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The data presented in this article regroup characterisation of organic matter and nutritional composition of 42 organic wastes and residues usually used as substrates for anaerobic digestion. Those wastes have different origins from agro-industrial, agricultural and urban sectors in France including: algae, slaughterhouse waste, fat, food waste, fruits and vegetables residues, green waste, slurry, manure, wastewater treatment plant sludge and agricultural residues. The properties of organic matter are distinguished between global parameters (pH, total solids, volatile solids, COD and BMP), organic matter fractionation (biochemical and Van Soest) and the main nutrients content (N, P, K, Mg, Ca and S). (C) 2018 The Authors. Published by Elsevier Inc.

Today, the increasing demands in terms of competitiveness require the design of electronic power systems having a minimal bulk while maintaining a good reliability. The combination of these two features is required at a system level as well as at a component level. It is particularly the case of liquid electrolyte aluminum capacitors, which are widely used as storage tanks forelectrostatic energy. This function is necessary in electronic power systems to provide energy to the different parts with each current draw. According to the literature, the study and the evaluation of the reliability of these systems rely heavily on that of liquid electrolyte aluminum capacitors as well as on other components identified as critical (MOS switching transistors, insulators in transformers, etc.). The first chapter begins with a detailed presentation of the technology of capacitors by indicating the various parameters that characterize them and the different work done in the literary on the study and evaluation of the reliability of these components. In the second chapter, aging tests are developed based on the mission profile of the system. Then, the evolutions of characteristics having a significant degradation are modeled. The third chapter deals with the physico-chemical characterization of the capacitor in order to understand and to explain the failure modes recorded during the aging tests. The last chapter is devoted to performing aging tests on a system which is simulating the heat dissipation of components adjacent to capacitors. Electrical measurements are realized in real time to monitor the voltage at their terminals. Finally, a mechanical stress test is carried out to evaluate the impact of vibrations on the connection of new and aged capacitors.; Aujourd’hui, les exigences croissantes en termes de compétitivité requièrent la conception de systèmes électronique de puissance ayant un encombrement minimal tout en gardant une bonne fiabilité. La combinaison de ces deux caractéristiques est absolument requise au niveau d’un système aussi bien qu’au niveau d’un composant. On cite notamment le cas des condensateurs d’aluminium à électrolyte liquide, qui sont largement utilisés comme réservoir de stockage de l’énergie électrostatique. Cette fonction est nécessaire dans les systèmes électroniques de puissance pour fournir l’énergie aux différentes parties à chaque appel de courant. D’après la littérature, l’étude et l’évaluation de la fiabilité de ces systèmes reposent fortement sur celle des condensateurs d’aluminium à électrolyte liquide ainsi que sur d’autres composants identifiés comme critiques (Transistors MOS de découpage, isolants dans les transformateurs, …etc.). Le premier chapitre débute par une présentation de la technologie des condensateurs est détaillée en indiquant les différents paramètres qui les caractérisent et les différents travaux réalisés dans la littéraire sur l’étude et l’évaluation de la fiabilité de ces composants. Dans le deuxième chapitre, les essais de vieillissement sont élaborés en se basant sur le profil de mission du système. Ensuite, les évolutions des caractéristiques ayant une dégradation significative sont modélisées. Le troisième chapitre porte sur la caractérisation physico-chimique du condensateur afin de comprendre et expliquer les modes de défaillance enregistré pendant les essais de vieillissement. Le dernier chapitre est consacré à la réalisation des essais de vieillissement sur système simulant la dissipation de la chaleur des composants adjacents aux condensateurs. Des mesures électriques sont faites en temps réel afin de superviser la tension à leurs bornes. Enfin, un essai de stress mécanique est réalisé afin de permettre d’évaluer l’impact des vibrations sur la connectique des condensateurs neufs et vieillis.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]QUASARE [ADD1_IRSTEA]Systèmes aquatiques soumis à des pressions multiples; International audience; To what extent is water quality related to lake size? This was investigated through the analysis of a database concerning 250 French lakes of various types and sizes. The ecological evaluation of these lakes according to the European Water Framework Directive implied the analysis of at least four water samples during one year to determine physico-chemical parameters and phytoplankton composition. The samples were integrated over the euphotic zone and taken at a single station (where depth is maximal). Then, statistically, the question can be the following: is it possible to predict lake size from the analysis of four annual water samples? Random forest models were derived to predict lake volume, mean depth, and surface area from several hundreds of parameters. Mean depth was the most predictable lake dimension (75 % of variance explained) whereas surface area can hardly be inferred from water quality (only 12 %). The variables most related to lake depth were suspended particulate matter concentration, some elemental ratios, the diversity of phytoplankton communities and the abundance of some particular species. Moreover, simulations with the simple mechanistic model LakeMab where carried out to show how phosphorus concentration and its annual variations are influenced by lake depth and area.

