La présente thèse se concentre tout d'abord à mettre en place des expérimentations de compaction dynamique de poudres.Un montage expérimentale est conçu, testé puis validé. Le but de ce dernier est de générer des ondes de compaction unidimensionnelles et de pouvoir observer le milieu granulaire à l'échelle des grains. Deux types de poudres sont considérés : une poudre de polypropylène et une poudre d'explosif (RDX).Pour cela, des caméras ultra-rapides (50 000 images/s) sont utilisée pour enregistrer les essais. Une technique de corrélation d'image est utilisée pour remonter aux champs de déplacement et de vitesse des grains.Un modèle de compaction multiphasique est implémenté. Les phénomènes de friction grain/paroi sont ajoutés au modèle suite aux observation expérimentale. Une partie du travail a été consacré à l'amélioration de l'équation d'état granulaire et à sa détermination expérimentale.Les résultats numériques sont en bon accord avec les expérimentations, tant que le montage expérimental ne se déforme pas sous l'effet de la pression des grains.De premières expérimentations avec les poudres d'explosifs ont été réalisées. Le montage expérimental nécessite encore certaines améliorations mais il a prouvé son utilité dans l'étude de la transition combustion-déflagration-détonation. / The first part of the present PhD focuses on the conception and the validation of an experimental set up. The aim of the experiments is to generate one-dimensional compaction waves and to observe the media at the grains scale. Two type of powder are used : polypropylene powder and an explosive powder (RDX).The experimental apparatus uses ultra-fast cameras (50 000 images/s) to record the tests. Image correlation is used to compute the displacement and velocity fields.A multiphasic compaction model is then coded. Grain/wall friction is added as the experimental work underlined its importance. Additional work has been provided concerning the granular equation of state and its experimental determination.Numerical results are in good agreement with the experimenations, as long as the experimental set up is not deformed because of the grains' pressure.A few experiments have been done with explosive powders. The experimental set up still needs some improvement but it proved its usefullness for deflagration to detonation studies.

M.Sc. / The organochlorine insecticides were amongst the first pollutants shown to cause adverse population effects. The potential adverse effects of these pollutants on wildlife are a cause for great concern. Severities of their effects were sometimes surprising given the low levels of the compounds in environmental compartments such as surface waters and soils. High lipophilicity combined with chemical stability and very slow biodegradation are characteristic features of these toxic Persistent Organic Pollutants (POPs). Regional declines in fish, bird as well as invertebrate populations resulting from long term exposure to POPs such as 1,1-bis (4-chlorophenyl) -2,2,2-trichloroethane (DDT) and its stable metabolite 1,1-bis (4-chlorophenyl) -2,2-dichloroethene (DDE), could be related to some biochemical, endocrine and physiological effects in individuals. Some POPs have been suggested to have negative effects disrupting physiological processes and resulting in alterations of homeostasis, reproduction, development and behavior. Such adverse effects upon populations may be avoided if the potential of chemicals to cause them is recognized before problems arise. The aim of this study was to determine whether or not the ongoing spraying of DDT in the Limpopo Province is negatively affecting the health of aquatic species found in surface water of the area. Extensive research has shown that biomarkers have been very effective in the trace determination of a number of adverse effects caused by metals, and thus, are also being used for POPs. A battery of biomarkers (EROD, CAT and CEA) were used, both in the field and in a controlled laboratory environment, in order to try and determine the long term effects of exposure to low environmentally relevant levels of DDE in the selected area. DDT levels in the biota, water and sediment samples were also measured to determine the possible levels of exposure. Dose-response relationships were most successfully determined by the EROD and the CEA biomarkers in this study. In a controlled laboratory study, a definite effect was noted on the Mozambique Tilapia with increasing concentrations of DDE. In the natural environment, dose-response relationships to DDE exposure were more difficult to quantify as additional chemicals and natural environmental stressors also affect the results.

