7 resultados para Aluminium, dissolved
em Université de Lausanne, Switzerland
Resumo:
The hydrogen and oxygen isotopes of water and the carbon isotope composition of dissolved inorganic carbon (DIC) from different aquifers at an industrial site, highly contaminated by organic pollutants representing residues of the former gas production, have been used as natural tracers to characterize the hydrologic system. On the basis of their stable isotope compositions as well as the seasonal variations, different groups of waters (precipitation, surface waters, groundwaters and mineral waters) as well as seasonably variable processes of mixing between these waters can clearly be distinguished. In addition, reservoir effects and infiltration rates can be estimated. In the northern part of the site an influence of uprising mineral waters within the Quaternary aquifers, presumably along a fault zone, can be recognized. Marginal infiltration from the Neckar River in the cast and surface water infiltration adjacent to a steep hill on the western edge of the site with an infiltration rate of about one month can also be resolved through the seasonal variation. Quaternary aquifers closer to the centre of the site show no seasonal variations, except for one borehole close to a former mill channel and another borehole adjacent to a rain water channel. Distinct carbon isotope compositions and concentrations of DIC for these different groups of waters reflect variable influence of different components of the natural carbon cycle: dissolution of marine carbonates in the mineral waters, biogenic, soil-derived CO2 in ground- and surface waters, as well as additional influence of atmospheric CO2 for the surface waters. Many Quaternary aquifer waters have, however, distinctly lower delta(13)C(DIC) values and higher DIC concentrations compared to those expected for natural waters. Given the location of contaminated groundwaters at this site but also in the industrially well-developed valley outside of this site, the most likely source for the low C-13(DIC) values is a biodegradation of anthropogenic organic substances, in particular the tar oils at the site.
Resumo:
Recently, a number of cases of smuggling dissolved cocaine in wine bottles have been reported. The aim of the present study was to determine whether cocaine dissolved in wine can be detected by proton magnetic resonance spectroscopy ((1) H MRS) on a standard clinical MR scanner, in intact (i.e. unopened) wine bottles. (1) H MRS experiments were performed with a 3 Tesla clinical scanner on wine phantoms with or without cocaine contamination. The aromatic protons of cocaine displayed resonance peaks in the 7-8 ppm region of the spectrum, where no overlapping resonances of wine were present. Additional cocaine resonances were detected in the 2-3 ppm region of the spectrum, between the resonances of ethanol and other wine constituents. Detection of cocaine in wine (at 5 mM, i.e. ∼1.5 g/L) was feasible in a scan time of 1 min. We conclude that dissolved cocaine can be detected in intact wine bottles, on a standard clinical MR scanner. Thus, (1) H MRS is the technique of choice to examine this type of suspicious cargo, since it allows for a non-destructive and rapid content characterization. Copyright © 2010 John Wiley & Sons, Ltd.
Resumo:
Dans les dernières années du 20ème siècle, l'aluminium a fait l'objet de beaucoup de communications outrancières et divergentes cautionnées par des scientifiques et des organismes faisant autorité. En 1986, la société PECHINEY le décrète perpétuel tel le mouvement « L'aluminium est éternel. Il est recyclable indéfiniment sans que ses propriétés soient altérées », ce qui nous avait alors irrité. Peu de temps après, en 1990, une communication tout aussi outrancière et irritante d'une grande organisation environnementale, le World Wild Fund, décrète que « le recyclage de l'aluminium est la pire menace pour l'environnement. Il doit être abandonné ». C'est ensuite à partir de la fin des années 1990, l'explosion des publications relatives au développement durable, le bien mal nommé. Au développement, synonyme de croissance obligatoire, nous préférons société ou organisation humaine et à durable, mauvaise traduction de l'anglais « sustainable », nous préférons supportable : idéalement, nous aurions souhaité parler de société durable, mais, pour être compris de tous, nous nous sommes limités à parler dorénavant de développement supportable. Pour l'essentiel, ces publications reconnaissent les très graves défauts de la métallurgie extractive de l'aluminium à partir du minerai et aussi les mérites extraordinaires du recyclage de l'aluminium puisqu'il représente moins de 10% de la consommation d'énergie de la métallurgie extractive à partir du minerai (on verra que c'est aussi moins de 10% de la pollution et du capital). C'est précisément sur le recyclage que se fondent les campagnes de promotion de l'emballage boisson, en Suisse en particulier. Cependant, les données concernant le recyclage de l'aluminium publiées par l'industrie de l'aluminium reflètent seulement en partie ces mérites. Dans les années 1970, les taux de croissance de la production recyclée sont devenus plus élevés que ceux de la production électrolytique. Par contre, les taux de recyclage, établis à indicateur identique, sont unanimement tous médiocres comparativement à d'autres matériaux tels le cuivre et le fer. Composante de l'industrie de l'aluminium, le recyclage bénéficie d'une image favorable auprès du grand public, démontrant le succès des campagnes de communication. A l'inverse, à l'intérieur de l'industrie de l'aluminium, c'est une image dévalorisée. Les opinions émises par tous les acteurs, commerçants, techniciens, dirigeants, encore recueillies pendant ce travail, sont les suivantes : métier de chiffonnier, métier misérable, métier peu technique mais très difficile (un recycleur 15 d'aluminium n'a-t-il pas dit que son métier était un métier d'homme alors que celui du recycleur de cuivre était un jeu d'enfant). A notre avis ces opinions appartiennent à un passé révolu qu'elles retraduisent cependant fidèlement car le recyclage est aujourd'hui reconnu comme une contribution