Scour around important foundation elements for bridges and other coastal infrastructure is the leading cause of failure and instability of those structures. Traditional scour mitigation methods, such as the placement of riprap, the use of collars or slots, embedding foundations deeper, or a combination thereof can be costly, require long-term maintenance, and can potentially have detrimental environmental effects downstream. These difficulties with traditional methods are potentially alleviated with the implementation of self-sustaining bivalve (e.g., mussel, oyster, scallop) farms that could act as mats of interconnected living barriers, protecting the seabed from scour. The mats would help to attract larval settlement by making the substrate a more suitable habitat, contributing to the sustainability of the bivalve farms. Colonies of bivalves are already being used as living shorelines for retreatment mitigation, embankment stabilization, and supporting habitat for other marine life. These applications are accomplished, in part, by bivalves' strong attachment capabilities from the bioadhesives they secrete that act as a strong underwater glue, adhering their shells to granular substrate. Some species of mussels have been shown to withstand water flow velocities greater than 6 m/s without detaching. For reference, riprap with a median grain size of about 655 mm has been shown to require a flow velocity of at least 1.7 m/s for incipient motion of the boulder-sized riprap. In addition to the contiguous living bivalve mat offering scour protection, the whole or fragmented shells (i.e., shell hash) that are left behind from dead bivalves are hypothesized to reduce erosion potential. Shell hash-laden sediments should be able to better withstand shearing, thereby increasing the critical shear stress required to erode material, compared to sediment without shell hash. Habitat suitability for bivalve colonies is also an important consideration to evaluate what surface enhancements may be needed for a site to be selected for implementation of bivalve scour mats. Bed surfaces that consist of unconsolidated fine-grained sediment are unlikely to be able to support bivalve species as the organisms could sink into the sediment, not allowing solid anchoring points. In contrast, harder substrates typically found in granular sediments offer much more suitable habitats. Along with testing the influence of shell hash and bioadhesive on sediment behavior, this thesis aims to establish a methodology to evaluate whether a section of seafloor can support bivalves or enhancement materials (e.g., shell, shale, or slag fragments) without them sinking, thereby depriving them of oxygen. Together, the examining of geotechnical aspects of bivalve habitat enhancement through seabed soil alteration and the influence of shell hash and bioadhesives on sediment shear behavior are part of a novel multidisciplinary approach toward this proposed bioengineered scour solution. Consequently, the research objectives explored in this thesis are as follows: (1) characterize morphology of existing bivalve colonies through acoustic and direct field measurements; (2) evaluate the spatial variation of the sediment shear strength in terms of proximity to bivalve colonies; (3) expand the domain of confining pressures and shell hash weight fractions used in sediment strength testing; (4) quantify the changes in shear strength and erodibility from laboratory tests on sampled material with and without the presence of bioadhesives, as well as shell fragments mixed in with the sediment; and, (5) develop a methodology ranking system for the suitability of a surficial sediments to support seeding material to improve benthic life habitat substrates. Three exploratory field surveys were conducted where colonies of oysters and other benthic life were present: in the Piankatank River in Virginia, in the Northwest Arm of the Sydney Harbour in Nova Scotia, Canada, and at the Rachel Carson Reserve in North Carolina. Field sampling techniques included Ponar grab samples, hand-dug samples, X-ray rectangular prism cores, and cylindrical push cores, which were all pivotal to understanding sediment composition, size and shape of particle distributions, as well as in-situ depth profiles of shells. Remote sensing and intrusive instrumentation included a rotary scanning sonar, acoustic Doppler current profilers, CTD (Conductivity, Temperature, Depth) probes, underwater cameras, a portable free-fall penetrometer, and in-situ jet erosion testing which helped to characterize the morphology of the bivalve colonies and the spatial variability of sediment strength. Subsequent laboratory experiments included grain size distribution analyses, vacuum triaxial tests to measure changes in shear strength with and without shell hash, and miniature vane and pocket erodometer tests on bioadhesive-treated sediments. The results showed: (1) a significant increase in the standard deviation of the backscatter intensity where the oyster reef was located; (2) the in-situ sediment shear strength increased slightly closer to the oyster reef at the Piankatank River site; (3) samples with a higher oyster density exhibited less uniform particle size distributions; (4) the presence of less than approximately 4% (by weight) of shell fragments increased the secant friction angle by approximately 6° relative to samples with no shell fragments; and, (5) the harbor bed of the Northwest Arm of the Sydney Harbour is a suitable stiffness for enhancement with shell hash over about 23% of its area. Preliminary testing showed a subtle increase in the torsional shear