188 research outputs found
Oxydation atmosphérique hétérogène de HAP et de PBDE : cinétique, produits et génotoxicité
No full textCe travail a eu pour objectif l’étude de la dégradation hétérogène d’hydrocarbures aromatiques polycycliques (HAP) et de polybromo diphényles éthers (PBDE) en présence d’oxydants atmosphériques. La réactivité du benzo[a]pyrène et du dibenzo[a,l]pyrène pour les HAP et du BDE 153 (hexabromé) et du BDE 209 (décabromé) pour les PBDE, a été étudiée lorsqu’ils sont adsorbés sur des particules minérales modèles (des particules de silice) et exposés à l’ozone, au dioxyde d’azote ou aux radicaux hydroxyles. L’extraction et l’analyse de ces composés ont été optimisées. Le suivi de l’évolution de la concentration en composé adsorbé en fonction de son temps d’exposition à l’oxydant a permis de déterminer les paramètres cinétiques de chaque composé, pour chaque oxydant. L’influence de la concentration particulaire et de la structure moléculaire sur la réactivité a ainsi été évaluée et débattue. L’identification des produits de réactions majoritaires a été effectuée pour les réactions des HAP avec le dioxyde d’azote et les radicaux hydroxyles et les réactions des PBDE avec les radicaux hydroxyles. Enfin, l’étude de la génotoxicité des extraits de particules pour différents temps d’exposition aux oxydants a été réalisée. Cette étude regroupe une approche cinétique, une approche mécanistique et une approche toxicologique.This work deals with the heterogeneous degradation of polycyclic aromatic hydrocarbons (PAH) and polybromo diphenyls ethers (PBDE) with various atmospheric oxidants. The reactivity of Benzo[a]pyrene (BaP) and dibenzo[a,l]pyrene (DalP) for PAH and BDE 153 and BDE 209 for PBDE, had been studied when they are adsorbed on a model of mineral particles (silica particles) and exposed to ozone, nitrogen dioxide and hydroxyl radical. Extraction and analyse of compounds were optimised. For all studied reactions, kinetic parameters were obtained following the remaining concentration of compound for different exposure times. Influence of the particle loading and molecular structure on the reactivity had been evaluated and discussed. Identification of the main degradation products was made for the reaction of PAH with nitrogen dioxide and hydroxyl radical and for the reaction of PBDE with hydroxyl radical. Then, the genotoxicity of the particle extracts was made for different exposure times. This study talks about kinetics, mechanistic and genotoxicity
Oxydation atmosphérique hétérogène de HAP et de PBDE : cinétique, produits et génotoxicité
No full textCe travail a eu pour objectif l’étude de la dégradation hétérogène d’hydrocarbures aromatiques polycycliques (HAP) et de polybromo diphényles éthers (PBDE) en présence d’oxydants atmosphériques. La réactivité du benzo[a]pyrène et du dibenzo[a,l]pyrène pour les HAP et du BDE 153 (hexabromé) et du BDE 209 (décabromé) pour les PBDE, a été étudiée lorsqu’ils sont adsorbés sur des particules minérales modèles (des particules de silice) et exposés à l’ozone, au dioxyde d’azote ou aux radicaux hydroxyles. L’extraction et l’analyse de ces composés ont été optimisées. Le suivi de l’évolution de la concentration en composé adsorbé en fonction de son temps d’exposition à l’oxydant a permis de déterminer les paramètres cinétiques de chaque composé, pour chaque oxydant. L’influence de la concentration particulaire et de la structure moléculaire sur la réactivité a ainsi été évaluée et débattue. L’identification des produits de réactions majoritaires a été effectuée pour les réactions des HAP avec le dioxyde d’azote et les radicaux hydroxyles et les réactions des PBDE avec les radicaux hydroxyles. Enfin, l’étude de la génotoxicité des extraits de particules pour différents temps d’exposition aux oxydants a été réalisée. Cette étude regroupe une approche cinétique, une approche mécanistique et une approche toxicologique.This work deals with the heterogeneous degradation of polycyclic aromatic hydrocarbons (PAH) and polybromo diphenyls ethers (PBDE) with various atmospheric oxidants. The reactivity of Benzo[a]pyrene (BaP) and dibenzo[a,l]pyrene (DalP) for PAH and BDE 153 and BDE 209 for PBDE, had been studied when they are adsorbed on a model of mineral particles (silica particles) and exposed to ozone, nitrogen dioxide and hydroxyl radical. Extraction and analyse of compounds were optimised. For all studied reactions, kinetic parameters were obtained following the remaining concentration of compound for different exposure times. Influence of the particle loading and molecular structure on the reactivity had been evaluated and discussed. Identification of the main degradation products was made for the reaction of PAH with nitrogen dioxide and hydroxyl radical and for the reaction of PBDE with hydroxyl radical. Then, the genotoxicity of the particle extracts was made for different exposure times. This study talks about kinetics, mechanistic and genotoxicity
Reaction of NO2 with Selected Conjugated Alkenes
