Dissertations / Theses on the topic 'Sediments'

The study examines sediments of the Productive Series from the western South Caspian Basin. The main goal of this work is to reconstract provenance of the sediments and its relation to the climatic variability during the deposition of the Productive Series. The Productive Series is divided into a lower and upper division. The Russian Platform was the main sediment source area for the Lower Division. Three different sediment source areas were determined for the Upper Division: the Russian Platform was sediment source area for the Absheron Peninsula; the Greater Caucasus was the main sediment source area for the South Absheron Offshore Zone and the Lesser Caucasus was the main sediment source area for the Baku Archipelago. The sediments of the Lower Division have variable smectite and illite concentrations which indicate climate change between humid and arid conditions in the Russian Platform. The Upper Division of the Productive Series from the Absheron Peninsula is characterised by high amounts of illite. It suggests physical weathering under arid climatic condition on the Russian Platform at the time of deposition. Variation of the smectite and illite assemblages of the Upper Division from the South Absheron Offshore Zone probably indicate that the climate alternated between humid and arid conditions in the Greater Caucasus. The low amount of the TOC ratios in the Productive Series are associated with arid climatic condition in the Russian Platform and the Greater Caucasus. The much higher TOC/TN ratios (>35) indicate that sediments of the Productive Series were impacted by oil. However the low TOC/TN ratios (<12) in some intervals of the Productive Series suggest an aquatic source for an organic matter.

Os sedimentos marinhos são receptores finais de vários compostos da coluna de água, possuindo uma participação ativa nos ciclos biogeoquímicos. Comunidades microbianas possuem um papel crucial nestes ciclos, sendo responsáveis por grande parte da remineralização da matéria orgânica em sedimentos superficiais. Foram realizados dois experimentos com simulações de processos oceanográficos em microcosmos: Enriquecimento Orgânico, testando a diferença entre a chegada de fitoflagelados e diatomáceas no sedimento e Ressuspensão, simulando a passagem de frente fria. Foram analisados os compostos referentes à qualidade e quantidade da matéria orgânica sedimentar, assim como o fluxo de nutrientes da interface água-sedimento. No Experimento Enriquecimento, as diferentes algas causaram respostas distintas nos processos de degradação da matéria orgânica, aumentando a qualidade e o metabolismo das comunidades presentes, além de modificar os fluxos de nutrientes, sendo notada uma resposta mais rápida nos mecanismos de degradação devido à adição do fitoflagelados. No Experimento Ressuspensão, o distúrbio físico ocasionou uma resposta imediata e significativa na liberação dos nutrientes do sedimento para a interface água-sedimento e alterações nas concentrações de ácidos graxos, principalmente nos dois primeiros dias após a simulação. Logo, os diferentes eventos oceanográficos simulados comprovaram sua influência frente aos processos biogeoquímicos, principalmente na disponibilidade de ácidos graxos e na liberação de nutrientes para a água sobrejacente
Marine sediments are the final receivers of many organic compounds from the water column, playing an important role in biogeochemical cycles. Microbial communities are important to these cycles as they remineralize organic matter within surface sediments. Microcosm experiments were conducted to simulate two important oceanographic processes: Organic Enrichment, to test differences between sinking patterns of phytoflagellates and diatoms and Resuspension, simulating the passage of a cold front. The quality and amount of the organic matter was assessed, as well as the nutrient flow between the sediment-water interface. In the Enrichment Experiment, distinctive responses in the degradation processes were noted between treatments where the addition of phytoflagellates increased the quality of the organic matter, caused faster metabolism communities present in the sediment, and modify the patterns of nutrient flux rates. In the Resuspension Experiment, the physical disturbance caused an immediate and significant release of nutrients from the sediment to the sediment-water interface and changed the in the concentrations of fatty acid content most notably during two days after the resuspension event. Thus, the different simulated oceanographic events influenced biogeochemical processes, particularly in the availability of fatty acids and the release of nutrients to the overlying water

Bottom water hypoxia and its influence on the environment have been topics of increasing concern for many coastal regions. This research addresses both spatial and temporal variability in sediment biogeochemistry at the southeastern region of Corpus Christi Bay, TX, where seasonal (summer) hypoxia occurs. Traditional techniques for determination of a variety of dissolved and solid components, benthic oxygen demand, and sulfate reduction rates were augmented by measurements using solid state microelectrodes to simultaneously determine concentrations of dissolved O2, Mn2+, Fe2+, and [sigma]H2S in multiple small - interval (1 mm) depth profiles of sediment microcosms. Oxygen concentrations in the overlying water were manipulated in the sediment microcosms and electrode depth profile measurements were made over ~ 500 hours of experimentation. Laboratory and field microelectrode results were in good agreement for both norm - oxic and anoxic time periods. Results indicated that iron (Fe2+) and sulfide ([sigma]H2S) were the redox reactive species in these sediments. During hypoxic conditions an upward migration of dissolved Fe2+and [sigma]H2S through the sediment column and, at times, into the overlying water was observed as the dissolved oxygen concentrations decreased. A corresponding decline in the vertical extent of these redox species occurred when the overlying water was re-oxidized. When both dissolved iron and sulfide coexisted, FeS minerals were formed in the sediment, preventing sulfide diffusion into the overlying water. However, after a long duration of hypoxia (> 200 hours) this buffering capacity was exceeded and both iron and sulfide penetrated into the overlying waters. Results indicated that iron may have a greater influence on hypoxia than sulfide because its concentration in the overlying waters during induced hypoxia was an order of magnitude greater than those of sulfide. Moreover, in the southeastern region of the Bay, where mixing was minimal and the water column was shallow, the sediments alone may have caused the onset of the hypoxic event in a relatively short time period (< 5.5 days). These results demonstrated that in shallow marine environments where seasonal hypoxia occurs, such as Corpus Christi Bay, the associated major changes that take place in the sediment biogeochemistry must be included in benthic - pelagic models for overlying water hypoxia.

Experimentos em mesocosmos, por se tratarem de estudos in-situ, possibilitam extrapolar para o campo, investigações realizadas em menor escala, com maior seguridade. Em fevereiro de 2002, foram instalados às margens da represa do Lobo (22º15\'S e 47º49\'W) nove mesocosmos, construídos com plástico (PVC) em forma de hexágono com 2 metros de altura, com fundo aberto em contato com o sedimento e volume variando entre 4,5 e 5,1 m3, em função da declividade do terreno. De acordo com a resolução 20/86 do Conselho Nacional do Meio Ambiente, as concentrações máximas permitidas para os metais cobre (0,02 mg/L) e cromo (0,5 mg/L) em corpos d\'água Classe 2 foram adicionadas aos mesocosmos, originando-se triplicatas, adotando-se outros três mesocosmos como controles. O objetivo principal deste trabalho foi verificar as possíveis alterações no ambiente sedimento, particularmente o enriquecimento e a indução de toxicidade, em função da adição dos metais mencionados. Para tanto, amostras foram coletadas através de dragas e testemunhos nos tempos 0 dia (antes da contaminação), 10 dias, 20 dias e 30 dias após a contaminação (final do experimento). Em seguida, as amostras foram preparadas e submetidas às análises físicas e químicas, caracterização da macrofauna bentônica e diversos ensaios toxicológicos. A partir dos dados gerados, efetuou-se o estudo integrativo da tríade de qualidade de sedimentos. Os resultados obtidos mostraram um discreto aumento na concentração total dos metais cobre e cromo nos sedimentos dos mesocosmos contaminados em comparação aos controles, sendo verificada diminuição na abundância de organismos bentônicos e efeitos tóxicos sobre os organismos-teste submetidos a estes sedimentos. As respostas da tríade foram essenciais para a caracterização da qualidade dos sedimentos dos mesocosmos controle em relação aos dos mesocosmos contaminados.
In-situ mesocosms experiments allow the extrapolation of laboratory data to the field with high reliability. In the present study, nine hexagonal PVC mesocosms with 2 m height and 4.5 to 5.1 m3 volume were installed in contact with the sediment near the Lobo reservoir dam (22º15\'S e 47º49\'W) in february of 2002. In accordance with the National Environmental Council (CONAMA) 20/86 resolution for Class 2 water bodies, the maximum allowed concentrations of copper (0,02 mg/L) and chromium (0,5 mg/L) were added to the mesocosms (triplicate), and three other ones were used as controls. The main purpose of this study was to evaluate the possible changes in the sediment environment, particularly the enrichment and induction of toxicity, by the contamination of these metals. The sediment was sampled by means of Eckman-Birge and core samplers on the 0 (before the contamination), 10th, 20th and 30th days (end of the experiment). Afterwards, physical and chemical analyses, benthic macrofauna characterization and several toxicity assays were conducted with the samples. In order to better evaluate these results, the sediments quality triad was considered. A discrete increase in the total concentration of copper and chromium was observed in the sediments of the contaminated mesocosms when compared to the controls, as well as a reduction in the abundance of benthic organisms and toxic effects over the organisms tested with these sediments. The triad responses were essential for quality characterization of the control mesocosms sediments in comparison with the contaminated ones.

