Environmental Parameter Effects on the Fate of a Chemical Slick

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Liver antioxidant and plasmatic immune responses in juvenile golden grey mullet (Liza aurata) exposed to dispersed crude oil

International audienceDispersant application is an oil spill response technique. To evaluate the environmental cost of this operation in nearshore habitats, the experimental approach conducted in this study exposed juvenile golden grey mullets (Liza aurata) for 48 hours to chemically dispersed oil (simulating, in vivo, dispersant application), to dispersant alone in sea water (as an internal control of chemically dispersed oil), to mechanically dispersed oil (simulating, in vivo, natural dispersion), to the water-soluble fraction of oil (simulating, in vivo, an oil slick confinement response technique) and to sea water alone (control condition). Biomarkers such as fluorescence of biliary polycyclic aromatic hydrocarbon (PAH) metabolites, total glutathione liver content, EROD (7-ethoxy-resorufin-O-deethylase) activity, liver antioxidant enzyme activity, liver lipid peroxidation and an innate immune parameter (haemolytic activity of the alternative complement pathway) were measured to assess the toxicity of dispersant application. Significant responses of PAH metabolites and total glutathione liver content to chemically dispersed oil were found, when compared to water-soluble fraction of oil. As it was suggested in other studies, these results highlight that priority must be given to oil slick confinement instead of dispersant application. However, since the same patterns of biomarkers responses were observed for both chemically and mechanically dispersed oil, the results also suggest that dispersant application is no more toxic than the natural dispersion occurring in nearshore areas (e.g. waves). The results of this study must, nevertheless, be interpreted cautiously since other components of nearshore habitats must be considered to establish a framework for dispersant use in nearshore areas

Développements méthodologiques pour l'extraction et l'analyse des polluants organiques d'intérêt pour l'environnement marin (application aux hydrocarbures aromatiques polycycliques)

La présence d hydrocarbures dans l environnement que ce soit suite à un déversement accidentel de pétrole en mer ou suite à des apports chroniques, est une préoccupation majeure en raison de leur écotoxicité et de leur potentiel à être bioaccumulés, et ainsi, pénétrer la chaîne alimentaire. Par conséquent, ces molécules sont sous haute surveillance et il est nécessaire de disposer de méthodes analytiques permettant de les identifier et de les quantifier, et ceci, pour des concentrations allant du mg/L au ng/L. Cependant et dans la plupart des cas, les analyses en laboratoire des hydrocarbures, notamment aromatiques, se limitent à la quantification des 16 hydrocarbures aromatiques polycycliques (HAP) identifiés par l Agence américaine de Protection Environnementale (US-EPA) comme étant dangereux pour l environnement du fait de leur caractère cancérigène. Or, les hydrocarbures aromatiques polycycliques soufrés (HAPS) ainsi que leurs homologues substitués sont, sur le plan chimique, structurellement proches des HAP, et peuvent donc présenter des risques environnementaux similaires, à savoir être cancérigènes ou mutagènes. Le travail de recherche réalisé s inscrit dans ce contexte avec pour objectif des développements méthodologiques permettant l extraction et l analyse d une gamme plus large de HAP, des HAPS et leurs dérivés alkylés directement dans les produits pétroliers ou dissous en phase aqueuse. Des protocoles d extraction par "stir bar sorptive extraction" (SBSE) et par microextraction sur phase solide (SPME), et des méthodes d analyse par chromatographie en phase gazeuse couplée à la spectrométrie de masse simple (GC-MS) et en tandem (GC-MS-MS) ont été développés. Les résultats obtenus plaident en faveur de ces méthodologies aussi bien en termes de linéarité de la réponse qu en termes de sensibilité, méthodologies qui ont été appliquées avec succès pour la détermination des analytes d intérêt dans des fractions solubles préparées au laboratoire (WAF et WSF). Pour la CG-MS-MS, si elle se révèle particulièrement adaptée car elle apporte un degré de certitude élevé, elle n en reste pas moins une technique délicate à mettre en oeuvre, notamment dans le cas des composés alkylés pour lesquels des solutions étalons ne sont pas disponibles. Pour pallier cette difficulté, un produit de référence contenant l ensemble des analytes d intérêt a été caractérisé. Pour les composés alkylés non disponibles commercialement, des appro-ximations ont été effectuées par MS simple en se basant sur une analyse comparée des coefficients de réponse en mode MRM et SIM. La méthodologie ainsi mise au point a permis de caractériser le fioul de l Erika avec une faible variabilité des résultats. Ce produit peut servir de référence pour l analyse quantitative de l ensemble des familles de composés identifiés dans cette étude.The presence of hydrocarbons in the environment either as a result of oil spills at sea or due to chronic discharge is a major concern because of their ecotoxicity and their potential to bioaccumulate and thus enter the food chain. Therefore, these molecules are closely monitored and reliable analytical methods are required to identify and quantify them, for concentrations ranging from mg/L to ng/L. However, in most cases, laboratory analyses of hydrocarbons, especially aromatic hydrocarbons, are limited to the quantification of 16 polycyclic aromatic hydrocarbons (PAHs) identified by the U.S. Environmental Protection Agency (U.S. EPA) as hazardous to the environment due to their carcinogenic nature. However, polycyclic aromatic sulphur heterocycles (PASHs) and their substituted homologs are, in chemical terms, structurally similar to PAHs, and therefore can pose similar environmental risks, i.e. they can be carcinogenic or mutagenic. In this context, the research work carried out aims to develop methodologies for the extraction and analysis of a wider range of PAHs, PASHs and their alkyl derivatives directly in oil or dissolved in the aqueous phase. Extraction protocols by stir bar sorptive extraction (SBSE) and solid phase microextraction (SPME), and methods of analysis by gas chromatography coupled with mass spectrometry (GC-MS) and with tandem mass spectrometry (GC-MS-MS) have been developed. The results argue in favor of these methodologies both in terms of linearity of the response and in terms of sensitivity. These methodologies that have been successfully applied for the determination of analytes of interest in the water accommodated fraction and water soluble fraction prepared in the laboratory (WAF and WSF). For GC-MS-MS, while it is particularly suitable because it provides an additional level of selectivity, it is a difficult technique to implement, in particular in the case of molecules for which no calibration solutions are available. To overcome this difficulty, a reference oil containing all the target molecules was characterized. For alkylated compounds that are not commercially available, approximations were made by simple MS, based on comparative analysis of response coefficients in MRM (Multiple Reaction Monitoring) and SIM (Single Ion Monitoring) modes. The finalized method was used to characterize the Erika fuel oil, with low variability in the results. This product can be used as a reference for the quantitative analysis of all the families of molecules identified in this study.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF

Interfacial properties, film dynamics and bulk rheology:A multi-scale approach to dairy protein foams

International audienceHypothesis: The effective contribution of interfacial properties to the rheology of foams is a source of many open questions. Film dynamics during topological T1 changes in foams, essentially studied for low molecular weight surfactants, and scarcely for proteins, could connect interfacial properties to protein foam rheology. Experiments: We modified whey protein isolate (WPI), and its purified major protein b-lactoglobulin (b-lg) by powder pre-conditioning and dry-heating in order to obtain a broad variety of interfacial properties. We measured interfacial properties, film relaxation duration after a T1 event and bulk foam rheology. Findings: We found that, for b-lg, considered as a model protein, the higher the interfacial elastic modulus, the longer the duration of topological T1 changes and the greater the foam storage and loss moduli and the yield stress. However, in the case of the more complex WPI, these correlations were less clear. We propose that the presence in WPI of other proteins, lactose and minerals modify the impact of pre-conditioning and dry-heating on proteins and thereby, their behaviour at the interface and inside the liquid film

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Etude expérimentale de la biorestauration in situ de sédiments marins contaminés par du pétrole brut

La biorestauration de sédiments marins contaminés par du pétrole brut a été étudiée lors de deux éxpérimentations in situ avec pour objectifs d'examiner l'intérêt de mettre en oeuvre une fertilisation et une oxygénation combinées d'un sédiment à caractère vaseux et d'en vérifier l'innocuité sur des organismes tests, et aussi d'évaluer les effets de deux formulations de fertilisant sur la cinétique de biodégradation d'un hydrocarbure contaminant un littoral sableux. Les résultats obtenus ont montré l'ambiguité de la fertilisation, l'importance de l'oxygénation et que l'efficacité d'un agent de biorestauration dépend étroitement de la nature de substrat contaminé ainsi que des paramètres environnementaux. L'efficacité de la biorestauration, en tant que technique d'intervention suite à une pollution par hydrocarbures, n'est plus à démontrer et elle apparaît comme une technique de "finition" afin d'éliminer le pétrole restant une fois les opérations de nettoyage conventionnelles achevées.The bioremediation of marine sediments polluted by crude oil was studied through two field experiments to evaluate the interest of fertilisation and oxygenation on a muddy sediment, to test the toxicity of these techniques on a marine organism, and to determine the efficiency of two bioremediation products on oil biodegradation kinetic. The experiment on muddy sediment shown that first bioremediation techniques should, in the first place, compensate the oxygen depletion and, only after, they should supply nutrient. The results of the second experiment shown that bioremediation product efficiency is strongly linked to environmental parameters, and particularly to marine hydro dynamism. The efficiency of bioremediation techniques as a response method to cleanup coasts affected by an oil spill has been acknowledged but bioremediation treatments should be implemented as a fine cleanup method once standard cleanup is terminated.BREST-BU Droit-Sciences-Sports (290192103) / SudocPLOUZANE-Bibl.La Pérouse (290195209) / SudocSudocFranceF

Operational Device and Procedure to Test the Initial Dissolution Rate of Chemicals After Ship Accidents: the Cedre Experimental Column

