Impact des émissions naturelles sur les épisodes de pollution photochimique. Application à la région du fossé rhénan

Les Composés Organiques Volatils (COV) biotiques jouent un rôle significatif dans la formation et le développement d'épisodes de pollution photochimique. Leur forte réactivité et leur abondance dans la troposphère, en font des précurseurs significatifs de l'ozone, des PANs et du formaldéhyde. La prise en compte de ces COV par les modèles de prévision de la qualité de l'air se heurte aux incertitudes relatives à la quantification de leurs émissions et aux mécanismes chimiques de la troposphère dans lesquels ils sont impliqués. Dans ce contexte, la prise en compte des COV biotiques dans le modèle de chimie-transport CHIMERE a été améliorée en intégrant une double approche, numérique et expérimentale. Concernant les émissions biotiques, des mesures de terrain réalisées lors d'une campagne européenne, ont permis la détermination sur site de taux et flux d'émission de COV biotiques de trois espèces forestières très abondantes en France : Abies alba, Fagus sylvatica et Pseudotsuga menziesii, à partir de la méthode des cuvettes instrumentées. Ces résultats, complétés par une étude bibliographique, ont permis de mettre à jour la base de données des facteurs d'émission spécifique de la zone d'étude et de la France. Cette base de données a été utilisée pour estimer les émissions annuelles de COV par l'écosystème forestier français. Concernant la réactivité des COV biotiques, une synthèse critique de la bibliographie a conduit à l'élaboration d'un nouveau mécanisme chimique permettant de mieux modéliser leur réactivité. Les développements effectués ont abouti à une nouvelle version du modèle CHIMERE dont les résultats ont été évalués par rapport aux observation disponibles dans la région du Fossé Rhénan, région fortement émettrice de COV biotiques. Si la modélisation des concentrations d'ozone est peu affectée par les modifications apportées, la modélisation des concentrations de PANs et de formaldéhyde y est nettement sensible. Une importante étude de sensibilité relative à la prise en compte des COV biotiques dans les modèles, a permis de mettre en évidence la nécessité et la pertinence de réaliser des compromis et des simplifications pour modéliser la contribution des COV biotiques dans la formation d'épisode photochimique à l'ozone. Des mesures de terrain et des travaux pour affiner la connaissance des processus réactionnels seront néanmoins toujours nécessaires pour simuler correctement les autres polluants secondaires ainsi que les aérosols organiques

The COMBAT project : controlling and progressively minimizing the burden of vector-borne animal trypanosomosis in Africa

Vector-borne diseases affecting livestock have serious impacts in Africa. Trypanosomosis is caused by parasites transmitted by tsetse flies and other blood-sucking Diptera. The animal form of the disease is a scourge for African livestock keepers, is already present in Latin America and Asia, and has the potential to spread further. A human form of the disease also exists, known as human African trypanosomosis or sleeping sickness. Controlling and progressively minimizing the burden of animal trypanosomosis (COMBAT) is a four year research and innovation project funded by the European Commission, whose ultimate goal is to reduce the burden of animal trypanosomosis (AT) in Africa. The project builds on the progressive control pathway (PCP), a risk-based, step-wise approach to disease reduction or elimination. COMBAT will strengthen AT control and prevention by improving basic knowledge of AT, developing innovative control tools, reinforcing surveillance, rationalizing control strategies, building capacity, and raising awareness. Knowledge gaps on disease epidemiology, vector ecology and competence, and biological aspects of trypanotolerant livestock will be addressed. Environmentally friendly vector control technologies and more effective and adapted diagnostic tools will be developed. Surveillance will be enhanced by developing information systems, strengthening reporting, and mapping and modelling disease risk in Africa and beyond. The socio-economic burden of AT will be assessed at a range of geographical scales. Guidelines for the PCP and harmonized national control strategies and roadmaps will be developed. Gender equality and ethics will be pivotal in all project activities. The COMBAT project benefits from the expertise of African and European research institutions, national veterinary authorities, and international organizations. The project consortium comprises 21 participants, including a geographically balanced representation from 13 African countries, and it will engage a larger number of AT-affected countries through regional initiatives.The European Union’s Horizon 2020 research and innovation programme.https://open-research-europe.ec.europa.euam2023Veterinary Tropical Disease