This volume comprises ninety-one contributions to the Sediment 2011 conference of the Central European section of the Society for Sedimentary Geology (SEPM-CES) and the Geologische Vereinigung (GV) at the University of Leipzig held in June 2011. The central theme of this meeting was “Sediments: Archives of the Earth System” in order to bring together young and established researchers from all fields of soft-rock geology and beyond to shape a stimulating interdisciplinary program on the role of sediments in understanding the System Earth and the evolution of paleoenvironments and climate through time.

Several sediment characteristics were analyzed to determine their suitability for use as potential normalization factors for the bioavailability of neutral organic compounds sorbed to sediments. Percent organic carbon, cation exchange capacity and particle surface area were measured sediment characteristics that varied sufficiently to encompass the range in observed sediment toxicity. Laboratory sediment toxicity test data using fluoranthene suggest that there is no biologically significant correlation between sediment toxicity and sediment characteristics (organic carbon, cation exchange capacity, particle size distribution, particle surface area). Fluoranthene amended sediments with similar organic carbon contents do not yield similar toxicities due to sorbed fluoranthene and thus do not support the organic carbon normalization approach for evaluating sediment quality or for sediment criteria development.

Aquesta tesi estudia la dinàmica hidro-sedimentària de rius mediterranis, tant ‘naturals’ com regulats per preses. Amb aquest objectiu, s’ha realizat un estudi a escala multi-temporal i multi-espacial, que inclou treball de camp en trams de riu representatius, l’anàlisi de dades a nivell de conca, i experiments en canals de laboratori. L’alteració hidrològica aigües avall dels embassaments s’ha observat a diferents escales temporals, afectant notablement la magnitud i freqüència de les crescudes. A nivell sedimentari, s’observa un dèficit de sediments, fet que facilita l’establiment de biofilm i que, a la vegada, afavoreix l’estabilització del llit del riu. A més, l’emmagatzematge temporal de sediments a la llera modula el balanç i regula l’entrada de sediments en embassaments. La tesi mostra els efectes d’un conjunt d’activitats antròpiques en procesos fluvials i com això altera les interaccions bio-físiques del riu, i posa èmfasi en la necessitat d’una gestió contínua per la preservació dels ecosistemes fluvials.
Esta tesis estudia la dinámica hidro-sedimentaria de ríos mediterráneos, tanto ‘naturales’ como regulados por presas. Con este objetivo, se ha realizado un estudio a escala multi-temporal y multi-espacial, que incluye trabajo de campo en tramos de río representativos, análisis de datos a nivel de cuenca, y experimentos en canales de laboratorio. La alteración hidrológica aguas abajo de los embalses se ha observado a diferentes escalas temporales, afectando notablemente la magnitud y frecuencia de las crecidas. A nivel sedimentario, se observa un déficit de sedimentos, lo que facilita el establecimiento de biofilm y, a la vez, favorece la estabilización del lecho del río. Además, el almacenamiento temporal de sedimentos en el lecho modula el balance y regula la entrada de sedimentos en embalses. La tesis muestra los efectos de un conjunto de actividades antrópicas en procesos fluviales y en la alteración en las interacciones bio-físicas del río, y enfatiza la necesidad de una gestión continua para la preservación de los ecosistemas fluviales.
This PhD thesis studies hydro-sedimentary dynamics in Mediterranean rivers, both in ‘natural’ and in dammed rivers. For this purpose, a multi-temporal and spatial research was carried out, including field measurements in representative river reaches, data analysis at the basin scale, and experiments in artificial streams. The hydrological alteration downstream from dams was documented at different temporal scales, notably affecting the magnitude and frequency of floods. Regarding sediments, a severe deficit was observed below dams, a fact that facilitates the establishment of biofilm which, in turn, favours river bed stabilisation. Moreover, the study shows how in-channel storage influences the river sediment budget and regulates sediment input in reservoirs. The thesis examines the effects of a suit of human activities on fluvial processes and how this alter rivers’ bio-physical interactions, and emphasises the need of continuous monitoring of all these processes to achieve a sound management of fluvial ecosystems.

A erosão do solo tem sido extensamente estudada dentro do ponto de vista agrícola, pois está relacionada a sérias perdas em termos de produtividade das mais variadas culturas e conseqüentemente, é causa de prejuízos econômicos. Recentemente tem-se dado atenção especial aos problemas ambientais relacionados à erosão, transporte e deposição de sedimentos, já que são, provavelmente, os mais significativos de todos os poluentes em termos de sua concentração na água e dos seus impactos e efeitos no transporte de substâncias químicas, entre elas o nitrogênio aplicado na forma de fertilizantes. O foco central do presente trabalho foi a investigação dos padrões de transporte de sedimentos por erosão hídrica e suas influências na transferência de nitrogênio aos cursos d\'água. A fonte de nitrogênio avaliada foi o sulfato de amônio aplicado superficialmente como fertilizante em um latossolo vermelho amarelo, em diferentes preparos do solo, sem cobertura vegetal e sob chuva simulada em diferentes intensidades. Os resultados permitiram identificar a fração argilosa dos sedimentos erodidos transportados em suspensão na água da enxurrada como a principal via de transporte/transferência de nitrogênio proveniente do fertilizante. Este processo de transferência deu-se mais intensamente nas primeiras chuvas. Constatou-se que os valores de perdas de solo e água não influenciam a capacidade de transporte de nitrogênio entre a área de cultivo e os cursos d\'água. O preparo do solo influenciou as concentrações de nitrogênio transportadas pela enxurrada. As concentrações de nitrogênio nos sedimentos são altas mesmo com baixo volume e intensidade de chuva.
Soil erosion has been extensively studied from the agricultural point of view, because it is related with serious damages in terms of a huge variety of plantations productivity and its consequent economic detriments. Currently, special attention is given to the environmental problems caused by erosion processes and the transport and deposition of the sediments, since they are, probably, the most significant pollutants in terms of its concentration in the water and its impacts and effects in the chemical substances transport, such as nitrogen which is applied in the form of fertilizer. The central focus of the present work was the research of the standards sediment transport origined by the water erosion and their influences in the transference of nitrogen to the water bodies. The evaluated nitrogen source was the ammonium sulphate applied superficially as a fertilizer in a latossolo vermelho amarelo soil, under different soil tillage systems, without vegetal covering and under different intensities of simulated rain. The results allowed to identified that the argillaceous fraction of the eroded sediments carried in the runoff suspension was the main way of the nitrogen transport/transference derived from the fertilizer. This transference process was more intensely observed in the first rains. It was evidenced too, that the losses values of soil and water did not influence the nitrogen transport capacity between the planted areas and the water bodies. Aditionally, soil tillage influenced in nitrogen concentrations carried by the runoff. The nitrogen concentrations in the sediments were high, in spite of the low volumes and low intensities of the rain.

Thesis (M.S.)--University of Nevada, Reno, 20007.
"December 2007." Includes bibliographical references (leaves 122-124). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2008]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.

