Study of sources and atmospheric dynamics of particulate organic pollutants in Alpine valleys : contribution of new organic tracers for receptor modelling applications

Récemment, la qualité de l'air dans la région Rhône-Alpes est devenue un sujet sensible depuis sa mise en demeure par l'Union Européenne pour non respect des normes en vigueurs concernant les taux de particules fines (PM). Effectivement, certaines zones géographiques de la région connaissent de nombreux dépassements en PM10, particulièrement dans les vallées alpines durant la période hivernale. Ces dépassements en particules sont aussi accompagnés de fortes concentrations en composés organiques comme les hydrocarbures aromatiques polycycliques (HAP) constituants ces PM. Un accroissement des connaissances sur les sources de pollution atmosphérique particulaire et leurs dynamiques au sein des vallées alpines est alors nécessaire, ceci afin d'améliorer la mise en place des politiques de diminution des émissions grâce à une meilleure connaissance de l'influence des différentes sources au niveau régional. Ces travaux de thèse sont axés autour des émissions des sources industrielles encore mal connues et plus particulièrement l'industrie du carbone très présente dans les bassins industriels de ces fonds de vallées. Les approches classiques par les éléments métalliques n'étant pas spécifiques, l'exploration de la fraction organique a permis de proposer un profil chimique organique complet et d'avancer le benzo(b)naphtho(2,1-d)thiophène (BNT(2,1)), composé particulaire majoritaire de la famille des Hydrocarbures Aromatiques Polycycliques soufrés (HAPS) comme traceur de cette source. Ce composé a été détecté et quantifié sur plusieurs sites en proximité d'activités industrielles confirmant ainsi sa source potentielle. De plus le profil industriel a été introduit comme profil « source » afin d'évaluer sa robustesse dans les méthodologies de type modèle récepteur de bilan de masse comme le « Chemical Mass Balance » (CMB) et statistique comme la « Positive Matrix Factorization » (PMF). Les résultats ont confirmé l'intérêt de l'ajout des composés organiques à ces méthodologies. Ainsi, le profil industriel et les composés organiques HAPS ont permis de mieux tracer la source appelée génériquement « industrie du carbone » (combustions de charbon, de coke et de matériaux graphitiques) dans les vallées alpines mais aussi sur différents sites urbains français. En parallèle, un modèle de régression non linéaire multivarié (MRNL) a été développé pour la quantification des sources de HAP, basé sur l'utilisation de traceurs spécifiques de source (lévoglucosan, hopanes….) et de données météorologiques (gradient thermique). Son application a été validée sur un ensemble de sites alpins des vallées de l'Arve et de la Tarentaise. Un couplage entre ce modèle et les données de mesures optiques du carbone suie (BC) par aéthalomètre, a permis de proposer une solution aux mauvais résultats de corrélation entre les HAP mesurés et modélisés par le modèle MRNL sur le site de la vallée de la Maurienne. Ces faibles corrélations peuvent être liées à une mauvaise représentativité des composés organiques utilisés à tracer correctement les sources d'émission sur certains sites.Enfin, l'inter-comparaison de ces méthodologies pour la détermination des sources de HAP et plus particulièrement de la source industrielle permet de valider cette méthodologie dans une perspective opérationnelle de suivi des sources de HAP sur ces différents sites. Ces travaux réalisés au cours de cette thèse mettent en évidence l'intérêt de la caractérisation de la fraction organique des PM et les biais qui peuvent exister sur l'utilisation des composés organiques pour l'étude des sources d'émissions. Des alternatives y sont proposées afin de soulever ces ambiguïtés et d'améliorer l'étude des sources de HAP par les modèles récepteurs.Recently, Air quality has become a sensitive topic for Rhône-Alpes region due to the formal notice which was addressed by the European Commission for non-compliance with legislation in force. Indeed, certain geographic areas in the region present a lot of overruns in PM10, especially in Alpine valleys during winter. These overruns particles are also accompanied by high concentrations of organic compounds such as polycyclic aromatic hydrocarbons (PAHs), which constitute these PMs. An increase in khowledge about the sources of particulate air pollution and their dynamics in Alpine valleys is necessary, in order to improve the implementation of policies to reduce emissions through better knowledge of the influence of different sources at regional level. This thesis is focused around emissions from industrial sources still poorly known and particularly of the carbon industry highly present in these industrial areas of the valley bottoms. Traditional approaches by metallic elements being not specific, exploration of the organic fraction allowed to propose a complete organic chemical profile. In addition they led us to evidence the benzo(b)naphtho(2,1-d)thiophene (BNT(2,1)), the most abundant particulate compound of the family of sulfur-containing polycyclic aromatic hydrocarbons (PASHs), as a tracer of this source. This compound was detected and quantified on multiple sites in near industrial activities confirming its potential source. In addition the industrial profile was introduced as profile “source” in order to assess its robustness in methodologies of receptor model like the “Chemical Mass Balance “(CMB) and the “Positive Matrix Factorization” (PMF). The results confirmed the interest of the addition of organic compounds to these methodologies. Thus, the industrial profile and the PASHs compounds have allowed to better trace the source usually called “carbon industry” (coal, coke and graphite materials combustions) in the Alpine valleys but also in different French urban sites. In parallel, a non linear regression model (NLRM) was developed to PAH source apportionment, based on the use of specific molecular markers (levoglucosan, hopanes…) and of meteorological data (altitudinal temperature lapse rate). Its implementation has been validated on a set of sites of the Alpine valleys of Arve and Tarentaise. Coupling between this model and the optical measurements of black carbon (BC) by aethalometer, allowed to propose a solution to the poor performance of correlation between PAHs measured and modeled by NLRM model on this site of the Maurienne valley. These low correlations may be related to poor representativeness of organic compounds used to correctly trace the emission sources at some sites. Finally, the inter-comparison of these methodologies for the determination of PAH sources and especially of industrial source allows to validate this methodology in an operational perspective of monitoring of PAH levels on these sites. The work performed during this thesis highlights the interest of the characterizatin of the organic fraction of PM and the biases that may exist on the use of organic compounds for the study of the emission sources. Some alternatives are suggested to clarify ambiguities and improve the source apportionment of PAHs by receptor models

