Étude de la production des ions bromate lors de l'ozonation des eaux de la Banlieue de Paris : choix du mode d'ozonation et variation des param tres physico-chimiques

Cette étude a permis d'évaluer l'importance de la concentration en ions bromure, de la température et de la nature de la Matière Organique Naturelle (MON) sur la production des ions bromate en s'appuyant sur des expériences conduites en laboratoire et sur pilote semi-industriel (Centre d'Essais de Méry-sur-Oise).Trois campagnes d'ozonation effectuées en parallèle à Méry-sur-Oise et au LCEE (Laboratoire de Chimie de l'Eau et de l'Environnement) sur des eaux filtrées sable, ont montré que les expériences conduites en laboratoire et sur pilote semi-industriel mènent à des résultats similaires, soit une relation linéaire [BrO3-]=f (C∙τ) vérifiant une pente identique pour des conditions expérimentales données (teneur en ions bromure, température, origine de l'eau). Ces travaux ont montré de façon nouvelle qu'une faible variation de la concentration en ions bromure (± 15 à 20 µg.L-1) suffisait à modifier significativement la formation des ions bromate. A C∙τ=10 et T=21°C, la production des ions bromate est passée de 16 à 27 µg.L-1 pour une augmentation de la concentration en ions bromure de 80 à 95 µg.L-1. Les résultats obtenus ont montré de plus que la température est un facteur important puisqu'une différence de 8°C (13 à 21°C) a entraîné, pour la même eau (80 µg.L-1 d'ions bromure, C∙τ=10), une augmentation de la concentration en ions bromate de 10 à 16 µg.L-1. Pour d'autres eaux (Seine, Marne et Oise), trois autres campagnes conduites avec des eaux clarifiées ont été effectuées après ajustement de la teneur en ions bromure et régulation de la température, ces trois eaux présentant par ailleurs des caractéristiques similaires en ce qui concerne le pH et l'alcalinité. A C∙τ équivalent, la production d'ions bromate s'est avérée significativement plus faible pour l'eau de l'Oise que pour les deux autres eaux. La nature de la MON pourrait donc avoir une influence notable sur la formation des ions bromate.The publication of Kurokawa et al. in 1990 confirming the toxicity of bromate of rats and mice, initiated the research effort that was internationally conducted during the last seven years to better understand the reaction mechanisms of bromate formation during the ozonation of natural waters. Based on the research findings regarding the effect of a number of parameters (bromide, ozone dose, pH, temperature, alkalinity, DOC content, ammonia, ...), predictive models (empirical and reaction kinetic based models), including molecular and/or radical pathways, have been developed with more or less success. Complementary results are still needed to better understand this complex mechanism.The main objective of our work was to evaluate how the seasonal variation of the physical chemical characteristics of Paris-area source waters (i.e. bromide content, temperature, natural organic matter) can affect the production of bromate during ozonation. In order to confirm that lab-scale experiments could be proposed to develop such research program, parallel tests were first conducted at the bench- and pilot-scale based on comparable C∙τ conditions. The lab-scale reactor was a 380 ml glass column (internal diameter: 0.02 m; height: 1.2 m) equipped with a water jacket to allow temperature to be varied and maintained. These reactor was used as a continuous flow reactor with recirculation. The pilot-scale ozonation contactor installed at the Méry sur Oise water treatment plant was comprised of four 30-liter columns in series (diameter: 0.1m ; height: 4m). The first column is used as the application column while the three others are used as residence column. The results have shown that lab-scale ozonation experiments conducted on Méry sur Oise sand filtered water led to similar results compared to pilot ozonation conducted on the same water and at the same temperature (sampled the same day) using the Méry sur Oise pilot-scale reactor. For applied C∙τ that ranged from 4 to 20 mg O3/L.min, similar linear relationship between bromate formation and applied C∙τ was obtained with the two reactors.A survey conducted on the Oise River has shown that the bromide concentration ranged from 40 µg/L (winter period) to 80 µg/L (summer period). If it is already well known that higher the bromide content, higher the bromate formation, our work has also pointed out that even a small increase of the bromide concentration from 80 to 95 µg/L (15 µg/L of bromide spiked as KBr) can significantly impact the bromate formation (same experimental conditions) that, as an example, increased from 16 to 27 µg/L for C.t of 10 at 21 °C.The temperature of the Oise river can vary from 5 °C up to 25 °C. Using carefully controlled temperature conditions, one can observed that the slope of the bromate production versus applied C∙τ increased with increasing temperature (same water). For example, the production of bromate during the ozonation (applied C∙τ=10) of the Méry sur Oise sand filtered water was 7, 10 and 16 µg/L for 5, 13 and 21 °C, respectively. Complementary experiments, have shown that the impact of the variation of the initial bromide concentration was proportionally more important for low-temperature water (5 to 13 °C) than for moderate-temperature water (20 °C).The origin and nature of the water is considered to play a significant role on the formation of bromate during ozonation, however few studies have evaluated the importance of these parameters using carefully controlled experimental conditions. In order to better define how important is the change in bromate production with the modification of the quality of the Paris suburbs water sources, especially the organic content (nature and concentration of the NOM), two sets of experiments were conducted.In the first part of the work, the Méry sur Oise sand filtered water was sampled at three different periods of the year 1996 (June, July and December), and the ozonation experiments were conducted at the same temperature (21 °C) after bromide concentration was adjust to 80 µg/L. The three water samples had the same pH and did not contain ammonia. Significant differences were observed in the bromate production, showing a larger production with the winter water as compared to the summer water. The fact that the winter water was enriched in DOC (3.7 mg/L of DOC) as compared to the two others (2.6 - 2.7 mg/L of DOC) may explain this difference since a larger ozone dose was probably necessary (ozone transfert not controlled because of the small size of the lab-scale reactor) to reach the same applied C∙τ due to a higher ozone consumption from the natural organic matter. The slightly lower alkalinity of the winter sample (200 mg/L as CaCO3 as compared to 250 mg/L CaCO3 for the summer samples) could have led to a less pronounced scavenger effect, condition that favors the radical pathway which is generally predominant. However, it is also known that carbonate species can also promote the formation of bromate due to the production of carbonate radicals. Comparing the results obtained with the water samples collected during the summer period, more bromate was produced in July than in June. The higher hydrophobic character (more aromatic in character) of the NOM of the water sampled in July (SUVA=2.15) as compared to the June sample (SUVA=1.88), characteristic that favor the ozone consumption and consequently the OH radical production, may justify this finding.In the second part of the work, the bromate formation obtained during the ozonation of the three major water sources of the Paris suburbs (sampled after clarification), Oise River, Marne River and Seine River, was compared (same temperature) after the bromide content was adjust to 80 µg/L. Similar results were obtained with the clarified Marne river and Seine River, the two waters showing the same physical chemical characteristics (2.2 and 2.5 mg/L of DOC; pH 7.9 and 7.8; Alkalinity: 225 and 210 mg/L as CaCO3). A lower production of bromate as a function of the applied C∙τ was observed with the clarified Oise river, result that is in contradiction with our previous hypotheses since this water source showed the highest DOC content, the highest SUVA and the lowest alkalinity among the three waters studied.More work needs to be done to better understand the impact of the origin and nature of the NOM on the bromate formation mechanisms. As a general conclusion, this work also confirmed that the physical chemical characteristics of source water (DOC, temperature, alkalinity, bromide content,…) are more important factors as compared to the hydraulic characteristics of the reactor.Keywords

