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Laser-Induced Breakdown Spectroscopy applied to industrial and environmental issues
No full textLa technique LIBS (Laser-Induced Breakdown Spectroscopy) ou spectroscopie de plasma induit par laser est une technique d’analyse multi élémentaire. Elle consiste à focaliser un faisceau laser impulsionnel sur un échantillon à analyser (solide, liquide, gaz, ou aérosol). Au point de focalisation, la matière est très fortement chauffée, provoquant l’allumage d’un plasma. La lumière émise par ce dernier peut être analysée par spectroscopie d’émission. Tous les éléments chimiques présents dans le matériau sondé peuvent être identifiés dans une large gamme de pression. La préparation de l’échantillon n’est pas nécessaire. De plus, elle est non intrusive de part son caractère tout optique. Elle est potentiellement rapide, de quelques secondes à quelques minutes selon le nombre de tirs laser nécessaires à l’obtention d’un signal exploitable. Elle permet de déterminer (1) la nature chimique élémentaire de la matière analysée et (2) les concentrations en masse in-situ et en temps réel des différents éléments. De nombreuses problématiques dans les domaines nucléaires, industriels et environnementaux nécessitent de réaliser des analyses de terrain. Or, les techniques courantes requièrent des procédures coûteuses en temps. Ainsi, des personnels sont envoyés sur site pour prélever des échantillons. Puis ceux-ci sont ramenés au laboratoire où ils sont préparés avant d’être analysés. Plusieurs jours à plusieurs semaines peuvent s’écouler avant que les résultats ne soient connus. Les résultats présentés dans ces travaux mettent en évidence l’utilisation de la technique LIBS appliquée à des problématiques nucléaires, industrielles et environnementales pour des analyses sur site en temps réel. Les qualités de la technique LIBS pour le contrôle de procédés, les mesures dans les ambiances de travail ou dans les rejets industriels sont ainsi mises en avant
Phenomenological study of the pre-mixing step of sodium-water explosive interaction
No full textInternational audienceThe present experimental study aims at better understanding sodium-water explosive interaction in a hypothetical situation. Various experiments were performed in the past, but they still lead to large uncertainties in both interpreting experimental results and predicting accident-scale processes. From the moment it was considered that the explosive nature of the reaction could be due to a very fast water vaporization, sodium-water explosive interaction is studied by addressing the influence of the pre-mixing step (i.e. time between contact and explosion) on its consequences. A better understanding of the phenomena, and especially of the quantity and the rate of energy release, is needed to estimate the consequences of large term source accidents. The experimental measurements and their analytical discussion demonstrate that bubble destabilization is at the origin of pressure wave emission in the surroundings. Under the studied mixing conditions, sodium-water interaction severity depends mainly on the liquid sodium into water penetration limits (kinematic and thermodynamic). Only a fraction of the initial available reaction energy is likely to produce explosive effects, in accordance with the phenomenological model based on the steam explosion assumption
An additive geostatistical model for mixing total and partial PM10 observations with CHIMERE rCTM
No full textInternational audienceEuropean Legislation (Directive, 2008/50/EC) requires the Member State to identify the areas where limit or target values are exceeded and to estimate the population exposed to these exceedances. The monitoring network of particulate matter with diameter less than 10 μs (PM10) and 2.5 μm (PM2.5) is homogeneous enough in Western Europe to describe accurately their daily spatial distribution. Daily mapping is required to correctly quantify the population exposed to the exceedances. Geostatistical methods are commonly used in Air Quality to interpolate the observations by taking into account the spatial dependencies between the data. The case of particulate matter is specific: in addition to the total PM10 observations, there are, for historical reasons, measurements of the so-called non-volatile fraction of the particles. The non-volatile fraction dataset is corrected and used as an observation of the total PM applied for mapping. It provides therefore a meaningful information on the chemical composition of the particles. Along this line, PM2.5 data, which are a subset of PM10, also bring an important information on the spatial distribution of the PM10, and conversely. This work demonstrates the importance of keeping an information considered as secondary in the monitoring network and how it is possible to improve the estimation of PM concentrations. An additive modelling for PM10 and its subset is used to link the explanatory variables between them and the related cokriging is presented. Maps and scores are shown and confronted to univariate kriging estimations throughout the first three months of 2015 in metropolitan France
Effect of acute exposure to radiofrequency electromagnetic fields emitted by a mobile phone (GSM 900 MHz) on electrodermal responsiveness in healthy human
No full textInternational audiencePurpose : The present study aimed to determine the effect of acute exposure to electromagnetic fields (EMF) emitted by a mobile phone on electrodermal activity (EDA) in response to an auditory stimulus. Materials and methods : The EDA of 28 young volunteers was recorded following 26 min of exposure to a GSM mobile phone (900 MHz). Palmar sensors enabled repeat recording of 2 min 45 s in the pre-exposure, exposure and post-exposure phases in response to sound stimuli. Results : The latency, amplitude of skin conductance responses (SCRs), integral of skin conductance response and number of SCRs in response to the auditory stimuli were not modified by exposure. Skin conductance and tonic activity decomposition of the recorded signal were significantly different between the two sessions (p < .0001), but the changes could not be attributed to EMF exposure. There was also a tendency toward a fast reduction in the amplitude and number of electrodermal responses after placement of the mobile phone. In response to successive stimuli, there was a significant difference between the first response and subsequent responses for all variables except latency. Conclusions : Our results showed a decrease in the number of responses and their amplitude as a result of placement of the mobile device and whether it was turned 'on' or 'off', but there were no changes associated with exposure to GSM radiofrequency waves in this group of volunteers