Today, the increasing demands in terms of competitiveness require the design of electronic power systems having a minimal bulk while maintaining a good reliability. The combination of these two features is required at a system level as well as at a component level. It is particularly the case of liquid electrolyte aluminum capacitors, which are widely used as storage tanks forelectrostatic energy. This function is necessary in electronic power systems to provide energy to the different parts with each current draw. According to the literature, the study and the evaluation of the reliability of these systems rely heavily on that of liquid electrolyte aluminum capacitors as well as on other components identified as critical (MOS switching transistors, insulators in transformers, etc.). The first chapter begins with a detailed presentation of the technology of capacitors by indicating the various parameters that characterize them and the different work done in the literary on the study and evaluation of the reliability of these components. In the second chapter, aging tests are developed based on the mission profile of the system. Then, the evolutions of characteristics having a significant degradation are modeled. The third chapter deals with the physico-chemical characterization of the capacitor in order to understand and to explain the failure modes recorded during the aging tests. The last chapter is devoted to performing aging tests on a system which is simulating the heat dissipation of components adjacent to capacitors. Electrical measurements are realized in real time to monitor the voltage at their terminals. Finally, a mechanical stress test is carried out to evaluate the impact of vibrations on the connection of new and aged capacitors., Aujourd’hui, les exigences croissantes en termes de compétitivité requièrent la conception de systèmes électronique de puissance ayant un encombrement minimal tout en gardant une bonne fiabilité. La combinaison de ces deux caractéristiques est absolument requise au niveau d’un système aussi bien qu’au niveau d’un composant. On cite notamment le cas des condensateurs d’aluminium à électrolyte liquide, qui sont largement utilisés comme réservoir de stockage de l’énergie électrostatique. Cette fonction est nécessaire dans les systèmes électroniques de puissance pour fournir l’énergie aux différentes parties à chaque appel de courant. D’après la littérature, l’étude et l’évaluation de la fiabilité de ces systèmes reposent fortement sur celle des condensateurs d’aluminium à électrolyte liquide ainsi que sur d’autres composants identifiés comme critiques (Transistors MOS de découpage, isolants dans les transformateurs, …etc.). Le premier chapitre débute par une présentation de la technologie des condensateurs est détaillée en indiquant les différents paramètres qui les caractérisent et les différents travaux réalisés dans la littéraire sur l’étude et l’évaluation de la fiabilité de ces composants. Dans le deuxième chapitre, les essais de vieillissement sont élaborés en se basant sur le profil de mission du système. Ensuite, les évolutions des caractéristiques ayant une dégradation significative sont modélisées. Le troisième chapitre porte sur la caractérisation physico-chimique du condensateur afin de comprendre et expliquer les modes de défaillance enregistré pendant les essais de vieillissement. Le dernier chapitre est consacré à la réalisation des essais de vieillissement sur système simulant la dissipation de la chaleur des composants adjacents aux condensateurs. Des mesures électriques sont faites en temps réel afin de superviser la tension à leurs bornes. Enfin, un essai de stress mécanique est réalisé afin de permettre d’évaluer l’impact des vibrations sur la connectique des condensateurs neufs et vieillis.

