Spéciation des organoétains dans les eaux et sédiments du bassin Adour-Garonne

De par leurs nombreuses propriétés physico- chimiques, les organoétains sont très utilisés dans l’industrie et en agriculture et entrent dans la composition de nombreux produits domestiques. Ils sont cependant extrêmement toxiques et la Communauté Européenne les a classés parmi les substances prioritaires dans le domaine de l’eau.Un suivi des organoétains a été réalisé sur onze rivières du bassin Adour-Garonne et sur l’estuaire de l’Adour. Ces composés y sont systématiquement présents, les butylétains et les octylétains étant les espèces les plus fréquemment détectées. Les concentrations varient de la limite de détection (0.2-0.5 ng(Sn)/l en moyenne) à 50 ng(Sn)/l dans les eaux, et de 15 à 300 µg(Sn)/kg dans les sédiments dulcicoles. Des pics de contamination ont été observés en fin de printemps et d’été, dans plusieurs rivières. Ils correspondent à la présence des mono- butyl- et -phénylétains principalement, leurs concentrations pouvant atteindre 700 à 900 ng(Sn)/l d’eau. Les rivières les plus contaminées sont la Garonne, le Gave de Pau, l’Adour, la Charente et le Thoré. Dans les matières en suspension de l’estuaire de l’Adour les concentrations atteignent quelques mg(Sn)/kg. L’ensemble des données recueillies a permis de mieux comprendre les origines et le devenir des organoétains dans le cycle hydrologique.Because of their physico-chemical properties, organotin compounds (OTC) are widely used in industry and are present in a significant number of agricultural pesticides and domestic products. They are highly toxic and the European Community has listed them as priority pollutants in the aquatic environment. Organotins have been monitored in the Adour- Garonne basin and the Adour estuary. They are systematically present in the rivers, with butyl- and octyltins being the species most frequently detected. These species, especially octyltins, probably come from the continuous leaching of plastic tubes. The OTC concentrations ranged from just over detection limits (≥ 0.2-0.5 ng (Sn)/L) to 50 ng (Sn)/L in water and from 15 to 300 µg (Sn)/kg in freshwater sediment. Important seasonal variations were also observed. Thus, at the end of spring and summer, very high monophenyltin (MPhT) concentrations of up to 700-900 ng (Sn)/L were found in the dissolved phase. This phenomenon could be partly attributed to specific triphenyltin (TPhT)-based agricultural treatments, MPhT being one of the TPhT degradation products. High monobutyltin (MBT) concentrations of up to 150 ng (Sn)/L were also detected during the same period. This latter compound comes from leaching of plastics and from tri- and di-butyltin (TBT, DBT) degradation. It represents 80 to 100% of the butyl species found in sediments.Considering OTC concentrations, speciation and toxicity, the most contaminated rivers appeared to be the Garonne, Gave de Pau, Adour, Charente and Thoré. Urban activities have significant influence on the levels of OTC contamination for most of the rivers, demonstrating continuous OTC inputs from domestic and industrial treatment plants. This is especially the case for the Charente and Thoré rivers, where some specific industrial activities devoted to leather and wood are present close to the sampling points.A statistical study was performed on the different physico-chemical parameters (temperature, water flow rate, dissolved oxygen concentration) and OTC concentrations. A significant positive correlation between water flow rate and organotin concentrations in the dissolved phase was observed. This correlation was very important when only sampling points far from potential OTC sources were considered, the octyltin concentrations showing the strongest correlation. These observations confirm the presence of a continuous OTC diffusion into aquatic media. A comparison between the present results in Adour-Garonne and OTC monitoring performed in the Rhin- Meuse basin shows that the level of contamination was quite similar in the two basins, especially considering rivers without fluvial traffic. A similar correlation existed between OTC concentrations in the dissolved phase and water flow rate.Special attention was given to the Adour sub-basin because of its particular geographic position and especially the large built-up area in the estuary. Butyltins remain the main OTC compound present, in terms both of frequency and concentration. According to the different sampling points in this sub-basin, mean OTC concentrations in the estuary did not appear to be really influenced by human activities located upstream, the concentrations in this part reaching 50 ng (Sn)/L in the dissolved phase. In contrast, OTC amounts found in the estuary were considerable higher. The built-up area of the estuary had a strong influence on concentrations, which were 6 to 14 times higher in the city centre than those upstream from the city (in an agricultural region). In addition to the influence of local sources, both a strong dilution effect and significant adsorption/ sedimentation phenomena in the downstream region of the estuary could be important. In the suspended matter of the Adour estuary, organotin concentrations were extremely high, reaching concentrations as high as mg (Sn)/kg. Such concentrations have already been reported for nearby regions of the harbour [Bravo et al. (2004)]. However, in the present case, there should be considerable concern considering the possible environmental consequences. The estuarine sediments appeared obviously contaminated by butyltins, but the concentrations were lower than those that could be expected (2000 µg (Sn)/ kg maximum). This observation could be explained by water flow rates as well as the tide, which could export large amounts of suspended matter outside the estuary. MPhT and TPhT were also detected, especially in sediments from the extreme downstream region of the estuary. Their presence could be attributed to the marina. The different solid/ dissolved partition coefficients were also evaluated. These partition coefficients ranged from over 40x104 for sediments up to 200x104 for suspended matter. Finally, the information on the Adour sub-basin showed that the estuary was more strongly contaminated than the upstream region.Generally, all these data have contributed to the first evaluation of OTC contamination in the Adour-Garonne basin, and identified organotin sources. The statistical study, comparisons between the different parts of the aquatic environment, and the observation of solid/ liquid distributions lead to a better understanding of the environmental fate of OTCs. Even if differences exist between the level of contamination in freshwater and estuarine environments, the ubiquitous presence of OTC must remain a subject of concern, especially with regard to the high toxicity of organotins. For example, TBT and TPhT have lethal effects on trout and algal species at aquatic concentrations in the µg (Sn)/L range or even below this concentration [TOOBY et al. (1975), WONG et al. (1982)]. Considering this high toxicity, other studies will have to be performed in order to increase the current database concerning OTC in rivers. It is also important to know the conditions that control OTC uptake by biota, and in order to propose effective environmental management strategies