Etude des sources et de la dynamique atmosphérique de polluants organiques particulaires en vallées alpines : apport de nouveaux traceurs organiques aux modèles récepteurs

Recently, Air quality has become a sensitive topic for Rhône-Alpes region due to the formal notice which was addressed by the European Commission for non-compliance with legislation in force. Indeed, certain geographic areas in the region present a lot of overruns in PM10, especially in Alpine valleys during winter. These overruns particles are also accompanied by high concentrations of organic compounds such as polycyclic aromatic hydrocarbons (PAHs), which constitute these PMs. An increase in khowledge about the sources of particulate air pollution and their dynamics in Alpine valleys is necessary, in order to improve the implementation of policies to reduce emissions through better knowledge of the influence of different sources at regional level. This thesis is focused around emissions from industrial sources still poorly known and particularly of the carbon industry highly present in these industrial areas of the valley bottoms. Traditional approaches by metallic elements being not specific, exploration of the organic fraction allowed to propose a complete organic chemical profile. In addition they led us to evidence the benzo(b)naphtho(2,1-d)thiophene (BNT(2,1)), the most abundant particulate compound of the family of sulfur-containing polycyclic aromatic hydrocarbons (PASHs), as a tracer of this source. This compound was detected and quantified on multiple sites in near industrial activities confirming its potential source. In addition the industrial profile was introduced as profile “source” in order to assess its robustness in methodologies of receptor model like the “Chemical Mass Balance “(CMB) and the “Positive Matrix Factorization” (PMF). The results confirmed the interest of the addition of organic compounds to these methodologies. Thus, the industrial profile and the PASHs compounds have allowed to better trace the source usually called “carbon industry” (coal, coke and graphite materials combustions) in the Alpine valleys but also in different French urban sites. In parallel, a non linear regression model (NLRM) was developed to PAH source apportionment, based on the use of specific molecular markers (levoglucosan, hopanes…) and of meteorological data (altitudinal temperature lapse rate). Its implementation has been validated on a set of sites of the Alpine valleys of Arve and Tarentaise. Coupling between this model and the optical measurements of black carbon (BC) by aethalometer, allowed to propose a solution to the poor performance of correlation between PAHs measured and modeled by NLRM model on this site of the Maurienne valley. These low correlations may be related to poor representativeness of organic compounds used to correctly trace the emission sources at some sites. Finally, the inter-comparison of these methodologies for the determination of PAH sources and especially of industrial source allows to validate this methodology in an operational perspective of monitoring of PAH levels on these sites. The work performed during this thesis highlights the interest of the characterizatin of the organic fraction of PM and the biases that may exist on the use of organic compounds for the study of the emission sources. Some alternatives are suggested to clarify ambiguities and improve the source apportionment of PAHs by receptor models.Récemment, la qualité de l'air dans la région Rhône-Alpes est devenue un sujet sensible depuis sa mise en demeure par l'Union Européenne pour non respect des normes en vigueurs concernant les taux de particules fines (PM). Effectivement, certaines zones géographiques de la région connaissent de nombreux dépassements en PM10, particulièrement dans les vallées alpines durant la période hivernale. Ces dépassements en particules sont aussi accompagnés de fortes concentrations en composés organiques comme les hydrocarbures aromatiques polycycliques (HAP) constituants ces PM. Un accroissement des connaissances sur les sources de pollution atmosphérique particulaire et leurs dynamiques au sein des vallées alpines est alors nécessaire, ceci afin d'améliorer la mise en place des politiques de diminution des émissions grâce à une meilleure connaissance de l'influence des différentes sources au niveau régional. Ces travaux de thèse sont axés autour des émissions des sources industrielles encore mal connues et plus particulièrement l'industrie du carbone très présente dans les bassins industriels de ces fonds de vallées. Les approches classiques par les éléments métalliques n'étant pas spécifiques, l'exploration de la fraction organique a permis de proposer un profil chimique organique complet et d'avancer le benzo(b)naphtho(2,1-d)thiophène (BNT(2,1)), composé particulaire majoritaire de la famille des Hydrocarbures Aromatiques Polycycliques soufrés (HAPS) comme traceur de cette source. Ce composé a été détecté et