Endocrine disrupting chemicals (EDCs) such as DDT have the ability to disrupt hormonally controlled processes, such as spermatogenesis, which is the maturation of germ cells into spermatozoa. During normal spermatogenesis, germ cell apoptosis can occur, but the degree of apoptosis within the testis could possibly be affected by exposure to EDCs. In 2004, a pilot study on the reproductive health of two freshwater fish species, Oreochromis mossambicus and Clarias gariepinus, from three impoundments in the Luvuvhu River, found concerning levels of DDT and its metabolites in both species from the Nandoni Dam, and in O. mossambicus from the Xikundu Weir. This was not surprising as a large part of the Luvuvhu River catchment is located within an area where ongoing DDT-spraying occurs for vector control purposes. Hence, in 2006, a larger WRC-funded project began to further investigate the findings from the pilot study. A subsidiary study, spanning two seasons, was initiated to investigate testicular apoptosis in fish from the polluted systems, the Nandoni Dam (ND) and the Xikundu Weir (XW), as well as a reference site, the Albasini Dam (AD), utilizing caspase-3 and TUNEL immunoexpression as apoptotic markers. In addition, three fixatives, Bouin’s Fluid (BF), Neutrally Buffered Formalin (NBF) and Paraformaldehyde (PFA), were used to determine which would be the optimal fixative for both histological and immunohistochemical assessments. Sampling occurred during season 1, the low-flow season (October 2007), during DDT spraying of the surrounding area, and season 2, the high–flow season (February 2008), two months after the DDT-spraying was completed. The testes of O. mossambicus (n = 19 season 1, n = 25 season 2) and C. gariepinus (n = 19 season 1, n = 20 season 2) were fixed in the above-mentioned fixatives, embedded in paraffin wax, prepared for immunohistochemistry, and exposed to caspase-3 antibodies and TUNEL antibodies individually. The results indicated that the residues of p,p´-DDT - DDD and - DDE were found in the fat samples of both O. mossambicus and C. gariepinus, in AD, ND and XW. Testicular apoptotic assessment using the caspase-3 assay clearly labeled spermatocytes in the process of cellular death in both seasons, in all three fixatives. When comparing the two assays, a significant difference is found between the caspase-3 and TUNEL positive cells. The results further show that, when comparing the three sampling sites, the highest amount of positive cells are found at the XW. The decrease observed in season two, in both the caspase-3 and TUNEL assay may possibly be linked to the stage of spermatogenesis, coinciding with hormonal changes associated with the different sampling seasons (i.e. breeding and non-breeding seasons). The levels of DDT found in the fat tissue, could not be correlated to an up-regulation in apoptotic cells. The results The results indicated that the choice of fixative, could affect the identification of the amount of positive cells. The utility of the caspase-3 and TUNEL assays, in conjunction with all three fixatives, proves a successful tool in assessing and quantifying modulated testicular apoptosis, creating greater research potential in the assessment of the effects of aquatic pollution. Copyright / Dissertation (MSc)--University of Pretoria, 2008. / Physiology / unrestricted

No description available.

<p>The shallow soils of a former orchard area in Point Pelee National Park, near Leamington, Ontario, Canada have elevated concentrations of chlorinated pesticides above the regulatory limits. Previous studies in this area have shown that the DDT, DOE and ODD are highly persistent with an estimated half-life of DDT in the range of 15-30 years. In 2002 a pilot-scale field remediation experiment involving the application of cyclodextrin was conducted. This experiment resulted in substantial decrease of DDT, DDE and DDD concentrations in the upper soil layer within the remediation grid. Soil samples were collected within the treatment plots a year after the cyclodextrin application was completed to assess any further changes in concentrations of DDT, DDE and DDD. Groundwater samples were collected in the vicinity of the soil remediation grid which provided DDT, DDE and DDD concentrations in groundwater to assess the vertical mobilization of the compounds. Mass balance of the "soil - groundwater" system was calculated in order to estimate the degradation rate of DDT within the remediation zone. The 2-D unsaturated/saturated flow and solute transport numerical model "HYDRUS 2-D" was used to gain a better estimation of DDT, DDE and DDD mass and distribution in groundwater. The effectiveness of cyclodextrin application for remediation of DDT contaminated soils was assessed. After remediation treatments had stopped, there was no indication of further degradation of DDT and its metabolites in the upper layer of soil. The groundwater concentration of DDT, DDE and DDD near the remediation grid was 10-100 times higher than background value. This increase in groundwater concentration is a direct indication of DDT, DDE and DDD mobilization by cyclodextrin. The estimates of total mass of DDT in groundwater are less than 1% of mass leached from the soil. It was concluded that the application of cyclodextrin promoted enhanced co-metabolic biodegradation of DDT and it metabolites DDE and DDD. The estimated half-life for the displaced DDT was less than 2 months. This work demonstrates that cyclodextrin can be a highly effective agent for remediation of DDT contaminated soils.<p> / Thesis / Master of Science (MSc)

No description available.