Mise en suspension d'une poudre micronique par effet vortex

National audienceNew materials based on nanotechnology are reaching the market in a wide variety of consumer products. Since these nanostructured materials can be in powder form, a suspending powder system is essential for many purposes: For in vivo inhalation toxicological studies,for workers and consumers protection, for instrumental development widening aerosol measurement spectrum. Different powders suspending systems have been developed like the rotating drum or the single drop. They are used as a reference method to evaluate bulk materials dustiness. Usually cumbersome, these systems need a huge amount of powder (a few hundred grams) and require time-consuming cleaning processes which could be even more tedious when a nanostructured material and/or a toxic powder is used. The aim of this work is to evaluate the behavior of a powder suspending system by vortex effect. This system is very simple and requires a very small amount of powder (a few grams) in a tube [1,2]. It has been set up to study the dustiness under controlled and reproducible conditions. Different tests have been performed with a Al2O3 powder. They allowed not only to characterize the influence of shaking speed and powder mass, but also to measure the particle size and the number concentration as shown on the figures belowLa mise en suspension de poudres est un processus essentiel dans différents domaines : il permet d'étudier la physico-chimie de la phase " aérosol " d'une poudre donnée ; un tel système est indispensable pour mener des études toxicologiques par inhalation in vivo ; dans le domaine de la protection des personnes (travailleur, consommateur) et de l'environnement, il permet d'évaluer l'émissivité potentielle des poudres, et en conséquence d'adapter les mesures de protection ; un tel dispositif facilite également le développement instrumental, en donnant accès à un spectre large d'aérosols. Nous rapportons ici les résultats d'une étude consacrée à la mise en suspension par effet vortex. Ce système est particulièrement simple [2, 3] : il consiste en l'agitation d'une faible quantité de poudre, placée dans un tube à essai. Nos essais ont porté sur une poudre micronique d'alumine. L'aérosol obtenu a été caractérisé en nombre et taille à l'aide de systèmes CNC, SMPS, et APS. Des essais de sensibilité ont été menés en termes de quantité de produit, et de niveau d'agitation. Nous avons relevé une très bonne répétabilité des résultat

