L’utilisation massive des antibiotiques, depuis les années 50, génère une libération importante de ces molécules dans l’environnement (excrétion via les urines et les fèces) que l’on peut retrouver à des concentrations allant de 1 à 100 ng/L dans les eaux usées urbaines. Parce qu’elle réunit microorganismes résistants et antibiotiques, la station d’épuration d’eaux usées urbaines pourrait être une zone propice au transfert des gènes de résistance. Cependant, avec sa position stratégique à l’interface entre les activités humaines et l’environnement, la station d’épuration pourrait constituer un « rempart » contribuant à limiter leur dissémination dans l’environnement.Les paramètres qui influencent ces transferts dans les stations d’épuration sont encore mal connus, en particulier du fait de limitations méthodologiques. Aussi l’objectif de notre travail était de déterminer les facteurs environnementaux influant sur la stabilité et le transfert d’un élément génétique mobile modèle, le plasmide pB10, dans des communautés bactériennes (biomasses de stations d’épuration et sédiments de rivière) maintenues en microcosmes. Jusqu’à présent, les transferts de gènes de résistance ont été principalement étudiés avec des méthodes reposant sur la culture de microorganismes sur milieux sélectifs, dont nous savons aujourd’hui qu’elles sous-estiment les phénomènes observés. Aussi, nous avons élaboré une approche basée sur la PCR quantitative pour détecter la dissémination d’un ADN mobile modèle amené via une bactérie hôte E. coli DH5α. Les couples amorces/sondes très spécifiques ont pu être élaborés en tirant profit de la structure mosaïque du génome bactérien. L’approche proposée repose sur des mesures comparées du nombre de plasmide pB10 et de son hôte bactérien DH5α au cours du temps, où une augmentation du rapport (pB10/DH5α) implique une dissémination du plasmide vers les bactéries indigènes. Outre l’intérêt du développement méthodologique proposé, cette méthode a permis d’évaluer l’incidence de quelques paramètres environnementaux sur la dissémination d’un ADN au sein de communautés microbiennes complexes. Deux groupes de facteurs ont pu être distingués selon qu’ils influencent la persistance du plasmide pB10 dans les communautés dans son hôte initial (oxygénation/brassage, ajout d’antibiotiques en concentrations sub-inhibitrices comme l’amoxicilline et le sulfaméthoxazole fréquemment retrouvés en station d’épuration) ou/et qu’ils favorisent sa dissémination dans les communautés bactériennes (biofilms, sédiments). Sans induire de transferts génétiques, les antibiotiques testés, même en concentrations sub-létales, pourraient participer à la dissémination de gènes de résistance en favorisant leur persistance / The widespread use of antibiotics since the 50s, generates a significant release of these molecules in the environment (excretion via urine and feces) which can be found at concentrations ranging from 1-100 ng/L in wastewater. Due to the high microbial biomass and the abundance of nutrients, wastewater treatment plants (WWTP) represent a suitable habitat for horizontal gene transfer. Because they occupy a key position between human activities and the environment, WWTP may play a major role in limiting the dissemination of antibiotic resistance genes, therefore contributing to the preservation The parameters which influence these transfers in wastewater treatment plants are still poorly known, especially because of methodological limitations. Therefore the aim of our study was to identify environmental factors affecting the stability and transfer of a mobile genetic element model, the plasmid pB10 in bacterial communities (biomass from wastewater treatment plants and river sediments) maintained in microcosms. So far, the transfer of resistance genes have been studied mainly with methods based on the cultivation of microorganisms on selective media that we know now they underestimate the observed phenomena. Also, an approach based on quantitative PCR was developed for detecting the release of a mobile DNA template from the host bacterium E. coli DH5α. Couples of designed primers/probes were very specific and have been developed by taking advantage of the mosaic structure of the bacterial genome. The proposed approach is based on the over time measurements of the number of plasmids pB10 and its bacterial host DH5α, where an increased ratio (pB10/DH5α) implies a release of the plasmid to the indigenous bacteria. This method was used to assess the impact of some environmental parameters on the release of DNA in complex microbial communities. Two groups of factors could be distinguished according to whether they influence the persistence of plasmid pB10 in communities in microcosms (oxygenation / mixing, addition of antibiotics at sub-inhibitory concentrations as amoxicillin and sulfamethoxazole frequently found in treatment plant) and / or they favor his release in bacterial communities (biofilms, sediments). Without inducing genes transfers, the antibiotics tested, even at sub-lethal concentrations, could participate in the dissemination of resistance genes by facilitating their persistence