A novel time-lapse synchrotron deep-UV microscopy methodology was developed that made use of the natural tryptophan fluorescence of proteins. It enabled the monitoring in situ of the microstructural changes of protein gels during simulated gastric digestion. Two dairy gels with an identical composition, but differing by the coagulation mode, were submitted to static in vitro gastric digestion. The kinetics of gel particle breakdown were quantified by image analysis and physico-chemical analyses of digesta. The results confirm the tendency of rennet gels, but not acid gels, to form compact protein aggregates under acidic conditions of the stomach. Consequently, the kinetics of proteolysis were much slower for the rennet gel, confirming the hypothesis of a reduced pepsin accessibility to its substrate. The particle shapes remained unchanged and the disintegration kinetics followed an exponential trend, suggesting that erosion was the predominant mechanism of the enzymatic breakdown of dairy gels in these experimental conditions.

International audience; UV-C radiation, widely known for preventing decay and increasing fruit quality, was applied to ‘Camarosa’ strawberries during cultivation (preharvest) and harvested fruits were divided into external and internal tissue portions. UV-C promoted increase in total polyphenolic and volatile organic content, mostly in proanthocyanidins, anthocyanins and esters in external tissues. UV-C treatment increased vitamin C, but did not affect significantly SS, AT and, firmness. In contrast, furane and mesifurane, important volatile compounds for the aroma character of strawberry, decreased upon UV-C treatment.

International audience; Laboratory Visible-Near Infrared (Vis-NIR) spectroscopy is a good alternative to costly physical and chemical soil analysis to estimate a wide range of soil properties. Various statistical methods relate soil Vis-NIR spectra to soil properties including partial least-squares regression (PLSR), the most common multivariate statistical technique in soil science. Most efforts are generally dedicated to the comparison of methodologies and their optimization for the estimation of soil properties. Instead, the focus of this paper is to assess the prediction of soil properties from laboratory Vis-NIR spectroscopy data in regards to spectral degradation. Consecutively, both spectra quality and PLSR models quality are analyzed across the definition of different spectral configurations, each one characterized by three parameters: the number of spectral bands, the spectral resolution and the spectral sampling interval. The originality of this work is to perform this study on four soil properties with different spectral absorption features due to their various physico-chemical interactions with soil substrate, namely: clay, free iron oxides, calcium carbonate (CaCO3) and pH. The initial database is composed of 1961 spectral bands, spectral resolutions of 3 and 10 nm in the 400'1000 nm and 1000'2500 nm ranges, respectively, with a resampled spectral interval of 1 nm. Seven degraded spectral configurations were built from this reference database with a number of spectral bands decreasing from 328 to 10, a spectral resolution decreasing from 3 nm to 200 nm, and a spectral sampling interval equaling the spectral resolution (i.e., uniform interval sampling). All of these databases were composed of 148 soil samples collected at a Mediterranean site. PLSR predicted the four selected soil properties, and the results were as follows: (1) the prediction performances of the PLSR models were accurate and globally stable with a spectral resolution between 3 and 60 nm regardless of the soil properties (R2 decreased from 0.8 to 0.77 for clay, from 0.88 to 0.84 for CaCO3, from 0.66 to 0.58 for pH and remained constant at 0.78 for iron), (2) the prediction performances decreased, but remained acceptable for clay, iron oxides and CaCO3 at spectral resolutions between 60 and 200 nm (R2 > 0.7), (3) the sensitivity of a given soil property to spectral configurations depended on its spectral features and correlations with other soil properties.

Our objective was to compare fruit morphology, physico-chemistry and bioactive compounds content of the edible pulp of six Mammea americana accessions. The results showed that this fruit was rather big, weighing on average 600 to 1100 g depending on the accession, and spherical to oblate-shaped. The pulp represented between 50 and 70% of the weight of the whole fruit. The pulp adhered only partially to the seeds in 5 of the 6 accessions studied, while the last one exhibited full adherence. The fresh pulp was acidic, sweet, succulent and crunchy. The fruits studied had a variety of qualities, providing various opportunities for post-harvest uses: fruit salads, nectar preparation, jams and jellies, or export. We have established for the first time the total phenolic compounds and total flavonoids contents in the pulp of mamey apple fruits. The pulp colour was highly correlated with total phenolic compounds and total carotenoids contents.