Bifenilos policlorados (PCBs) e pesticidas organoclorados são poluentes resistentes à degradação e têm sido identificados em vários compartimentos do ambiente marinho. O objetivo deste trabalho foi otimizar e validar a metodologia, e avaliar a contaminação por pesticidas organoclorados e PCBs em algas e sedimentos costeiros no Estuário e Baía de Santos-São Vicente e no Complexo Estuarino-Lagunar de Iguape e Cananéia (SP). Foram coletadas nessas regiões um total de 37 amostras de sedimento superficial, 3 testemunhos com 27 sub-amostras e 10 amostras de alga, no período de 1998-2001. O método, que incluiu a extração e purificação com solventes orgânicos e análise por GC-ECD, mostrou-se satisfatório dentro dos padrões internacionais. Na região de Cananéia-Iguape predominaram os DDTs (sedimentos: 0,78 a 14,52 ng.g-1 peso seco) e as maiores concentrações ocorreram nas proximidades da Cidade de Cananéia e Baía de Trapandé. Na região de Santos predominaram os PCBs (sedimentos: 4,08 a 133,42 ng.g-1 peso seco, testemunhos de sedimentos: 3, 70 a 44,65 ng.g-1 peso seco e algas: 15,83 a 43,21 ng.g-1 peso seco) e os maiores valores foram encontrados no emissário submarino, no Estuário de Santos, em locais próximos as indústrias, e no Estuário de São Vicente. De maneira geral, as concentrações tanto de PCBs quanto de pesticidas organoclorados em Santos e Cananéia-Iguape foram baixas. Santos apresentou maior incidência de PCBs, provavelmente devido à industrialização, enquanto que em Cananéia-Iguape predominaram os pesticidas organoclorados, que podem ser atribuídos às antigas campanhas de saúde pública ou aplicações nas lavouras. / Polychlorinated biphenyls and chlorinated pesticides are degradation resistant pollutants. They have been detected in several compartments of marine environment. The objective of this study was the optimization of the methodology and the evaluation of the contamination of chlorinated pesticides and PCBs em algae and coastal sediments in the Estuary and Bay of Santos-São Vicente and in the Lagunar Complex of Iguape and Cananéia (SP). An amount of 37 samples of superficial sediment, 3 cores with 27 subsamples and 10 samples of algae was collected in the period of 1998-2001. The methodology was considered satisfactory within international standards, that includes extraction and clean up with organic solvents and analysis with GC-ECD. In the Cananéia-Iguape region, DDTs were predominant and the highest levels were found around the city of Cananéia and in Trapandé Bay. In the Santos area, the PCBs were predominant and the highest values were found around the Santos Bay outfall and in the Estuary of Santos-São Vicente. In general, either the concentrations of PCBs or chlorinated pesticides in Santos and Cananéia-Iguape were low. Santos presented higher incidence of PCBs, probably due to industrialization, while in Cananéia-Iguape the chlorinated pesticides predominated, and that can be attributed to past public health campaigns or to agricultural uses.

Obiettivo di questo lavoro è definire il processo di interazione con la televisione digitale terrestre secondo una prospettiva psicosociale, che tenga conto delle e modalità di rappresentazione e fruizione della stessa da parte degli utenti e degli esperti del settore. Dal materiale prodotto (interviste agli utenti e analisi della Prima Conferenza Nazionale sulla DTT) emerge una diversità tra i due punti di vista: i telespettatori mostrano di essere ancora legati ad una fruizione tradizionale del medium televisivo, mentre gli esperti ritengono che il digitale sia un prodotto per la massa, in grado di rispondere al bisogno di ascolto e di partecipazione che gli spettatori manifestano. / Aim of this work is to define the process of interaction with the DTT according to a psychosocial perspective, taking into account its representation and fruition, from part of the users and the experts of the field. From the data collected (interviews to DTT users and analysis of the First National Conference on DTT) a difference rises between the comparison of the two points of view: the televiewers seem to be still bound to a traditional fruition of the medium; but regarding the experts' representations the digital is thought as a product for the mass that at the same time can answer to that need of participation the televiewers show.