Detailed knowledge from physical properties of sediment such as erosion and settling velocity are crucial for modelling as well as for water protection planning and management. The main purpose of this research was to determine the critical shear stress (τcr) and settling velocity of the organic sediments in different peatland drainage areas and headwaters in Finland. Further, KINEROS2 erosion model was applied to peatland forestry and peat extraction conditions to simulate runoff hydrograph and suspended solid yield from two experimental catchments. To determine mean τcr and settling velocity totally 119 undisturbed sediment samples were taken from the natural streams, ditches and brooks across Finland. The samples covered main peatland uses, peatland forestry and peat extraction sites. Furthermore, to determine the effect of peat soil properties on sediment erosion and settling, peat soil samples were collected from 9 peat extraction areas. These samples were used to prepare sediments in laboratory setting. Cohesive strength meter (CSM) was applied to measure the τcr and settling velocity in laboratory and in-situ conditions. Results were compared against physical properties of sediment or peat soils and further compared against different peatland uses. The critical shear stress over all samples ranged from 0.0057 to 0.428 N m⁻² (mean value 0.116 ± 0.07 N m⁻²). τcr in peatland forestry ditches ranged from 0.0057 to 0.428 N m⁻² (mean value 0.07 ± 0.1 N m⁻²), and in peat extraction sites from 0.006 to 0.421 N m⁻² (mean value 0.12 ± 0.06 N m⁻²). Similarly, τcr of artificially prepared samples from peat extraction area ranged from 0.012 to 0.112 N m⁻² (mean value of 0.059 ± 0.028 N m⁻²). At Koivupuro peatland forestry site, measurements were done in laboratory as well as in-situ. Results gave slightly different values; in-situ τcr ranged from 0.005 to 0.305 N m⁻² with the mean value of 0.03 ± 0.075 N m⁻², and the laboratory results ranged from 0.008 to 0.310 N m⁻² with the mean value of 0.125 ± 0.06 N m⁻². Degree of humification (DOH) and dry bulk density were found to be positively related to critical shear stress. The settling velocity results for Koivupuro catchment ranged from 0.0004 to 0.131 m h⁻¹ (mean value 0.016 ± 0.034 m h⁻¹) and 0.0004 to 0.456 m h⁻¹ (mean value 0.144 ± 0.134 m h⁻¹) for other organic peat samples. Degree of humification (DOH) and settling velocity showed no correlation while dry density of settled sediment was found inversely proportional to settling velocity. This study showed that CSM can be used to determine τcr and settling velocity from organic sediment samples. Results can be applied in modelling purposes, and in dimensioning of water protection methods such as settling basins. Eleven rainfall-runoff events from two different catchments were selected for the study to simulate runoff hydrographs and associated sediment yields in different conditions. When properly calibrated for each event, KINEROS2 model produced sufficient estimations of runoff hydrographs for peatland forestry and peat extraction sites but failed to produce reliable estimations of suspended sediment yields. Moreover, unrealistic parameter values sometimes had to be used in model calibration due to model inability to simulate groundwater or soil water response in ditch flow. Thus the model could not be validated for varying initial conditions and rainfall events.

Thesis (M. S.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008.
Committee Co-Chair: Joseph B. Hughes; Committee Co-Chair: Kurt D. Pennell; Committee Member: Danny D. Reible; Committee Member: Frank E. Loeffler; Committee Member: Jim C. Spain; Committee Member: Martial Taillefert; Committee Member: Terry W. Sturm.

O conhecimento dos processos que envolvem o transporte, deposição e suspensão de sedimentos em rios é de vital importância na conservação, desenvolvimento e utilização dos recursos hídricos e do meio ambiente. Entretanto, no Brasil, que possui como base energética a hidroeletricidade, não se tem dado a devida atenção no que se refere à sedimentação em virtude da dificuldade na aquisição desses dados e custos envolvidos. Sendo assim esta pesquisa teve como objetivo definir as necessidades relativas à precisão, facilidade, custo e freqüência de aquisição dos dados referentes ao aporte de sedimentos em rios, identificando as tecnologias atuais e as tecnologias promissoras que estarão disponíveis em curto prazo para satisfazer essas necessidades.
The knowledge of the processes involving the transport, deposition and suspension of sediment in rivers is of vital importance in the conservation, development and utilization of water resources and the environment. Meanwhile, in Brazil, which has based the hydropower energy, has not given proper consideration with regard to sedimentation due to the difficulty in acquiring such data and costs involved. So this research aimed to define the needs on the accuracy, ease, cost and frequency of data acquisition for the supply of sediment in rivers, identifying current technologies and promising technologies that will be available on short notice to meet those needs.

The profundal sediment of many lakes is contaminated by heavy metals and persistent organic pollutants (POPs) deposited from the atmosphere, yet there has been little assessment of the biological effects of these toxicants. A Tier I sediment ecological risk assessment of profundal lake sediment that covers the range of contamination in the UK and Ireland was completed. Three laboratory sediment bioassays were used, Daphnia magna 7-day survival and reproduction, Gammarus pulex 14-day survival and growth and Chironomus riparius 10-day survival and growth/reproduction, and the concentrations of seven heavy metals and four groups of POPs (polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, organochlorine pesticides and polybrominated diphenyl ethers) were determined.

Mineral dissolution is an inherent chemo-hydro-mechanical coupled diagenetic process in sediments. This ubiquitous geological phenomenon affects all properties in sediments, however, its engineering impact remains largely unknown. This research centers on the effects of mineral dissolution on sediment behavior with emphasis on dissolution modes in nature and their engineering implications. Five different dissolution modes are identified: homogeneous, pressure-dependent, and localized dissolution, and the dissolution of shallow and deep dissolvable inclusions. The consequences of each dissolution mode are investigated through experiments and discrete element methods. While each dissolution mode triggers unique consequences, it is observed that in all cases 1) significant displacement takes places during dissolution, 2) there is a pronounced effect of internal friction and the extent of dissolution on the evolution of the sediment, 3) the sediment has higher compressibility and exhibits a more contractive tendency after dissolution, 4) a porous honeycomb-shaped internal fabric develops accompanied by contact force concentration along dissolved inclusions, and 5) horizontal stress reduction takes place during dissolution and shear localization may develop under zero lateral strain conditions. Mineral dissolution has important engineering implications, from soil characterization to slope stability and shallow foundations. Pre- and post-dissolution CPT studies show that dissolution decreases the tip resistance proportional to the extent of dissolution. Dissolution in sloping ground induces global settlement as the prevailing deformation pattern, and prominent lateral movements near the slope surface; sudden undrained shear failure may take place during otherwise quasi-static dissolution. While footings experience larger settlements during post-dissolution loading, subsequent dissolution beneath a previously loaded footing causes displacements that are greater than the sum of dissolution-induced and load-induced settlements.

Polystyrene latices of particle diameter 0.97 ~, 1.41 ~ and 1.92 ~, at an electrolyte concentration of 0.5 mol dm- 3 sodium chloride, were' sterically stabilised by the adsorption of a monolayer of a monodisperse nonionic surface active agent, C12E6• Optical microscopy showed that the resultant systems were weakly flocculated, with only slight agitation required to destroy the flocs. Calculations showed that the van der Waals attractive potential dominated the highly screened electrostatic repulsive potential; the particles were prevented from coagulating into the primary minimum through the presence of the steric barrier. Potential energy well depths of 7 - 15 kT were obtained. Rapid sedimentation of the systems occurred by consolidation of r..he aggregated structure after an induction period which increased with increasing volume fraction to give a final sediment volume fraction of approximately 0.4 - 0.45. Constant stress viscometry demonstrated that the suspensions were shear thinning with a limiting Newtonian viscosity at low stresses. At high stresses the viscosity was similar to that expected for a dispp.rsion of hard spheres as calculated from Krieger's equation~2 Shear wave propagation experiments were performed to measure the high frequency limit of the shear modulus as a function of volume fraction. The values obtained were compared with a theoretical model due to Zwanzig and Mountain79 and based on a statistical mechanical description of the microstructure combined with the pair interaction potential of the particles. Parameters required for the model were the suspension volume fraction, the Stern potential, the Hamaker constant and the extent of the adsorbed layer, all of which were determined independently of the rheological measurements. Good agreement was obtained between theoretical and experimental data when using a Barker Henderson perturbed hard sphere potential model to calculate the pair distributionfunction. The model thus provided a strong test of the use of liquid state theory for the prediction of the transport properties of colloidal suspensions. Predictions of the zero shear viscosity were made using a similar model.