Impact des émissions naturelles sur les épisodes de pollution photochimique (application à la région du Fossé Rhénan)

Les Composés Organiques Volatils (COV) biotiques jouent un rôle significatif dans la formation et le développement d'épisodes de pollution photochimique. Leur forte réactivité et leur abondance dans la troposphère, en font des précurseurs significatifs de l'ozone, des PANs et du formaldéhyde. La prise en compte de ces COV par les modèles de prévision de la qualité de l'air se heurte aux incertitudes relatives à la quantification de leurs émissions et aux mécanismes chimiques de la troposphère dans lesquels ils sont impliqués. Dans ce contexte, la prise en compte des COV biotiques dans le modèle de chimie-transport CHIMERE a été améliorée en intégrant une double approche, numérique et expérimentale. Concernant les émissions biotiques, des mesures de terrain réalisées lors d'une campagne européenne, ont permis la détermination sur site de taux et flux d'émission de COV biotiques de trois espèces forestières très abondantes en France : Abies alba, Fagus sylvatica et Pseudotsuga menziesii, à partir de la méthode des cuvettes instrumentées. Ces résultats, complétés par une étude bibliographique, ont permis de mettre à jour la base de données des facteurs d'émission spécifique de la zone d'étude et de la France. Cette base de données a été utilisée pour estimer les émissions annuelles de COV par l'écosystème forestier français. Concernant la réactivité des COV biotiques, une synthèse critique de la bibliographie a conduit à l'élaboration d'un nouveau mécanisme chimique permettant de mieux modéliser leur réactivité. Les développements effectués ont abouti à une nouvelle version du modèle CHIMERE dont les résultats ont été évalués par rapport aux observation disponibles dans la région du Fossé Rhénan, région fortement émettrice de COV biotiques. Si la modélisation des concentrations d'ozone est peu affectée par les modifications apportées, la modélisation des concentrations de PANs et de formaldéhyde y est nettement sensible. Une importante étude de sensibilité relative à la prise en compte des COV biotiques dans les modèles, a permis de mettre en évidence la nécessité et la pertinence de réaliser des compromis et des simplifications pour modéliser la contribution des COV biotiques dans la formation d'épisode photochimique à l'ozone. Des mesures de terrain et des travaux pour affiner la connaissance des processus réactionnels seront néanmoins toujours nécessaires pour simuler correctement les autres polluants secondaires ainsi que les aérosols organiques.TOULOUSE-ENSIACET (315552325) / SudocSudocFranceF

Biogenic volatile organic compounds (BVOCs) emissions from Abies alba in a French forest

International audienceAir quality studies need to be based on accurate and reliable data, particularly in the field of the emissions. Biogenic emissions from forests, crops, and grasslands are now considered as major compounds in photochemical processes. Unfortunately, depending on the type of vegetation, these emissions are not so often reliably defined. As an example, although the silver fir (Abies alba) is a very widespread conifer tree in the French and European areas, its standard emission rate is not available in the literature. This study investigates the isoprene and monoterpenes emission from A. alba in France measured during the fieldwork organised in the Fosse' Rhe'nan, from May to June 2003. A dynamic cuvette method was used. Limonene was the predominant monoterpene emitted, followed by camphene, a-pinene and eucalyptol. No isoprene emission was detected. The four monoterpenes measured showed different behaviours according to micrometeorological conditions. In fact, emissions of limonene, a-pinene and camphene were temperature-dependant while eucalyptol emissions were temperature and light dependant. Biogenic volatile organic compounds emissions were modeled using information gathered during the field study. Emissions of the three monoterpenes previously quoted were achieved using the monoterpenes algorithm developed by Tingey et al. (1980) [Tingey D, Manning M, Grothaus L, Burns W. Influence of light and temperature on monoterpene emission rates from slash pine. Plant Physiol 1980;65: 797-801.] and the isoprene algorithm [Guenther, A., Monson, R., Fall, R., 1991. Isoprene and monoterpene emission rate variability: observations with eucalyptus and emission rate algorithm development. J Geophys Res 26A: 10799-10808.]; [Guenther, A., Zimmerman, P., Harley, P., Monson, R., Fall, R., 1993. Isoprene and monoterpene emission rate variability: model evaluation and sensitivity analysis. J Geophys Res 98D: 12609-12617.]) was used for the eucalyptol emission. With these methods, simulation results and observations agreed fairly well. The standard emission rate (303 K) and b-coefficient averaged for limonene, camphene and a-pinene were respectively of 0.63 micro g gdw-1 h-1 and 0.06 K-1. For eucalyptol, the standard emission rate (T=303 K and PAR=1000 umol m-2 s-1) was 0.26 micro g gdw-1 h-1. This classified A. alba as a weak monoterpenes emitter