No full textInternational audienceThe gas phase reactions of selected alkenes (isoprene, myrcene, ocimene, and 1,3-cyclohexadiene) with NO2 under dark condition have been investigated at T 298 K and P 760 Torr of purified air. The kinetic studies were performed under pseudo-first-order conditions using a large excess of NO2 concentration to those of the alkenes. The rate coefficients (in 10-19 cm3 molecule-1 s-1) obtained are 1.1 ± 0.2 for isoprene, 2.5 ± 0.3 for myrcene, 8.5 ± 1.2 for ocimene, and 15 ± 1 for 1,3-cyclohexadiene. Several products were identified by using in situ Fourier transform infrared (FT-IR) spectrometry, and acetone was found to be the major product from the reactions of NO2 with myrcene and ocimene, with a formation yield of 22 ± 3% and 26 ± 7%, respectively. The oxidation products from the reactions of NO2 with isoprene and 1,3-cyclohexadiene were found to be mainly nitro compounds identified by FT-IR spectroscopy. Reaction mechanisms were proposed to account for the products observed
Oxydation atmosphérique hétérogène de HAP et de PBDE (cinétique, produits et génotoxicité)
No full textCe travail a eu pour objectif l étude de la dégradation hétérogène d hydrocarbures aromatiques polycycliques (HAP) et de polybromo diphényles éthers (PBDE) en présence d oxydants atmosphériques. La réactivité du benzo[a]pyrène et du dibenzo[a,l]pyrène pour les HAP et du BDE 153 (hexabromé) et du BDE 209 (décabromé) pour les PBDE, a été étudiée lorsqu ils sont adsorbés sur des particules minérales modèles (des particules de silice) et exposés à l ozone, au dioxyde d azote ou aux radicaux hydroxyles. L extraction et l analyse de ces composés ont été optimisées. Le suivi de l évolution de la concentration en composé adsorbé en fonction de son temps d exposition à l oxydant a permis de déterminer les paramètres cinétiques de chaque composé, pour chaque oxydant. L influence de la concentration particulaire et de la structure moléculaire sur la réactivité a ainsi été évaluée et débattue. L identification des produits de réactions majoritaires a été effectuée pour les réactions des HAP avec le dioxyde d azote et les radicaux hydroxyles et les réactions des PBDE avec les radicaux hydroxyles. Enfin, l étude de la génotoxicité des extraits de particules pour différents temps d exposition aux oxydants a été réalisée. Cette étude regroupe une approche cinétique, une approche mécanistique et une approche toxicologique.This work deals with the heterogeneous degradation of polycyclic aromatic hydrocarbons (PAH) and polybromo diphenyls ethers (PBDE) with various atmospheric oxidants. The reactivity of Benzo[a]pyrene (BaP) and dibenzo[a,l]pyrene (DalP) for PAH and BDE 153 and BDE 209 for PBDE, had been studied when they are adsorbed on a model of mineral particles (silica particles) and exposed to ozone, nitrogen dioxide and hydroxyl radical. Extraction and analyse of compounds were optimised. For all studied reactions, kinetic parameters were obtained following the remaining concentration of compound for different exposure times. Influence of the particle loading and molecular structure on the reactivity had been evaluated and discussed. Identification of the main degradation products was made for the reaction of PAH with nitrogen dioxide and hydroxyl radical and for the reaction of PBDE with hydroxyl radical. Then, the genotoxicity of the particle extracts was made for different exposure times. This study talks about kinetics, mechanistic and genotoxicity.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF
The broadband light analyzer of complex aerosol: characterization and first applications
No full textWe introduce a new instrument to measure spectral light absorption by aerosol particles. BLAnCA (Broadband Light Analyzer of Complex Aerosol) is an automatic laboratory instrument for offline measurement of aerosol collected on suitable media. BLAnCA is equipped with a white light source and a high-resolution spectrometer, and measures in the range between 375 and 1000 nm with a spectral resolution of 5 nm. This allows for the determination of fine structure of the absorption properties of a sampled aerosol, which can lead to improvement in the robustness and scope of source apportionment and the evaluation of climate-relevant properties such as the aerosol mass absorption cross-section. The new instrument has been validated against a multi-wavelength absorbance analyzer, obtaining an agreement of up to 99 % between absorption coefficient measurements. The absorption coefficient limit of detection for BLAnCA has been estimated at 1.20 Mm−1 (2.70 Mm−1) for standard EU (EPA) sampling conditions, corresponding to an elemental carbon detection limit of about 1.3 g cm−2, if a mass absorption cross-section of m2g−1 at 1000 nm is considered. The instrument has been used to characterize several types of aerosol samples, each with its own distinct absorption features, which show the potential for BLAnCA to identify different kinds of particulate matter based on their optical properties
Laboratory investigation of the optical absorption properties of brown carbon in the CESAM simulation chamber using a photoacoustic spectrophone at 405 nm