The leakages of metals from acid sulfate soils and their potential toxicity to benthic invertebrates were studied in the sediment profiles of Lillkvasjön and Lövselefjärden - a lake and an estuary known to be affected by acid sulfate soils - in Västerbotten, northern Sweden. The concentrations of 25 different elements were analyzed throughout both sediment profiles through X-Ray Fluorescence (XRF) Spectrometer analysis. Organic matter was measured through loss-on-ignition (LOI). By performing correlation analysis and normalizations to LOI on all sediment variables, Cu, Fe, Ni, Pb, S and Zn were found to be leached from acid sulfate soils to both sites, while Mg and Mn were related to leakages from acid sulfate soils in Lövselefjärden. The concentrations of Cu (195 mg kg-1), Ni (55 mg kg-1), Pb (90 mg kg-1) and Zn (398 mg kg-1) in the surface sediment of Lövselefjärden were classified as potentially toxic to benthic invertebrates. In Lillkvasjön, Cu (210 mg kg-1) and Ni (87 mg kg-1) were classified to have an increased risk of negative impacts on benthic invertebrates, while the concentrations of Pb (121 mg kg-1) and Zn (329 mg kg-1) were likely to low to have any negative effects. These results strengthen previous finds of impacts from acid sulfate soils in the two catchment areas and elucidate the importance of further studies on the impact of acid sulfate soils on benthic invertebrates.

The main objective of this thesis is to investigate the impact of microbial extracellular polymeric substances (EPS) on sediment stability and the related factors which influence “biogenic stabilisation” as a basis to the prediction of sediment erosion and transport. The ability to make direct and sensitive measurements of the physical properties of the biofilm is a critical demand to further understanding of the overall biostabilisation processes. Therefore, attention has been focused on developing a new technique, Magnetic Particle Induction (MagPI) for measuring the adhesive properties of the biofilm. MagPI determines the relative adhesive properties or “stickiness” of the test surface, whether a biofilm, a sediment or other submerged material. The technique may have future applications in physical, environmental and biomedical research. Newly developed Magnetic Particle Induction(MagPI) and traditional techniques Cohesive Strength Meter (CSM) for the determination of the adhesion/cohesion of the substratum were used to assess the biostabilisation capacity of aquatic microorganisms. Whilst these devices determine slightly different surface properties of the bed, they were found to complement each other, increasing the range of measurements that could be made and presented a strong correlation in the overlapping portion of the data. It is recognized that microorganisms inhabiting natural sediments significantly mediate the erosive response of the bed (“ecosystem engineers”) through the secretion of naturally adhesive organic material (EPS: extracellular polymeric substances). Interactions between main biofilm consortia microalgae, cyanobacteria and bacteria in terms of their individual contribution to the EPS pool and their relative functional contribution to substratum stabilisation were investigated. The overall stabilisation potential of the various assemblages was impressive, as compared to controls. The substratum stabilisation by estuarine microbial assemblages was due to the secreted EPS matrix, and both EPS quality (carbohydrates and proteins) and quantity (concentration) were important in determining stabilisation. Stabilisation was significantly higher for the bacterial assemblages than for axenic microalgal assemblages. The peak of engineering effect was significantly greater in the mixed assemblage as compared to the bacterial and axenic diatom culture. This work confirmed the important role of heterotrophic bacteria in “biostabilisation” and highlighted the interactions between autotrophic and heterotrophic biofilm components of the consortia. An additional approach, to investigate the impact of toxins on biostabilisation capacity of aquatic organism was performed on cultured bacterial and natural freshwater biofilm. The data suggest a different mode of triclosan (TCS) action ranging from suppressing metabolisms to bactericidal effects depending on the TCS concentration. The inhibitory effect of triclosanon bacterial and freshwater biofilms was confirmed. This information contributes to the conceptual understanding of the microbial sediment engineering that represents an important ecosystem function and service in aquatic habitats.