This study examines foredune evolution along a 2100 m section of coast adjacent to the Tugela River. The foredunes vary in both height and shape along the study area and form the southern most extension of the Tugela foredune-ridge plain. Sand accumulation and erosion was measured at regular intervals over a 30 month period by tacheometric surveys. The foredunes and beaches are comprised of over 99 % sand. The sediment was predominantly composed of quartz and feldspar with subordinate lithic fragments. The quartz grains display conchoidal fractures and mechanical v-shaped pits and curved grooves. The beach and dune sand is well sorted and slightly negatively skewed with a mean grain size of 1.62 ф. The vegetation structure and floristic composition of the foredunes are explored. A range of factors influencing foredune morphology and evolution, including canopy density, height and distribution, wind velocity and a variety of ecological and environmental processes are examined. Ridge and swale morphology as well as alongshore variation in the dunefield could not be related to biological processes. The development of a foredune-ridge topography depends on a large sediment supply from the Tugela River over the long-term. Periods of high discharge introduce a fresh source of sediment to the littoral zone. Reworking of fluvial sediment landwards results in wide beaches. Onshore winds transport the sand from the beaches to the foredunes. Scaevola thunbergii encourages rapid vertical accretion and hummock dunes are formed. Lateral extensive invasion by seedlings may result in the hummock dunes joining to form coast parallel foredunes. Under periods of reduced sediment discharge erosion of the shoreline results in steep narrow beaches. Despite a negative beach budget foredunes continue to accrete vertically. Marine erosion results in either the complete destruction of embryo foredunes or their landward shift. Natural breaks in the dune crestline were attributed to changes in the delivery of sediment to the beaches. The processes operating in the study area conform to Psuty's (1988,1989) sediment budget model of foredune development. Sediment availability to the coastline produces characteristic morphologies. / Thesis (M.Sc.)-University of Natal, Durban, 1998.

This study involves the application of the ACRU Agrohydrological Model to a selected study catchment in the Lower Mgeni Catchment, and its discretized subcatchments, immediately downstream of the Inanda Dam. This study was initiated on the assumption that the Inanda Dam, which came into operation in 1989, would have significant impacts on the downstream (Lower Mgeni) hydrology, geomorphology and ecology. The overall aim of this study, to set up and run the ACRU model for the delimited study catchment, was successfully accomplished. This aspect of the study involved firstly, the setting up of an input database for each distributed catchment within the catchment; secondly, the processes and techniques used to translate data into hydrological information; and finally the "running" of the hydrological model, which in turn "drives" the system and simulates the catchment hydrology. Specific objectives of the study entailed the simulation of hydrology, which focussed on simulated runoff and streamflow; and sediment yield responses of the subcatchments and the total study catchment of the Lower Mgeni, with respect to gross volumes and sediment yield rates produced. The streamflow results reported indicated a season of "Iow" flow, with a monthly flowrate ranging from 1155m3s-1 to 2735m3s-1 , from April to September; and is identified and distinguished from the period of "high" flowrate, ranging from approximately 483m3s-1 to 1747m3s-1 , for the remaining months of the year. The mean annual volume for the delimited subcatchment is 22 278.5 million m3 , exceeding the annual volume required to maintain riverine and estuarine ecology, which according to DWAF (1990) is 18.5 million m3 . The simulated results of sediment yield indicate that Subcatchment 3 and 4 have the lowest sediment yield rates of 32.3 t km-2 a-1 and 32.6 t km-2 a-1 , respectively. Subcatchment 2 has the highest yield rate at the value of 617 t km-2 a-1 , while subcatchment 1 has a rate of 53.2 t km-2 a-1 . Annual sediment production in the Lower Mgeni subcatchment is 10 855.1 tons per annum with respect to gross mass, resulting in a sediment yield rate of 73.8 t km-2 a-1 . The outcomes of this study compare very favourably with other studies conducted on hydrology and sediment yield, especially those undertaken within this geographical area. It may be assumed therefore, that the results produced herein can be applied with confidence to enable appropriate planning and management of resources within this catchment. Modelling of hydrology in the Lower Mgeni is expected to contribute significantly towards meeting riverine and estuarine ecological and geomorphological streamflow requirements. It would facilitate the development of an appropriate management and dam release strategy of Inanda Dam, in order to meet these requirements. The modelling of sediment yield is expected to contribute to the development of a sustainable sandwinning policy and strategy for the Lower Mgeni, as current extraction rates exceed the annual sediment production. Once the model has been applied to a selected catchment, it has the ability to consider different scenarios, providing an invaluable tool for planning. Based on the results of this study, the ACRU model may be applied, with confidence, to other similar ungauged catchments. / Thesis (M.Sc.)-University of Natal, Durban, 2001.

