Publications

We have recently shown in this journal (Müller et al. Anal. Chem. 2017, 89, 10889–10897) how a proton-transfer-reaction mass spectrometry (PTR-MS) analyzer measured particulate organic matter in urban atmospheres using the “Chemical Analysis of Aerosol Online” (CHARON) inlet. Our initial CHARON studies did not take into account fragmentation of protonated analyte molecules, which introduced a small but significant negative bias in the determination of bulk organic aerosol parameters. Herein, we studied the ionic fragmentation of 26 oxidized organic compounds typically found in atmospheric particles. This allowed us to derive a correction algorithm for the determination of the bulk organic mass concentration, m_OA, the bulk-average hydrogen-to-carbon ratio, (H:C)_bulk, the bulk-average oxygen-to-carbon ratio, (O:C)_bulk, and the bulk-average molecular formula, MF_bulk. The correction algorithm was validated against AMS data using two sets of published data. Finally, we determined MF_bulk of particles generated from the reaction of α-pinene and ozone and compared and discussed the results in relation to the literature.

• Leglise, J 1
• Muller, M 2
• Piel, F 2,4
• Otto, T 3
• Wisthaler, A 4,5

1. CNRS-ICARE, 45100 Orleans, France
2. IONICON Analytik GmbH, 6020 Innsbruck, Austria
3. Atmospheric Chemistry Department (ACD), Leibniz Institute for Tropospheric Research (TROPOS), 04318 Leipzig, Germany
4. Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, 6020 Innsbruck, Austria
5. Department of Chemistry, University of Oslo, 0315 Oslo, Norway

Scientific progress in aerosol chemistry is still hampered by the lack of analytical methods that characterize the organic composition of particulate matter directly and in real-time. As a consequence, dilution-driven and oxidation induced changes of organic aerosol remain poorly characterized on the molecular level. Recently, the “Chemical
Analysis of Aerosol Online” (CHARON) particle inlet has been introduced, enabling proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) instruments to directly characterize particulate-bound organics in real-time down to the molecular sum formula level. For this study, we coupled a CHARON PTR-ToF-MS instrument to a flow reactor to analyze secondary organic aerosol (SOA) formed by the ozonolysis of -pinene, limonene and 3-carene, respectively. In addition, a thermodenuder was added between the reactor and the CHARON-PTRToF-MS instrument for measuring the volatility of SOA constituents and for comparing experimental data with predictions based on the 2D volatility basis set (2D-VBS). We found that the saturation mass concentration of the bulk aerosol can be predicted to within one order of magnitude based on the speciated chemical information obtained by CHARON-PTR-ToF-MS.
J.L. and F. P. received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement number 690958 (MARSU) and grant agreement Nº674911 (IMPACT), respectively.

• Muller, M 1
•  Leglise, J 2
• Piel, F 1
• Wisthaler, A 3,4

1. IONICON Analytik GmbH, 6020 Innsbruck, Austria
2. CNRS-ICARE, 45100 Orleans, France
3. Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, 6020 Innsbruck, Austria
4. Department of Chemistry, University of Oslo, 0315 Oslo, Norway

Herein we present a detailed characterization of CHARON PTR-TOF based on the detection of a set of pure compounds including ionic fragmentation, sensitivity and response times. We present a recipe on how to quantitatively and qualitatively measure the organic fraction of aerosol in realtime. Intercomparison studies with alternative instruments show great agreements for urban aerosol and secondary organic aerosol (SOA) formed in various oxidation reactors. We will show first results of the characterization of SOA produced from the ozonolysis of a set of monoterpenes. These results include the chemical composition as well as the volatility of the bulk SOA and individual constituents.

• Muller, M 1
• Leglise, J 2
• Piel, F 1
• Wisthaler, A 3,4

1. IONICON Analytik GmbH, 6020 Innsbruck, Austria
2. CNRS-ICARE, 45100 Orleans, France
3. Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, 6020 Innsbruck, Austria
4. Department of Chemistry, University of Oslo, 0315 Oslo, Norway

Bacteria are ubiquitous in the near-surface atmosphere where they constitute an important component of aerosols with the potential to affect climate change, ecosystems, atmospheric process and human health. Limitation in tracking bacterial diversity accurately has thus far prevented the knowledge of airborne bacteria and their pathogenic properties. We performed a comprehensive assessment of bacterial abundance and diverse community in PM_2.5 collected at Mt. Tai, via high-throughput sequencing and real-time PCR. The samples exhibited a high microbial biodiversity and complex chemical composition. The dominating populations were gram-negative bacteria including Burkholderia, Delftia, Bradyrhizobium, and Methylobacterium. The PM mass concentration, chemical composition, bacterial concentration and community structure varied under the influence of different air-mass trajectories. The highest mass concentration of PM_2.5 (61 μg m^-3) and major chemical components were recorded during periods when marine southeasterly air masses were dominant. The local terrestrial air masses from Shandong peninsula and its adjacent areas harbored highest bacterial concentration loading (602 cells m^-3) and more potential pathogens at the site. In contrast, samples influenced by the long-distance air flow from Siberia and Outer Mongolia were found to have a highest richness and diversity as an average, which was also marked by the increase of dust-associated bacteria (Brevibacillus and Staphylococcus). The primary research may serve as an important reference for the environmental microbiologist, health workers, and city planners.