quantifié sur plusieurs sites en proximité d'activités industrielles confirmant ainsi sa source potentielle. De plus le profil industriel a été introduit comme profil « source » afin d'évaluer sa robustesse dans les méthodologies de type modèle récepteur de bilan de masse comme le « Chemical Mass Balance » (CMB) et statistique comme la « Positive Matrix Factorization » (PMF). Les résultats ont confirmé l'intérêt de l'ajout des composés organiques à ces méthodologies. Ainsi, le profil industriel et les composés organiques HAPS ont permis de mieux tracer la source appelée génériquement « industrie du carbone » (combustions de charbon, de coke et de matériaux graphitiques) dans les vallées alpines mais aussi sur différents sites urbains français. En parallèle, un modèle de régression non linéaire multivarié (MRNL) a été développé pour la quantification des sources de HAP, basé sur l'utilisation de traceurs spécifiques de source (lévoglucosan, hopanes….) et de données météorologiques (gradient thermique). Son application a été validée sur un ensemble de sites alpins des vallées de l'Arve et de la Tarentaise. Un couplage entre ce modèle et les données de mesures optiques du carbone suie (BC) par aéthalomètre, a permis de proposer une solution aux mauvais résultats de corrélation entre les HAP mesurés et modélisés par le modèle MRNL sur le site de la vallée de la Maurienne. Ces faibles corrélations peuvent être liées à une mauvaise représentativité des composés organiques utilisés à tracer correctement les sources d'émission sur certains sites.Enfin, l'inter-comparaison de ces méthodologies pour la détermination des sources de HAP et plus particulièrement de la source industrielle permet de valider cette méthodologie dans une perspective opérationnelle de suivi des sources de HAP sur ces différents sites. Ces travaux réalisés au cours de cette thèse mettent en évidence l'intérêt de la caractérisation de la fraction organique des PM et les biais qui peuvent exister sur l'utilisation des composés organiques pour l'étude des sources d'émissions. Des alternatives y sont proposées afin de soulever ces ambiguïtés et d'améliorer l'étude des sources de HAP par les modèles récepteurs

Effect of energy renovation on indoor air quality of a French school building

International audienceIndoor air quality (IAQ) and thermal comfort issues in schoolsare of particular public concern because children represent avulnerable population group to air pollution. In fact, their respiratoryand immune systems are still developing and a long-term exposureto indoor air pollutants might have a significant impact on theirhealth and scholarly. This study focuses on the effect of the energyrenovation of two classrooms which consists of the implementationof a dual flow ventilation system with high efficiency filters (F7).The classrooms are located in an alpine valley (France) known forits high level of atmospheric pollution. To do this, carbon dioxide(CO2), temperature (T), relative humidity (RH) and PM2.5 weremonitored continuously over twice two-month periods before andafter the renovation in winter 2018 and 2020, respectively. Inaddition, the ventilation airflows were measured and a dailyquestionnaire that report the information on general condition in theclassroom were recorded day-to-day. The results of these campaignsindicate that before the renovation, the two rooms were confined,estimated by IAQ index such as ICONE index which are equal to 2.The CO2 concentration reached to 4790 ppmv due to a very low airexchange rate 0.05 h-1. During the high PM2.5 levels episodesobserved in outdoor air, the low air exchange rate limited thetransport of PM2.5 from the outside to the inside of the classrooms.As a result, the percentages of concentration exceedance comparedto WHO recommendations were 23% and 17%, in class 1 and class2 respectively, while it reached 68% in outdoor air.After the renovation, the ventilation airflow was higher thanbefore renovation and reached to 2.46 h-1. As consequence, a drasticreduction of the confinement was measured with ICONE index ofclass 2 reaching to 0. The CO2 concentrations are remained low witha maximum value of 1150 ppmv. Rather the high air renewalgenerates a significant inflow of outdoor particulate pollution whichthe indoor PM2.5 concentrations range were 20-80 µg.m-3 during theoutdoor air pollution episodes. However, the indoor concentrationswere all the time lower than those observed outside withindoor/outdoor concentration ratio about 0.5. It can be assumed thatthe filtration of the supply air allowed to limit the entrance of theparticles. However, this figure should be taken with caution becauseof the complex physic associated with particle behaviours (e.g.sedimentation, resuspension, etc). In addition, it is interesting to notethat a dysfunction of the ventilation system led to a situation closeto that before renovation, both with regard to the rate of ventilationairflow, as well as the concentrations of CO2 and PM2.5