Metals are naturally found in ecosystems but can also enter via human activity such as fossil fuel combustion, and disposal of metal products. Copper, lead, and iron have frequently been detected throughout Indiana freshwaters based on historical samples. Since microbial activity is a holistic measure of ecosystem function, changes in microbial activity in response to metals may indicate potential areas of concern. Metal concentrations in seven streams of the Upper White River watershed of central Indiana were measured during spring (May) and summer (August) in conjunction with measurement of sediment nitrification rates using the nitrapyrin-inhibition technique. Additionally, the influence of copper, lead, and iron on microbial nitrification was studied using in vitro mesocosms inoculated with stream sediment from selected sites. Copper, lead, and iron concentrations in stream sediment and water varied among sites with sediment concentrations ranging 654 – 1985 mg Fe/kg sediment and 1.00 - 2.91 mg Cu/kg sediment. Water concentrations ranged from below detection to 0.10 mg Fe /L, and 0.01 – 0.02 mg Cu/L. Lead concentrations were below detection at all sites except in May at one site (Pleasant Run Creek 0.47 mg Pb/kg sediment) and in August at one site (Mud Creek 0.38 mg Pb/ kg sediment). Stream sediment nitrification rates were positively correlated to stream sediment copper concentration (r = 0.78, p = 0.001). There was no significant correlation between sediment nitrification rates and stream sediment iron, pH, dissolved iron, or total dissolved solids (TDS; p > 0.05). Positive correlations were found between nitrification response rates and total Fe (r = 0.61, p = 0.02) and Cu (r = 0.74, p = 0.002) concentrations. Experimental mesocosms indicate metal addition of 127 mg/L may reduce stream sediment nitrification rates though stream physiochemical characteristics and history of metal exposure likely dictate microbial response. Further, metal concentrations in the stream sediment may have more of an influence on nitrifying microbes than dissolved metal in the water column. / Department of Biology

CAPES / Este estudo avaliou a qualidade das águas e dos sedimentos da sub-bacia do rio Barigüi, Região Metropolitana de Curitiba, em relação à presença, disponibilidade química e potencial tóxico de espécies químicas (Al, Fe, Ti, K, Ca, P, S, Zr, Mn, Zn, Sr, Cu, Nb, Y, Rb, Ni, Cr, Cd e Pb) majoritárias e traços. Sedimentos de bacias urbanas são matrizes ambientais complexas e multielementares, que se tornaram objeto de estudo de muitas pesquisas devido ao caráter ativo. Este compartimento intercambia espécies químicas com a coluna d’ água afetando sua qualidade, influenciando sua toxicidade e interferindo na biota aquática. As quatro campanhas de amostragem foram realizadas em três pontos de modo a cobrir regiões distintas da sub-bacia, sendo estas sujeitas a diversos impactos ambientais devido à urbanização e industrialização. Para a quantificação de espécies químicas nos sedimentos e na coluna d’água fez-se uso das técnicas instrumentais Espectrometria de Absorção Atômica com Atomizador Chama (FAAS) e Espectrometria de Fluorescência de Raios-X por Energia Dispersiva (EDXRF), segundo protocolos 3030B (APHA), 3050B (USEPA) e 200.2 (USEPA). Parâmetros acessórios tais como potencial redox, pH, amônia, fósforo total e ortofosfato, alcalinidade total e clorofila-a foram determinados nas amostras de águas. As amostras de água também foram caracterizadas por espectroscopia de absorção molecular e por espectroscopia de fluorescência molecular. Estabeleceu-se o estado de trofia das águas por meio do Índice de Estado Trófico IET e compararam-se os valores determinados com os valores regulamentadores da resolução 357 de 2005 do CONAMA. Os sedimentos passaram por análises térmicas (TGA/DSC), granulométricas, de umidade (%) e determinaram-se seus indicies geoquímicos de qualidade. Os resultados permitiram diferenciar as regiões estudadas, e observar que as amostras de águas e sedimentos sofrem influência da urbanização e industrialização como os principais responsáveis pelas cargas poluentes. Nesse sentido, o ponto amostral de Araucária encontra-se mais degradado em relação aos de Almirante Tamandaré e Santa Felicidade sobre a sub-bacia do rio Barigüi-PR, indicando a necessidade de ações de gestão ambiental sobre o sistema hídrico. / This study evaluated the water and sediment quality of the Barigui River sub-basin, Greater Curitiba, in terms of the presence, chemical availability, and toxic potential of common chemical species as