Over the last decades, fast urban sprawl and accelerated land use change have drastically increased the pressure on water resources of the capital Brasília and its surrounding area. The water supply of the metropolitan region of Brasília depends largely on surface water collected in reservoirs. There are increasing concerns regarding water shortages due to sediment aggradations, and of water quality due to geochemical modification of sediments from human activities. The complexity of various socio-environmental problems, such as non-point source pollution, soil erosion or silting of water reservoirs within urban catchments evoked the need for more effective and sustainable strategies to use land and water resources. Accurate identification and management of sediment source areas, however, is hampered by the lack of reliable information on the primary sources of sediment and on sediment geochemistry. The fingerprinting approach and a multivariate mixing model have been proven to be a valuable sediment source tracing technique across the globe and for various environmental settings. A multi-component methodology, including geochemical and geophysical analyses of representative sediment source and alluvial sediment samples, statistical analyses and a multivariate mixing model, was utilized to obtain the impact of different anthropogenic activities on sediment and water quality and to identify the major sources of sediments within the Lago Paranoá catchment. However, sediment source appointment and geochemical signatures of sediments in urbanized tropical regions, such as the Lago Paranoá catchment in the DF, are hampered by severe challenges; (i) the presence of various types of land use and heavy urbanized areas, (ii) large differences between sub-catchments and (iii) model structural failures in representing the sediment source contribution within urban tropical river basins. The present cumulative thesis addresses the challenges in geochemical analyses of different types of source and alluvial sediments, and in sediment source appointment for the Lago Paranoá catchment and it´s five sub-catchments. The aim of the study was to assess the distribution of chemical elements and geochemical/physical properties of potential sediment sources in the Lago Paranoá catchment. Principal component analysis and hierarchical cluster analysis were used to investigate the influence of different land use types on the geochemistry of sediments. Geochemical fingerprints of anthropogenic activities were developed based on the results of the cluster analysis grouping. The anthropogenic input of land use specific geochemical elements was examined and quantified by the calculation of enrichment factors using the local geological background as reference. The existing findings suggest a strong relationship between land use and quantifiable features of sediment geochemistry, and identified the combined effects of specific anthropogenic activities and metal enrichment in source and alluvial sediments. Through comparison of the geochemical signature of potential sediment sources and alluvial sediments of the Lago Paranoá and sub-catchments, the relative contribution of land use specific sediment sources to the sediment deposition of the main water reservoir were estimated. This assessment indicated that urban land use had the greatest responsibility for recent silting in the Lago Paranoá. In fact, one of the most challenging issues within the scope of IWRM is to quantify the contribution of sediment sources within fast urbanizing, mixed used, tropical catchments. Therefore, statistically verified composite fingerprints and a modified multivariate mixing model have been used to identify the main land use specific sources of sediment deposited in the silting zones of the Lago Paranoá, Central Brazil. Because of the great variability of urban land use types within the Lago Paranoá sub-catchments, the fingerprinting approach was additionally undertaking for the Riacho Fundo sub-catchment. This sediment source tracing technique provides valuable information on the response of the main sediment sources in a fast growing agglomeration with respect to specific land uses and human activities and allowed to examine the uncertainty in model prediction. The main contributions from individual source types (i.e. surface materials from residential areas, constructions sites, road deposited sediment, cultivated areas, pasture, farm tracks, woodland and natural gullies) varied between the whole catchment and the Riacho Fundo sub-catchment, reflecting the different proportions of land uses. The sediments deposited in the silting zones of the Lago Paranoá originate largely from urban sources (85±4%). Areas with (semi-) natural vegetation and natural gullies contribute 10±2% of the sediment yield. Agricultural sites have only a minor sediment contribution of about 5±4 % within the whole catchment. However, there is no mechanism considered to reflect seasonality in the tropics, e.g. phenological change of the vegetation between wet and dry season, or and temporal changes in land use, e.g. construction sites, which influence model estimates. Nevertheless, the study reveals that even 58 % of the land remains in (semi-) natural state, the main sediment source are urban areas. Beside the analyses of sediments, it was found that metal concentrations in surface water of the main tributaries to the Lago Paranoá are generally low, but show seasonal variability. Terrestrial inputs of metals occur during the rainy season and depend largely on the influence of urban land use. The present thesis shows the great influence of anthropogenic activities on sediment generation, and at least to some degree, on sediment associated pollution loads. It depicts region specific challenges, but also provides essential information to guide management responses towards more effective sediment source-reduction strategies
Im Gebiet des Bundesdistrikts Brasilien ist ein erheblicher Druck auf die Wasserressourcen zu beobachten, der vorwiegend durch starkes Bevölkerungswachstum, ungeplante Suburbanisierung und Landnutzungsänderungen innerhalb der letzten Jahrzehnte ausgeübt wird. Die Wasserversorgung der jungen Hauptstadt Brasília und seiner suburbanen Räume wird im Wesentlichen durch in Stauseen gesammeltes Oberflächenwasser gewährleistet. Durch die voranschreitende Ausdehnung von urbanen und landwirtschaftlichen Flächen spielen insbesondere Sedimenteinträge in die Stauanlagen sowie sedimentgebundene Stoffbelastungen durch anthropogene Aktivitäten für die verfügbare Wasserquantität und Wasserqualität eine bedeutende Rolle. Damit verbundene negative Umweltauswirkungen sowie die daraus resultierenden sozioökonomische Konsequenzen erfordern daher dringend wirksame und nachhaltige Strategien im Land-und Wasserressourcenmanagement. Eine deutliche Minimierung der Sedimenteinträge und Stoffbelastungen in das Gewässernetz ist jedoch nur mit Kenntnis der Primärquellen von Sedimenten und der Sedimentgeochemie zu erreichen. Der "Fingerprinting"-Ansatz und der Einsatz eines "Multivariate Mixing-Modell", sind geeignete Werkzeuge um den Einfluss anthropogener Eingriffe in das landschaftsökologische Prozessgefüge der Sedimentgenerierung zu klären. Die vorliegende kumulative Dissertation zeigt dies anhand der Anwendung einer Multikomponenten-Methodik. Diese beinhaltet sowohl geochemische und geophysikalische Analysen repräsentativer Sedimentproben der Sedimentquellen und der finalen Senken (Auenbereiche und Bereiche der Zuflüsse zum Lago Paranoá) als auch umfassende statistische Analysen sowie die Anwendung eines modifizierten "Multivariate Mixing-Modells". Der Einsatzder "Fingerprinting" Methodik in urbanen Einzugsgebieten der wechselfeuchten Tropen, wie das des Lago Paranoá in Zentralbrasilien, ist jedoch mit erheblichen Herausforderungen verbunden. Das betrifft insbesondere die Heterogenität der Landnutzungstypen innerhalb einer Landnutzungsklasse (urban, landwirtschaftlich, semi-natürlich) und die Unterschiede der Landnutzungsanteile zwischen den einzelnen Teileinzugsgebieten als auch modelstruktureller Unzulänglichkeiten bei der Sedimentherkunftsberechnung für urbane Einzugsgebiete. Eine Hauptkomponentenanalyse und hierarchische Clusteranalyse wurden verwendet, um den Einfluss der verschiedenen Landnutzungstypen auf der Geochemie der Sedimente zu untersuchen. Geochemische Fingerprints verschiedener anthropogener Aktivitäten wurden auf der Grundlage der Ergebnisse der Clusteranalyse ("grouping") entwickelt. Die Berechnung von Anreicherungsfaktoren ("Enrichmentfactors") auf Basis der gemessenen Elementgehalte, mit dem lokalen geologischen Hintergrundwerten als Referenz, ermöglichte die Quantifizierung des Einflusses der verschiedenen Landnutzungen auf die Metalleinträge in die Sedimente. Die vorhandenen Ergebnisse legen nahe, dass eine direkte Beziehung zwischen Landnutzung und quantifizierbarer Merkmale der Sedimentgeochemie existiert. Ein Vergleich der geochemischen Signatur von potentiellen Sedimentquellen und mit jenen der alluvialen Sedimente unterstützt die Hypothese, dass urbane Gebiete einen beachtlichen Beitrag zur Sedimentgenerierung und letztendlich zur Sedimentablagerung in den Auen- und Zuflussbereichen des Lago Paranoá leisten. Da diese relative Betrachtung von Elementzusammensetzungen der Sedimente keine quantitativen Aussagen zur Bedeutung der einzelnen Sedimentquellen zulässt, wurden statistisch verifizierte "composite fingerprints" und ein an urbane Bedingungen modifiziertes multivariate mixing-Modell (Hybrid) entwickelt und angewendet. Die Modellberechnungen erfolgten für das gesamte Einzugsgebiet des Lago Paranoá und separat für das Riacho Fundo Teileinzugsgebiet, welches Die angepassten Modellschätzungen zeigten, dass die in den Verlandungszonen des Lago Paranoá abgelagerten Sedimente weitgehend aus urbane Räumen (85 ± 4%) generiert wurden. Dahingegen stammen nur 10 ± 2% der Sedimente aus Gebieten mit (semi-) natürlicher Vegetation, obwohl 58 % der gesamten Einzugsgebietsfläche des Lago Paranoá stets (semi-) natürliche Verhältnisse aufweist. Landwirtschaftliche Gebiete haben generell nur einen geringen Anteil von etwa 5 ± 4% am Sedimenteintrag. Die Unterschiede in den Sedimentbeträgen sowohl zwischen den verschiedenen Sedimentquelltypen als auch zwischen den einzelnen Teileinzugsgebieten scheinen maßgeblich von den Flächennutzungsanteilen (urban, landwirtschaftlich, semi-natürlich) in dem jeweiligen Teileinzugsgebiet abhängig zu sein. Trotz umfassender Probennahme, Probenanalytik, Modellanpassung und Unsicherheitsanalyse sind die Ergebnisse nur für den Beprobungszeitraum, für die analysierte Stoffgruppe (organische Stoffeinträge sind im Rahmen dieser Dissertation nicht erfasst) und für die ausgewählten Lokalitäten repräsentativ. Zeitliche Einflussgrößen wie die Saisonalität in den Tropen oder Änderungen der Landnutzung, wie z.B. temporäre Baustellen, konnten mit den hier verwendeten Methoden nicht erfasst werden. Um die hohe räumliche und zeitliche Variabilität der Sedimentdynamik und eine deutliche Minimierung der Sedimenteinträge in das Gewässernetz zu erzielen, sind demnach die Einrichtung und der Betrieb eines langfristigen Monitoring-Netzwerkes für Sedimente im Einzugsgebiet des Lago Paranoá von hoher Priorität. Die vorliegende Dissertation bringt neue Einsichten in verschiedene wichtige Aspekte der geochemischen Beeinflussung von Sedimenten durch anthropogene Aktivitäten und liefert erstmalig quantitative Aussagen zu den Sedimentquellgebieten im Einzugsgebiet des Lago Paranoá. Sie stellt regionsspezifische Herausforderungen heraus, liefert gleichzeitig aber auch wichtige Informationen zu Sedimentbelastungen und -Einträgen und damit einen wichtigen Beitrag als Entscheidungsunterstützung im Rahmen eines Sedimentmanagementplans

The dissertation deals with clogging of reservoirs and ponds by redundant sediments which penetrate water system by erosion. It describes methods of extracting pond sediments. It contains measurement of dewatering of sediments on hydrocyclone and design of laboratory hydrocyclone and filter unit. In the conclusion there is design of technology of dewatering sediments which were extracted by wet method by drainage excavator. Numerical simulation of flowing in hydrocyclones is simulated in the CFX programme and dewatering technology is simulated in the CHEMCAD programme.

