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Improvement in Modeling of OH and HO2 Radical Concentrations during Toluene and Xylene Oxidation with RACM2 Using MCM/GECKO-A
No full textInternational audienceDue to their major role in atmospheric chemistry and secondary pollutant formation such as ozone or secondary organic aerosols, an accurate representation of OH and HO2 (HOX) radicals in air quality models is essential. Air quality models use simplified mechanisms to represent atmospheric chemistry and interactions between HOX and organic compounds. In this work, HOX concentrations during the oxidation of toluene and xylene within the Regional Atmospheric Chemistry Mechanism (RACM2) are improved using a deterministic-near-explicit mechanism based on the Master Chemical Mechanism (MCM) and the generator of explicit chemistry and kinetics of organics in the atmosphere (GECKO-A). Flow tube toluene oxidation experiments are first simulated with RACM2 and MCM/GECKO-A. RACM2, which is a simplified mechanism, is then modified to better reproduce the HOX concentration evolution simulated by MCM/GECKO-A. In total, 12 reactions of the oxidation mechanism of toluene and xylene are updated, making OH simulated by RACM2 up to 70% more comparable to the comprehensive MCM/GECKO-A model for chamber oxidation simulations
Integrated Biological Approach to Characterize and Discriminate Contaminated Wasteland in the Context of Its Requalification to an Ecological Use
No full textInternational audienceUrban and industrial activities led to the discharge of a wide range of hazardous chemicals in soils. Among abandoned wasteland, those whose soil functions were not altered beyond repair may ends up hosting transitional ecosystems with ecological values. However, there is a lack of screening methodologies to characterize and categorize among these sites. The main concern is to differentiate the soils/sites which are potential candidates for immediate upgrading to an “ecological usage” (e.g. biodiversity reserve) from those that require a comprehensive ecological risk assessment (which is sometimes difficult to applied for economical and/or technical reasons). In this context, the project TIPOMO (transfer and index of concern: tools for valuing medium-contaminated wasteland) aims at building an “index of concern” that allow the categorization of polluted soils hosting transitional ecosystems. This index will be calculated by considering the levels of soil contamination and its ability to trap polluting substances (characterization of bioavailability fraction). This method will be tested and validated in real case study. To do so, an integrated approach based on pollution characterization, and biological endpoints (both ex situ and in situ) were applied on 16 soil composites collecting on 8 sites mainly contaminated with HAP and/or hydrocarbons and/or metals. The biological endpoints were characterized by using a battery of ecotoxicity tests to assess the soil hazard and the potential pollutant bioavailability. Effect on species representative of bacteria (i.e. dehydrogenase inhibition activity in Arthrobacter Globiformis), mesaufauna (i.e. Growth and reproduction test of the nematodes), macrofauna (i.e. earthworms behavior and acute toxicity test) and higher plants (i.e. oats and turnip) were studied. The accumulation of HAP, hydrocarbons and metals were determined ex situ in earthworms. In addition, the aquatic ecotoxicity of the hydrosoluble fraction of pollutant were investigated on freshwater microalgae and microinvertebrate. Finally, in situ ecological criteria (i.e. plant inventory) and pollutant transfer in plants were investigated on each site. The poster will present the proposed approach as well as the first results and their interpretation regarding the categorization of the investigated sites
Multi-Biomarkers Approach in Three-Spined Stickleback (Gasterosteus Aculeatus, L.) Using an ENvironmental Biomonitoring Analysis : Genotoxic Biomarkers Integration
No full textInternational audienceIn order to improve the diagnosis of environmental contamination of freshwater, multi-biomarkers approaches have been developed to better reflect the physiological state of an organism and potentially detect exposures to xenobiotics. Genotoxic biomarkers seem to be quite relevant due to the multitude of substances interacting with the DNA molecule which can affect its integrity in somatic and germ cells. Among the existing tools used to highlight the genotoxicity on fish erythrocytes, the alkaline comet assay (SCGE) is the most widely used method to detect primary DNA strand breaks and flow cytometry (FCM) is becoming a fast and convenient tool to notice chromosomal damages for aquatic biomonitoring. The present work proposes to evaluate the relevance to include two genotoxic biomarkers (primary DNA strand breaks and chromosomal damages) in the existing battery of multi-biomarkers developed on three-spined stickleback (Gasterosteus aculeatus). After 21 days of exposure, biological samples were recovered from sticklebacks caged in six sites in Northern France to constitute the battery. The inclusion of genotoxicity biomarkers seems to bring a little improvement to the discriminating power of sites as obtained by a Principal Component Analysis (PCA) explaining 30.8% of the variance, although they provide a complementary information on the toxicity of sites. The “Rhonelle” river was the most affected by primary DNA strand breaks measured in fish but this parameter was not well represented on axis, in opposition to fish caged in “Deule” and “Sensée Bouchain” sites showing lower levels of chromosomal damages, in accordance with the first component axis of the PCA