Groupe de travail d’anthropologie sociale comparative

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Groupe de travail d’anthropologie sociale comparative

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Groupe de travail d’anthropologie sociale comparative

Jean-Claude Galey, directeur d’études avec Cécile Barraud et André Iteanu, directeurs de recherche au CNRSStephen C. Headley, chargé de recherche au CNRS Le holisme et la méthode comparative. Morphologie sociale et approche monographique, comparaison : parenté, localité, échanges Rituels, échange, don André Iteanu a introduit le séminaire en proposant une nouvelle lecture de la relation entre échange et rituels. De Mauss à Sahlins, la notion d’échange comme fait social total a englouti la not..

Groupe de travail d’anthropologie sociale comparative

Cécile Barraud, directeur de recherche au CNRSJean-Claude Galey, directeur d’étudesStephen C. Headley, chargé de recherche au CNRSAndré Iteanu, directeur de recherche au CNRS Le holisme et la méthode comparative. Morphologie sociale, parenté, localité, échanges Approche monographique et ethnographie Quatre thèmes ont été développés à partir de contributions ethnographiques originales ou d’une réflexion méthodologique. Autour de la comparaison : rationalité, hiérarchie et pouvoir, comparaison ..

Influence of Gamma-Ray Emission on the Isotopic Composition of Clouds in the Interstellar Medium

We investigate one mechanism of the change in the isotopic composition of cosmologically distant clouds of interstellar gas whose matter was subjected only slightly to star formation processes. According to the standard cosmological model, the isotopic composition of the gas in such clouds was formed at the epoch of Big Bang nucleosynthesis and is determined only by the baryon density in the Universe. The dispersion in the available cloud composition observations exceeds the errors of individual measurements. This may indicate that there are mechanisms of the change in the composition of matter in the Universe after the completion of Big Bang nucleosynthesis. We have calculated the destruction and production rates of light isotopes (D, 3He, 4He) under the influence of photonuclear reactions triggered by the gamma-ray emission from active galactic nuclei (AGNs). We investigate the destruction and production of light elements depending on the spectral characteristics of the gamma-ray emission. We show that in comparison with previous works, taking into account the influence of spectral hardness on the photonuclear reaction rates can increase the characteristic radii of influence of the gamma-ray emission from AGNs by a factor of 2-8. The high gamma-ray luminosities of AGNs observed in recent years increase the previous estimates of the characteristic radii by two orders of magnitude. This may suggest that the influence of the emission from AGNs on the change in the composition of the medium in the immediate neighborhood (the host galaxy) has been underestimated.Comment: 13 pages, 13 figures, 3 table