well as trace elements. Urban basin sediments are complex multi-element environmental matrices and have become the subject of many studies because of their active character. These matrices interchange chemical species with the water column, which affects its quality, influences its toxicity, and interferes with aquatic life. Four sampling operations were completed at three different sites, subject to several environmental impacts due to urbanization and industrialization, in order to cover distinct regions of the sub-basin. For the quantification of chemical species in the sediments and water column, flame-atomizer atomic absorption spectroscopy (FAAS) and energy-dispersive X-ray fluorescence spectroscopy (EDXRF) techniques were used, according to protocol 3030B (APHA), 3050B (USEPA) and 200.2 (USEPA). Auxiliary parameters such as redox potential, pH, ammonia, total phosphorus and orthophosphate, total alkalinity, and chlorophyll a were determined for the water samples. The water samples were also characterized by molecular absorption spectroscopy and molecular fluorescence spectroscopy. The trophic state of the water was established using the trophic state index (TSI) and the determined values were compared with the regulatory values pertaining to CONAMA (2005) resolution 357. The sediments were subjected to thermal analysis (TGA/DSC), particle size and moisture content (%) estimation, and geochemical quality index determination. The results allowed us to differentiate between the studied regions and to conclude that the water and sediment samples are influenced by urbanization and industrialization, which are the main agents responsible for pollution. In this context, the Araucária sample was more degraded than those in Almirante Tamandaré and Santa Felicidade in the Barigui River sub-basin – PR, indicating the need for environmental management in this water system.

CAPES / Este estudo avaliou a qualidade das águas e dos sedimentos da sub-bacia do rio Barigüi, Região Metropolitana de Curitiba, em relação à presença, disponibilidade química e potencial tóxico de espécies químicas (Al, Fe, Ti, K, Ca, P, S, Zr, Mn, Zn, Sr, Cu, Nb, Y, Rb, Ni, Cr, Cd e Pb) majoritárias e traços. Sedimentos de bacias urbanas são matrizes ambientais complexas e multielementares, que se tornaram objeto de estudo de muitas pesquisas devido ao caráter ativo. Este compartimento intercambia espécies químicas com a coluna d’ água afetando sua qualidade, influenciando sua toxicidade e interferindo na biota aquática. As quatro campanhas de amostragem foram realizadas em três pontos de modo a cobrir regiões distintas da sub-bacia, sendo estas sujeitas a diversos impactos ambientais devido à urbanização e industrialização. Para a quantificação de espécies químicas nos sedimentos e na coluna d’água fez-se uso das técnicas instrumentais Espectrometria de Absorção Atômica com Atomizador Chama (FAAS) e Espectrometria de Fluorescência de Raios-X por Energia Dispersiva (EDXRF), segundo protocolos 3030B (APHA), 3050B (USEPA) e 200.2 (USEPA). Parâmetros acessórios tais como potencial redox, pH, amônia, fósforo total e ortofosfato, alcalinidade total e clorofila-a foram determinados nas amostras de águas. As amostras de água também foram caracterizadas por espectroscopia de absorção molecular e por espectroscopia de fluorescência molecular. Estabeleceu-se o estado de trofia das águas por meio do Índice de Estado Trófico IET e compararam-se os valores determinados com os valores regulamentadores da resolução 357 de 2005 do CONAMA. Os sedimentos passaram por análises térmicas (TGA/DSC), granulométricas, de umidade (%) e determinaram-se seus indicies geoquímicos de qualidade. Os resultados permitiram diferenciar as regiões estudadas, e observar que as amostras de águas e sedimentos sofrem influência da urbanização e industrialização como os principais responsáveis pelas cargas poluentes. Nesse sentido, o ponto amostral de Araucária encontra-se mais degradado em relação aos de Almirante Tamandaré e Santa Felicidade sobre a sub-bacia do rio Barigüi-PR, indicando a necessidade de ações de gestão ambiental sobre o sistema hídrico. / This study evaluated the water and sediment quality of the Barigui River sub-basin, Greater Curitiba, in terms of the presence, chemical availability, and toxic potential of common chemical species as well as trace elements. Urban basin sediments are complex multi-element environmental matrices and have become the subject of many studies because of their active character. These matrices interchange chemical species with the water