Eric Villenave

University of Bordeaux (FRANCE) · CNRS UMR 5805 EPOC

Organic aerosol (OA) still remains one of the most difficult components of the atmospheric aerosols to simulate, given the multitude of its precursors, the uncertainty of its formation pathways and the lack of measurements of its detailed composition. The LANDEX project (The LANDes Experiment), during its intensive field campaign in summer 2017, gi...

The massive use of pesticides in agriculture has led to widespread contamination of the environment, particularly the atmospheric compartment. Thirty-six pesticides, most used in viticulture, were monitored in ambient air using polyurethane foams as passive air samplers (PUF-PAS). Spatiotemporal data were collected from the samplers for 10 months (...

Atmospheric organic vapors play essential roles in the formation of secondary organic aerosol. Source identification of these vapors is thus fundamental to understanding their emission sources and chemical evolution in the atmosphere and their further impact on air quality and climate change. In this study, a Vocus proton-transfer-reaction time-of-...

This study presents a comparison of five methodologies to apportion primary (POA) and secondary organic aerosol (SOA) sources from measurements performed in the Paris region (France) during a highly processed PM pollution event. POA fractions, estimated from EC-tracer method and positive matrix factorization (PMF) analyses, conducted on measurement...

Trace gas measurements were performed during the LANDEX (the LANDes EXperiment) Episode 1 field campaign in the summer 2017, in one of the largest European maritime pine forests (> 95% Pinus pinaster) located in southwestern France. Efforts have been focused on obtaining a good speciation of 20 major biogenic volatile organic compounds (BVOCs, incl...

MBTCA (3-methyl-1,2,3-butanetricarboxylic acid), a low-volatile, highly oxidized, secondary-generation product of monoterpenes, is one of the most relevant tracer compounds for biogenic secondary organic aerosols (SOAs). In this study, laboratory-generated, micrometer-sized, pure-MBTCA, mono-/di-/trisodium MBTCA salts and MBTCA–NaCl mixture aerosol...

Atmospheric organic vapors play essential roles in the formation of secondary organic aerosol. Source identification of these vapors is thus fundamental to understand their emission sources and chemical evolution in the atmosphere and their further impact on air quality and climate change. In this study, a Vocus proton-transfer-reaction time-of-fli...

Atmospheric particles play a major role in both air quality and climate change. Formation of secondary particles in the atmosphere has been observed over many different environments and is believed to provide up to half of the atmospheric cloud condensation nuclei (CCN) at a global scale. However, high uncertainties are still remaining in the descr...

Abstract. Secondary organic aerosols (SOAs), which are formed and transformed through complex physicochemical processes in the atmosphere, have attracted considerable attention over the past decades because of their impacts on both climate change and human health. Recently, 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA), a low volatile, highly oxi...

The capabilities of the recently developed Vocus proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF) are reported for the first time based on ambient measurements. With the deployment of the Vocus PTR-TOF, we present an overview of the observed gas-phase (oxygenated) molecules in the French Landes forest during summertime 2018 and g...

Total hydroxyl radical (OH) reactivity measurements were conducted during the LANDEX intensive field campaign in a coniferous temperate forest located in the Landes area, southwestern France, during July 2017. In order to investigate inter-canopy and intra-canopy variability, measurements were performed inside (6 m) and above the canopy level (12 m...

The presence in the atmosphere of pollutants emitted from agriculture or impacting crop production, their concentration levels and their residence time depend on a series of physical, chemical and biological processes. This chapter describes the basic mechanisms and the main factors involved in air pollutant emissions and fate in agricultural syste...

Estimating agriculture’s contribution to air pollution and global warming is needed to understand and limit its impacts on the environment and climate. It is equally important to estimate the capacity of agricultural practices to mitigate these emissions and to characterize atmospheric deposition and the impacts of air pollutants on agroecosystems....