majeure au développement supportable de l'aluminium. C'est bien pour cette raison que, en 2000, l'industrie de l'aluminium mondiale a décidé d'abandonner le qualificatif « secondaire » jusque là utilisé pour désigner le métal recyclé. C'est en raison de toutes ces données discordantes et parfois contradictoires qu'a débuté ce travail encouragé par de nombreuses personnalités. Notre engagement a été incontestablement facilité par notre connaissance des savoirs indispensables (métallurgie, économie, statistiques) et surtout notre expérience acquise au cours d'une vie professionnelle menée à l'échelle mondiale dans (recherche et développement, production), pour (recherche, développement, marketing, stratégie) et autour (marketing, stratégie de produits connexes, les ferro-alliages, et concurrents, le fer) de l'industrie de l'aluminium. Notre objectif est de faire la vérité sur le recyclage de l'aluminium, un matériau qui a très largement contribué à faire le 20ème siècle, grâce à une revue critique embrassant tous les aspects de cette activité méconnue ; ainsi il n'y a pas d'histoire du recyclage de l'aluminium alors qu'il est plus que centenaire. Plus qu'une simple compilation, cette revue critique a été conduite comme une enquête scientifique, technique, économique, historique, socio-écologique faisant ressortir les faits principaux ayant marqué l'évolution du recyclage de l'aluminium. Elle conclut sur l'état réel du recyclage, qui se révèle globalement satisfaisant avec ses forces et ses faiblesses, et au-delà du recyclage sur l'adéquation de l'aluminium au développement supportable, adéquation largement insuffisante. C'est pourquoi, elle suggère les thèmes d'études intéressant tous ceux scientifiques, techniciens, historiens, économistes, juristes concernés par une industrie très représentative de notre monde en devenir, un monde où la place de l'aluminium dépendra de son aptitude à satisfaire les critères du développement supportable. ABSTRACT Owing to recycling, the aluminium industry's global energetic and environmental prints are much lower than its ore extractive metallurgy's ones. Likewise, recycling will allow the complete use of the expected avalanche of old scraps, consequently to the dramatic explosion of aluminium consumption since the 50's. The recycling state is characterized by: i) raw materials split in two groups :one, the new scrap, internal and prompt, proportional to semi-finished and finished products quantities, exhibits a fairly good and regular quality. The other, the old scrap, proportional to the finished products arrivïng at their end-of--life, about 22 years later on an average, exhibits a variable quality depending on the collect mode. ii) a poor recycling rate, near by that of steel. The aluminium industry generates too much new internal scrap and doesn't collect all the availa~e old scrap. About 50% of it is not recycled (when steel is recycling about 70% of the old scrap flow). iii) recycling techniques, all based on melting, are well handled in spite of aluminium atiiníty to oxygen and the practical impossibility to purify aluminium from any impurity. Sorting and first collect are critical issues before melting. iv) products and markets of recycled aluminium :New scraps have still been recycled in the production lines from where there are coming (closed loop). Old scraps, mainly those mixed, have been first recycled in different production lines (open loop) :steel deoxidation products followed during the 30's, with the development of the foundry alloys, by foundry pieces of which the main market is the automotive industry. During the 80's, the commercial development of the beverage can in North America has permitted the first old scrap recycling closed loop which is developing. v) an economy with low and erratic margins because the electrolytic aluminium quotation fixes scrap purchasing price and recycled aluminium selling price. vi) an industrial organisation historically based on the scrap group and the loop mode. New scrap is recycled either by the transformation industry itself or by the recycling industry, the remelter, old scrap by the refiner, the other component of the recycling industry. The big companies, the "majors" are often involved in the closed loop recycling and very seldom in the open loop one. To-day, aluminium industry's global energetic and environmental prints are too unbeara~ e and the sustainaЫe development criteria are not fully met. Critical issues for the aluminium industry are to better produce, to better consume and to better recycle in order to become a real sustainaЫe development industry. Specific issues to recycling are a very efficient recycling industry, a "sustainaЫe development" economy, a complete old scrap collect favouring the closed loop. Also, indirectly connected to the recycling, are a very efficient transformation industry generating much less new scrap and a finished products industry delivering only products fulfilling sustainaЫe development criteria.
Resumo:
The aim of our study was to present a new headspace-gas chromatography-mass spectrometry (HS-GC-MS) method applicable to the routine determination of hydrogen sulfide (H(2)S) concentrations in biological and gaseous samples. The primary analytical drawback of the GC/MS methods for H(2)S measurement discussed in the literature was the absence of a specific H(2)S internal standard required to perform quantification. Although a deuterated hydrogen sulfide (D(2)S) standard is currently available, this standard is not often used because this standard is expensive and is only available in the gas phase. As an alternative approach, D(2)S can be generated in situ by reacting deuterated chloride with sodium sulfide; however, this technique can lead to low recovery yield and potential isotopic fractionation. Therefore, N(2)O was chosen for use as an internal standard. This method allows precise measurements of H(2)S concentrations in biological and gaseous samples. Therefore, a full validation using accuracy profile based on the β-expectation tolerance interval is presented. Finally, this method was applied to quantify H(2)S in an actual case of H(2)S fatal intoxication.