column, which affects its quality, influences its toxicity, and interferes with aquatic life. Four sampling operations were completed at three different sites, subject to several environmental impacts due to urbanization and industrialization, in order to cover distinct regions of the sub-basin. For the quantification of chemical species in the sediments and water column, flame-atomizer atomic absorption spectroscopy (FAAS) and energy-dispersive X-ray fluorescence spectroscopy (EDXRF) techniques were used, according to protocol 3030B (APHA), 3050B (USEPA) and 200.2 (USEPA). Auxiliary parameters such as redox potential, pH, ammonia, total phosphorus and orthophosphate, total alkalinity, and chlorophyll a were determined for the water samples. The water samples were also characterized by molecular absorption spectroscopy and molecular fluorescence spectroscopy. The trophic state of the water was established using the trophic state index (TSI) and the determined values were compared with the regulatory values pertaining to CONAMA (2005) resolution 357. The sediments were subjected to thermal analysis (TGA/DSC), particle size and moisture content (%) estimation, and geochemical quality index determination. The results allowed us to differentiate between the studied regions and to conclude that the water and sediment samples are influenced by urbanization and industrialization, which are the main agents responsible for pollution. In this context, the Araucária sample was more degraded than those in Almirante Tamandaré and Santa Felicidade in the Barigui River sub-basin – PR, indicating the need for environmental management in this water system.

This work deals with the characteristics of platinum metals and problems related to their toxicity and mobility in the environment, especially in the aquatic environment. These metals are released into the environment due to the use of automotive catalysts. Their function is based on the catalytic properties of platinum metals. Because of the high temperatures, these metals can be oxidized in the catalyst and subsequently emitted together with the combustion products into the surrounding atmosphere. The aim of the thesis is to measure real samples of river sediments of the river Svratka on the territory of the city of Brno and to find the possibility of contamination of the aquatic environment with these metals.

Logging and associated skid trails, haul routes, and roads can have significant impacts on the magnitude and timing of sediments in streams in forested watersheds. Loss of vegetation, soil compaction, use of heavy logging equipment, and alteration of natural hydrologic patterns within the watershed can increase landslide rates, create erosion, and generate fine sediments. Selective logging, also called thinning, is a logging practice that leaves some trees within sale units unharvested. The ecological impacts of thinning on stream ecosystems are not fully understood and need further study. My hypothesis was that macroinvertebrate assemblages would be different in streams in non-reference areas that contain recent selective logging compared to streams in reference areas, and in downstream vs. upstream of selective logging units. I also hypothesized that selective logging and high road densities would be associated with increased instream fine sediments. I sampled water quality parameters and macroinvertebrates in three managed and three reference streams in the Clackamas River Basin during the field season of 2013. Turbidity, temperature, dissolved oxygen, conductivity, total dissolved solids (TDS), suspended sediment concentrations (SSC), and flow were sampled at each stream on four occasions during spring through early fall. Macroinvertebrates were sampled once in late summer or early fall. EPA rapid habitat assessments, canopy cover, pebble counts, embeddedness, and slope were also determined. Water quality parameters and macroinvertebrate indices in reference and non-reference sites were compared using t-tests, Welch's tests, or rank based equivalents. Macroinvertebrate assemblage patterns and associated environmental variables were characterized using non-metric multidimensional scaling (NMDS) ordination plots and envfit overlays. Macroinvertebrates had higher abundance and taxa richness in non-reference streams, and indices suggested poorer water quality in non-reference streams. Non-reference streams had a lower percentage of shredders and a higher portion of gatherer-collectors. Associations between land use, fine sediments, and changes in macroinvertebrate metrics and