No full textInternational audienceLight absorption by atmospheric aerosol particles, such as black and brown carbon (BC and BrC), has important effects on the Earth’s radiative balance and climate. Accurate knowledge of the optical absorption properties of such carbonaceous aerosols is highly needed in order to provide the necessary parameterizations for climate models and for remote sensing in order to constrain their global and regional radiative effect. Nowadays, large-scale model calculations are still too poorly constrained to make sufficiently accurate assessments of the climate effects of absorbing aerosols [1]. In this context, filter-free measurement technique based on photoacoustic spectrophone (PAS) has been developed in order to provide in situ measurements of light absorption by aerosols in their natural suspended state to avoid the measurement artefacts associated with traditional, filter-based absorption photometers. In the framework of the ANR B2C project, a custom-made PAS operating at 405 nm has been deployed for filter-free measurement of absorption coefficient of brown carbon, produced from oxidation of naphthalene by OH radicals in the CESAM atmospheric simulation chamber [2,3]. Performances of the deployed PAS has been evaluated and characterized with the help of the reference instruments deployed in the measurement campaign, such as aethalometer (AE33), scanning mobility particle sizer (SMPS), NOx Monitor (APNA-370) and TEOM monitor (based on tapered element oscillating microbalances technology). Experimental details and the preliminary results will be discussed and presented. Acknowledgments This work is partially supported by the French national research agency (ANR) under the B2C (ANR-19-CE01-0024), Labex CaPPA (ANR-10-LABX-005) and PIA-ADEME SEAM contracts, the CPER ECRIN program, and the EU H2020-ATMOS project. The CNRS-INSU is gratefully acknowledged for supporting the CESAM chamber as a national facility as well as the AERIS data center for distributing and curing the data produced by the CESAM chamber. References [1] C. Cappa, R. Kotamarthi, A. Sedlacek, C. Flynn, E. Lewis, A. McComiskey, N. Riemer, "Absorbing Aerosols Workshop Report", U.S. Department of Energy, Climate and Environmental Sciences Division, January 20-21, 2016. [2] J. Wang, J. F. Doussin, S. Perrier, E. Perraudin, Y. Katrib, E. Pangui, and B. Picquet-Varrault, "Design of a new multi-phase experimental simulation chamber for atmospheric photosmog, aerosol and cloud chemistry research", Atmos. Meas. Tech. 4 (2011) 2465–2494 [3] H. Yi, M. Cazaunau, A. Gratien, V. Michoud, E. Pangui, J.-F. Doussin, W. Chen, "Intercomparison of IBBCEAS, NitroMAC and FTIR for HONO, NO2 and CH2O measurements during the reaction of NO2 with H2O vapour in the simulation chamber CESAM", Atmos. Meas. Tech. 14 (2021) 5701–571
Homology model of the rainbow trout estrogen receptor (rtERalpha) and docking of endocrine disrupting chemicals (EDCs)
No full textA model for rainbow trout (Oncorhynchus mykiss) estrogen receptor (rtERa) was built by homology with the human estrogen receptor (hERa). A high level of sequence conservation between the two receptors was found with 64% and 80% of identity and similarity, respectively. Selected endocrine disrupting chemicals were docked into the ligand binding domain (LBD) of rtERa and the corresponding free binding energies ?(?G(bind)) values were calculated. A Quantitative Structure-Activity Relationship (QSAR) model between the relative binding affinity data and the ?(?G(bind)) values was derived in order to predict which further organic pollutants are likely to bind to rtERa
An experimental study of the reactivity of terpinolene and β-caryophyllene with the nitrate radical
No full textInternational audienceBiogenic volatile organic compounds (BVOCs) are intensely emitted by forests and crops into the atmosphere. They can rapidly react with the nitrate radical (NO3) during the nighttime to form a number of functionalized products. Among them, organic nitrates (ONs) have been shown to behave as reservoirs of reactive nitrogen and consequently influence the ozone budget and secondary organic aerosols (SOAs), which are known to have a direct and indirect effect on the radiative balance and thus on climate. Nevertheless, BVOC + NO3 reactions remain poorly understood. Thus, the primary purpose of this study is to furnish new kinetic and mechanistic data for one monoterpene (C10H16), terpinolene, and one sesquiterpene (C15H24), β-caryophyllene, using simulation chamber experiments. These two compounds have been chosen in order to complete the few experimental data existing in the literature. Rate constants have been measured using both relative and absolute methods. They have been measured to be (6.0 ± 3.8) ×10-11 and (1.8 ± 1.4) ×10-11 cm3 molec.−1 s−1 for terpinolene and β-caryophyllene respectively. Mechanistic studies have also been conducted in order to identify and quantify the main reaction products. Total organic nitrates and SOA yields have been determined. Both terpenes appear to be major ON precursors in both gas and particle phases with formation yields of 69 % for terpinolene and 79 % for β-caryophyllene respectively. They are also major SOA precursors, with maximum SOA yields of around 60 % for terpinolene and 90 % for β-caryophyllene. In order to support these observations, chemical analyses of the gas-phase products were performed at the molecular scale using a proton transfer reaction-time-of-flight-mass spectrometer (PTR-ToF-MS) and FTIR. Detected products allowed proposing chemical mechanisms and providing explanations through peroxy and alkoxy reaction pathways
Laboratory experimental simulation activity: a key contribution to constrain the estimate of the aerosol-radiation interaction
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