The present work is an extensive laboratory study of organosulfate (OS) formation from the reaction of α-pinene oxidation products or proxies with acidified ammonium sulfate aerosols in three different acidity conditions ((NH4)2SO4 0.06 M; (NH4)2SO4/H2SO4 0.06 M/0.005 M; (NH4)2SO4/H2SO4 0.03 M/0.05 M). The kinetics of the reactions of α-pinene, α-p...

A new online gas chromatographic method dedicated to biogenic volatile organic compound (BVOC) analysis was developed for the measurement of a 20 BVOC gaseous mixture (isoprene; β-pinene; α-pinene; limonene; ocimene; myrcene; sabinene; Δ3-carene; camphene; 1,8 cineole; terpinolene; linalool; α-phellandrene; nopinone; citral; α-terpinene; β-caryophy...

The capabilities of the recently developed Vocus proton-transfer-reaction time-of-flight mass spectrometer (PTR-12 TOF) are reported for the first time based on ambient measurements. With the deployment of the Vocus PTR-TOF, we present 13 an overview of the observed gas-phase (oxygenated) molecules in the French Landes forest during summertime 2018...

A new online gas chromatographic method dedicated to Biogenic Volatile Organic Compounds (BVOC) analysis was developed for the measurement of a 20 BVOC gaseous mixture (isoprene, β-pinene, α-pinene, limonene, trans-β-ocimene, myrcene, sabinene, Δ³-carene, camphene, 1,8 cineole, terpinolene, linalool, α-phellandrene, nopinone, citral, α-terpinene, β...

Total OH reactivity measurements were conducted during the LANDEX intensive field campaign in a coniferous temperate forest located in the Landes area, south-western France, during July 2017. In order to investigate inter-canopy and intra-canopy variability, measurements were performed inside (6 m) and above the canopy level (12 m), as well as at t...

The present study proposes an advanced methodology to refine the source apportionment of organic aerosol (OA). This methodology is based on the combination of offline and online datasets in a single Positive Matrix Factorization (PMF) analysis using the multilinear engine (ME-2) algorithm and a customized time synchronization procedure. It has been...

Secondary organic aerosol (SOA) is known to account for a major fraction of airborne particulate matter, with significant impacts on air quality and climate at the global scale. Despite the substantial amount of research studies achieved during these last decades, the source apportionment of the SOA fraction remains difficult due to the complexity...

During two growing seasons of a maritime pine stand, in 2014 and 2015, ozone (O3) fluxes have been determined using the eddy covariance (EC) method and compared to the outputs of a big-leaf O3 deposition model including stomatal, cuticular and soil pathways. The model developed in this study generally allowed to properly reproduce the measured ozon...

PM10 source apportionment was performed by positive matrix factorization (PMF) using specific primary and secondary organic molecular markers on samples collected over a one year period (2013) at an urban station in Grenoble (France). The results provided a 9-factor optimum solution, including sources rarely apportioned in the literature, such as t...

The present study aimed at performing PM10source apportionment, using positive matrix factorization (PMF), based on filter samples collected every 4h at a sub-urban station in the Paris region (France) during a PM pollution event in March 2015 (PM10>50μgm-3for several consecutive days). The PMF model allowed to deconvolve 11 source factors. The use...

Improving the understanding of processes related to atmospheric particle sources is essential to better assess future climate. Especially, how biogenic volatile organic compounds (BVOCs) are involved in new particle formation (NPF) is still unclear, highlighting the need for field studies in sites that have not yet been explored. Weakly anthropised...

Total individual concentrations (in both gaseous and particulate phases) of 80 polycyclic aromatic compounds (PACs) including 32 nitro-PAHs, 27 oxy-PAHs (polycyclic aromatic hydrocarbons) and 21 parent PAHs have been investigated over a year in the ambient air of Grenoble (France) together with an extended aerosol chemical characterization. The res...

This work is focused on the gas-phase oxidation of acenaphthylene and acenaphthene by OH radicals and associated secondary organic aerosol (SOA) formation under low and high-NOx conditions. Experiments were carried out in an atmospheric simulation chamber using a proton transfer reaction time-of-flight-mass spectrometer (PTR-TOF-MS) and an aerosol...