Evaluation de l'efficacité de prélèvement d'un précipitateur électrostatique

National audienceEasy-to-use particle sampling techniques leading to easy-to-analyze samples is a growing need for nanosafety. Electrostatic precipitation [Dickens 1999] commercialized by TSI (Nanometer Aerosol Sampler model 3089) could be an answer. However, more information is needed on the performance of this instruments. On the one hand, real time sampling efficiency of the NAS regarding voltage has been studied. On the other hand, the sampling efficiency for 80 nm polystyrene particles has been considered through both real time CPC measurements and TEM analysis: these methods lead to very different results, respectively 62-70% and < 0,1 %. These results are discussed regarding literatureConnaître la composition des particules constitue un enjeu grandissant dans le domaine des particules ultrafines. Il est essentiel de disposer de techniques de prélèvement simples, pouvant permettre une analyse différée, tout particulièrement par microscopie électronique. A ce titre, le prélèvement par précipitateur électrostatique semble être une technique prometteuse. La société TSI commercialise depuis quelques années un échantillonneur de ce type, le modèle 3089 NAS (Nanometer Aerosol Sampler). Le travail présenté ici a pour objectif d'étudier l'efficacité de prélèvement de cet appareil, dans le cas d'une mise en oeuvre en aval d'un analyseur de mobilité électrique. Pour ce faire, un aérosol monodispersé a été produit par atomisation et extraction par analyse de mobilité. L'efficacité de prélèvement a été considérée pour différents modes de fonctionnement. Il ressort de cette étude que si une efficacité notable de dépôt est relevée à l'échelle du NAS, ce dépôt ne se ferait que de manière minoritaire sur la grille de prélèvement. Ces résultats sont discutés au regard de références bibliographique

Kinetic Approach to Multilayer Sorption: Equations of Isotherm and Applications

An analytical isotherm equation that describes the multilayer adsorption on fractal surfaces with adsorbate-adsorbate interactions (measured in terms of free energy) different from that of bulk liquid was developed. Assuming mathematical functionalities for the variation of the free energy, it is possible to evaluate the influence of the adsorbate-adsorbate interactions on the adsorption capacity of solids of high degree of surface irregularity. For those surfaces with relatively low degree of irregularity, it results that the free energy variation with the layer number in the multilayer region affects considerably the sorption capacity of the adsorbent, even for water activities lower than those corresponding to the monolayer moisture content. The energy interactions between adjacent adsorbate layers become less important as the fractal dimension of the adsorbent increases. For a fractal surface, the growing of the multilayer seems to mainly controlled by the degree of surface roughness characteristic of microporous adsorbents, where the volume and pore dimension are the true limitants to the sorption capacity. The isotherm equations obtained were tested fitting published experimental equilibrium data of various water vapor-biopolymer systems

Exploración de alternativas para el desarrollo sostenible de sistemas de producción hortícola-ganaderos familiares en el sur de Uruguay

La sostenibilidad de la mayoría de los predios hortícolas familiares en el sur de Uruguay está amenazada por ingresosinsuficientes y por el deterioro de los recursos naturales. En este estudio se cuantificó el efecto de la inclusión de diferentesactividades de producción ganadera en la estructura y en los resultados económico-productivos y ambientales de diferentestipos de sistemas de producción (predios) hortícolas. Se realizó un estudio exploratorio a escala predial con modelos desimulación utilizando dos predios como estudio de caso. Los resultados sugieren que la inclusión de actividades de producciónganadera en los sistemas de producción hortícolas es un factor determinante para reducir la erosión promedio del áreacultivada. Para reducir la erosión el modelo diseñó predios que reducen el área de hortalizas al tiempo que expanden larotación forrajera. Como consecuencia de esto, también se redujo el ingreso familiar (IF) entre 12 % y 31 % según el casoestudiado. Sin embargo, pudimos diseñar sistemas de producción con erosión menor a la tolerable para el tipo de suelo e IFmayor al objetivo, en los dos predios. De las actividades ganaderas evaluadas las más apropiadas para incluir en predios hortícolasson el engorde de novillos o vaquillonas en ciclos de 14 a 18 meses, debido al menor costo para reposición de animales y al menoruso de concentrados, lo que disminuye las necesidades de capital y la dependencia de insumos externos