: This paper describes an experimental procedure recently developed to simulate and study the behaviour of various chemicals in seawater during their transfer in a 5 m deep water column. Since chemical pollution can be harmful to the environment, anticipating the evolution of a chemical spill is important for authorities, so that they can act rapidly and efficiently after a spill. In the case of a sunken wreck containing chemicals with a lower density than seawater in its leaking tanks, it could be useful to estimate the quantity of chemicals that should be found at the sea surface. On the other hand, in the case of a spill occurring at the sea surface, the mass of chemicals liable to sink and accumulate on the seabed without being dissolved during sinking is an important piece of information required to choose the most suitable response strategy. The solubility of a particular chemical is not always available from the literature. In particular, the solubility in seawater is seldom documented and, whenever it is, it is usually in the form of solubility limits. As important as this parameter may be, it is not the most significant one in situations in which the interface between the (sea) water and the chemical involved undergoes permanent renewal. A more operational parameter would be the initial dissolution rate. The Cedre Experimental Column (C.E.C.) was designed for this purpose and a method was defined. The volume and dimensions of droplets of chemicals were studied in order to characterize the dissolution of different products throughout their journey through the water column. The dissolution rate can be expressed as a volume loss during a flow time or between two given depths. Experiments were performed on eight chemicals with different water solubility limits (8.7 to 290 g L-1) using video imagery to analyze the chemicals' behaviour. If the initial dissolution rate is dependent on solubility, it appears clearly that other physical parameters are also relevant to predict the behaviour of a product, for instance its density and viscosity. In addition to these intrinsic parameters, the dissolution kinetics of a product are also linked to its injection flow in the water column, determined, for example, by the size of the hole in the ship which will define the droplet speed. The C.E.C is therefore an operational tool which can be used to study the behaviour of specific chemicals, either as part of a particular study or in the event of a spill, taking into account all the relevant factors involved. It provides accurate and detailed information on the product's dissolution kinetics, enabling it to be used to assist in decision-making for emergency response

Comportement interfacial et propriétés moussantes de protéines de blanc d œuf

Les protéines de blanc d œuf sont utilisées dans de nombreuses formulations alimentaires en raison de leurs excellentes propriétés fonctionnelles, notamment moussantes. Des mesures mécaniques et optiques permettent d étudier les mécanismes de formation des mousses en se basant sur les propriétés interfaciales de ces protéines de blanc d œuf. Les études ont été réalisées à l interface air/eau grâce à des techniques appropriées optiques et spectroscopiques ainsi que des mesures de propriétés moussantes. Les différents mélanges d ovalbumine et de lysozyme à la concentration totale de 10 g·l-1 montrent qu il existe une synergie entre ces deux protéines au cours de leur adsorption à l interface. Suite à ces travaux, l étude spécifique du ratio équimolaire par adsorption séquentielle a permis de suggérer l existence d une organisation stratifiée des deux protéines en mélange avec de l ovalbumine pour la couche la plus proche de l interface et du lysozyme venant s adsorber sous ce film d ovalbumine formant ainsi des multicouches.Egg albumen proteins are used in numerous food formulations owing to their excellent functional properties, notably foaming properties. Mechanical and optic measurements allow to study the foams formation s mechanisms by being based on the interfacial properties of these egg white proteins. The studies have been performed at the air/water interface thanks to suitable techniques and measures of foaming properties. Different mixtures of ovalbumin and lysozyme at a total protein concentration of 10 g·l-1 show that there is a synergy in the interfacial adsorption between the two proteins. Further to these experiments, the specific study of equimolar ratio by sequential adsorption allowed to suggest the existence of a stratified organization of both proteins in mixtures with ovalbumin for the closest layer to interface and lysozyme which is located just under this ovalbumin s film forming multilayers.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Opposite sense ground rotations of a pair of Cavendish balances in earthquakes

International audienceAmong the intermingled translational and rotational effects occurring in earthquakes, the translational effects are rather well understood. Recent experiments have been performed to investigate the rotational effects which have been observed for centuries that remain intriguing and less well understood. Although rotational seismology is of interest in a wide range of disciplines, rotational ground motions remain challenging to detect directly, especially their sense of rotation. To avoid a possible random response of a single balance, we locate two Cavendish balances in an ultra-low-noise laboratory. For the two successive 2012 Italian earthquakes in Emilia detected in exactly the same direction, opposed counterclockwise and clockwise responses of the two balances are recorded at the same site. Despite the complex combinations of Rayleigh and Love surface waves in the far-field, the two circular fundamental eigenmodes of the gravity-free torsion balances permit the determination of the ground rotation senses, which are indirectly confirmed by the phase shifted acceleration components in the balance frequency bandwidth, as well as the corresponding opposite driving angular impulses. The versatility of the Cavendish balances suggests that they could be used as inexpensive rotational sensor arrays in seismic areas to follow the propagation of ground rotations from the epicentre