Effect of energy renovation on indoor air quality and thermal environment in winter of a primary school in a highly polluted French alpine valley

International audienc

On-site assessment of the IAQ benefits of an innovative airflow window having an electrostatic particle filter

International audienceIn France, 85 % of buildings with mechanical ventilation have an exhaust ventilation system. In such situations, mechanical filtration of the fresh air is hardly possible for technical and practical reasons, which may result in serious IAQ problems in areas with high airborne particle concentrations. An innovative solution coupling an airflow window with an electrostatic precipitator was developed to address this issue. The window allows heat recovery and particle filtration at the fresh air inlet, thus improving IAQ. The electrostatic precipitator uses a needle ionizing technology as a pre-charger combined with a collection stage. The IAQ improvement provided by the system was assessed by comparing particle concentrations in twin rooms of 6 m3 for several weeks. One had the filtering airflow window while the other had a standard airflow window. Particle concentrations were monitored using particle counters for ventilation airflow rates ranging from 10 to 50 m3/h. Ozone and NOx concentrations were also monitored using analyzers to assess the by-product emissions from the ESP. The results showed promising results. For instance, the efficiency is 63 ±5% for PM10 and 79 ±5% for PM1 for an exhaust airflow rate of 40 m3/h, while only 30 m3/h passes through the airflow window in these conditions (10 m3/h is due to infiltrations through the cell envelope). Moreover, the indoor ozone concentration was increased by a maximum of 5 ppb in the test room, when compared to the reference room

Nickel-Manganese Catalysts as Biomimics of the active site of NiFe hydrogenases: a Combined Electrocatalytical and DFT Mechanistic Study

International audienc

The N stable isotopes from particulate ammonium nitrate: understanding of the atmospheric processes and the sources of PM10 in France

Aerosol nitrate is an important fraction of the mass of the fine particles (PM) in atmosphere. Moreover, aerosol nitrogen species are predominantly anthropogenic over Europe (traffic, industry and farming). In the view of the increasingly drastic constraints of the European air quality standard for PM, the understanding of these sources has become crucial in France. Indeed, during the months of March and April, several high concentration of PM are observed on a large scale throughout the national territory. During these specific events, the ammonium nitrate (NH4NO3) is a predominant component of the airborne PM. There are two main ways that produces NH4NO3 in air with many precursors as NH3 from specific primary sources (agricultural activity). The presence of these species in PM is the result of complex primary and secondary processes which are always investigated. In literature, many studies propose the nitrogen stable isotope ratio (?15N) of NOx as an indicator for NOx source apportionment ((Walters, Goodwin, et Michalski 2015; Felix, Elliott, et Shaw 2012) but there is a lack of information regarding the ?15N ratio of NH4. Thus, these last two years, the main objectives of the INAC and INCAS-2 programs were to collect various samples from ambient rural (2 sites) and urban (5 sites) background sites in order to quantify the nitrogen isotope ratio of nitrate and ammonium in PM. Then, subsequently the characterization of emissions of the different types of samples (traffic, biomass burning, and agriculture activity) was performed to provide clear information between the nitrogen isotope ratio and the sources. Currently, this study represents the most important French database (long-term and source data) on ?15N composition of particulate ammonium nitrate in PM. The first results show that ?15N-NOx has a high seasonal variability which is relatively difficult to interpret as the impact of the specific sources. Whereas, the ?15N of NH4 seems to contain information about the pollution sources. Indeed, this isotope composition appears to be negatively correlated with particulate NH4NO3 events on several sites as described on Figure 1 (urban site, Grenoble). We observed that the values of ?15N-NH4 ranged from 10‰ to 25‰ in large part of years and decreased significantly toward negative values during these periods of peak agricultural activity. Based on these first results, source apportionments of PM10 collected over one years at each sampling sites were conducted with Positive Matrix Factorization (US EPA PMF v5.0) and Multilinear-Engine (ME-2 SoFI from PSI). In this work, the interest to include such isotope measurements as input data for PMF will be discussed for the first time, focusing on their application to identify specific source of ammonium nitrate in PM