Présenté au 40. World Congress of Vine and Wine 29 mai – 2 juin 2017, Sofia, Bulgarie; Abstract. Aims: The management of O2, CO2 and SO2 at bottling and the choice of the closure are two keyfactors of the shelf life of wine in bottles before bringing them to market. The impact of four screw caps, twosynthetic and two technical corks was evaluated on a red wine of Merlot/Tannat.Methods and results: Analytical monitoring (O2, CO2, SO2, aphrometric pressure, L*, a*, b*) was carriedout during 538 days of storage at 20 ◦C. Two sensory analyses at 10 and 17 months completed the study.The wine was bottled with an average total oxygen content of 2 mg/L. The heterogeneity intra and interprocedure was controlled, including for the dissolved carbon dioxide content.Conclusion: Unlike closures with highest OTR, the two technical corks and the two screw caps with Saranexseal, harboring the lowest OTR, matched with the wines exhibiting a low total O2 content at equilibrium(from 4th to 18th month), with more free SO2 and less changed colour. However this OTR gradient (5 to67μg/d) observed through the physicochemical analyses was not necessarily confirmed by both sensoryanalyses performed.Significance and impact of study: This study puts into perspective the impact of OTR closure on sensorycharacteristics evolution of wine consumed during the first two years, especially when the total oxygen atbottling exceeds 1.5 mg/L.

Material degradation due to the specific space environment becomes a key parameter for space missions. The use of large surface of brittle materials on satellites can produce, if impacted by hypervelocity particles, ejected volumes of mater 100 times higher than the impacting one. The presented work is devoted to the use of silica aerogels as passive detectors. Aerogels have been exposed to the low earth orbit of the ISS for 18 months. The study describes the aerogels process and the choice of synthesis parameters in such a way to get expected features in terms of porosity, mechanical properties, internal stresses, and transparency. Low-density aerogels (0.09 g·cm−3) have been prepared. The control of transparency necessary to see and identify particles and fragments collected is obtained using a base catalysis during gel synthesis. After return to earth, the aerogels samples have been observed using optical microscopy to detect and quantify craters on the exposed surface. First results obtained on a small part of the aerogels indicate a large number of debris collected in the materials.

The use of ultrasound in the food industry presents numerous advantages, such as the increase of productivity, decrease of costs andenvironmental impact, resulting in the release of better products in the market. In the first part of this work, a brief introduction of ultrasoundtheory and its uses in the food industry are described, followed by the development of an aqueous ultrasound-assisted extraction of polyphenolsfrom apple pomace, which was optimized with great results both in the laboratory and pilot scales, showing the potential of ultrasound in therecovery of molecules of interest from by-products. A great potential was also evidenced in the development of ultrasound to assist foodpreparation. Although this promising technique has presented innumerous advantages, high lipid content food material seems to presentalterations when treated by ultrasound. Therefore, in the second part, a review on the effects of sonication in food products is presented, andthen a detailed study of edible oils submitted to ultrasounds followed up by physicochemical, sensorial and EPR analysis, allowing theproposition of a mechanism of the lipid degradation by ultrasound; L’utilisation des ultrasons dans l’industrie agro-alimentaire présente de nombreux avantages, tels que l’augmentation de la productivité et la diminution des coûts et des impacts environnementaux. Dans la première partie de ce travail, une brève introduction sur la théorie des ultrasons et ses applications en agro-alimentaire et l’utilisation de ces derniers pour l’extraction des polyphénols de marc de pomme en solution aqueuse seront présentés. Cette étude a été optimisée et présente d’excellents résultats aussi bien à l’échelle du laboratoire qu’à l’échelle pilote. Ce travail a permis de mettre en évidence le potentiel des ultrasons en termes d’extraction de métabolites secondaires de sous-produits. Une autre utilisation des ultrasons a été également mise en évidence en utilisant ces derniers pour la préparation de plats cuisinés. Bien que cette technique a présenté des nombreux avantages, une odeur de rance est apparue à l’issue de la préparation de produits riches en lipides. Ces aliments semblent présenter des altérations lors d’un traitement par ultrasons. Par conséquent, dans la deuxième partie, une étude fondamentale sur les effets des ultrasons sur les produits alimentaires a été réalisée avec notamment une étude plus détaillée sur les huiles comestibles soumises aux ultrasons. Des analyses physicochimiques, sensorielles et par résonance paramagnétique électronique ont été réalisés afin de proposer un mécanisme de dégradation des lipides par ultrasons