• Xu, C 1
• Wei, M 3
• Chen, J 3
• Zhu, C 1,2,4,5
• Li, J 1
• Xu, X 2
• Wang, W 2
• Zhang, Q 2
• Ding, A 4
• Kan, H 5
• Zao, Z 5
• Mellouki, A 1,3,6
  

1. Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP, Fudan Tyndall Centre, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, China
2. College of Geography and Environment, Shandong Normal University, Jinan 250100, China
3. Environment Research Institute, School of Environmental Science and Engineering, Shandong University, Ji’nan 250100, China
4. Institute for Climate and Global Change Research, School of Atmospheric Sciences, Nanjing University, Nanjing 210023, Jiangsu, China
5. School of Public Health, Key Lab of Public Health Safety of the Ministry of Education and NHC Key Laboratory of Health Technology Assessment, Fudan University, Shanghai 200032, China
6. CNRS, Inst Combust Aerotherm Reactivite & Environm, F-45071 Orleans 02, France

Aiming to a better understanding sources contributions and regional sources of fine particles, a total of 273 filter samples (159 of PM2.5 and 114 of PM1.0) were collected per 8 h during the winter 2016 at a southwest suburb of Beijing. Chemical compositions, including water soluble ions, organic carbon (OC), and elemental carbon (EC), as well as secondary organic carbon (SOC), were systematically analyzed and estimated. The total ions concentrations (TIC), OC, and SOC of PM2.5 were with the following order: 16:00-24:00 > 08:00-16:00 > 00:00-08:00. Since primary OC and EC were mainly attributed to the residential combustion in the night time, their valley values were observed in the daytime (08:00-16:00). However, the highest ratio value of SOC/OC was observed in the daytime. It is because that SOC is easily formed under sunshine and relatively high temperature in the daytime. Positive matrix factorization (PMF), clustering, and potential source contribution function (PSCF) were employed for apportioning sources contributions and speculating potential sources spatial distributions. The average concentrations of each species and the source contributions to each species were calculated based on the data of species concentrations with an 8 h period simulated by PMF model. Six likely sources, including secondary inorganic aerosols, coal combustion, industrial and traffic emissions, road dust, soil and construction dust, and biomass burning, were contributed to PM2.5 accounting for 29%, 21%, 17%, 16%, 9%, 8%, respectively. The results of cluster analysis indicated that most of air masses were transported from West and Northwest directions to the sampling location during the observation campaign. Several seriously polluted areas that might affect the air quality of Beijing by long-range transport were identified. Most of air masses were transported from Western and Northwestern China. According to the results of PSCF analysis, Western Shandong, Southern Hebei, Northern Henan, Western Inner Mongolia, Northern Shaanxi, and the whole Shanxi provinces should be the key areas of air pollution control in China. The exposure-response function was used to estimate the health impact associated with PM2.5 pollution. The population affected by PM2.5 during haze episodes reached 0.31 million, the premature death cases associated with PM2.5 reached 2032. These results provided important implication for making environmental policies to improve air quality in China.

• Xu, Xianmang 1
• Zhang, Hefeng 2
• Chen, Jianmin 1,3,4
• Li, Qing 3
• Wang, Xinfeng 1
• Wang, Wenxing 1
• Zhang, Qingzhu 1
• Xue, Likun 1
• Ding, Aijun 4
• Mellouki, Abdelwahid 1,3,5 

1. Shandong Univ, Environm Res Inst, Sch Environm Sci & Engn, Jinan 250100, Shandong, Peoples R China
2. Chinese Res. Inst Environm Sci, Atmospher Environm Inst, Minist Environm Protect, Beijing 100012, Peoples R China
3. Fudan Univ, Dept Environm Sci & Engn, Fudan Tyndall Ctr, Shanghai Key Lab Atmospher Particle Pollut & Prev, Shanghai 200433, Peoples R China
4. Nanjing Univ, Inst Climate & Global Change Res, Sch Atmospher Sci, Nanjing 210023, Jiangsu, Peoples R China
5. CNRS, Inst Combust Aerotherm Reactivite & Environm, F-45071 Orleans 02, France

The Yangtze River is the longest river in China; nearly one-third of the national population lives along the river. Air quality over the Yangtze River is important as it may have significant influences on the aquatic ecosystem, the health of everyone living along the Yangtze River, and regional climate change. Chemical compositions of ambient aerosol were determined during a comprehensive cruise campaign carried out along the mid–lower reaches of the Yangtze River (MLYR) in winter of 2015. The total average concentration of PM_2.5 was 119.29±33.67µgm⁻³, and the dominant ionic composition in PM_2.5 was SO²⁻₄ with an average concentration of 15.21±6.69µgm⁻³, followed by NO⁻₃ (13.76±4.99µgm⁻³), NH⁺₄ (9.38±4.35µgm⁻³), and Ca²⁺ (2.23±1.24µgm⁻³) in this cruise. Based on the filter samples, the concentration and chemical composition of PM_2.5 were remarkably varied or fluctuated from coastal areas to inland over the MLYR region. Crustal elements (Ca, Mg, Al, and K) from floating dust showed peak concentrations in the Yangtze River Delta (YRD) region, while secondary inorganic species (SO²⁻₄, NO⁻₃, and NH⁺₄) and some of the most enriched elements (Pb, As, Se, and Cd) presented high levels in central China (Wuhan region). The significant correlation between Se and SO²⁻₄ suggested that coal combustion may play an important role in secondary inorganic aerosol formation. The relatively high enrichment factors (EFs) of Ca (EFs > 100) suggested the crustal elements may derive from anthropogenic sources. Furthermore, the concentration of levoglucosan in PM_2.5 and the CO column level from satellite observation were greatly enhanced in the rural areas (Anhui and Jiangxi), indicating that biomass burning may make a remarkable contribution to rural areas. The concentrations of typical tracer for heavy oil (V and Ni) significantly increased in the Shanghai port, which was mainly ascribed to ship emissions, based on the air mass source analysis and the relatively high ratio of V∕Ni as well. The results shown herein portray a good picture of air pollution along the Yangtze River.