Monoterpene emissions from Beech (Fagus sylvatica) in a french forest and impact on secondary pollutants formation at regional scale

International audienceBiogenic emissions from forest, crops, and grasslands are now considered major compounds in photochemical processes. Air quality analyses require more and more accurate input data, particularly emissions. Unfortunately, depending on the type of vegetation, these emissions are not always reliably defined. For example, Fagus sylvatica, which is a very abundant deciduous tree in France and in Europe, is a weak monoterpene emitter in the European inventory developed by Simpson et al. [1999. Journal of Geophysical Research 104, 8113-8152], but is a strong monoterpene emitter in Luchetta [1999. Caractérisation et quantification dans la basse atmosphère de composés organiques volatils biogéniques et anthropiques contribuant à la pollution de l'air. Ph.D. thesis, INPT Toulouse]. Beech (F. sylvatica) emission potential has never been measured in France. This study investigates the isoprene and monoterpenes emission measurements from F. sylvatica in France during a research program INTERREG III in Fosse Rhenan, during May and June 2003. A dynamic cuvette method was used. Sabinene is the main monoterpene emitted, composing more than 90 % of biogenic emissions. The remaining is composed of alpha-pinene, beta-pinene and limonene. No isoprene emissions were detected. The monoterpene emissions from F. sylvatica are affected by temperature and photosynthetic active radiation (PAR). In order to describe monoterpene emissions, the "isoprene algorithm" developed by Guenther et al. [1991. Journal of Geophysical Research 26A, 10799-10808; 1993. Journal. of Geophysical Research 98D, 12609-12617] has been used. With this algorithm, simulation results and observations agree fairly well. The standard emission rate (T = 303 K and PAR = 1000 mu mol m(-2) s(-1)) for total monoterpenes is 43.5 mu g g(dw)(-1)h(-1). This classifies F sylvatica as a strong monoterpene emitter. The European inventory [Simpson, et al., 1999. Journal of Geophysical Research 104, 8113-8152], which is the standard inventory of the model CHIMERE, is adjusted using this value. This induces an annual increase of 30% in simulated monoterpene emissions in France. These two inventories are used to simulate a regional pollution event during spring 2003. No significant differences are observed for ozone concentrations. Peroxy Acyl Nitrate (PANs) and formaldehyde concentrations increase by up to 10% in the adjusted inventory

New Directions:Time to tackle urban wood burning?

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Diesel, petrol or electric vehicles: What choices to improve urban air quality in the Ile-de-France region? A simulation platform and case study