Nitrogen's stable isotopes as a proxy to determine ammonium sources in PM using a Monte Carlo's simulation

During cold periods (from November to April) in France, PM concentrations regularly exceed the standard prescribed 50 μg.m-3 limit, which about 50 % in mass is composed on ammonium nitrate (NH4NO3) (Rouïl et al. 2015). The continental scale of such events is a threat to human health and decrease significantly the quality of our environment. The ammonium (NH4 +) is suspected to come from different sources, especially from the agricultural ammonia (NH3) but there is no direct evidence of it. The INACS program aims to investigate the sources proportion in the PM using several methods. This work tries to distinguish and quantify the source apportionment using nitrogen stable isotopes from ammonium nitrate in the PM since previous studies (Felix et al. 2014) highlighted the high level of correlation between the NH4 + concentration and the δ15N of NH4 +. From 2011 to 2013, PM were collected at 7 stations in France at daily sampling rate. δ15N of NH4 + was measured at these sites, ranging from ambient rural to urban background. Besides these isotopic measurements on ambient aerosol samples, the isotopic characterization of different emissions sources (traffic, biomass burning, and agricultural activities) was performed to obtain their specific source isotopic signatures. To the best of our knowledge, this database constitutes probably the most extensive dataset studied so far, with more than 500 δ15N of NH4 + aerosols' observations. In order to take into account the isotopic variability of the sources, a stochastic Monte Carlo's simulation (MCS) was conducted. This approach has in the past demonstrated its applicability for source apportionment method (Sheesley et al. 2011). Applying MCS to our dataset gives a probability distribution function (PDF) for each source and observation day as shown in Fig. 1 for the 2nd March 2013 in a French rural background site..

A nickel–manganese catalyst as a biomimic of the active site of NiFe hydrogenases: a combined electrocatalytical and DFT mechanistic study

International audienceThe dinuclear nickel–manganese complex [Ni(xbsms)Mn(CO)3(H2O)]+ (H2xbsms = 1,2-bis(4-mercapto-3,3-dimethyl-2-thiabutyl)benzene) is reported as a bio-inspired mimic of the active site of NiFe hydrogenases catalyzing hydrogen evolution from trifluoroacetic acid in DMF with an overpotential requirement of 860 mV. This is higher than that displayed by Ni–Ru systems [Canaguier et al., Chem.–Eur. J., 2009, 15, 9350–9364] but similar to that found for related noble metal free Ni–Fe mimics [Canaguier et al., Chem. Commun. 2010, 46, 5876–5878]. A combined electrochemical and theoretical (DFT) study suggests a heterolytic mechanism for hydrogen evolution from a hydride derivative. The structure of the active intermediate, with a bridging hydride ligand between Ni and Mn, resembles that of the Ni–C active state of NiFe hydrogenases

DÉVELOPPEMENT D'UNE FENÊTRE PARIÉTO-DYNAMIQUE FILTRANTE

International audienceThe objective of this work is to add to the excellent thermal, acoustic and comfort performances of an airflow window the ability to collect particles through an electrostatic precipitator. The ionisation process, its location and discharge polarity were studied. The results show that the addition of an electrofiltration process, consisting of an ionisation stage comprising 11 ionising needles and a collection stage, positioned between the glass panes, allows a reduction of more than 80% in the particles concentration in the ventilation air in the range 20 nm to 10 µm.L'objectif de ce travail est d'ajouter aux excellentes performances thermiques, acoustiques et de confort d'une fenêtre pariéto-dynamique la capacité à collecter les particules grâce à un procédé d'électrofiltration. Le procédé d'ionisation, son emplacement dans la fenêtre et la polarité de la décharge ont été étudiés. Les résultats montrent que l'ajout d'un module d'électrofiltration, constitué d'un étage d'ionisation comprenant 11 aiguilles ionisantes et d'un étage de collecte, positionnés entre les vitrages permet de réduire de plus de 80% la concentration en particules dans l'air de ventilation dans la gamme 20 nm à 10 µm