Intégration des phytotechnologies comme techniques de gestion et de traitement des sols pollués dans un projet de renouvellement urbain de la communauté d’agglomération CREIL-SUD OISE
No full textInternational audienceLa Communauté d’Agglomération Creil-Sud Oise, dans le cadre de la mise en œuvre de son plan environnement et de son projet de rénovation urbaine du quartier intercommunal de Gournay les Usines, dont une partie des sols est polluée, et l’INERIS, ont lancé une expérimentation sur le phytomanagement pour traiter et gérer in situ tout ou partie de ces sols. Les techniques de phytoextraction et de phytostabilisation ont ainsi été mises en œuvre sur 2 sites pollués par les métaux avec comme objectifs la valorisation du foncier pollué dans des aménagements paysagers, la dépollution partielle des sols, la réduction des expositions et la valorisation des phytomasses produites en filières non-alimentaires. Ces sites de démonstration accueillent depuis 2013 des projets de recherche appliquée dont le projet EXTRA-Zn (2019-2022 ; APR Graine ADEME 2017). Les principaux résultats obtenus jusqu’alors montrent le succès sur le long terme de l’implantation des espèces végétales testées sur ces sites pollués et leur parfaite intégration au regard de l’objectif paysager. De plus, les espèces accumulatrices et hyperaccumulatrices de Cd et de Zn (saules des vanniers, arabette de Haller) testées en phytoextraction ont affichées des performances intéressantes en termes de dépollution partielle des sols en lien avec l’optimisation de leurs itinéraires culturaux. Sur la base des concentrations en métaux contenus dans les phytomasses, des débouchées sont envisagés pour viabiliser le phytomanagement (combustion, paillage, compostage, méthanisation, chimie verte). L’acceptabilité sociale et le cadre règlementaire de la filière sont également étudiés afin d’identifier les éventuels freins au déploiement du phytomanagement comme méthodes de gestion de certains sites pollués
Deep geothermal-induced seismicity: controlling factors and hazard mitigation measures
No full textInternational audienceAs many industrial activities impacting the underground, deep geothermal projects can be associated with the occurrence of induced seismic events. This seismicity is sometimes a direct consequence of stimulation operations needed to enhance the permeability of geothermal reservoirs, but, in other cases, it can also occur in different phases of geothermal projects, as during wells shut-in, after injection operations, or during the production phase, which generally implies lower flow rates and injection pressures. The intensity of this seismicity, in terms of magnitudes of seismic events, can be extremely variable, from microseismic events (M 5) that pose a serious risk to neighboring populations and may lead to the abandon of geothermal projects. In this context, it is of paramount importance to: i) better characterize and understand the interactions between natural and anthropogenic factors which may lead to geothermal-induced seismicity and ii) evaluate currently applied approaches to handle and minimize associated risks. The objective of this work is to establish a state of the art about deep geothermal-induced seismicity, by describing factors that have a bearing on the generation of seismic events, as well as by discussing existing means to handle their occurrence. Based on a worldwide review of geothermal projects, we created a large database describing each selected case study in terms of geological properties and tectonic setting, operational parameters and type of geothermal systems, as well as spatio-temporal characteristics of the observed induced seismicity. Collected data are analyzed in order to better understand possible cause-effect relationships between induced seismicity and geothermal operations with the aim of identifying the most important preexisting and anthropogenic factors, as well as their interactions, which may have a key role on the occurrence of seismic activity
Plastic additives: challenges in ecotox hazard assessment
No full textInternational audienceThe risk of plastic debris, and specifically micro(nano)plastic particles, to ecosystems remains to be fully characterized. One particular issue that warrants further characterization is the hazards associated with chemical additives within micro (nano)plastic as they are not chemically bound within the polymers and can be persistent and biologically active. Most plastics contain additives and are therefore potential vectors for the introduction of these chemicals into the environment as they leach from plastic, a process that can be accelerated through degradation and weathering processes. There are knowledge gaps on the ecotoxicological effects of plastic additives and how they are released from parent plastic materials as they progressively fragment from the meso to micro and nano scale. This review summarizes the current state of knowledge of the ecotoxicity of plastic additives and identifies research needs to characterize the hazard they present to exposed biota. The potential ecological risk of chemical additives is of international concern so key differences in governance between the European Union and New Zealand to appropriately characterize their risk are highlighted