In the present study, quasi-static reactor and atmospheric simulation chamber experiments were performed to investigate the formation of α-pinene-derived organosulfates. Organosulfates (R-OSO3H) were examined for the reactions between acidified ammonium sulfate particles exposed to an individual gaseous volatile organic compound, such as α-pinene a...

Polycyclic aromatic hydrocarbons (PAHs) are recognized as important secondary organic aerosol (SOA) precursors in the urban atmosphere. In this work, the gas-phase ozonolysis of acenaphthylene was investigated in an atmospheric simulation chamber using a proton transfer reaction time-of-flight-mass spectrometer (PTR-TOF-MS) and an aerosol time-of-f...

The chlorine atom (Cl) initiated oxidation of three PAHs (naphthalene, acenaphthylene and acenaphthene) has been investigated. Experiments were carried out in an atmospheric simulation chamber using a proton transfer reaction time-of-flight-mass spectrometer (PTR-TOF-MS) and an aerosol time-of-flight-mass spectrometer (ATOFMS) to characterise the o...

In the present study, formation of aromatic organosulfates (OSs) from the photooxidation of polycyclic aromatic hydrocarbons (PAHs) was investigated. Naphthalene (NAP) and 2-methylnaphthalene (2-MeNAP), two of the most abundant gas-phase PAHs and thought to represent "missing" sources of urban SOA, were photochemically oxidized in an outdoor smog c...

Aging processes of secondary organic aerosol (SOA) may be a source of oxygenated organic aerosols; however the chemical processes involved remain unclear. In this study we investigate photochemical aging of SOA produced by the gas-phase oxidation of naphthalene by hydroxyl radicals and acenaphthylene by ozone. We monitored the SOA composition using...

Reactions of polycyclic aromatic hydrocarbons (PAHs) with chlorine atoms may occur in specific areas such as coastal regions and the marine boundary layer. In this work, rate constants for the gas-phase reactions of naphthalene, acenaphthene and acenaphthylene with chlorine atoms have been measured using the relative rate technique. Experiments wer...

The objectives of this study were to characterize polycyclic aromatic hydrocarbons from particulate matter emitted during wood combustion and to determine, for the first time, the isotopic signature of PAHs from nine wood species and Moroccan coal from the Mediterranean Basin. In order to differentiate sources of particulate-PAHs, molecular and iso...

Reactivity of polycyclic aromatic compounds (PACs) adsorbed on natural aerosol particles exposed to different atmospheric oxidants (O3, OH and NO2/O3 mixture) was studied. Decay of polycyclic aromatic hydrocarbons (PAHs) and formation/decay of oxygenated PAHs (OPAHs) and nitrated PAHs (NPAHs) were monitored. Overall, benzo[a]pyrene appeared to be t...

Aromatic hydrocarbons are important components of polluted ambient air. The reaction of OH radicals with HexaMethylBenzene (HMB) is a prototype system to study ipso addition leading eventually to dealkylation. We have investigated the OH + HMB and OD + HMB reactions between 323 and 433 K using a discharge fast-flow reactor coupled to a time-of-flig...

Particulate concentrations of polycyclic aromatic compounds (PACs) including, 17 polycyclic aromatic hydrocarbons (PAHs), 9 oxygenated PAHs (OPAHs) and 18 nitrated PAHs (NPAHs) were determined at traffic and suburban sites located in the region of Paris. A 12h sampling basis time resolution was applied in order to study their diurnal and nocturnal...

The size distribution of particulate nitrated and oxygenated polycyclic aromatic hydrocarbons (NPAHs and OPAHs) was determined during two field campaigns at a traffic site in summer 2010 and at a suburban site during the MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for a...

The objectives of this study were to characterize polycyclic aromatic hydrocarbons from particulate matter emitted during wood combustion and to determine, for the first time, the isotopic signature of PAHs from nine wood species and Moroccan coal from the Mediterranean Basin. In order to differentiate sources of particulate-PAHs, molecular and iso...