This study was part of the work done by the ANSES working group on ambient particulate matter (chemical composition and road traffic emissions)International audienceAir pollution from road traffic and its mitigation is a major concern in most cities. A platform for simulating pollutant emissions and concentrations was developed and applied to the Île-de-France Region (Greater Paris) of France, taking account of anthropogenic and natural sources and ‘imported’ pollution from elsewhere in France and Europe. Four technological scenarios for 2025 were studied and compared to the 2014 reference situation (1-REF). These scenarios included the current evolution of the park with widespread adoption of diesel particulate filters (DPFs) (2-BAU), decline in the sale of diesel vehicles and a corresponding increase in petrol vehicle sales (3-PET), promotion of electric vehicles in urban areas (4-ELEC), and a combinaison with a decrease in traffic of about 15% in the densely populated area inside the A86 outer ring road (5-AIR). The corresponding vehicle fleets were determined using a fleet simulation model.Traffic pollutant emissions were computed with the COPERT4 European methodology and hourly traffic data over the Île-de-France road network. Particulate matter (PM10, PM2,5 and PM1,0), particles number (PN), black carbon (BC), organic matter (OM), nitrogen oxides (NOx) and nitrogen dioxide (NO2), non-methane volatile organic compounds (VOC), ammonia (NH3), carbon monoxide (CO) and carbon dioxide (CO2) were considered. Emissions for other sectors were taken from a regional inventory. Emissions outside the Île-de-France region (Europe and France) were derived from the European and French emission inventories. Pollutant concentrations (PM2,5, PM10, organic and inorganic PM10, PN, BC, NO2 and O3) were simulated over nested domains (Europe, France and Île-de-France) using the Polyphemus platform for two scenarios (2-BAU and 3-PET). Methodological aspects and results for Île-de-France are discussed here.All scenarios led to a sharp decrease in traffic emissions in Île-de-France (−30% to −60%) by 2025. The decline in diesel induced a stronger renewal of the fleet. PM and NOx emissions were more strongly reduced than VOC or NH3. Traffic reduction reduced all emissions in the densely populated area within the A86 outer ring road (−20% to −45% for exhaust particles and gaseous pollutants).The 2-BAU and 3-PET scenarios lowered annual average concentrations, especially for NO2 and BC, and more strongly influenced daily-peak than daily-average concentrations. In Île-de-France, PM of diameter <10 μm (PM10), and NO2 concentrations, decreased in the most densely populated areas. The entire population would benefit from a PM10 annual mean concentration decrease of ≥0.4 μg/m3, and the annual mean NO2 concentration would decrease by ≥ 10 μg/m3 for 40–50% of the population. For other pollutants (PM2.5, secondary pollutants, etc.), reductions were more limited, due to the other activity sectors and atmospheric chemistry. Ozone concentrations might even increase in urban locations, suggesting an increase in oxidants and thus an increase in secondary aerosol formation if precursors were not reduced.Differences between 2-BAU and 3-PET scenarios were slight. For PM and NO2 concentrations, the petrol scenario was slightly more favorable than the “business-as-usual” scenario with diesel vehicles and DPF; differences were strong for primary particles and NO2 and weak for secondary compounds. This slight advantage was due to lower emissions and accelerated fleet renewal (higher proportion of Euro 5 & 6)

Estimating biogenic contributions to ozone production at continental scale

International audienc

Modeling of carbonaceous aerosols with CHIMERE. Focus on secondary organic aerosols

Most of chemical transport models fairly simulate the major inorganic compounds in aerosols such as nitrate, sulfate, ammonium, chloride and sodium. The main pathways for the oxidation and gas/particle partitioning of inorganics are well identified, and above all, the number of species involved in those mechanisms is small. The organic fraction in aerosols is a complex mixture of hundreds major species interacting between each other and with the inorganic species. Organics can be emitted by resuspension of biogenic materials (waxes, vegetative and animal debris, etc... ) and by direct emissions of combustion processes. But a large amount of organic species are produced by oxidation of volatile organic compounds and condensation of the oxidation products or oligomerization of some condensed compounds. The resulting products (the so called SOA) are both biogenic and anthropogenic in origin. This particular chemistry involves a huge number of reactions and produces thousands of potential secondary organic species. Moreover, recent researches have pointed out that primary organic aerosols (POA) issued from the combustion processes could be an important source of SOA. These latter processes are not taken into account in models. The CHIMERE model used in the framework of the air quality forecasting system in France is now designed to account for carbonaceous species, a new SOA scheme has been implemented. Some applications are presented, the next key developments to improve SOA modelling are addressed

Regional modeling of carbonaceous aerosols over Europe—focus on secondary organic aerosols

International audienceIn this study, an improved and complete secondary organic aerosols (SOA) chemistry scheme was implemented in the CHIMERE model. The implementation of isoprene chemistry for SOA significantly improves agreement between long series of simulated and observed particulate matter concentrations. While simulated organic carbon concentrations are clearly improved at elevated sites by adding the SOA scheme, time correlation are impaired at low level sites in Portugal, Italy and Slovakia. At several sites a clear underestimation by the CHIMERE model is noticed in wintertime possibly due to missing wood burning emissions as shown in previous modeling studies. In Europe, the CHIMERE model gives yearly average SOA concentrations ranging from 0.5μg/m3 in the Northern Europe to 4μg/m3 over forested regions in Spain, France, Germany and Italy. In addition, our work suggests that during the highest fire emission periods, fires can be the dominant source of primary organic carbon over the Mediterranean Basin, but the SOA contribution from fire emissions is low. Isoprene chemistry has a strong impact on SOA formation when using current available kinetic schemes