Neste trabalho foi feito o desenvolvimento e validação de métodos para a determinação do hormônio 17\'alfa\'-metiltestosterona em amostras de água e de sedimentos de uma piscicultura situada no município de Socorro-SP. O local de estudo foi escolhido porque no município de Socorro há um grande número de pisciculturas e também pelo fato da cidade fazer parte do Circuito das Águas. Toda a água utilizada no processo de reversão sexual das tilápias do Nilo (Oreochromis niloticus) é descartada no Ribeirão dos Machados, um dos afluentes do rio Mogi-Guaçu, sem o devido tratamento. Foi desenvolvido o método analítico para a extração do hormônio das amostras de água, empregando a extração em fase sólida com adsorvente C18 (octadesilsilano). Também foi desenvolvido o método para a extração do hormônio das amostras dos sedimentos, empregando o equipamento de ultra-som. Foram feitos estudos de recuperação para as amostras de água e sedimentos em três níveis de fortificação. Empregou-se 300 mL da água de água de nascente (branco), e água do rio Santa Maria do Leme para os estudos de recuperação. Empregou-se 10 g de sedimentos (branco) coletados no rio Santa Maria do Leme, em São Carlos. Estas amostras foram fortificadas com o hormônio estudado. A técnica analítica empregada para a determinação do hormônio foi a cromatografia líquida de alta eficiência com detector UV-Vis e coluna RP-18. Para a determinação do hormônio foi utilizada a fase móvel acetonitrila/água 35:65 v/v. O volume injetado foi de 20 \'mü\'L, o fluxo de 1,0 mL/min e comprimento de onda de 245 nm. Os resultados indicaram que os métodos desenvolvidos e validados se mostraram lineares, sensíveis, seletivos, precisos e exatos nas condições estabelecidas, com limites de detecção e de quantificação adequados para a análise do hormônio. A aplicação desses métodos só foi possível pela adição de padrão, que possibilitou a identificação e quantificação do hormônio nas amostras de água e de sedimentos. Foram também feitos testes de ecotoxicidade do hormônio empregando-se os organismos Daphnia similis e Ceriodaphnia silvestrii para verificar a reprodução das espécies. Foram feitos testes para verificar a reversão sexual com a Ceriodaphnia silvestrii. Foi utilizado o programa computacional TOXSTAT 3.3 para a aplicação dos testes estatísticos com a Daphnia similis, pois os testes com a espécie Ceriodaphnia silvestrii não apresentou o número de 15 neonatos por organismo, não sendo possível a aplicação do referido teste. Verificou-se que não ocorreu reversão sexual nos testes com a Ceriodaphnia silvestrii nas concentrações estudadas (1,0 e 50,0 \'mü\'g/L). O estudo de avaliação e identificação de substâncias emergentes deve ser incorporado nos programas de controle e gestão de recursos hídricos, porque é importante verificar se o hormônio é responsável por algum tipo de toxicidade.
In this work the development and validation of methods for the determination of 17\'alfa\'-methyltestosterone hormone in water and sediments samples was achieved. The samples studied were extracted from pisciculture sites in the city of Socorro, Sao Paulo State. This place was chosen because it has a great number of pisciculture sites and is also localized near important tourist resources, known as the \'Circuito das Águas\'. One of the main concerns is the fact that water volumes used in the process of sexual reversion of the Nile Tilapia (Oreochromis niloticus), are discarded without previous treatment in the Machado river, a tributary of Mogi- Guaçu river, the main water resource in this area. Therefore, there are evident potential threats and care must be taken to analyze the potential contamination of water resources in the neighborhood. Two analytical methods were developed to extract hormone from water and sediments samples: a) using solid phase extraction with sorbente C18; b) using ultrasonic facilities. The recovering of the water and sediments samples was made in three levels of fortification. To perform comparisons, standards were built using 300 mL water samples collected in safe places and samples of fortication in the Santa Maria do Leme river, in Sao Carlos, and 10 g of sediments collected in the Santa Maria do Leme river, in Sao Carlos. These samples were contaminated with hormone under carefully controlled conditions. Hormone level determinations were carried out using HPLC with UVVis detector and column RP-18. The hormone determinations were made using the mobile phase acetonitrile/water 35:65 v/v. The experiments were carried out under the following conditions: a) the injected volume was 20 \'mü\'L; b) the flow speed was 1,0 mL/min ; c) a wavelength of 245 nm was used. The results obtained shows efficiency of the methods developed and validated in this as the correlations observed were linear, sensible, selective and accurate under the established conditions. Therefore, the experimental conditions used for detention and quantification were adequate for hormone analysis. Is worth to note that the identification and quantification of the hormone in the samples of water and sediments, is possibly only by making comparison with the standard discussed above. The organisms Daphnia similis and Ceriodaphnia silvestrii were also used to verify the ecotoxicity of the hormone, using reproduction of these species as the parameter to be monitored. Therefore, tests were made to verify the sexual reversion of Ceriodaphnia silvestrii. In these investigations, the computational program TOXSTAT 3.3 was used to perform the statistical tests. Nevertheless, only the studies performed with the Daphnia similis had statistical means, as the tests with the Ceriodaphnia silvestrii species did not present statistical significance. Therefore, it was verified that Ceriodaphnia silvestrii in the conditions studied here (concentrations of 1,0 and 50,0 \'mü\'g/L) did not present evidences of sexual reversion. As a main conclusion, the present study demonstrates the need of incorporating the evaluation and identification of emergent substances in the protocols used for the control and management of water resources. Among the concerns, special care must be taking to verify correlations between hormone and toxicity.

A contaminação dos ecossistemas aquáticos por metais-traço demanda preocupação já que estes contaminantes podem exercer efeitos tóxicos sobre a biota e aumentar os custos para tratamento da água. Em geral, tais problemas de degradação são decorrentes de uma gestão de recursos hídricos deficiente. Tendo como área de estudo a represa Paiva Casto, reservatório integrante do Sistema Cantareira, maior sistema de abastecimento público da região metropolitana de São Paulo, este trabalho teve o intuito de: investigar o histórico da contaminação por metais-traço (Cd, Cr, Cu, Ni, Pb, Zn, Mn, Al) por meio da geocronologia por 210Pb e indicar um valor de referência para estes; identificar a heterogeneidade espacial destes contaminantes; analisar a biodisponibilidade e com base na possibilidade de adequar etapas do sistema de gestão de recursos hídricos europeu, a Diretiva Quadro da Água (DQA) discutir a qualidade química dos sedimentos da represa em estudo. Foram efetuadas duas coletas em campo, destinadas à avaliação do histórico da contaminação ambiental por metais-traço e à análise da biodisponibilidade por meio da técnica de sulfetos volatilizáveis por acidificação (SVA) e metais simultaneamente extraídos (MES). O histórico da contaminação por metais-traço abrangeu um período de 100 anos e indicou que os maiores impactos na região, em relação a estes contaminantes, ocorreu em período anterior ao início de operação da represa Paiva Castro, com exceção do Cu. Para o Cu, em sedimentos superficiais, os teores excederam até três vezes e meia o VR. Este resultado é provável consequência da aplicação de sulfato de cobre para o controle de florações de algas. Os dados para os VR divergiram daqueles estabelecidos para a crosta terrestre, porém foram semelhantes aos encontrados para a bacia do Alto Tietê, com exceção dos metais Cr e Pb. A análise de (SVA/MES) indicou que os metais não estavam biodisponíveis. Dentre as áreas amostradas, a região da barragem apresentou ao longo do tempo as maiores taxas de acumulação para metais-traço em contraposição à área de captação das águas para abastecimento público. Em relação a DQA, constatou-se que existe capacidade científica para avançar na incorporação de novos instrumentos na gestão, principalmente no Estado de São Paulo, entretanto, é preciso que haja sistemas de saneamento e monitoramento adequados e especialmente decisão política e rigor na aplicação destes novos instrumentos, caso contrário a incorporação da DQA é inviável. Aplicando algumas das normas da DQA na avaliação da qualidade química dos sedimentos da represa Paiva Castro constatou-se que a qualidade geral para este manancial é boa. Apesar disto é necessário que as políticas públicas sejam de fato aplicadas contra a degradação deste importante manancial, caso contrário a boa qualidade deste reservatório estará em risco
Contamination of aquatic ecosystems by trace metals demand concern since these contaminants may cause toxic effects on biota and increase costs for water treatment. In general, such degradation problems are due to a poor water management. A study was conducted at Paiva Castro reservoir, one of the reservoirs of the Cantareira System, largest public water supply system in the metropolitan region of São Paulo, this study aimed to: investigate the history of the accumulation of trace-metals (Cd, Cr, Cu, Ni, Pb, Zn, Mn, Al), through geochronology by 210Pb; establish background values (BV); analyze spatial heterogeneity; bioavailability and based on the possibility of adjusting some instruments of the European water resources management system, the Water Framework Directive (WFD), discuss the chemical quality of Paiva Castro\'s sediments. Two collections were performed, to assess the historical environmental contamination by trace-metals and to analyze the bioavailability using the technique of sulfides volatilizable by acidification (AVS) and simultaneously extracted metals (SEM). The history of contamination by trace- metals covered a period of 100 years and indicated that the greatest impacts in the region occurred in periods prior to the reservoir operation, with the exception of Cu. For Cu, in surface sediments, the levels exceeded three times and a half the BV. This result is probable consequence of copper sulphate application for controlling algal blooms. Data for BV were different from those found in the earth\'s crust, but similar to those found for the Alto Tietê basin, except for Cr and Pb metals. Analysis (AVS/ SEM) indicated that metals were not bioavailable. Among the sampled areas, the region of the dam, showed the highest rates of accumulation for trace- metals in contrast to the catchment area for public water supply. Regarding WFD, it was observed that there is scientific capacity to incorporate new instruments in the management, mainly in São Paulo, however, there must be adequate sanitation and monitoring systems and especially political decision and rigor in the application of these new tools, otherwise the incorporation of the WFD is unviable. Applying some of the WFD instruments in assessing the chemical quality of Paiva Castro\'s sediments, it was found that the quality of this ecosystem is good. Nevertheless, it is necessary that public policies are actually applied against the degradation of this important ecosystem; otherwise, reservoir\'s \'good quality\' will be at risk