The size distribution of particulate nitrated and oxygenated polycyclic aromatic hydrocarbons (NPAHs and OPAHs) was determined during two field campaigns at a traffic site in summer 2010 and at a suburban site during the MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for a...

Les hydrocarbures aromatiques polycycliques (HAP) sont des composés émis en phase gazeuse et particulaire au cours de processus de combustions incomplètes. Leur surveillance est très importante du fait de leur potentiel cancérigène et/ou mutagène (classés 1 par l'IARC pour certains). Outre leur toxicité, certains HAP posent également des problèmes...

Benzo[a]pyrene (B[a]P) which is used as a tracer for PAH family is very toxic and reactive. It may be degradated by different oxidants in the atmosphere or during its sampling on filters. PAH on-filter degradation was studied during two field campaigns (traffic site and photooxidation site). A MnO2 denuder was used to protect the sampling filter fr...

Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous organic compounds widely found in all environmental compartments. The main concern of PAHs is that some of them are reported to have carcinogenic and mutagenic properties. In the atmosphere, they are mainly emitted as by-products of organic matter and fossil fuel incomplete combustion such as,...

Polycyclic aromatic hydrocarbons (PAHs) are emitted both in gas and particulate phases during incomplete combustions. Due to the mutagenicity and carcinogenicity of some of them, their monitoring is of prime interest. Particularly for the Benzo[a]pyren (B[a]P) which is commonly used as a tracer for this compounds family due to his high toxicity. B[...

In the present paper, we apply our new semi-empirical method to characterize the oxidation by OH of a series of large polycyclic aromatic hydrocarbons (PAHs) adsorbed on a soot surface modeled by a large graphene-like cluster. This method is based on an electrostatic and induction contribution calculated at the SCF AM1 level to which a sum of two-b...

In this work, we use quantum chemistry (DFT-UBH&HLYP/6-311G(d,p)) coupled to kinetic calculations to obtain a detailed view of the mechanism of the Cl+aldehyde reactions when the size of the aldehyde increases. A series of linear and ramified aliphatic aldehydes: CH3C(O)H, CH3CH2C(O)H, CH3CH2CH2C(O)H, CH3CH2CH2CH2C(O)H, (CH3)2CHC(O)H and (CH3)3CC(O...

The primary oxidation steps of (γ-terpinene+OH) and (d-limonene+OH) reactions are investigated using two techniques: an excimer laser photolysis set-up coupled with UV absorption spectrometry performed at atmospheric pressure and a fast-flow reactor coupled to time of flight mass spectrometry at low pressure. OH radicals are generated either by pho...

This experimental study deals with heterogeneous reactions of benzo(a)pyrene (BaP) with ozone nitrogen dioxide and hydroxyl radicals BaP was adsorbed on silica particles chosen here as a model of mineral atmospheric particles Compound extractions were assisted by focused microwave and analyses were performed by gas chromatography coupled with mass...

The heterogeneous reactivity of OH radicals with pyrene and 1-nitropyrene adsorbed on model particles has been investigated using a discharge flow reactor, in the presence of a large excess of NO 2 . Graphite was chosen as a simple model of carbonaceous particles, whereas silica was chosen as a representative surrogate of mineral atmospheric aeroso...

This work deals with the kinetic study of the reactions of ozone with pyrene, 1-hydroxypyrene and 1-nitropyrene, adsorbed on model particles. Experiments were performed at room temperature and atmospheric pressure, using a quasi-static flow reactor in the absence of light. Compounds were extracted from particles using pressurized fluid extraction (...

Large amounts of unsaturated hydrocarbons are continuously being emitted into the Earth's atmosphere, originating from both biogenic and anthropogenic sources. The degradation of unsaturated VOCs in the troposphere is mainly initiated by reactions with OH radicals. For these OH reactions the addition channel is always the dominant one. However ther...

The heterogeneous reactivity of nitrogen dioxide with pyrene and 1-nitropyrene (1NP) adsorbed on silica particles has been investigated using a fast-flow-tube in the absence of light. Reactants and products were extracted from particles using pressurised fluid extraction (PFE) and concentration measurements were performed using gas chromatography/m...

The formation of secondary organic aerosol (SOA) is one of the research focuses in atmospheric chemical process. Monoterpenes, which are important constituents of biogenic non methanic organic compound emissions, are the principal natural precursors of SOA. Indeed, their degradation with atmospheric oxidants such as hydroxyl radicals, yields low vo...

The size distribution of polycyclic aromatic hydrocarbons (PAHs) and PAH derivatives was determined during the intensive sampling campaigns of the POVA (Pollution des Vallées Alpines) research programme, in two French alpine valleys, in winter and summer. The size distributions of PAHs, oxygenated PAHs (OPAHs) and nitrated PAHs (NPAHs) present larg...

Ambient measurements (gas+particle phases) of 16 polycyclic aromatic hydrocarbons, 17 nitrated PAHs (NPAHs) and eight oxygenated PAHs (OPAHs) were carried out during the winter 2002–2003 and the summer 2003 in two French alpine valleys on various types of sites (traffic, sub-urban, altitude and rural). Atmospheric concentrations of these classes of...

The objective of this study was to characterize the NPAHs and OPAHs in ambient air on various sites (traffic, suburban, rural and altitude). Atmospheric concentrations of these classes of compounds are of interest because they include potential mutagens and carcinogens. Samplings were performed within the framework of the French research program PO...

Primary products of the reactions of gas-phase ozone with anthracene and phenanthrene adsorbed on silica model particles have been investigated. Silica was selected as proxy for mineral atmospheric particles. The particles, coated with anthracene or phenanthrene and placed on a filter, were exposed in a reaction cell to a gaseous ozone flow. Ozone...

In this experimental study, rate constants were measured for the reactions of ozone with 13 polycyclic aromatic hydrocarbons (PAHs) adsorbed on different types of particles. Graphite and silica were chosen to model, respectively, carbonaceous and mineral atmospheric particles. The pseudo-first order rate constants were obtained from the fit of the...

The kinetics and the mechanism of the reaction CH3C(O)O2 + HO2 were reinvestigated at room temperature using two complementary approaches: one experimental, using flash photolysis/UV absorption technique and one theoretical, with quantum chemistry calculations performed using the density functional theory (DFT) method with the three-parameter hybri...

A flash photolysis setup coupled to UV absorption spectrometry detection was used to measure the UV absorption spectra of the (CH3)2(CH2O2.)CC(O)C(CH3)3 and (CH3)2(CH2O2.)CC(O)CH3 radicals between 207 and 290 nm. The self-reaction rate constants of these radicals were measured at 298 K: k((CH3)2(CH2O2.)CC(O)C(CH3)3 + (CH3)2(CH2O2.)CC(O)C(CH3)3) = (...

The heterogeneous reactions of NO2 and OH radicals with polycyclic aromatic hydrocarbons (PAHs) naturally present in diesel particulate exhaust (NIST SRM 1650a) have been investigated. Using a fast flow reactor, relative degradation rate constants have been determined by following the decays of particulate-PAH concentrations vs. the reaction time....

The kinetics and mechanism of the reactions of Cl atoms and OH radicals with CH3CH2CHO were investigated at room temperature using two complementary techniques: flash photolysis/UV absorption and continuous photolysis/FTIR smog chamber. Reaction with Cl atoms proceeds predominantly by abstraction of the aldehydic hydrogen atom to form acyl radicals...

The hydroxyl radical initiated oxidation of diisopropyl ether has been studied in the large-volume outdoor European Photoreactor (EUPHORE) and in a small, laboratory-based reactor system. The product distributions determined from the experiments were found to be significantly dependent on the reaction conditions and provide strong evidence for the...

This experimental work deals with the kinetic study of the reactions of nitrogen dioxide (NO2) radical with tri- to hexa-aromatic hydrocarbons adsorbed on silica particles. Measurements were performed using a flow-tube, at 295 K, in the absence of light. Polycyclic aromatic hydrocarbons (PAHs) were extracted from particles by focused microwave extr...

Pressurised fluid extraction (PFE) was used for the measurement of 13 polycyclic aromatic hydrocarbons (PAHs) adsorbed on different types of particles: two model particles (PAH-coated silica, PAH-coated graphite) and two natural atmospheric particles (urban dust and diesel exhaust, from NIST reference materials). Samples were analysed by gas chroma...

An apparatus has been developed to study the kinetics of radical reactions of interstellar and atmospheric interests. It consists of a fast flow reactor in which atoms and radicals are initially produced by a microwave discharge. The gas mixture is ionized either using electron ionization or using single photon ionization (at 10.2 eV) or (1+1) reso...

A discharge flow reactor was used to study the heterogeneous reactions of OH, NO2 and NO radicals with 11 polycyclic aromatic hydrocarbons (PAHs) adsorbed on 1–2 μm calibrated graphite particles. Graphite was chosen as a simple model of carbonaceous atmospheric particles. Relative kinetic information was obtained from the decays of particulate-PAH...

Particle size distributions and concentrations of Polycyclic Aromatic Hydrocarbons (PAHs) and Oxygenated PAH (OPAHs) in gas and particle phases were obtained during the program 'POllution des Vallées Alpines' (POVA). The general objectives of this program are the comparative studies of atmospheric pollution and the modeling of atmospheric emissions...

The kinetics and mechanism of the reactions Cl + (CH3)3CCHO and Cl + (CH3)2CHCHO were investigated at room temperature using two complementary techniques: flash photolysis/UV absorption and continuous photolysis/Fourier transform infrared (FTIR) smog chamber. Reactions proceed predominantly by abstraction of the aldehydic H atom to form acyl radica...

A discharge flow technique was used to study the heterogeneous reaction of OH with phenanthrene adsorbed on the Pyrex surface of the reactor, in the presence of NO2 and in the absence of light. The reaction kinetics were investigated by measuring the total loss of OH, followed by laser-induced fluorescence (LIF). The large efficiency of the heterog...

The kinetics and mechanism of the gas-phase reaction of the cyclohexadienyl radical c-C6H7 with O2 have been investigated using both experimental and theoretical approaches. The rate constant has been measured using conventional flash photolysis in the temperature range 302–456 K, 1 atm pressure. c-C6H7 radicals were produced by reacting Cl atoms w...

The laser flash photolysis technique has been used to measure rate coefficients for the self- and cross-reactions of four peroxy radicals, which have been selected as surrogate of those peroxy radicals resulting from the OH addition to monoterpenes: the 2-hydroxycyclohexylperoxy c-C6H10(OH)O2 (I), 2-hydroxy-1,2-dimethylcyclohexylperoxy c-C6H8(CH3)2...

A conventional flash photolysis technique was used to measure the self-reaction rate constants of the primary BrCH2CH2O2 (2-bromoethylperoxy) and secondary BrCH(CH3)CH(CH3)O2 (2-bromo-1-methylpropylperoxy) β-brominated peroxy radicals, at temperatures in the range of 275−373 K. The absolute UV absorption spectra of BrCH2CH2O2 and BrCH(CH3)CH(CH3)O2...

Flash photolysis UV absorption techniques were used to study the HO2 + CH3C(O)O2 reaction. It was found that the reaction HO2 + CH3CHO CH3CH(OH)O2 (2, −2) can interfere with the kinetic measurements. Thus, the kinetics and thermochemistry of this reaction were investigated. The UV spectrum of the CH3CH(OH)O2 radical was determined, and the rate con...

The kinetics of reactions of the tertiary β-brominated peroxy radical BrC(CH3)2C(CH3)2O2 (2-bromo-1,1,2-trimethylpropylperoxy) have been studied using the laser flash photolysis technique, photolysing HBr at 248 nm in the presence of O2 and 2,3-dimethylbut-2-ene. At room temperature, a rate constant of (2.0 ± 0.8) × 10−14 cm3 molecule−1 s−1 was det...