community assemblages were apparent at the reference vs. non-reference scale. It is likely that macroinvertebrates are responding, at least in part, to past logging and high road densities in non-reference streams. Fewer indications were found that recent logging may be affecting water quality and macroinvertebrates. Pearson's correlation coefficients show that the percent of recent logging upstream of study sites was correlated with several measures of fine sediments, suggesting that recent land use may be affecting sediment levels at the subwatershed scale. Stream temperatures increased from upstream to downstream in non-reference sites. Though no continual stream temperature data were collected in this study, the history of continuing temperature standard exceedances in the area suggest that further investigation of how selective logging may be affecting stream temperature and other water quality parameters in the Clackamas Basin is warranted. No other differences in water quality parameters were found from upstream to downstream, possibly because water quality was sufficiently protected, or because signals from land use impacts may be obscured by a several factors, including upstream confounding factors such as roads and past logging, and natural variability.

Thesis (S.M. in Civil and Environmental Engineering)--Joint Program in Applied Ocean Physics and Engineering (Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering; and the Woods Hole Oceanographic Institution), 1999. / Includes bibliographical references (leaves 54-57). / by Jonathan Dalrymple Woodruff. / S.M.in Civil and Environmental Engineering

Le but général de ce travail fut de quantifier la silice biogène (BSiO2) dans les sédiments du continuum de l'Escaut (estuaire – zone côtière), ainsi que son taux de recyclage - rétention. Le coefficient de diffusion moléculaire de la DSi a été déterminé pour différentes valeurs de température et deux salinités et une relation empirique reliant le coefficient de diffusion à la température et à la viscosité de la solution a été établie. La distribution longitudinale de la BSiO2 dans les sédiments de surface, ainsi que les profils verticaux de BSiO2 et de silice dissoute ont été déterminés durant différentes saisons en 2004 et 2005. Les flux de DSi ont été également estimés via des expériences d’incubations et par modélisation des profiles verticaux de DSi. Des expériences de dissolution des sédiments ont permis de déterminer (via modélisation) les constantes cinétiques de vitesse de la BSiO2 et une première évaluation du taux de recyclage de la BSiO2 (5 – 70%). Sur base des calculs à partir des profiles de DSi dans l’eau interstitielle, le taux de recyclage de la BSiO2 varie entre 8 et 92% dans l’estuaire, ce qui correspond à une rétention moyenne de la BSiO2 supérieure à 60%, et souligne ainsi l'efficacité du filtre estuarien par rapport à la silice. En revanche, le recyclage de BSiO2 dans la zone côtière apparaît comme très intensif, avec des valeurs souvent supérieures à 40%. Ces résultats montrent l'importance d'inclure les estuaires dans le calcul des budgets globaux de Si. / The general objective of this study was to quantify the BSiO2 in the sediments of the Scheldt continuum, together with its recycling and retention in this area. First an empirical relation linking the diffusion coefficient of DSi to temperature and salinity was determined, via diffusion experiments. The longitudinal BSiO2 distribution in surface sediments and the vertical BSiO2 and DSi profiles in sediment cores where then measured during 2 years and different seasons, together with other parameters characterizing pore waters, such as alkalinity, pH, sulphate… DSi fluxes were also estimated either directly through whole core incubations measurements or via modelling of interstitial water profiles. BSiO2 dissolution experiments allowed the evaluation of the kinetic rate constants also through modelling of the results, and gave preliminary information over the BSiO2 recycling rates (5 – 70%). The recycling rate as obtained from pore water profiles vary between 8 and 92%, with an average value of about 32%, which highlights the importance of the estuarine filter for silica. Recycling is much more intense in the coastal area, with values up to 40%, which we explain by higher salinity and higher sediment permeability. The different experiments and results also indicated that secondary mineral precipitation might be and important process affecting BSiO2 in the Scheldt sediments.<p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished