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Assessment of the stability of the Bonifacio cliff in the Citadel sector
No full textInternational audienceThe work presented in this paper is part of the hazard and risk assessment study related to the Citadel of Bonifacio (department of Southern Corsica) located partly on a cliff overhanging up to 20 m. The objective was to provide elements for improving the qualification and quantification of the “massive collapse” hazard.Les travaux présentés dans cet article s'inscrivent dans le cadre de l'étude d'évaluation des dangers et des risques liés à la Citadelle de Bonifacio (département de la Corse du Sud) située en partie sur une falaise surplombant jusqu'à 20 m. L'objectif était de fournir des éléments permettant d'améliorer la qualification et la quantification de l’aléa « effondrement massif »
Size of a representative sample by rare particles in concentration and size (81)
No full textInternational audienceThe theory of representative sampling of granular waste in terms of number of particles has been developed for the particles rare in concentration, typical of skewed concentration distributions observed in waste. In the “number of particles” derived from binomial distribution and used in waste sampling standards and in the Gy’s Theory Of Sampling, the particle size and the particle concentration are not simultaneously and explicitly considered. Nevertheless, according to numerous publications with many wastes, the composition and material of large particles are different from the composition and material of small particles, but in practice it is not known or ignored for sampling. A solution is offered: to calculate the size of a representative sample with the rare particles in concentration and in size using the same theory of sampling with the number of particles, based on the statistical drawing of particles with binary properties (having or not having the property of interest: a given concentration, a given size…), as described by the binomial distribution (as in waste sampling standards). For a variability of analyses of 10%, the number of particles “n” in a representative sample should be 100/p, “p” being the frequency of rare particles (p≤1). The transformation of the number of particles into a mass is then done for rare particles in concentration (as in sampling standards) and in size (new proposition). The assessment of “p” is critical. This simple and statistically valid approach is presented compared with 5 real cases (from 12 samples) with homogeneous and heterogeneous particle composition and particle size distribution, and the results are assessed coherent. A practical solution for additives or substances in products and waste to assess p is proposed (p = concentration limit/functional concentration). The statistical power of published waste sampling plans (bottom ash, shredded plastics, lamps, mixed commercial waste) is assessed
Uncertainty assessment for the airborne nanoparticle collection efficiency of a TEM grid-equipped sampling system by Monte-Carlo calculation
No full textInternational audienceA mini particle sampler (MPS) equipped with a transmission electron microscopy (TEM) grid enables convenient particle sampling to subsequent analysis. However, its sampling efficiency involves uncertainties, and accurate sampling efficiency is required for particle collection applications. In this study, the sampling efficiency uncertainties from measured data and models are quantified using Monte-Carlo methods. The Sobol variance-based sensitivity analysis is used to determine the contributions of parameters to the sampling efficiency uncertainties. The results reveal that the sampling efficiency uncertainties from experimental dispersion calibration and theoretical models are generally less than 1% and 9%, respectively. Most sampling efficiency measured data are covered by the efficiency uncertainty range simulated by theoretical models. Pore size and flowrate contribute significantly to the sampling efficiency uncertainties and require control to improve the sampling efficiency precision. Besides, the Cunningham correction factor is also a sensitivity parameter. The utilization of proper models is crucial to support simulations for further process optimization. This study offers a quantitative method for nanoparticle collection efficiency analysis, which will help assess nanomaterials’ workplace exposure
Retrospective Modeling of NO2 and PM10 Concentrations over the Lyon Metropolitan Area (France), 1990–2010—Performance Evaluation, Exposure Assessment and Correlation between Pollutants
No full textInternational audienceNumerous cancers develop years after subjects have been exposed to chemical compounds. Thus, environmental epidemiological studies need to accurately reconstruct exposures over long periods. To estimate exposure to NO2 and PM10 concentrations, we modelled ground-level air concentrations, at very fine temporal (1 h) and spatial (10 m) resolutions, over a large European metropolitan area and at subject’s address of a French national cohort, for five different years (1990, 1995, 2000, 2005 and 2010). Model performances were assessed by comparing the annual modelled concentration against monitoring station measurements. As input data, we used background concentrations from a large-scale dispersion model. The relevance of our approach was assessed by comparing results in 2010, with a modelling using monitoring values as background data. The comparison with measurement data showed good performance of the model for the majority of the period, with a performance declined in 1990. Concentrations at the subject’s residence decreased by 45% for PM10 and 38% for NO2. The proportion of subjects exposed above the WHO recommendations declined from 100% to 50% for PM10 and from 79% to 16% for NO2. The results of this study would provide a reference for future models to assess chronic exposures to PM10 and NO2 on a larger scale
Toward waste valorization by converting bioethanol production residues into nanoparticles and nanocomposite films
No full textInternational audienceA "waste-valorization" approach was developed to transform recalcitrant hydrolysis lignin (HL) from secondgeneration bioethanol production into multifunctional bio-based products. The hydrolysis lignin (HL) was extracted with aqueous acetone, yielding two fractions enriched in lignin and cellulose, respectively. The soluble hydrolysis lignin (SHL) was converted into anionic and cationic colloidal lignin particles (CLPs and c-CLPs). The insoluble cellulose-rich fraction was transformed into lignocellulosic nanofibrils that were further combined with CLPs or c-CLPs to obtain nanocomposite films with tailored mechanical properties, oxygen permeability and antioxidant properties. To enable prospective applications of lignin in nanocomposite films and beyond, CLPs and c-CLPs were also produced from a soda lignin (SL) and the influence of the lignin type on the particle size and ecotoxicity was evaluated. Finally, the carbon footprint of the entire process from hydrolysis lignin to films was assessed and an integration to industrial scale was considered to reduce the energy consumption. While most previous work utilizes purified lignin and pristine and often purified cellulose fibers to produce nanomaterials, this work provides a proof of concept for utilizing the recalcitrant lignin-rich side stream of the bioethanol process as raw material for functional nanomaterials and renewable composites
A multi-family offline SPE LC-MS/MS analytical method for anionic, cationic and non-ionic surfactants quantification in surface water
No full textInternational audienceOf the large number of emerging pollutants discharged from wastewaters into surface waters, surfactants are among those with the highest concentrations. However, few monitoring in river waters of these substances have already been performed and only on a few families, mostly anionic.This work aimed to develop a multi-family analytical strategy suitable for the quantification of low concentrations of surfactant in surface waters. Twelve families of surfactants, anionic, cationic and non-ionic were selected. Their quantification by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) and their extraction by SPE were optimized by comparing different retention mechanisms. The best performances were obtained with a C18 grafted silica LC column and a hydrophilic-lipophilic balanced (HLB) polymeric SPE cartridge.The final analytical method was validated and applied for the quantification of surfactants in 36 river water samples. Method limits of quantification (LQ), intra and inter days precision and trueness were evaluated. With LQ between 15 and 485 ng/L, and trueness over 80%, this method was suitable for monitoring surfactants in surface water. Application on French river water samples revealed the presence of anionic, cationic and non-ionic surfactants with median concentrations from 24 ng/L for octylphenol ethoxylates (OPEO), up to 4.6 μg/L regarding linear alkylbenzene sulfonates (LAS)
Monitoring of pesticides in ambient air: Prioritization of substances
No full textInternational audienceDespite the richness of data collected on pesticide concentrations in ambient air in France, knowledge on this topic remains partial and heterogeneous in the absence of specific regulations. The population exposure remains thus difficult to estimate; therefore it was necessary to define modalities for implementing national monitoring of pesticides in ambient air in metropolitan France and in the overseas territories. The objective of this work was to identify which active substances (a.s.) have to be monitored in priority. As part of a collective expertise, a group of multidisciplinary experts has developed a method to rank active substances authorised as plant protection products, biocides and antiparasitic agents, which were available on the French market in 2015. A 3-steps approach has been developed. The first step consisted of a theoretical approach based on a hierarchy of substances according to four criteria: (a) national uses, (b) emission potential to the air, (c) persistence in the air, and (d) chronic toxicity. The three first criteria give information on their potential to be present in the atmosphere, and the fourth criterion allows to consider their potential of hazard. The second step was an observational approach based on existing database on pesticide air measurements in France. In the third step, both approaches were combined using decision trees to select priority pesticides. Among the 1316 a.s. first identified from the EU Pesticides database, 90 were selected, among which 43 required metrological and/or analytical development. The experts recommended confirming the relevance of performing a longer term monitoring of these a. s. after a one-year exploratory campaign. The proposed method is reproduceable, transparent, easy to update (e.g. in the light of a change in product authorization), and can be adapted to other agricultural and geographical conditions, and objectives (e.g. monitoring of the ecotoxicological effects of pesticides)
Qualité de l’air intérieur et santé : quels sont les produits de consommation présentant les risques individuels les plus élevés ?