• Li, Zhong 1
• Li, Chunlin 1,2
• Ye, Xingnan 1
• Fu, Hongbo 1
• Wang, Lin 1
• Yang, Xin 1
• Wang, Xinke 3
• Zhao, Zhuohui 4
• Kan, Haidong 4
• Mellouki, Abdelwahid 5 
• Chen, Jianmin 1,4F

1. Fudan Univ, Inst Atmospher Sci, Shanghai Key Lab Atmospher Particle Pollut & Prev, Fudan Tyndall Ctr, Dept Environm Sci & Engn, Shanghai 200433, Peoples R China
2. Weizmann Inst Sci, Dept Earth & Planetary Sci, IL-7610001 Rehovot, Israel
3. Univ Lyon, Univ Claude Bernard Lyon 1, CNRS, IRCELYON, F-69626 Villeurbanne, France
4. Fudan Univ, Sch Publ Hlth, Shanghai 200032, Peoples R China
5. CNRS, Inst Combust Aerotherm Reactivite & Environm, F-45071 Orleans 02, France

Peatlands are efficient ecosystems for Carbon sequestration (30% of the world’s soil C stock). Under healthy ecosystem conditions, C is stored from atmospheric CO₂ assimilation (photosynthesis, vegetation growth, accumulation of organic maters which has not been completely decomposed, leading to peat formation and accumulation). Anthropogenic global changes (Climate, pollution, land use) have a strong impact on peatlands C exchange (as GreenHouse gases) with atmosphere and on peatlands survey, where C may be released instead of being stored. Sphagnum peatlands represent the main C pool and are mainly located in subarctic or temperate wet regions. Subarctic sphagnum peatlands will experience the most drastic climate changes (IPPC 2007). As a consequence the feedback of global changes on C exchange from sphagnum peatlands and in return the impact to the future climate evolution need to be assessed.

From the previous statements, investigation and parametrization of the key factors controlling GHG exchanges and C balance, and the impact of global changes of these factors, for sphagnum peatlands, is considered as a global priority to deal with global warming. Findings from such investigations will help to improve mitigation policy for global warming by conservation of natural peatlands or restoration of disturbed peatlands.

Key factors controlling GHG exchanges and C balance in peatlands are presented hereafter from field study at various scales:

-First at the vegetation scale: The approach to determine the major controlling factors of GHG fluxes and C balance is obtained as follow: Seasonal and daily cycles of CO₂, CH₄ and N₂O fluxes are monitored at the m² scale (with IR sensors and manual chambers). Then, fluxes are optimized from (empirical and/or mechanistic) modeling by scaling the most influent environmental parameters. Finally, gap filing for missing data at different scales (spatial and temporal) provides C balance at a yearly scale. From well controlled peat cores (mesocosms) extracted in a French peatland (La Guette), the investigation of the effect of vegetation, nitrate input, water table (drought) and artificial warming with open top chambers (following ITEX protocol) enabled us to determine the major controlling factors of GHG fluxes (Leroy et al., 2017). From field experiments in real sites (la Guette peatland) C balance has been estimated before water table restoration initiated by the installation of a dam upstream the peatland in the frame FEDER-EU, Région CVL :  CARBIODIV (2013-16) and CAREX (2017-21) projects (d’Angelo et al. 2016 and in preparation).

-Second at the ecosystem, regional and world scales: To improve C balance investigation, ecosystem level observations started to be studied since 2017 by the installation of an eddy covariance flux station in la Guette peatland supported by the project PIVOTS Région CVL (ARD2020, FEDER, CPER). Similar flux towers are under installation on 2 other sites of the French Peatland Observation Service (SNO Tourbières, CNRS/INSU-SIC) and on the CliMireSiber worldwide Network of peatlands (from Europe to Russia).

• Christophe Guimbaud 1
• S. Gogo 1
• F. Leroy 1
• B. d’Angelo 1
• Q. Li 1
• A. Jacotot 1
•  J.B. Paroissien 1
• L. Perdereau 1
• C. Robert 1 
• M. Chartier 1
• P. Jacquet 1
• E. Salmon 1
• A, Z. Hu 2
• S. Wang 2
• F. Jégou 1
• F. Laggoun 1

1. University of Orleans/CNRS, Orleans-France
2. School of Environmental Science and Engineering, Environment Research Institute, Shandong University, Qingdao, Shandong, China

The presentation first focus on the performances and applications of a new high resolution laser infrared spectrometer (SPIRIT) for measurements of greenhouse gas mixing ratios and fluxes from peatlands and hydrocarbon-contaminated soils to the atmosphere, with the ability to determine the δ¹³C/¹²C of CO₂ emissions.

The presentation then focuses on the ability to monitor the remediation dynamic from biodegradation of hydrocarbon contaminants in underground water by the CO₂ byproduct analysis emitted at ground surface (flux and δ¹³C/¹²C determination). The investigated site is an old gasoline station near Paris contaminated by BTEX hydrocarbons remaining from tanks leak. A bioactive barrier has been set to stimulated aerobic biodegradation by H₂O₂ liquid injection in the aquifer. Good cartographic correlation is observed from upstream to downstream the depollution plume between (i) the CO₂ flux emitted at soil surface and the BTEX concentration in the aquifer and (ii) the δ¹³C/¹²C of CO₂ emitted and the underground δ¹³C/¹²C of BTEX, with some fractionation factor. Results demonstrate the effectiveness of monitoring a stimulated bio-depollution in real time without excavation of soil matter by measurements of the surface CO₂ emission fluxes with δ¹³C/¹²C characterization. For the first time, the kinetic of bio-depollution could be quantified from the Rayleigh equations applied on the monitoring of δ¹³C/¹²C of the CO₂ released at ground surface. CO₂ monitoring at ground surface could be a cost effective way to monitor real time biological or chemical treatments of depollution in order to optimize soil bio-treatment.