Bifenilos policlorados (PCBs) e pesticidas organoclorados são poluentes resistentes à degradação e têm sido identificados em vários compartimentos do ambiente marinho. O objetivo deste trabalho foi otimizar e validar a metodologia, e avaliar a contaminação por pesticidas organoclorados e PCBs em algas e sedimentos costeiros no Estuário e Baía de Santos-São Vicente e no Complexo Estuarino-Lagunar de Iguape e Cananéia (SP). Foram coletadas nessas regiões um total de 37 amostras de sedimento superficial, 3 testemunhos com 27 sub-amostras e 10 amostras de alga, no período de 1998-2001. O método, que incluiu a extração e purificação com solventes orgânicos e análise por GC-ECD, mostrou-se satisfatório dentro dos padrões internacionais. Na região de Cananéia-Iguape predominaram os DDTs (sedimentos: 0,78 a 14,52 ng.g-1 peso seco) e as maiores concentrações ocorreram nas proximidades da Cidade de Cananéia e Baía de Trapandé. Na região de Santos predominaram os PCBs (sedimentos: 4,08 a 133,42 ng.g-1 peso seco, testemunhos de sedimentos: 3, 70 a 44,65 ng.g-1 peso seco e algas: 15,83 a 43,21 ng.g-1 peso seco) e os maiores valores foram encontrados no emissário submarino, no Estuário de Santos, em locais próximos as indústrias, e no Estuário de São Vicente. De maneira geral, as concentrações tanto de PCBs quanto de pesticidas organoclorados em Santos e Cananéia-Iguape foram baixas. Santos apresentou maior incidência de PCBs, provavelmente devido à industrialização, enquanto que em Cananéia-Iguape predominaram os pesticidas organoclorados, que podem ser atribuídos às antigas campanhas de saúde pública ou aplicações nas lavouras. / Polychlorinated biphenyls and chlorinated pesticides are degradation resistant pollutants. They have been detected in several compartments of marine environment. The objective of this study was the optimization of the methodology and the evaluation of the contamination of chlorinated pesticides and PCBs em algae and coastal sediments in the Estuary and Bay of Santos-São Vicente and in the Lagunar Complex of Iguape and Cananéia (SP). An amount of 37 samples of superficial sediment, 3 cores with 27 subsamples and 10 samples of algae was collected in the period of 1998-2001. The methodology was considered satisfactory within international standards, that includes extraction and clean up with organic solvents and analysis with GC-ECD. In the Cananéia-Iguape region, DDTs were predominant and the highest levels were found around the city of Cananéia and in Trapandé Bay. In the Santos area, the PCBs were predominant and the highest values were found around the Santos Bay outfall and in the Estuary of Santos-São Vicente. In general, either the concentrations of PCBs or chlorinated pesticides in Santos and Cananéia-Iguape were low. Santos presented higher incidence of PCBs, probably due to industrialization, while in Cananéia-Iguape the chlorinated pesticides predominated, and that can be attributed to past public health campaigns or to agricultural uses.

This thesis is focused on studies on the environmental fate and methodological improvements for determination of the global contaminants, PCBs and DDTs, and locally discharged phenolics, e.g. 4,5,6-trichloroguaiacol (4,5,6-TCG), and their transformation products. 4,5,6-TCG is released from bleached pulp mills, and was chosen as a model substance, to study its fate and effects in aquatic environments. In a brackish water model ecosystem, 4,5,6-TCG was shown to be transformed via demethylation, dechlorination, and methylation reactions. Marine periphyton exposed to 4,5,6-TCG was shown to form demethylated, brominated and dimeric metabolites. Several of these metabolites were identified and quantified. Also more tightly bound chlorophenolics were recovered from the substrate, after harsh extraction procedures had been applied. Conjugates of chlorophenols in fish bile were determined as useful tracers for monitoring effluents from bleached pulp mills, even in areas far from the discharge point. To facilitate calculations of water concentrations, bile to water bioconcentration factors (bBCF-values) were determined for several phenolics, including also alkali-labile chlorocatechols. PCBs and DDTs, were assessed in Swedish lakes with background exposure of these global contaminants. A methodological study focus on the contamination risks of airborne PCBs, during freeze-drying and storage of dry sediment samples. Eutrophication has been proposed to cause lower levels of pollutants in biota in lakes due to biomass dilution but in this thesis examples of higher levels of PCBs in sediment traps, sediment and in perch, and also in higher fluxes of PCBs to the sediment, were observed. Phytoplankton are supposed to be responsible for most of the transport of the contaminants. The composition of DDTs in soil, sediment traps and in dated sediment cores was studied in some detail. PCBs, DDTs, HCB and HCHs were measured in sediments from 100 reference lakes included in the National Swedish Environmental Program. The lakes have a large variation in lake characteristics, representative for different areas in Sweden. A gradient was observed for sPCB with decreasing levels from the south west towards the north. The results suggests that longrange transport is the dominating mechanism for distribution of the contaminants analysed. In this study the levles of PCBs and DDTs were lower in eutrophic lakes than in oligotrophic lakes, in an area with similar atmospheric exposure. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Submitted. Paper 6: Manuscript.</p>