Low‐Level Radiofrequency Exposure Induces Vasoconstriction in Rats
No full textInternational audienceRecent studies have revealed that rodents' physiological responses to low-intensity radiofrequency (RF) electromagnetic fields were similar to thermoregulatory responses to cold conditions. The primary autonomic response to cold exposure is peripheral vasoconstriction that allows rodents to reduce heat loss and maintain a relatively constant internal body temperature. In the present study, we investigated the effects of 900 MHz RF at a low level (SAR of 0.35 W/kg) on tail skin temperature (Ttail ) in rats. We showed that rats exposed to RF had lower Ttail than control rats at ambient temperatures between 27 and 28 °C, suggesting that RF could induce a noticeable degree of vasoconstriction under mild-warm ambient temperatures. This difference in Ttail was suppressed after the intraperitoneal injection of a vasodilator, an α-adrenergic antagonist, confirming the hypothesis of the vasoconstriction in exposed rats. Moreover, like a response to cold stimuli, RF exposure led to increased plasma concentrations of important factors: noradrenaline (a neurotransmitter responsible for vasoconstriction and thermogenesis) and fatty acids (markers of activated thermogenesis). Taken together, these findings indicate that low-intensity RF levels triggered some key physiological events usually associated with responses to cold in rats
The Use of Sorghum in a Phytoattenuation Strategy: A Field Experiment on a TE-Contaminated Site
No full textInternational audiencePhytoattenuation combines phytoextraction or phytostabilization with the economic valorization of the biomass produced on the contaminated soil. Sorghum bicolor is a suitable crop for this strategy, as it is known to be metal-tolerant and can be used for biogas or bioethanol production or in strategies toward biofortification. In the current investigation, two cultivars, Biomass 133 and Trudan Headless (HL), were studied in a metal-contaminated (Cd, Pb, Zn) field site located in northern France to assess their potential use in a phytoattenuation strategy. The biomass yield and the metal transfer in the produced biomass were monitored in three plots with different pollution levels. Both cultivars were tolerant to high levels of metal pollution in field conditions, with yields similar to that obtained on uncontaminated sites. Neither of the cultivars changed the metal mobility of the soil and both exhibited a metal-excluder behavior. Nevertheless, Cd concentration in the aboveground part of Trudan HL, and of Biomass 133 to a lesser extent, could restrict their use in some valorization options. However, biogas production was possible with the produced biomass, indicating anaerobic digestion to be a possible valorization route for sorghum grown on contaminated sites
Evaluation of Channel Capacity of a 3D Curvilinear Metasurface in the THz band
No full textInternational audienceMetasurface structures (MSs) are able to control an impinging electromagnetic wave, in terms of amplitude and phase. Based on the prominent results of a specific curvilinear MS [1], designed and described by its equivalent nonhomogeneous Transmission Line (TL) model, in this paper we are motivated to investigate the achievable channel capacity bounds of the structure in the THz band. Through its equivalent circuit model, we are able to derive the attenuation behavior of the proposed MS, which is dependent not only on the geometric features of the MS, but also on its TL components. We observe a MS geometry-and frequencydependence, which reflect also on the channel capacity upper bounds. Specifically, by varying the input power profile of an impinging electromagnetic wave, we can achieve different trends of the channel capacity. Best performance are reached assuming input femtosecond Gaussian-shaped power pulses, that allow to achieve Pbps channel capacity upper bounds
Ammonia and PM<sub>2.5</sub> Air Pollution in Paris during the 2020 COVID Lockdown
No full textInternational audienceDuring the COVID-19 pandemic, the lockdown reduced anthropogenic emissions of NO2 in Paris. NO2 concentrations recorded in 2020 were the lowest they have been in the past 5 years. Despite these low-NO2 levels, Paris experienced PM2.5 pollution episodes, which were investigated here based on multi-species and multi-platform measurements. Ammonia (NH3) measurements over Paris, derived from a mini-DOAS (differential optical absorption spectroscopy) instrument and the Infrared Atmospheric Sounding Interferometer (IASI) satellite, revealed simultaneous enhancements during the spring PM2.5 pollution episodes. Using the IASI maps and the FLEXPART model, we show that long-range transport had a statistically significant influence on the degradation of air quality in Paris. In addition, concentrations of ammonium (NH4+) and PM2.5 were strongly correlated for all episodes observed in springtime 2020, suggesting that transport of NH3 drove a large component of the PM2.5 pollution over Paris. We found that NH3 was not the limiting factor for the formation of ammonium nitrate (NH4NO3), and we suggest that the conversion of ammonia to ammonium may have been the essential driver