Albumin-Like Protein is the Major Protein Constituent of Luminal Fluid in the Human Endolymphatic Sac

The endolymphatic sac (ES) is an inner ear organ that is connected to the cochleo-vestibular system through the endolymphatic duct. The luminal fluid of the ES contains a much higher concentration of proteins than any other compartment of the inner ear. This high protein concentration likely contributes to inner ear fluid volume regulation by creating an osmotic gradient between the ES lumen and the interstitial fluid. We characterized the protein profile of the ES luminal fluid of patients (n = 11) with enlarged vestibular aqueducts (EVA) by proteomics. In addition, we investigated differences in the protein profiles between patients with recent hearing deterioration and patients without hearing deterioration. The mean total protein concentration of the luminal fluid was 554.7±94.6 mg/dl. A total of 58 out of 517 spots detected by 2-DE were analyzed by MALDI-TOF MS. The protein profile of the luminal fluid was different from the profile of plasma. Proteins identified from 29 of the spots were also present in the MARC-filtered human plasma; however, the proteins identified from the other 25 spots were not detected in the MARC-filtered human plasma. The most abundant protein in the luminal fluid was albumin-like proteins, but most of them were not detected in MARC-filtered human plasma. The concentration of albumin-like proteins was higher in samples from patients without recent hearing deterioration than in patients with recent hearing deterioration. Consequently, the protein of ES luminal fluid is likely to be originated from both the plasma and the inner ear and considering that inner ear fluid volumes increase abnormally in patients with EVA following recent hearing deterioration, it is tempting to speculate that albumin-like proteins may be involved in the regulation of inner ear fluid volume through creation of an osmotic gradient during pathological conditions such as endolymphatic hydrops

Opera and poison : a secret and enjoyable approach to teaching and learning chemistry

The storyline of operas, with historical or fictional characters, often include potions and poisons. This has prompted a study of the chemistry behind some operatic plots. The results were originally presented as a lecture given at the University of Minho in Portugal, within the context of the International Year of Chemistry. The same lecture was subsequently repeated at other universities as an invited lecture for science students and in public theaters for wider audiences. The lecture included a multimedia and interactive content that allowed the audience to listen to arias and to watch video clips with selected scenes extracted from operas. The present article, based on the lecture, demonstrates how chemistry and opera can be related and may also serve as a source of motivation and inspiration for chemistry teachers looking for alternative pedagogical approaches. Moreover, the lecture constitutes a vehicle that transports chemistry knowledge to wider audiences through examples of everyday molecules, with particular emphasis on natural products.The author is pleased to express his gratitude to Jorge Calado and Michael John Smith for useful discussions. The author also thanks the reviewers of the manuscript for their helpful comments and suggestions. Thanks are due to the Foundation for Science and Technology (FCT,Portugal), QREN and FEDER/EU for financial support through the research centers, CQ/UM PEst-C/QUI/UI0686/2011. Ciencia Viva, Portugal, is also acknowledged for financial support of the activities organized by the University of Minho during the International Year of Chemistry. The author also expresses his gratitude to Ana Paula Ferreira and Andre Cunha Leal from RTP Antena 2 who contributed immensely to the popularization of the lecture on which this paper is based on

Hepatopathy following consumption of a commercially available blue-green algae dietary supplement in a dog

BACKGROUND: Dietary supplement use in both human and animals to augment overall health continues to increase and represents a potential health risk due to the lack of safety regulations imposed on the manufacturers. Because there are no requirements for demonstrating safety and efficacy prior to marketing, dietary supplements may contain potentially toxic contaminants such as hepatotoxic microcystins produced by several species of blue-green algae. CASE PRESENTATION: An 11-year-old female spayed 8.95 kg Pug dog was initially presented for poor appetite, lethargy polyuria, polydipsia, and an inability to get comfortable. Markedly increased liver enzyme activities were detected with no corresponding abnormalities evident on abdominal ultrasound. A few days later the liver enzyme activities were persistently increased and the dog was coagulopathic indicating substantial liver dysfunction. The dog was hospitalized for further care consisting of oral S-adenosylmethionine, silybin, vitamin K, and ursodeoxycholic acid, as well as intravenous ampicillin sodium/sulbactam sodium, dolasetron, N-acetylcysteine, metoclopramide, and intravenous fluids. Improvement of the hepatopathy and the dog’s clinical status was noted over the next three days. Assessment of the dog’s diet revealed the use of a commercially available blue-green algae dietary supplement for three-and-a-half weeks prior to hospitalization. The supplement was submitted for toxicology testing and revealed the presence of hepatotoxic microcystins (MCs), MC-LR and MC-LA. Use of the supplement was discontinued and follow-up evaluation over the next few weeks revealed a complete resolution of the hepatopathy. CONCLUSIONS: To the authors’ knowledge, this is the first case report of microcystin intoxication in a dog after using a commercially available blue-green algae dietary supplement. Veterinarians should recognize the potential harm that these supplements may cause and know that with intervention, recovery is possible. In addition, more prudent oversight of dietary supplement use is recommended for our companion animals to prevent adverse events/intoxications