Evidence of major secondary organic aerosol contribution to lensing effect black carbon absorption enhancement
No full textInternational audienceAtmospheric black carbon (BC) has a strong positive, but still controversial, effect on global warming. In particular, BC absorption enhancement (E abs) due to internal mixing with other chemical species-so-called lensing effect-is poorly assessed. This bottleneck partly relies on the lack of long-term in situ measurements of both the optical and chemical properties of BC-containing particles. Here, we present experimental and computational results showing a significant E abs increase with the aerosol photochemical aging. This was associated with the production of highly oxidized secondary organic aerosols (SOA), especially at summertime. The 3-year-long continuous aerosol chemical and optical measurements used for the present study was obtained in the Paris region, France, which might be representative of near-future air quality within developing countries. These findings suggest that SOA could represent one of the most critical chemical species to be considered within climate models
Exposition maternelle aux champs électromagnétiques d’extrêmement basses fréquences et issues de grossesse : données de la cohorte Elfe
No full textInternational audienc
The territorialized exposome concept to characterize cumulative risk at the population level
No full textInternational audienceRisk assessors and risk managers are currently facing two realities: The need to consider the impact of multiple exposures and combined risks, and the substantial growth of environmental data production at the territory level. The exposome concept has been proposed as an emergent exposure science paradigm for conceptualizing the cumulative effects of environmental exposures across the whole human life. The need for risk manager to identify population at-risk in the context of substantial data deficiencies that hinder evaluation of cumulative health risks brings the operational declination of the concept at the territorial scale. The characterization of the territorialized exposome implies the development of dynamic, multidimensional, longitudinal approaches, and information systems that require the adoption of transdisciplinary methods of data analysis. Integrated approaches could bring together all information necessary for assessing the source-to--dose continuum using GIS, multimedia exposure and toxicokinetic model. Different approaches could be considered for screening-level analysis of spatialized cumulative risks based on toxicology data or multivariate approach to combine exposure variables at the population level. Several case studies will be presented in a tiered manner to illustrate organized data processing when the ultimate goal of cumulative risk assessment is to identify overexposed population. Review of toxicology data are conducted in order to group substances or risk factors sharing similar toxicological effect. In other cases, finding a common metric for dissimilar risks is not a strictly analytic process, because judgments must be made as how to link two or more separate scales of risks during a deliberative process, including stakeholders to identify operational actions adapted to the policy objectives
Nouveaux outils pour la détection et l’identification de perturbateurs endocriniens non réglementés en zone urbaine
No full textInternational audienc
Importance of safety considerations of furanics compounds and their side streams in advanced biorefineries
No full textInternational audienc
Optimization of an active biomonitoring approach using three-spined sticklebacks
No full textInternational audienceActive biomonitoring involves exposure of calibrate and well-known organisms to environmental pollution and is increasingly used in ecological studies. Despite of the advantages of caging (standardization of some biotic and abiotic parameters), caged organisms are subject to some constraints which can influence the organisms’ responses to pollution and therefore can be considered as confounding factors. In the way to make biomarkers efficient tools in active biomonitoring, it is necessary to precisely characterize the possible effects of constraints linked to caging on organism physiology. For this purpose, several studies were conducted on threeBspined sticklebacks (Gasterosteus aculeatus) to specify the impacts of i) fish-density inside cages, ii) short-transport after caging, iii) movement limitation and iv) food access restriction induced by caging. The optimization of caging conditions has been validated by assessment of several biomarkers including innate immune responses, antioxidant systems, metabolic detoxification, synaptic transmission and energy metabolism. Results have shown that a high density of fish (> 2.31 kg/m3) and a short transport after caging have induced an oxidative stress manifested by an overproduction of reactive oxygen species and a stimulation of the antioxidant system. The confinement stress had small impact on sticklebacks’ biomarkers. However, this stress seemed to accentuate the negative effects of food restriction on these biomarkers, particularly during their breeding period. Out of breeding time, most of investigate biomarkers were not impacted by food access restriction. These works have allowed to specify the conditions of application and interpretation of biomarkers during active monitoring using stickleback to ensure a good diagnosis of the quality of water bodies with this species