No full textInternational audienceLa qualité de l’air intérieur représente un enjeu de santé publique majeur. Les actions des pouvoirs publics portent notamment sur la réduction des sources de polluants volatils spécifiques aux environnements intérieurs, dont certains usages domestiques de produits de consommation. Pour contribuer à identifier les produits associés aux risques sanitaires les plus préoccupants, la démarche d’évaluation des risques sanitaires (ERS) a été appliquée à trois types de produits de consommation courante, présélectionnés en fonction de leurs risques individuels attendus : désodorisants combustibles (encens, bougies parfumées), produits ménagers et désodorisants non combustibles (sprays, diffuseurs). Le champ des ERS réalisées incluait les expositions par inhalation, chroniques et aiguës (expositions d’une heure), et les usages de type domestique. Ces ERS se sont basées sur des concentrations mesurées en conditions réelles et sur des scénarios d’exposition déterministes (« moyen » et « pire cas raisonnable ») élaborés à partir de sondages nationaux sur les usages des produits étudiés. Dans le cas particulier des produits ménagers, l’élaboration de séances de ménage complètes, « multiproduits » et « multipièces », s’est appuyée sur une consultation de parties prenantes. Les résultats obtenus suggèrent que, dans le cadre des produits testés et des hypothèses retenues dans ces ERS, (i) les usages les plus courants correspondent à des risques individuels chroniques non préoccupants, quel que soit le type de produit étudié, considéré individuellement ; (ii) les expositions les plus élevées ont besoin d’être réduites pour assurer l’absence de risque préoccupant, notamment en réduisant les émissions des produits les plus émissifs, quel que soit le type de produit étudié ; (iii) les encens et, dans une moindre mesure, les sprays désodorisants sont les produits présentant les risques individuels les plus élevés, parmi les produits étudiés. Les substances d’intérêt prioritaire identifiées sont l’acroléine, le benzène, le formaldéhyde et les particules fines (PM2,5). Les effets sanitaires potentiels incluent divers troubles du système respiratoire et un excès de risque de leucémie
Worst Case Scenario for Delayed Explosion of Hydrogen Jets at a High Pressure: Ignition Position
No full textInternational audienceDelayed explosion of free field hydrogen releases at a high pressure is subject of multiple investigation performed by various authors in the past years. These studied considered various parameters such as pressures, flow rates etc., and their influence on the resulting overpressure. However, the influence of the ignition position on the maximum overpressure was not fully explored. Current investigation addressed by computational fluid dynamics (CFD) simulations and experimental measurement fills this gap. This work demonstrates that the ignition positions corresponding to 55%-65% of H2/air mixture give the maximum overpressure. This observation initially observed numerically and afterword confirmed experimentally. A simple model is also suggested
Repeated exposure to nanosecond high power pulsed microwaves increases cancer incidence in rat
No full textInternational audienceHigh-power microwaves are used to inhibit electronics of threatening military or civilian vehicles. This work aims to assess health hazards of high-power microwaves and helps to define hazard threshold levels of modulated radiofrequency exposures such as those emitted by the first generations of mobile phones. Rats were exposed to the highest possible field levels, under single acute or repetitive exposures for eight weeks. Intense microwave electric fields at 1 MV m-1 of nanoseconds duration were applied from two sources at different carrier frequencies of 10 and 3.7 GHz. The repetition rate was 100 pps, and the duration of train pulses lasted from 10 s to twice 8 min. The effects on the central nervous system were evaluated, by labelling brain inflammation marker GFAP and by performing different behavioural tests: rotarod, T-maze, beam-walking, open-field, and avoidance test. Long-time survival was measured in animals repeatedly exposed, and anatomopathological analysis was performed on animals sacrificed at two years of life or earlier in case of precocious death. Control groups were sham exposed. Few effects were observed on behaviour. With acute exposure, an avoidance reflex was shown at very high thermal level (22 W kg-1); GFAP was increased some days after exposure. Most importantly, with repeated exposures, survival time was 4-months shorter in the exposed group, with eleven animals exhibiting a large sub-cutaneous tumour, compared to two in the sham group. A residual X-ray exposure was also present in the beam (0.8 Gy), which is probably not a bias for the observed result. High power microwaves below thermal level in average, can increase cancer prevalence and decrease survival time in rats, without clear effects on behaviour. The parameters of this effect need to be further explored, and a more precise dosimetry to be performed