International audience; Brazilian Latosols are characterized by low activity clay, little horizon differentiation, a weak macrostructure and a strong microgranular structure. The development of the latter that was reported as being possibly related to the fine material mineralogy, location in the landscape, parental material and biological activity is still under discussion. The aim of this study is to discuss the origin of the microgranular structure of Latosols located in the Brazilian Central Plateau. Ten Latosols (L) developed in different parent materials were selected along an approximately 350-km long regional toposequence across the South American Surface (SAS) (L1 to L4) and Velhas Surface (VS) (L5 to L10). The structure of the Latosols was studied in the field and samples of the diagnostic Bw horizons were collected for laboratory analyses. Basic soil characterization was performed on the

Diffuse pollution by pesticide applied in rural catchments may contribute to alter water quality. Besides actions relative to the way the substances are introduced into the environment, it is also possible to limit the contamination by interfering on their transfer pathways from fields to the main river network. Especially, interface areas such as buffer strips or small ditches may play a major part in pesticide diffuse pollution decrease. In ditches a great variety of materials may act as sorbents for organic contaminants: grass, leaves, wood debris or sediments. In this study, laboratory experiments were designed to determine sorption characteristics for three herbicides with different physicochemical properties on sediment and leaves in decay commonly found in agricultural ditches. Sorption capacities were assessed for the herbicides isoproturon, diuron and diflufenican. Experimental design was carried out to investigate the effects of five parameters on herbicide sorption on sediment and dead leaves. These parameters have been chosen according to parallel field experiment needs. Thus, the influence of initial sorbent moisture, herbicide form, i.e. active substance or commercial formulation, water quality (tap or natural ditch water), bromide ions (used as conservative tracers) and solid/liquid ratio have been tested. Within the parameters investigated, pesticide formulation and solid/liquid ratio were the most important parameters affecting pesticide sorption on both ditch materials.

Dans la décharge d'ordures ménagères d'Etueffont (Belfort, France) un traitement par lagunage naturel des lixiviats produits est effectué à l'aval de l'émissaire principal par l'intermédiaire de quatre bassins placés en série. Deux filtres à sable ont été installés dans la partie centrale et à l'amont du premier bassin, afin de réduire la charge organique et minérale de l'effluent. Un suivi analytique des paramètres classiques physiques et chimiques (éléments majeurs, métaux et composés organiques dont les AOX, les AGV et l'atrazine) a été réalisé dans le lixiviat brut, à la sortie des filtres à sables et à la sortie de la station de traitement par lagunage. Les résultats mettent en évidence une légère variation de la composition physico-chimique du lixiviat, vraisemblablement attribuable à la maturation de la décharge et un abattement très important des MES par les filtres à sable qui se répercute pour l'ensemble des paramètres suivis. Le fonctionnement sur le plan physico-chimique du filtre à sable est détaillé ainsi que l'efficacité du lagunage global sur les effluents issus de la décharge.

International audience

In the Etueffont landfill (Belfort, France), leachates product were treated by stabilisation ponds (4 basins). In order to ameliorate this process, two sand filters were installed in the upstream of the first basin. An analytical follow-up of physical and chemical parameters (major elements, metals and organics with AOX, AGV and atrazine) were carried out in the leachate, on the outlet side of the sand filters and in the treated leachate of the station at the end of lagooning. The results pointed out a short variations of physicochemical composition in the leachate between 2000 and 2001, most likely due to the maturation of the fill and a very significant removal of SM was observed due to the gravel filters which reflects for all the followed parameters. The physical and chemical reaction of the filter sand is detailed and also the efficiency of the natural lagooning on wastes fluids from landfill., Dans la décharge d’ordures ménagères d’Etueffont (Belfort, France) un traitement par lagunage naturel des lixiviats produits est effectué à l’aval de l’émissaire principal par l’intermédiaire de quatre bassins placés en série. Deux filtres à sable ont été installés dans la partie centrale et à l’amont du premier bassin, afin de réduire la charge organique et minérale de l’effluent. Un suivi analytique des paramètres classiques physiques et chimiques (éléments majeurs, métaux et composés organiques dont les AOX, les AGV et l’atrazine) a été réalisé dans le lixiviat brut, à la sortie des filtres à sables et à la sortie de la station de traitement par lagunage. Les résultats mettent en évidence une légère variation de la composition physico-chimique du lixiviat, vraisemblablement attribuable à la maturation de la décharge et un abattement très important des MES par les filtres à sable qui se répercute pour l’ensemble des paramètres suivis. Le fonctionnement sur le plan physico-chimique du filtre à sable est détaillé ainsi que l’efficacité du lagunage global sur les effluents issus de la décharge.