Magnetismo ambiental é uma área nova e multidisciplinar que estuda propriedades magnéticas de solos, sedimentos, rochas e relaciona essas propriedades com parâmetros ambientais e poluição. Assim a caracterização dos minerais presentes em solos e sedimentos é ferramenta fundamental de estudo, principalmente devido à presença do Fe. Com este objetivo, amostras de sedimentos foram coletadas na forma de testemunhos no Largo de Santa Rita (LSR) e Rio Casqueiro (CS2), Santos, São Paulo (no presente trabalho acrescentamos aos cálculos também a contribuição dos óxidos de ferro) e Ferraz (FZ) e Botany Point (BP), da baia do Almirantado, Ilha Rei George, Antártica Os testemunhos da baia de Santos são semelhantes porque são provenientes de uma região extremamente poluída. De outra forma, os testemunhos da Antártica são semelhantes por serem de regiões sem ocupação humana. Assim um interesse específico em estudar amostras destas regiões é justificado. E amostras isoladas de superfície da plataforma continental do Rio de Janeiro e São Paulo, incluindo amostras da ilha do Cardozo e ilha Anchieta, por apresentarem particularidades interessantes. As amostras foram caracterizadas por Espectroscopia Mössbauer (EM), Susceptibilidade Magnética (SM) e PIXE (Particle Induced X-ray Emission). Esta última técnica permite detectar e quantificar elementos químicos de número atômico acima de 12. Os elementos quantificados nos resultados de PIXE são: em todas as amostras Al, Si, S, Cl, K, Ti, Mn e Fe; no testemunho LSR: P, V, Co ; no testemunho CS2: P, V, Cr, Co, Ni, Cu, Zn, As, Br e Zr; no testemunho BP: V, Cr, Co, Cu, Zn, I e W; no testemunho FZ: V, Cr, Co, Ni, Cu, Zn e I; na amostra PEN: P, Co; na amostra CARD: P e Mo; na amostra P6947: Cr, Co, Ni, Cu, Zn, Br e I; na amostra P6949: Cr, Co, Cu, Zn e La; na amostra P6561: Cr, Co, Ni, Br e I; na amostra P6626: Co, Ni, Cu, Zn, I, Sr e Zr e na amostra P6627: Cr, Co, Ni, Cu, Zn, Br, I e Sr. A partir das medidas de EM determinamos as proporções de Fe2+, Fe3+ paramagnético e de Fe3+ ligado aos óxidos de ferro e os identificamos. Determinamos que o óxido de ferro presente nos testemunhos LSR e CS2 é a goethita. O óxido de ferro identificado nas amostras dos testemunhos Ferraz e Botany Point foi a hematita. Esta também foi identificada na amostra da praia do engenho, ilha Anchieta. Em única amostra entre as amostras da plataforma continental foi detectado e quantificado um óxido de ferro. Nas amostras dos testemunhos do litoral de São Paulo, a fase do ferro predominante é a paramagnética, portanto, associamos a fase paramagnética do ferro ao predomínio do intemperismo químico. Por outro lado amostras dos testemunhos da Antártica, a fase do ferro predominante é dos óxidos de ferro, portanto, associamos a fase de óxidos de ferro ao predomínio de intemperismo físico. Assim a presença de ferro amorfo (ferridrita ou fugerita) poderia ser um índice de quantidade de metais de transição presentes na coluna sedimentar. Modelamos o valor da susceptibilidade magnética ponderando as contribuições individuais de cada elemento químico e do Fe3+, do Fe2+ e dos óxidos de ferro. O cálculo da susceptibilidade magnética modelada é a contribuição original deste trabalho, onde verificamos que os picos no valor de Susceptibilidade Magnética correspondem às situações de maior contaminação ambiental. Por fim, concluímos que nossos resultados de Espectroscopia Mössbauer, PIXE e Susceptibilidade Magnética estão de acordo e podem ser usados em modelos com o objetivo de observar impactos ambientais.
Environmental magnetism is a new area that studies magnetic properties of soils, sediments and rocks and relates these properties with environmental parameters and pollution. With this proposal sets of sediments were collected from the Largo Santa Rita(LSR), Santos, São Paulo; from Baia do Almirantado, Rei George, Antarctic, Ferraz (FZ) and Botany Point (BP); Rio Casqueiro, Cubatão, São Paulo (CS2, re-studied in the present work including oxides contribution) and isolated samples of Plataforma Continental. The CS2 and LSR samples are similar from a heavily polluted region. On the other hand, FZ and BP samples are similar from regions without human occupation. Thus a specific interest to study samples from these regions is justified. The samples were characterized by Mössbauer Spectroscopy (MS), Magnetic Susceptibility and PIXE (Particle Induced X-ray Emission). The latter allowed to detect and to quantify the content of chemical elements of atomic number above 12. The presence of trace metals as Al, Si, S, Cl, K, Ti, Mn and Fe was detected and quantified using the PIXE technique in all samples. P, V, Co were detected and quantified in LSR samples. P, V, Cr, Co, Ni, Cu, Zn, As, Br and Zr were detected and quantified in CS2 samples. V, Cr, Co, Cu, Zn, I and W were detected and quantified in BP samples. V, Cr, Co, Ni, Cu, Zn and I were detected and quantified in FZ sample. P and Co were detected and quantified in PEN sample. P and Mo were detected and quantified in CARD sample. Cr, Co, Ni, Cu, Zn, Br and I were detected and quantified in P6947 sample. Cr, Co, Cu, Zn and La were detected and quantified in P6949 sample. Cr, Co, Cu, Zn and La were detected and quantified in P6561 sample. Co, Ni, Cu, Zn, I, Sr, Zr and La were detected and quantified in P6626 sample. Cr, Co, Ni, Cu, Zn, Br, I e Sr were detected and quantified in P6627 sample. The Mössbauer measurements presents Fe2+ and Fe3+ sites and in some samples an additional sextet, due the presence of goethite for LSR and CS2 samples, hematite for FZ and BP samples. The relative area of paramagnetic iron was larger than the others MS components in samples of São Paulo, Litoral, so we associated chemistry weathering with paramagnetic phases. On the other hand, the iron oxides relative áreas of Antarctic samples were larger than the others MS components, so we associated physical weathering with magnetic iron oxides phases. Thus the paramagnetic iron detected could be a measure of transition metals presence or a pollution index. The peaks of experimental magnetic susceptibility curve were related to pollution. The combined results of MS and PIXE allowed us to perform the fitting of the magnetic susceptibility curve that yield a perfect fit with experimental data. In the particular case of Fe we used the related proportions of Fe2+ and Fe3+ obtained by MS measurements. The iron oxides contributions are also found in literature. The model of magnetic susceptibility is the original contributed of the present work. We can conclude that our results of MS, PIXE and magnetic susceptibility are in good agreement and can be used in models with the objective to study the environmental impacts effects.