The application of ecologically intensive principles to the systemic redesign of livestock farms on native grasslands: A case of co-innovation in Rocha, Uruguay

CONTEXT: Family-run cow-calf farms based on native grasslands exhibit low economic and social sustainability, as reflected in low family incomes and high workloads. Experimental results have shown that pasture–herd interaction management could improve native grasslands and animal productivity OBJECTIVE: This paper analyzes the extent to which the sustainability of family-run livestock farms based on native grasslands could be enhanced by a systemic redesign informed by ecological intensification practices. The research questions address the initial state of farm sustainability, key bottlenecks to improving farm sustainability, and changes in sustainability criteria achieved over three years of farm redesign. METHODS: The study was executed as part of a multi-level co-innovation project in Uruguay in which a team of scientist-practitioners and seven farm families participated in farm characterization, diagnosis, and redesign. The farm characterization took the form of indicators to describe the farms’ management and bio-physical subsystems. Redesign plans were negotiated between the research team and the farmers. Frequent monitoring and evaluation cycles enabled finetuning across the years of implementation. RESULTS AND CONCLUSION: Improvements were observed in the economic indicators gross margin (+55%), return to labor (+71%), and family income (+53%) and in the social indicator workload ( 22%), and the environmental indicators bird diversity and ecosystem integrity index were maintained or increased slightly. These changes were explained by the uptake of coherent sets of ecological intensification practices causing changes in forage height (+30%), forage allowance (+69%), pregnancy (+22), weight of weaning calf per mating cow (+32%), and presence of tussocks (+65%). Ecological intensification principles resulted in synergistic positive effects between productivity–biodiversity tradeoffs and the scope for enhanced farm resilience and stability. SIGNIFICANCE: Cow-calf family-run farms can be transformed to produce positive environmental and social effects and viable economic results. The implementation of projects in a co-innovation context may be taken as a guide to scaling up and scaling out the ecological intensification of livestock production on native grasslands, contributing to an extension system at the national level with the aim of improving cow-calf systems sustainability.Estación Experimental Agropecuaria BarilocheFil: Ruggia, Andrea. Instituto Nacional de Investigacion Agropecuaria (INIA). Programa Nacional de Investigacion en Produccion Familiar. Estacion Experimental INIA Las Brujas; UruguayFil: Dogliotti, Santiago. Universidad de la República. Facultad de Agronomía. Departamento de Produccion Vegetal; UruguayFil: Aguerre, Maria Veronica. Instituto Nacional de Investigacion Agropecuaria (INIA). Programa Nacional de Investigacion en Produccion Familiar. Estacion Experimental INIA Las Brujas; UruguayFil: Albicette, Maria Marta. Instituto Nacional de Investigacion Agropecuaria (INIA). Programa Nacional de Investigacion en Produccion Familiar. Estacion Experimental INIA Las Brujas; UruguayFil: Blumetto, Oscar. Instituto Nacional de Investigacion Agropecuaria (INIA). Programa Nacional de Investigacion en Produccion Familiar. Estacion Experimental INIA Las Brujas; UruguayFil: Cardozo, Geronimo. Instituto Nacional de Investigacion Agropecuaria (INIA). Programa Nacional de Investigacion en Pasturas y Forrajes. Estacion Experimental INIA Treinta y Tres; UruguayFil: Leoni, Carolina. Instituto Nacional de Investigacion Agropecuaria (INIA). Programa Nacional de Investigacion en Produccion Familiar. Estacion Experimental INIA Las Brujas; UruguayFil: Quintans, Graciela. Instituto Nacional de Investigacion Agropecuaria (INIA). Programa Nacional de Investigacion en Carne y Lana. Estacion Experimental INIA Treinta y Tres; UruguayFil: Scarlato, Santiago. nstituto Nacional de Investigacion Agropecuaria (INIA). Programa Nacional de Investigacion en Produccion Familiar. Estacion Experimental INIA Las Brujas; UruguayFil: Tittonell, Pablo Adrian. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; ArgentinaFil: Tittonell, Pablo Adrian. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; ArgentinaFil: Rossing, Walter A.H. Wageningen University and Research. Farming Systems Ecology, Plant Sciences Group; Holand