• Christophe Guimbaud 1
• C. Noel 1 
• I. Ignatiadis 1
• C. Robert 1
• M. Chartier 1
• P. Jacquet 1
• J. Jacob 1
• A. Grossel 2
• A, Z. Hu 3
• S. Wang 3
• F. Jégou 1
• J.C. Gourry 1

1. University of Orleans/CNRS, Orleans-France
2. INRA, Orleans-France
3. School of Environmental Science and Engineering, Environment Research Institute, Shandong University, Qingdao, Shandong, China

To date, few comprehensive field observations of new particle formation (NPF) have been carried out at mountaintop sites in China. In this study, simultaneous measurements of particle size distribution, trace gases, meteorological parameters, and mass concentration and chemical composition of PM2:5 were performed at the summit of Mt. Tai (1534ma.s.l.) from 25 July to 24 August 2014 (Phase I), 21 September to 9 December 2014 (Phase II), and 16 June to 7 August 2015 (Phase III) to investigate characteristics and favorable conditions of NPF in a relatively clean mountaintop environment. The NPF events were identified based on particle size distribution measured by the neutral cluster and air ion spectrometer (NAIS), and 66 such events were observed during a period of 164 days – corresponding to an occurrence frequency of 40 %. The formation rates of 3 nm particles (J3) and growth rates were in the ranges of 0.82–25.04 cm-3 s-1 and 0.58–7.76 nm h-1, respectively. On average, the condensation sink (CS), O3 concentration, air temperature, and relative humidity were lower, whereas the SO2 concentration was higher on NPF days than that on non-NPF days. The CS on Mt. Tai was at a low level and lower CS was critical for NPF. NPF events were common when wind came from the east-southeast and west-southwest, which was probably associated with relatively lower CS in the east-southeast and higher SO2 concentration in the west-southwest. O3 was not a governing factor for NPF in this study, and a high level of NOx concentration might be responsible for the decreased O3 concentration on NPF days. Three categories of backward trajectories were classified, among which the continental air mass was the majority. The continental air mass passing through more polluted areas (denoted as Type I) favored NPF because of enhanced SO2 concentration and potential ammonia with it. An in-depth analysis of SO2 indicated that sulfuric acid was a dominant precursor on Mt. Tai; meanwhile, biogenic organics released from ambient forests in warm seasons and anthropogenic volatile organic compounds emitted from domestic heating in cold seasons also promoted NPF.

• Ganglin Lu 1
• Xiao Sui 1
• Jianmin Chen 1,2
• Rohan Jayaratne 3
• Abdelwahid Mellouki 1,4

1. School of Environmental Science and Engineering, Environment Research Institute, Shandong University, Jinan, Shandong 250100, China
2. Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Institute of Atmospheric Sciences, Fudan University, Shanghai 200433, China
3. International Laboratory for Air Quality and Health, Science and Engineering Faculty, Queensland University of Technology, G.P.O. Box 2434, Brisbane, QLD4001, Australia
4. Institut de Combustion, Aérothermique, Réactivité et Environnement, CNRS, 45071 Orléans CEDEX 02, France

The chemical characterization of the organic fraction of atmospheric particulate matter is still a challenge. Herein we present the novel modular “Chemical Analysis of Aerosol Online” (CHARON) particle inlet coupled to a new-generation proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF 6000 X2, Ionicon Analytik, Austria), The PTR-TOF 6000 X2 detects organic analytes in real-time at sub-pptV levels by chemical ionization with hydronium reagent ions. The CHARON inlet consists of a gas-phase denuder for stripping off gas-phase analytes (efficiency >99.999%), an aerodynamic lens for particle collimation, an inertial sampler for the particle-enriched flow and a thermodesorption unit for particle volatilization. With an enrichment factor of 30 for particle diameters (DP) between 120 nm and 1000 nm (lower enrichment for particles in the 60-to-120 nm diameter range), the CHARON PTR-TOF 6000 X2 system detects particulate organic matter online and in real-time down to 200 pg m-3. Proton transfer from hydronium ions quantitatively ionizes almost the full range of organic analytes in the intermediate to low volatility range. The high mass resolution (R > 6000) and mass accuracy (< 10 ppm) of the Ionicon PTR-TOF 6000 X2 allows to assign elemental compositions to organic analyte ions over a large mass range. We will present a detailed characterization of the CHARON PTR-TOF 6000 X2 instrument and first results from ambient air measurements in Innsbruck (Austria).

The development of CHARON was funded through the PIMMS ITN, which was supported by the European Commission’s 7th Framework Programme under grant agreement number 287382. J.L. received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement number 690958 (MARSU).

• Markus Müller 1,2
• Andreas Klinger 1
• Gregor Mayramhof 1
• Joris Leglise 3
• Armin Wisthaler 2, 4
  1. IONICON Analytik GmbH., Innsbruck, Austria
  2. Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
  3. CNRS-ICARE/University of Orleans, Orleans, France
  4. Department of Chemistry, University of Oslo, Oslo, Norway

Scientific progress in organic aerosol chemistry is still hampered by the lack of analytical methods that comprehensively and quantitatively characterize the organic composition of particulate matter in the atmosphere. Recently, the “Chemical Analysis of Aerosol Online” (CHARON) particle inlet has been introduced, enabling proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) instruments to characterize particulate-bound organics down to pg m-3 levels. Herein, we will demonstrate the potential of the CHARON-PTR-ToF-MS for aerosol chemistry and physics studies. Based on results from experiments on 36 pure compounds we will show how qualitative (elemental composition) and quantitative analyses (mass concentrations) can be corrected for biases caused by analyte ion fragmentation in the PTR-ToF-MS analyzer. We will further show how bulk elemental ratios (O:C, H:C) of urban aerosol and monoterpene-derived SOA compare with parallel TOF-AMS measurements and reported literature values. We will also compare the volatility of monoterpene-derived SOA on a molecular level as directly measured in thermodenuder experiments and predicted from the 2D-volatility basis set using the CHARON-PTR-ToF-MS-derived chemical composition. The implications for the aerosol chemistry of monoterpene-derived SOA will be discussed.