Resumo:
Introduction: Smuggling dissolved drugs, especially cocaine, in bottled liquids is a problem at borders nowadays. Common fluoroscopy of packages at the border cannot detect contaminated liquids. To find a dissolved drug, an immunological test using a drug-test panel has to be performed. This means that a control sample of the cargo must be opened to perform the test. As it is not possible to open all boxes, and as smugglers hide the drugcontaining boxes between regularly filled boxes, contaminated cargos can be overlooked. Investigators sometimes cannot perform the drug-test panel because they try not to arouse the smugglers' suspicion in order to follow the cargo and to find the recipient. Aims: The objective of our studies was to define non-invasive examination techniques to investigate cargos that are suspicions to contain dissolved cocaine without leaving traces on the samples. We examined vessels containing cocaine by radiological cross-section techniques such as multidetector computed tomography (MDCT) and magnetic resonance spectroscopy (MRS). Methods: In a previous study, we examined bottles of wine containing dissolved cocaine in different quantities using an MDCT unit. To distinguish between bottles containing red wine and those where cocaine was solved in the wine, cross sectional 2D-images have been reconstructed and the absorption of X-rays was quantified by measuring the mean density of the liquid inside the bottles. In our new study, we investigated phantoms containing cocaine dissolved in water with or without ethanol as well as cocaine dissolved in different sorts of commercially available wine by the use of a clinical magnetic resonance unit (3 tesla). To find out if dissolved cocaine could be detected, magnetic resonance spectroscopy (1H MRS) was performed. Results: By using a MDCT-unit and measuring the mean attenuation of X-rays, it is possible to distinguish weather substances are dissolved in a liquid or not, if a comparative liquid without any solutions is available. The increase of the mean density indicates the presence of dissolved substances without the possibility to identify the substance. By using magnetic resonance spectroscopy, dissolved cocaine can be clearly identified because it produces distinctive resonances in the spectrum. In contrast to MDCT, this technique shows a high sensitivity (detection of 1 mM cocaine in wine). Conclusions: Cross-sectional imaging techniques such as MDCT and MRS appropriated to examine cargos that are suspicious to contain dissolved cocaine. They allow to perform non-invasive investigations without leaving any trace on the cargo. While an MDCT scan can detect dissolved substances in liquids, identification of cocaine can be obtained by MR-spectroscopy. Acknowledgment: This work was supported by the Centre d'Imagerie BioMédicale (CIBM) of the University of Lausanne (UNIL), the Swiss Federal Institute of Technology Lausanne (EPFL), the University of Geneva (UniGe), the Centre Hospitalier Universitaire Vaudois (CHUV), the Hôpitaux Universitaire de Genève (HUG) and the Leenaards and the Jeantet Foundations.
Resumo:
This study presents an evaluation of the stable isotopic composition of water (hydrogen and oxygen) and dissolved inorganic carbon (DIC) of Lake Geneva, a deep, peri-alpine lake situated at the border between Switzerland and France. The research goal is to apply vertical and seasonal variations of the isotope compositions to evaluate mixing processes of pollutants, nutrients and oxygen. Depth profiles were sampled at different locations throughout Lake Geneva on a monthly and seasonal basis over the course of three years (2009-2011). The results of the oxygen isotopic composition indicate a Rhône River interflow, which can be traced for about 55 km throughout the lake during summer. The Rhône River interflow is 7 to 15 m thick and the molar fraction of Rhône water is estimated to amount up to 37 %. Calculated density of the water and measured isotopic compositions demonstrate that the interflow depth changes in conjunction with the density gradient in the water column during fall. Partial pressure of CO2 indicates that the epilimnion is taking up CO2 from the atmosphere between spring and fall. The epilimnion is most enriched in 13CDIC in September and a progressive depletion of 13CDIC can be observed in the metalimnion from spring to late fall. This stratification is dependent on the local density stratification and the results demonstrate that parameters, which are indicating photosynthesis, are not necessarily linked to δ13CDIC values. In addition, the amount of primary production shows a strong discrepancy between summer 2009 and 2010, but δ13CDIC values of the epilimnion and metalimnion do not indicate variations. In the hypolimnion of the deep lake δ13CDIC values are constant and the progressive depletion allows tracing remineralization processes. The combination of stable carbon and oxygen isotopic compositions allows furthermore tracing Rhône River water fractions, as well as wastewater, stormwater and anthropogenic induced carbon in the water column of the shallow Bay of Vidy. In combination with the results of measured micropollutants, the study underlines that concentrations of certain substances may be related to the Rhône River interflow and/or remineralization of particulate organic carbon. Water quality monitoring and research should therefore be extended to the metalimnion as well as sediment water interface.