Documenting and Understanding Workplace injuries among Latino Day Laborers

BACKGROUND: Latino day laborers face substantial injuries at work. We present a comprehensive assessment of their injury experience and explore the predictors of selfreported injuries. METHODS: Worker and injury characteristics were collected from 331 day laborers using an innnovative injury assessment tool. The odds of injury were estimated using a logistic regression. RESULTS: Participants were foreign-born, Spanish monolingual, and employed in construction. Sixty-seven individuals reported 88 past-year injuries, mostly involving the upper or lower extremities. Injuries were caused by moving heavy objects, falling, or being struck an object. Of the documented injuries, 24% were not reported at work due to fear of being fired; 64.4% resulted in missed workdays, 54.0% in temporary incapacitation, and 34.5% in permanent incapacitation. Being married significantly reduced the odds of reporting an injury. DISCUSSION: Better documentation can inform the development of better policy protections that ameliorate injuries experienced by Latino day laborers at the workplace

Phytochemicals as antibiotic alternatives to promote growth and enhance host health

There are heightened concerns globally on emerging drug-resistant superbugs and the lack of new antibiotics for treating human and animal diseases. For the agricultural industry, there is an urgent need to develop strategies to replace antibiotics for food-producing animals, especially poultry and livestock. The 2nd International Symposium on Alternatives to Antibiotics was held at the World Organization for Animal Health in Paris, France, December 12-15, 2016 to discuss recent scientific developments on strategic antibiotic-free management plans, to evaluate regional differences in policies regarding the reduction of antibiotics in animal agriculture and to develop antibiotic alternatives to combat the global increase in antibiotic resistance. More than 270 participants from academia, government research institutions, regulatory agencies, and private animal industries from >25 different countries came together to discuss recent research and promising novel technologies that could provide alternatives to antibiotics for use in animal health and production; assess challenges associated with their commercialization; and devise actionable strategies to facilitate the development of alternatives to antibiotic growth promoters (AGPs) without hampering animal production. The 3-day meeting consisted of four scientific sessions including vaccines, microbial products, phytochemicals, immune-related products, and innovative drugs, chemicals and enzymes, followed by the last session on regulation and funding. Each session was followed by an expert panel discussion that included industry representatives and session speakers. The session on phytochemicals included talks describing recent research achievements, with examples of successful agricultural use of various phytochemicals as antibiotic alternatives and their mode of action in major agricultural animals (poultry, swine and ruminants). Scientists from industry and academia and government research institutes shared their experience in developing and applying potential antibiotic-alternative phytochemicals commercially to reduce AGPs and to develop a sustainable animal production system in the absence of antibiotics.Fil: Lillehoj, Hyun. United States Department of Agriculture. Agricultural Research Service; ArgentinaFil: Liu, Yanhong. University of California; Estados UnidosFil: Calsamiglia, Sergio. Universitat Autònoma de Barcelona; EspañaFil: Fernandez Miyakawa, Mariano Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Patobiología; ArgentinaFil: Chi, Fang. Amlan International; Estados UnidosFil: Cravens, Ron L.. Amlan International; Estados UnidosFil: Oh, Sungtaek. United States Department of Agriculture. Agricultural Research Service; ArgentinaFil: Gay, Cyril G.. United States Department of Agriculture. Agricultural Research Service; Argentin