The thermal properties of hydrate bearing sediments remain poorly studied, in part due to measurement difficulties inside the hydrate stability envelope. In particular, there is a dearth of experimental data on hydrate-bearing sediments, and most available measurements and models correspond to bulk gas hydrates. However, hydrates in nature largely occur in porous media, e.g. sand, silt and clay. The purpose of this research is to determine the thermal properties of hydrate-bearing sediments under laboratory conditions, for a wide range of soils from coarse-grained sand to fine-grained silica flour and kaolinite. The thermal conductivity is measured before and after hydrate formation, at effective confining stress in the range from 0.03 MPa to 1 MPa. Results show the complex interplay between soil grain size, effective confinement and the amount of the pore space filled with hydrate on the thermal conductivity of hydrate-bearing sediments.

Reservoirs in areas with a high sediment yield will without mitigation sooner or later be filled up with sediments, reducing the volume available for regulation for electric generation. Flushing of sediments is a management strategy used in many reservoirs in the world, with varying degree of success. The Angostura reservoir is a shallow reservoir located on an inundated river, making it extra vulnerable to sedimentation. It is estimated a yearly inflow of 1.5 million tons of sediment. Other reservoirs are located upstream, and the flushing of these leads to large quantities of sediment inflow in a short period of time. In September every year, the water level in Angostura is partially drawn down to route this sediment through the reservoir. In November, the water level is drawn down completely, and a full sediment flushing is performed. The RESCON model is a spreadsheet program designed to find a technically feasible sediment management strategy that maximizes the economical benefits of the project. Flushing is modeled with a simple algebraic model. SSIIM is a three-dimensional computational fluid dynamics program designed for hydraulic engineering. Sediment erosion, transport and sedimentation can be modeled in a complex reservoir geometry using an adaptive grid with a moveable bed. The main objective of this thesis is to test the performance of the RESCON and SSIIM models. The RESCON model was tested on the November flushing to see if it can reproduce the measured volume of flushed sediments. SSIIM was used for simulation of sediment concentration distribution in the reservoir, and to model the September flushing. The results are compared to measured values. The reservoir geometry is based on bathymetry data from September 2011. Inflow series are from logged values at the hydropower plant. Depth-averaged concentration values are used to present the longitudinal concentration distribution, and Hunter Rouse profiles to present the vertical distribution. Using known reservoir values and the recommended coefficients, the RESCON model was not able to get close to the actual volume of flushed sediments. Although the model has given promising results in other cases, the complex reservoir geometry in Angostura sets heavy restrictions on the flushing processes in the reservoir, which an algebraic model of this type cannot reproduce. The steady state simulation was successful in explaining previously unexplained variations in the concentration in the lateral and longitudinal direction of the reservoir. The simulation reproduces the longitudinal and vertical concentration distribution well. A bug in the implementation of the second-order scheme in SSIIM was discovered, which has later been fixed, giving more similar results for the first-order and second-order schemes. The time allocated for the flushing simulation was not enough to get satisfactory results. The erosion in the upstream end is modelled well, but the measured sedimentation in the downstream area is much larger than in the simulations. With more time for this simulation, it would have been possible to increase the quality of the results.

Differential compaction within alluvial sediments results from the inherent juxtaposition of sand, si It, clay and peat on the floodplain. Differential compaction is primarily dependent on (a) the nature of overbank mudstone compaction, and (b) the relative timing of channel and adjacent overbank sediment deposition. Results from the analysis of modern overbank sediments indicate that the near-surface porosity of alluvial overbank sediment Is controlled by the complex interaction of grain shape, grain size, clay content, groundwater fluctuations, evaporation and transpiration, suggesting that the subsequent compaction of these sediments would be an extremely heterogeneous process, with n'o single controlling parameter. Porosity-depth curves derived from modern sediment analysis indicate that a significant amount of compaction occurs during the first few metres of burial. Examination of samples suggest that ·porosity loss may be due to the expulsion of water from the sediment pores, and the rearrangement of grains from an unstable packing arrangement to a more stable one. Early differential compaction will affect floodplain topography, and therefore directly influence the subsequent pattern of facies distribution. However, as significant amounts of compaction have occurred during very early burial, later stages of compaction will have a less marked effect on alluvial stratigraphy than has been previously suggested. In particular, simulation models such as Bridge & Leeder (1979) which suggest that channel "packing" increases with depth may not be entirely correct. If, within an alluvial sequence, there is no compactional deformation of features such as alluvial channel wings, it is unlikely that channel packing will have increased with depth. Studies of the Middle Jurassic alluvial sediments of North Yorkshire and the Cretaceous of the Isle of Wight, illustrate that the effects of differential compaction can be observed on several scale~: (a) channel belt, (b) individual channel or bedform, and (c) microscopic

Salt-marsh sediments can provide important achives of past sea levels if they can be securely dated. This thesis investigates eight methods for dating salt-marsh sediments. These include traditional and established dating methods (¹⁴C dating and the radionuclides ¹³⁷Cs and ²¹ºPb) and more novel approaches to dating the deposition of salt-marsh sediments (palaeomagnetic dating, the use of' atmospheric stable lead deposition, tephra chronologies, pollen markers, SCP analysis and the use of atmospheric ¹⁴C 'bomb spike' and high-precision AMS ¹⁴C measurements). Sites were selected to provide contrasting sediment sequences that differed both in lithology and accumulation rates and included salt marshes from the Taf estuary (southwest Wales), the Arne Peninsula (southern England) and Vioarholmi (western Iceland). The investigations in the Taf estuary produced the first palaeomagnetic chronology from a salt marsh. From the Arne Peninsula this thesis reports the first successful use of bomb-spike calibrated ¹⁴C analyses in a salt marsh as well as high-precision AMS ¹⁴C ages for the 'problem' period AD 1700-1950. Stable Pb analysis at all three sites produced a number of chronological markers that signalled the timing of increases in industrial Pb emissions, and the later use of Pb petrol additives during the 20th century. In addition, a unique isotopic signal, attributed to the working of Pb metal during the height of the Roman Empire in Europe, was found in the Icelandic sediments. The radionuclides ²¹ºPb and ¹³⁷Cs produced precise chronologies for the last 100 yr in the Taf estuary. However, post-depositional mobility of ¹³⁷Cs on the Arne Peninsula and low ²¹ºPb concentrations at Vioarholmi prevents the construction of reliable ²¹ºPb and ¹³⁷Cs chronologies. In contrast, the use of tephra at Vioarholmi, and pollen and spheroidal carbonaceous particle markers on the Arne Peninsula, showed great potential as independent unique-event dating tools that could be used to constrain conventional ¹⁴C calibrations. Finally, the chronological information produced by all the individual methods was combined to construct an integrated chronology for each site. This approach significantly reduced age uncertainties and produced higher resolution, and more robust, salt-marsh sedimentation histories