7 ± 0.6 mass% was determined for the biomass extracted with the green solvent ethanol. The EPA yield of 3.7 ± 0.1 mass% with the use of ethanol indicates that EPA production from N. oculata is economically beneficial, referring to prognosis from literature. The remaining biomass may eventually be used for energy recovery and other applications within a biorefinery concept.

Aerodyne aerosol mass spectrometer (AMS) and Aerodyne aerosol chemical speciation monitor (ACSM) mass spectra are widely used to quantify organic aerosol (OA) elemental composition, oxidation state, and major environmental sources. The OA CO

Urban case studies: general discussion

Cooking processes produce gaseous and particle emissions that are potentially deleterious to human health. Using a highly controlled experimental setup involving a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS), we investigate the emission factors and the detailed chemical composition of gas phase emissions from a broad variety of cooking styles and techniques. A total of 95 experiments were conducted to characterize nonmethane organic gas (NMOG) emissions from boiling, charbroiling, shallow frying, and deep frying of various vegetables and meats, as well as emissions from vegetable oils heated to different temperatures. Emissions from boiling vegetables are dominated by methanol. Significant amounts of dimethyl sulfide are emitted from cruciferous vegetables. Emissions from shallow frying, deep frying and charbroiling are dominated by aldehydes of differing relative composition depending on the oil used. We show that the emission factors of some aldehydes are particularly large which may result in considerable negative impacts on human health in indoor environments. The suitability of some of the aldehydes as tracers for the identification of cooking emissions in ambient air is discussed.

Mechanical processing using predominantly particle size and density as separation criteria is currently applied in the production of solid-recovered fuel or refuse-derived fuel. It does not sufficiently allow for the optimization of the quality of heterogeneous solid waste for subsequent energy recovery. Material-specific processing, in contrast, allows the separation criterion to be linked to specific chemical constituents. Therefore, the technical applicability of material-specific sorting of heterogeneous waste, in order to optimize its routing options, was evaluated. Two sorting steps were tested on a pilot and a large scale. Near infrared multiplexed sensor-based sorting devices were used (1) to reduce the chlorine (Cl) respectively pollutant content, in order to broaden the utilization options of SRF in industrial co-incineration, and (2) to increase the biogenic carbon (Cbio) content, which is highly relevant in the light of the EU emission trading scheme on CO2. It was found that the technology is generally applicable for the heterogeneous waste fractions looked at, if the sensor systems are appropriately adjusted for the sorting task. The first sorting step allowed for the removal of up to 40% of the Cl freight by separating only 3 to 5% of the material mass. Very low Cl concentrations were achieved in the output stream to be used as solid-recovered fuel stream and additionally, the cadmium (Cd) and lead (Pb) concentration was decreased. A two- to four-fold enriched Cbio content was achieved by the second sorting step. Due to lower yields in the large-scale test further challenges need to be addressed.

International audience; Incentives to use biofuels may result in increasing vehicular emissions of compounds detrimental to air quality. Therefore, regulated and unregulated emissions from a Euro 5a flex-fuel vehicle, tested using E85 and E75 blends (gasoline containing 85% and 75% of ethanol (vol/vol), respectively), were investigated at 22 and -7 degrees C over the New European Driving Cycle, at the Vehicle Emission Laboratory at the European Commission Joint Research Centre Ispra, Italy. Vehicle exhaust was comprehensively analyzed at the tailpipe and in a dilution tunnel. A fraction of the exhaust was injected into a mobile smog chamber to study the photochemical aging of the mixture. We found that emissions from a flex-fuel vehicle, fueled by E85 and E75, led to secondary organic aerosol (SOA) formation, despite the low aromatic content of these fuel blends. Emissions of regulated and unregulated compounds, as well as emissions of black carbon (BC) and primary organic aerosol (MA) and SOA formation were higher at -7 degrees C. The flex-fuel unregulated emissions, mainly composed of ethanol and acetaldehyde, resulted in very high ozone formation potential and SOA, especially at low temperature (860 mg O-3 km(-1) and up to 38 mg C kg(-1)). After an OH exposure of 10 x 10(6) cm(-3) h, SOA mass was, on average, 3 times larger than total primary particle mass emissions (BC + POA) with a high O:C ratio (up to 0.7 and 0.5 at 22 and -7 degrees C, respectively) typical of highly oxidized mixtures. Furthermore, high resolution organic mass spectra showed high 44/43 ratios (ratio of the ions m/z 44 and m/z 43) characteristic of low-volatility oxygenated organic aerosol. We also hypothesize that SOA formation from vehicular emissions could be due to oxidation products of ethanol and acetaldehyde, both short-chain oxygenated VOCs, e.g. methylglyoxal and acetic acid, and not only from aromatic compounds. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Fossil fuel-powered vehicles emit significant particulate matter, for example, black carbon and primary organic aerosol, and produce secondary organic aerosol. Here we quantify secondary organic aerosol production from two-stroke scooters. Cars and trucks, particularly diesel vehicles, are thought to be the main vehicular pollution sources. This needs re-thinking, as we show that elevated particulate matter levels can be a consequence of asymmetric pollution from two-stroke scooters, vehicles that constitute a small fraction of the fleet, but can dominate urban vehicular pollution through organic aerosol and aromatic emission factors up to thousands of times higher than from other vehicle classes. Further, we demonstrate that oxidation processes producing secondary organic aerosol from vehicle exhaust also form potentially toxic reactive oxygen speciesa. © 2014 Macmillan Publishers Limited.

Summary Wetlands worldwide are threatened by environmental change. Differences in groundwater composition is one of the factors affecting wetland terrestrial floristic biodiversity. However, few studies discuss variations in wetland groundwater composition. This study presents an analysis of local-scale spatial and short-term temporal variations in 15 groundwater composition parameters of the 7 km 2 Naardermeer wetland nature reserve in The Netherlands. Data is available from a network of 35 groundwater wells with 2–4 filters each, at depths between 50 and 800 cm, which were sampled about monthly over a 1-year period, totalling 1042 chemical analysis from 103 filter screens. Relative standard deviations indicate large differences in variation between parameters. Largest spatial and temporal variations were found for nutrients ( NO 3 - , PO 4 3 - , NH 4 + ) and redox sensitive parameters (Fe, Mn), and lowest variations for macroions and SiO 2 . A horizontal zonation in groundwater concentrations has been found related to soil type and soil wetness, with largest horizontal decrease in NO 3 - and SO 4 2 - , and largest increase in Fe and SiO 2 , going in the groundwater flow direction from dry sandy soils to wet peat/clay soils. No clear horizontal patterns have been found for the macroions. Spatial zonations in the north–south direction and with depth are absent for all parameters. Spatial and temporal variations were found to be related. 3D-maps indicate highest temporal fluctuations at filter screens with lowest median concentrations for NO 3 - , SO 4 2 - and Fe, but the reverse pattern for SiO 2 . High temporal variations of nutrients and redox sensitive parameters could not be traced back to a seasonal trend. The spatial and temporal variability of groundwater quality parameters as presented in this study, together with their reported effects on different vegetation types, may be used to design efficient monitoring schemes by nature managers having set specific vegetation development targets for different spatial locations.