The development of CHARON was funded through the PIMMS ITN, which was supported by the European Commission’s 7th Framework Programme under grant agreement number 287382. J.L. and T.O. received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement number 690958 (MARSU).

• Joris Leglise 1
•  Markus Müller 2,3
• Tobias Otto 4
• Armin Wisthaler 3, 5
  1. CNRS-ICARE/University of Orleans, Orleans, France
  2. IONICON Analytik GmbH., Innsbruck, Austria
  3. Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
  4. Leibniz-Institut für Troposhärenforschung e.V., Leipzig, Germany
  5. Department of Chemistry, University of Oslo, Oslo, Norway

A quantitative characterization of the organic fraction of atmospheric particulate matter is still challenging. Herein we present the novel modular “Chemical Analysis of Aerosol Online” (CHARON) particle inlet system coupled to a new-generation proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF 6000 X2, Ionicon Analytik, Austria) that quantitatively detects organic analytes in real-time and sub-pptV levels by chemical ionization with hydronium reagent ions. CHARON consists of a gas-phase denuder for stripping off gas-phase analytes (efficiency > 99.999%), an aerodynamic lens for particle collimation combined with an inertial sampler for the particle-enriched flow and a thermodesorption unit for particle volatilization prior to chemical analysis. With typical particle enrichment factors of around 30 for particle diameters (D_P) between 120 nm and 1000 nm (somewhat reduced enrichment for 60 nm < D_P < 120 nm) we boost the already excellent limits of detection of the PTR-TOF 6000 X2 system to unprecedented levels. We demonstrate that particulate organic analytes of mass concentrations down to 100 pg m^-3 can be detected on-line and in single-minute time-resolutions. In addition, PTR-MS allows for a quantitative detection of almost the full range of particulate organics of intermediate to low volatility. With the high mass resolution (R > 6000) and excellent mass accuracies (< 10 ppm) chemical compositions can be assigned and included in further analyses.

• Markus Müller 1,2
• Andreas Klinger 2
• Gregor Mayramhof 2
• Joris Leglise 3
• Tobias Otto 4
• Armin Wisthaler 1, 5
  1. Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
  2. IONICON Analytik GmbH., Innsbruck, Austria
  3. CNRS-ICARE/University of Orleans, Orleans, France
  4. Leibniz-Institut für Troposhärenforschung e.V., Leipzig, Germany
  5. Department of Chemistry, University of Oslo, Oslo, Norway

Films of biogenic compounds exposed to the atmosphere are ubiquitously found on the surfaces of cloud droplets, aerosol particles, buildings, plants, soils and the ocean. These air/water interfaces host countless amphiphilic compounds concentrated there with respect to in bulk water, leading to a unique chemical environment. Here, photochemical processes at the air/water interface of biofilm-containing solutions were studied, demonstrating abiotic VOC production from authentic biogenic surfactants under ambient conditions. Using a combination of online-APCI-HRMS and PTR-ToF-MS, unsaturated and functionalized VOCs were identified and quantified, giving emission fluxes comparable to previous field and laboratory observations. Interestingly, VOC fluxes increased with the decay of microbial cells in the samples, indicating that cell lysis due to cell death was the main source for surfactants and VOC production. In particular, irradiation of samples containing solely biofilm cells without matrix components exhibited the strongest VOC production upon irradiation. In agreement with previous studies, LC-MS measurements of the liquid phase suggested the presence of fatty acids and known photosensitizers, possibly inducing the observed VOC production via peroxy radical chemistry. Up to now, such VOC emissions were directly accounted to high biological activity in surface waters. However, the results obtained suggest that abiotic photochemistry can lead to similar emissions into the atmosphere, especially in less biologically-active regions. Furthermore, chamber experiments suggest that oxidation (O3/OH radicals) of the photochemically-produced VOCs leads to aerosol formation and growth, possibly affecting atmospheric chemistry and climate-related processes, such as cloud formation or the Earth’s radiation budget.

• Martin Brüggemann 1,∆,
• Nathalie Hayeck 1,∆,
• Chloé Bonnineau 2,
• Stéphane Pesce 2,
• Peter A. Alpert 1,†,
• Sébastien Perrier 1,
• Christoph Zuth 3,
• Thorsten Hoffmann 3,
• Jianmen Chen 4
• Christian George1,*

1. Univ Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, F-69626, Villeurbanne, France
2. Irstea, UR MALY, centre de Lyon-Villeurbanne, F-69616 Villeurbanne, France
3. Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg-Universität, 55128 Mainz, Germany
4. Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Fudan Tyndall Centre, Shanghai 200433, China
   ∆These authors contributed equally.
   †now at: Paul Scherrer Institute, 5232 Villigen, Switzerland

Bacteria are abundant in atmospheric water phase with the potential to influence atmospheric processes and human health, yet relatively little information is known about the bacterial characteristics at high altitudes. Here we investigated the bacterial community by high throughput sequencing in 24 cloud water samples collected from September 26 to October 31, at the summit of Mt. Tai (36°15′ N, 117°06′ E, 1534 m a.s.l) in China. Diverse bacterial population were identified and the gram-negative bacteria contributed the majority of total bacteria including Proteobacteria (81.6%) and Bacteroidetes (3.9%), followed by gram-positive bacteria Firmicutes (7.1%) and Actinobacteria (2.3%). These gram-negative taxa mainly inhabited in leaf-surface and cold environments. Meanwhile bacteria involved in the cloud condensation nuclei and ice nuclei formation were observed such as Sphingomonas (6.7%), Pseudomonas (4.1%), and Bacillus (1.1%). In addition, Sphingmonas was more active than that in daytime and participated in the cloud chemistry process. Meanwhile O3 and SO2 critically contributed to the variation of bacterial community. It is the first report on the bacterial community structure of cloud water over Asian area. Our results can serve as an important reference for environmental scientists, and biologists.

• Caihong Xu a,
• MinWei a,
• Jianmin Chen a,b,
• Xiao Sui a,
• Chao Zhua,
• Jiarong Li a,
• Lulu Zheng b,
• Guodong Sui b,
• Weijun Li a,
• WenxingWang a,
• Qingzhu Zhang a,
• Abdelwahid Mellouki b,c

1. Environment Research Institute, School of Environmental Science and Engineering, Shandong University, Ji’nan 250100, China
2. Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP), Fudan Tyndall Centre, Department of Environmental Science & Engineering, Fudan University,
   Shanghai 200433, China
3. Institut de Combustion, Aérothermique, Réactivité et Environnement, CNRS, 45071 Orléans cedex 02, France

In January 2014, severe haze episodes which sweep across Chinese cities have attracted public concern and interest at home and abroad. In addition to the physicochemical properties of air pollutants, bacteria are thought to be responsible for the spread of respiratory diseases and various allergies. We attempted the bacterial characterization of submicron particles (PM0.18–0.32, PM0.32–0.56, and PM0.56–1) under severe haze episodes using high-throughput sequencing and real-time quantitative PCR detecting system based on 21 samples collected from January to March 2014 at Ji’nan, China. The high bacterial concentration in PM0.32–0.56 (7314 cells m− 3), PM0.18–0.32(7212 cells m− 3), and PM0.56–1 (6982 cells m− 3) showed significant negative correlations with SO2, NO2, and O3. Under sufficient sequencing depth, 37 phyla, 71 classes, 137 orders, 236 families, and 378 genera were classified, and the bacterial community structure varied significantly in different size fractions. For example, Holophagaceae (Acidobacteria) in PM0.32–0.56 showed 6-fold higher abundance than that in PM0.18–0.32. Moreover, functional categories and bacterial species (Lactococcus piscium, Pseudomonas fragi, Streptococcus agalactiae, and Pseudomonas cichorii) that may potentially be responsible for infections and allergies were also discovered. Source track analysis showed that the ambient bacteria mainly originated from soils, leaf surfaces, and feces. Our results highlighted the importance of airborne microbial communities by understanding the concentration, structure, ecological and health effects, especially those in submicron particles during haze episodes.

• Caihong Xu a,
• MinWei a,
• Jianmin Chen a,b,
• XinfengWang a,
• ChaoZhu a,
• Jiarong Li a,
• Lulu Zheng b,
• Guodong Sui b,
• Weijun Li a,
• WenxingWang a,
• Qingzhu Zhang a,
• Abdelwahid Mellouki a,c

1. Environment Research Institute, School of Environmental Science and Engineering, Shandong University, Ji’nan 250100, China
2. Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP), Fudan Tyndall Centre,Department of Environmental Science&Engineering, FudanUniversity, Shanghai 200433, China
3. Institut de Combustion, Aérothermique, Réactivité et Environnement, CNRS, 45071 Orléans cedex 02, France

Fungi are ubiquitous throughout the near-surface atmosphere, where they represent an important component of primary biological aerosol particles. This study combined internal transcribed spacer region sequencing and quantitative real-time polymerase chain reaction (qPCR) to investigate the ambient fungi in fine (PM2. 5, 50 % cutoff aerodynamic diameter Da50 =  2.5 µm, geometric standard deviation of collection efficiency σg =  1.2) and submicron (PM1, Da50 =  1 µm, σg =  1.2) particles at the summit of Mt. Tai located in the North China Plain, China. Fungal abundance values were 9.4  ×  104 and 1.3  ×  105 copies m−3 in PM2. 5 and PM1, respectively. Most of the fungal sequences were from Ascomycota and Basidiomycota, which are known to actively discharge spores into the atmosphere. The fungal community showed a significant seasonal shift across different size fractions according to Metastats analysis and the Kruskal–Wallis rank sum test. The abundance of Glomerella and Zasmidium increased in larger particles in autumn, whereas Penicillium, Bullera, and Phaeosphaeria increased in smaller particles in winter. Environmental factors, namely Ca2+, humidity, and temperature, were found to be crucial for the seasonal variation in the fungal community. This study might serve as an important reference for fungal contribution to primary biological aerosol particles.

• Caihong Xu 1,
• Min Wei 1,a,
• Jianmin Chen 1,2,3
• Chao Zhu 1,
• Jiarong Li 1,
• Ganglin Lv 1,
• Xianmang Xu 1,
• Lulu Zheng 2,
• Guodong Sui 2,
• Weijun Li 1,
• Bing Chen 1,
• Wenxing Wang 1,
• Qingzhu Zhang 1,
• Aijun Ding 3
• Abdelwahid Mellouki 1,4

1. Environment Research Institute, School of Environmental Science and Engineering, Shandong University, Jinan 250100, China
2. Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Fudan Tyndall Centre, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, China
3. Institute for Climate and Global Change Research, School of Atmospheric Sciences, Nanjing University, Nanjing 210023, Jiangsu, China
4. Institut de Combustion, Aérothermique, Réactivité et Environnement, CNRS, 45071 Orléans Cedex 02, France
   anow at: College of Geography and Environment, Shandong Normal University, Jinan 250100, China

The dihydroxycarbonyls 3,4-dihydroxy-2-butanone (DHBO) and 2,3-dihydroxy-2-methylpropanal (DHMP) formed from isoprene oxidation products in the atmospheric gas phase under low-NO conditions can be expected to form aqSOA in the tropospheric aqueous phase because of their solubility. In the present study, DHBO and DHMP were investigated concerning their radical-driven aqueous-phase oxidation reaction kinetics. For DHBO and DHMP the following rate constants at 298 K are reported: k(OH + DHBO) = (1.0 ± 0.1) × 10⁹ L mol^–1 s^–1, k(NO₃ + DHBO) = (2.6 ± 1.6) × 10⁶ L mol^–1 s^–1, k(SO₄^–+ DHBO) = (2.3 ± 0.2) × 10⁷ L mol^–1 s^–1, k(OH + DHMP) = (1.2 ± 0.1) × 10⁹ L mol^–1 s^–1, k (NO₃ + DHMP) = (7.9 ± 0.7) × 10⁶ L mol^–1 s^–1, k(SO₄^– + DHMP) = (3.3 ± 0.2) × 10⁷ L mol^–1 s^–1, together with their respective temperature dependences. The product studies of both DHBO and DHMP revealed hydroxydicarbonyls, short chain carbonyls, and carboxylic acids, such as hydroxyacetone, methylglyoxal, and lactic and pyruvic acid as oxidation products with single yields up to 25%. The achieved carbon balance was 75% for DHBO and 67% for DHMP. An aqueous-phase oxidation scheme for both DHBO and DHMP was developed on the basis of the experimental findings to show their potential to contribute to the aqSOA formation. It can be expected that the main contribution to aqSOA occurs via acid formation while other short-chain oxidation products are expected to back-partition into the gas phase to undergo further oxidation there.

• Otto, T.,
• Stieger, B.,
• Mettke, P.,
• Herrmann, H.,
  Leibniz Institute for Tropospheric Research (TROPOS), Atmospheric Chemistry Department (ACD), Permoserstrasse 15, 04318 Leipzig, Germany

• A. Tilgner,
• Herrmann, H.,
  Leibniz Institute for Tropospheric Research (TROPOS), Atmospheric Chemistry Department (ACD), Permoserstrasse 15, 04318 Leipzig, Germany

The oceans are an important source for marine aerosol particles and the chemical composition of the particles determines their microphysical properties. However, there are few available field data of the composition of organic matter in the marine environment, especially on molecular level.

This study presents measurements of nitrogen containing organic compounds (free amino acids and amines) in marine field samples as an important subgroup of marine organic matter. Concerted measurements, meaning the simultaneous sampling of bulk water, the sea surface microlayer (SML) as well as marine aerosol particles (PM₁) were performed at a remote atmospheric station in the tropical Atlantic Ocean, the Cape Verde Atmospheric Observatory (CVAO). Analytical measurements were based on derivatization with 6-Aminochinolyl-N-hydroxy-succinimidyl-carbamate (AQC) reagent and LC-MS analysis. The results of the concerted measurements show that free amino acids and amines are present in the marine compartments SML and aerosol particles. Phenylalanine could be quantified in concentration ranges between 142.18 nmol/L and 145.65 nmol/L in the SML samples and on the corresponding aerosol particles from 0.03 ng/m³ up to 0.21 ng/m³. Methylamine is present in SML samples in average concentration of 647.25 nmol/L and on the corresponding aerosol particles in concentration range between 0.36 ng/m³ and 0.69 ng/m³.

These concentrations are in the same order of magnitude compared to field studies in other marine areas. For example, concentration of free amino acids in marine seawater samples from the west coast of Scottland were also in the nmol/L range (Sommerville and Preston 2001) and free phenylalanine was detected in marine aerosol particles of eastern Mediteranean in average concentration of 0.3 ± 0.7 ng/m³ (Mandalakis, Apostolaki et al. 2010).

However, most studies focus on only one marine compartment: either aerosol particles or seawater investigations. The simultaneous determination of the amines and amino acids in the SML and in aerosol particles presented here will allow a more comprehensive analysis of nitrogen containing compounds in the marine environment including their enrichment in the SML and their transfer across the air-sea interface.

• Triesch N.,
• van Pinxteren M.,
• Herrmann, H.,
  Leibniz Institute for Tropospheric Research (TROPOS), Atmospheric Chemistry Department (ACD), Permoserstrasse 15, 04318 Leipzig, Germany

The oceans are an important source for marine aerosol particles and the chemical composition of the particles determines their microphysical properties. However, there are few available field data of the composition of organic matter (OM) in the marine environment, especially on molecular level.

This study presents measurements of organic compounds (free (FAA)/combined amino acids (CAA) and proteins) in marine field samples as important subgroups of marine OM. Concerted measurements- the simultaneous sampling of bulk water (ULW), sea-surface-microlayer (SML) as well as marine aerosol particles (PM₁) were performed at a remote atmospheric station in the tropical Atlantic Ocean, the Cape Verde Atmospheric Observatory(CVAO).

Analytical measurements of FAA and CAA (after hydrolysis) were based on derivatization with 6-Aminochinolyl-N-hydroxy-succinimidyl-carbamate(AQC)-reagent and LC-MS analysis. Proteins were quantified as Coomassie stainable particles.

The results of the concerted measurements show that the analytes are present in all three measured marine compartments. Phenylalanine was quantified in SML samples with an enrichment factor (EF) in up to 15 compared to ULW and an EF of Phenylalanine in the corresponding aerosol particles up to 944. These results are in the same order of magnitude compared to other field studies: The EF of FAA in SML of the western Mediterreanean Sea is up to 26 (Rheinthaler et.al 2008) and the EF of total organic carbon in aerosol samples of the Atlantic ocean is up to 10⁴/10⁵ -depending on chlorophyll-a-concentration (van Pinxteren et.al 2017).

However, most studies focus on only one marine compartment: either aerosol particles or seawater investigations. The simultaneous determination of the analytes in aerosol particles and in SML/ULW presented here will allow a more comprehensive analysis of OM on molecular level in the marine environment including its sources in the oceans, enrichment in SML, transfer across the air-sea-interface and the chemical composition of marine aerosol particles.

• Triesch N.,
• van Pinxteren M.,
• Herrmann, H.,

Leibniz Institute for Tropospheric Research (TROPOS), Atmospheric Chemistry Department (ACD), Permoserstrasse 15, 04318 Leipzig, Germany

Rate coefficients for the reaction of NO₃ radicals with 6 unsaturated volatile organic compounds (VOCs) in a 7300 L simulation chamber at ambient temperature and pressure have been determined by the relative rate method. The resulting rate coefficients were determined for isoprene, 2-carene, 3-carene, methyl vinyl ketone (MVK), methacrolein (MACR) and crotonaldehyde (CA), as (6.6 ± 0.8) × 10^-13, (1.8 ± 0.6) × 10^-11, (8.7 ± 0.5) × 10^-12, (1.24 ± 1.04) × 10^-16, (3.3 ± 0.9) × 10^-15 and (5.7 ± 1.2) × 10^-15 cm³/(molecule^–·sec), respectively. The experiments indicate that NO₃ radical reactions with all the studied unsaturated VOCs proceed through addition to the olefinic bond, however, it indicates that the introduction of a carbonyl group into unsaturated VOCs can deactivate the neighboring olefinic bond towards reaction with the NO₃ radical, which is to be expected since the presence of these electron-withdrawing substituents will reduce the electron density in the π orbitals of the alkenes, and will therefore reduce the rate coefficient of these electrophilic addition reactions. In addition, we investigated the product formation from the reactions of 2-carene and 3-carene with the NO₃ radical. Qualitative identification of an epoxide (C₁₀H₁₆OH⁺), caronaldehyde (C₁₀H₁₆O₂H⁺) and nitrooxy-ketone (C₁₀H₁₆O₄NH⁺) was achieved using proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) and a reaction.

• Ren, Yangang 1
• McGillen, Max 1,2
• Ouchen, Ibrahim 3
• Daele, Veronique 1
• Mellouki, Abdelwahid 1

1. CNRS, Inst Combust Aerotherm Reactivite & Environm, F-45071 Orleans 02, France
2. Le Studium Loire Valley Institute for Advanced Studies, Orléans 45071, France
3. Earth Sciences Department, Scientific Institute, Mohammed V- University, Rabat 10106, Morocco

Ground surface analysis of CO₂ emissions with δ¹³C determination is experimentally demonstrated to be a potential methodology to monitor, on line, the dynamics of petroleum hydrocarbon aerobic biodegradation to optimize soil treatment, thanks to the improvement of IRIS instrument performances. For the first time, the biodegradation rate of remaining hydrocarbon substrates is tried to be quantified using the Rayleigh equations for CO₂δ¹³C released at ground surface above the pollution plume, instead of usual approaches based on  underground hydrocarbons δ¹³C analysis. This CO₂δ¹³C ground surface analysis approach is applied in a contaminated site from a gasoline station and compared to the cartography of CO₂ fluxes above land surface and ground water hydrocarbon-BTEX concentrations and δ¹³C values, both. In that site, or for many similar ones, BTEX are the main remaining hydrocarbons after long history spills or leaks from gasoline station. This CO₂δ¹³C new applications of Rayleigh equations is on the way to provide a non-intrusive (without soil excavation), fast, and low cost online method to monitor the efficiency of a biodegradation process for aerobic soil remediation  (natural or bio-stimulated).

• Guimbaud, Christophe 1
• Noel, Cecile 1,2
• Verardo, Elicia 3
• Grossel, Agnes 4
• Jegou, Fabrice 1
• Hu, Zhen 5
• Robert, Claude 1
• Chartier, Michel 1
• Jacob, Jeremy 6
• Colombano, Stefan 2
• Ignatiadis, Ioannis 2,5
• Gourry, Christophe 2

1. Laboratoire de Physique et de Chimie de l’Environnement et de l’Espace (LPC2E), CNRS et Université d’Orléans, 3A av. de la recherche scientifique, 45071, Orléans cedex 2, France
2. Bureau de Recherches Géologiques et Minières (BRGM), 3 av. Claude Guillemin, 45060 Orléans cedex 2, France
3. Ecole Nationale Supérieure en Environnement, Géoressources et Ingénierie du Développement durable (ENSEGID), Université Bordeaux III
4. Institut National de la Recherche Agronomique (INRA), UR 0272 Science du sol, Centre de recherche d’Orléans, CS 40001 Ardon, 45075 Orléans cedex, France
5. Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100, China
6. Laboratoire des Sciences du Climat et de l’Environnement, UMR 8212 CNRS-CEA UVSQ, Domaine du CNRS, 91198, Gif sur Yvette, France