Objective of the three-year monitoring study on the Peugue, which started in 1996, was to understand the effects of wet weather flows and runoff pollutants on the Peugue ecosystem from upstream to downstream, in order to design an optimal management program for flood protection while maintaining protection for the Peugue ecosystem, and then to develop a transposable general methodology for measuring the effects of stormwater on the aquatic ecosystem. During rainfall events, the Peugue river is used as a separate stormwater sewer system. The basin drains a 676-ha semi-urban area. In the upstream part of this catchment, the residential development is new and sparse with many wooded areas. Housing becomes more and more dense in the downstream part. The descriptive linear approach of the Peugue stream allowed the highlighting of various basic elements relative to the functioning of this system. On a hydrological level, the inertia of the flow related to the rain is weak. The flow variations (measured at Le Burck) are significant and sudden, able to pass in one hour from a few tens of l/s to more than one m3/s. From the whole of the analytical results obtained, the physicochemical quality of the Peugue water arises strongly degrading from upstream to downstream. The metal contents of the sediments are in the same order of magnitude as those measured on surface corings carried out in the laying-up of Bourgailh basin. Macrophyte index results are in good coherence with the results of physicochemical quality of water. This is particularly well illustrated between Peugue and its affluent. More generally, a good correlation between the various biological (macrophytes, diatoms) and physico-chemical parameters and the various discharges indexed is registered.

Trois espèces de thons constituent la ressource cible des pêcheries palangrières en Polynésie française : le germon (#Thunnus alalunga$), le thon à nageoires jaunes (#Thunnus albacares$) et le thon obèse (#Thunnus obesus$). Les distributions géographique et bathymétrique de cette ressource sont étroitement liées aux paramètres hydrologiques et trophiques de l'environnement. Dans le cadre du programme Ecotap, des pêches expérimentales réalisées à l'aide d'une palangre instrumentée ont été couplées à des relevés hydrologiques et des prospections acoustiques. La structure hydrologique est étudiée à l'aide de profils de température, salinité et d'oxygène dissous jusqu'à 500 mètres de profondeur. Une analyse typologique des stations menée à partir de ces variables permet de définir trois zones hydrologiques. Les écho-prospections réalisées entre 0 et 500 mètres, à l'aide d'un sondeur Simrad EK 500 permettent de mesurer une réponse acoustique considérée comme représentative de la biomasse en poissons micronectoniques. Cette biomasse est considérée comme un indice de la capacité trophique du milieu pour les thons. L'étude de la distribution verticale et horizontale du micronecton permet de définir trois zones assez similaires aux zones hydrologiques quant à leur distribution spatiale. La distribution des thons est étudiée à partir des captures réalisées à la palangre instrumentée ainsi qu'à l'aide des échos individualisés détectés par acoustique pouvant être considérés comme étant des thonidés. Dans les deux cas, des informations spatio-temporelles précises sont disponibles pour chaque poisson. Les distributions horizontale et verticale des thons sont étudiées en fonction du volume d'habitat et de la capacité trophqiue du milieu. La stratégie d'occupation de l'espace apparaît différente selon les espèces... (D'après résumé d'auteur)

Objective of the three-year monitoring study on the Peugue, which started in 1996, was to understand the effects of wet weather flows and runoff pollutants on the Peugue ecosystem from upstream to downstream, in order to design an optimal management program for flood protection while maintaining protection for the Peugue ecosystem, and then to develop a transposable general methodology for measuring the effects of stormwater on the aquatic ecosystem. During rainfall events, the Peugue river is used as a separate stormwater sewer system. The basin drains a 676-ha semi-urban area. In the upstream part of this catchment, the residential development is new and sparse with many wooded areas. Housing becomes more and more dense in the downstream part. The descriptive linear approach of the Peugue stream allowed the highlighting of various basic elements relative to the functioning of this system. On a hydrological level, the inertia of the flow related to the rain is weak. The flow variations (measured at Le Burck) are significant and sudden, able to pass in one hour from a few tens of l/s to more than one m3/s. From the whole of the analytical results obtained, the physicochemical quality of the Peugue water arises strongly degrading from upstream to downstream. The metal contents of the sediments are in the same order of magnitude as those measured on surface corings carried out in the laying-up of Bourgailh basin. Macrophyte index results are in good coherence with the results of physicochemical quality of water. This is particularly well illustrated between Peugue and its affluent. More generally, a good correlation between the various biological (macrophytes, diatoms) and physico-chemical parameters and the various discharges indexed is registered.

Afin de déterminer l'effet de différents paramètres physico-chimiques du sol sur les nématodes phytoparasites de la matière organique ainsi que des sels (KNO3 et NaCl) ont été ajoutés à du sable ou à un sol sableux stérilisé. Cinq espèces de nématodes parmi les plus fréquemment rencontrées au Sénégal ont été inoculées sur du mil ensemble ou individuellement. Les espèces testées sont #Helicotylenchus dihystera$, #Pratylenchus pseudopratensis$, #Tylenchorhynchus gladiolatus$, #Scutellonema cavenessi$ et #Criconemalla curvata$. Les biomasses racinaires et aériennes ont été mesurées en fin d'expérience. La matière organique n'a pas d'effet sur la biomasse aérienne mais réduit la biomasse racinaire lorsqu'elle est présenté en forte proportion tandis que KNO3 stimule à la fois la biomasse racinaire et aérienne. Lorsque #H. dihystera$ est inoculée seule, cette espèce induit une plus forte biomasse racinaire. Le taux de reproduction d'espèces telles que #S. cavenessi$ et #C. curvata$ n'est pas affecté par le substrat alors que celui de #H. dihystera$, #T. gladiolatus$ et #P. pseudopratensis$ l'est. L'addition de KNO3 et NaCl n'a pas d'influence sur #T. gladiolatus$ mais réduit la reproduction de #H. dihystera$. Ces effets disparaissent lorsque les nématodes sont inoculés conjointement. Ces expériences montrent que les caractéristiques du sol ainsi que celles de la solution du sol influencent les interactions entre nématodes, mais ne conduisent pas nécessairement à une réduction de la pathogénicité car la sensibilité de la plante peut être transformée dans l'environnement modifié. (Résumé d'auteur)

This paper presents CFC and nontransient tracer observations in the western equatorial Atlantic Ocean on repeated sections along 7°30′N, the 35°W meridian, and a transect crossing the Ceara Rise. Three World Ocean Circulation Experiment cruises have been carried out in this area, in February-March 1993 (CITHER 1) and September-October 1995 and April-May 1996 (ETAMBOT 1 and 2). Together with the tracer data, the direct current measurements are used to deduce the circulation pathways. The data confirm the principal circulation features of the Upper North Atlantic Deep Water within the area. The Deep Western Boundary Current flows southward along the continental slope, while, adjacent to the DWBC, there is a northward flow corresponding to the DWBC recirculation whose origin appears variable. The largest variability is observed along the 35°W meridional section, where the DWBC bifurcates eastward north of 3°S but the eastward equatorial flow does not appear to be permanent. At the Middle North Atlantic Deep Water level, CFC distributions exhibit the most important contrast between waters of northern and southern origin. The circulation at the Lower North Atlantic Deep Water level, mainly controlled by the topography, looks more permanent because the DWBC is regularly observed during the three cruises, and there is no evidence for a northwestward recirculation along the Mid-Atlantic Ridge. The transient behavior of CFC distributions, which is superimposed on local circulation effects, can be seen clearly through their temporal evolution within the DWBC. The variability of the deep circulation observed during the 1993–1996 interval rules out a dominant variability in response to semi annual forcing.

The annual cycle of Vibrio cholerae in the environment surrounding the Layo aquaculture facility (Ebrié lagoon) was studied from March 1991 to April 1992. Vibrio cholerae counts were coupled with the determination of physical and chemical characteristics of water and the estimation of biological richness of this environment.