resistance and a decrease in erodibility for bioadhesive-treated samples; however, further testing is needed for confidence to be achieved in the results due to bioadhesive supply issues. / Master of Science / Oysters and mussels are aquatic mollusks (i.e., bivalves) that are known to be able to withstand strong storm flows without detaching from rocks and other hard surfaces. Knowing this and the increasing need for environmental- and ecological-friendly solutions in engineering and construction further accelerated by climate change and sea level rise are the motivations for studying whether bivalves can be used in this capacity. Traditional methods to protect against bridge failures caused from individual piers that become unstable from sediment eroding away from their bases can be costly, require long-term maintenance efforts, and can potentially have detrimental environmental impacts. As an alternative to or supplement to traditional methods, bivalves could be laid down in mats near the base of piers to act as a protective interconnected layer, diverting strong water flows away from the otherwise exposed sediments susceptible to erosion while strengthening the seabed. Much is known and has been investigated on the biology of bivalves but understanding how these organisms influence the sediments near them has not been studied extensively from a geotechnical engineering perspective. Specifically, within geotechnical engineering, this study is focused primarily on the influence of oyster shell fractures, naturally found in the vicinity of bivalve colonies, and the organic glue that bivalves use to attach themselves to rocks on the engineering behavior of nearby sediments. Secondary to that main objective is to establish a methodology to evaluate whether a section of seafloor can support bivalves without them sinking, thereby suffocating them. In summary, this thesis investigates methods to evaluate whether the seafloor is suitable for supporting bivalves and if their presence changes the way sediments behave after various forces are applied. To accomplish these research goals, three exploratory field surveys were conducted for this thesis: in the Piankatank River in Virginia, in the Northwest Arm of the Sydney Harbour in Nova Scotia, Canada, and at the Rachel Carson Reserve in North Carolina where bivalves were present. Through field sediment sampling, underwater sonar imagery, penetrating probes, and subsequent geotechnical laboratory testing, shell-sediment interactions were characterized. The results showed: (1) an oyster reef in the Piankatank River could be observed in great detail with sonar imagery; (2) sediment strength increased slightly the closer to the oyster reef; samples with more oyster shells in them exhibited (3) a wider range of particle sizes and (4) an increase in sediment strength; and (5) less than a quarter of the harbor bed of the Northwest Arm of the Sydney Harbour is suitable for armoring the seafloor with pieces of shell, shale, and slag to support bivalve growth. Initial tests with the organic underwater glue from bivalves showed promising results with respect to improvements in sediment strength and decreased erodibility, however, further testing is needed as supply of the organic glue was limited.

This research experimentally shows the effect of sediment roughness characteristics on the acoustic reflection coefficient. This information is useful when trying to classify various types of sediment over an area. This research was conducted in an indoor laboratory tank at Applied Research Laboratories (ARL) at the University of Texas at Austin. A single beam echo-sounder (SBES) system was developed to project and receive a wideband (3 kHz to 30 kHz) acoustic pulse. A method was developed using the system transfer function to create a custom pulse that would minimize the dynamic range over the wide frequency band. A matched filtering and data processing algorithm was developed to analyze data over the full frequency bandwidth and over smaller frequency bands. Analysis over the smaller frequency bands showed the effect of the roughness on the reflection coefficient with respect to frequency. It was found that the reflection coefficient is significantly lower at the higher frequencies (above 20 kHz) than at the lower frequenices [sic] due to off specular scattering. It was also found that the variability of the reflection coefficient was significantly higher for the rough sediment than for the smooth sediment. / text

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No. of bitstreams: 1 Dissertação-Lorena Mota de Castro.pdf: 3075802 bytes, checksum: b59b09dae6173c79ab6b505213e08e8e (MD5) Previous issue date: 2015-09-11 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The Amazon basin, the largest watershed in the world, accounts for approximately 16% of the water discharged into the ocean and its broad scope results in greater sensitivity of its rivers to global climate change. The dynamic and availability of chemical elements in a system as complex rely on natural processes such as leaching of chemicals contained in the rocks as well as a source of anthropogenic activity. The objective of this study was to evaluate the spatial variation of physical and chemical parameters (temperature, turbidity, conductivity, total suspended solids, pH) and anion concentration (F-, Cl-, NO3-, NO2- and SO42-) in sections covering the main forming the Amazon: Solimões and Madeira river, in addition to characterize the bottom sediment of these systems in regard to its particle size, mineralogical composition (XRD) and concentration of the metals Fe, Mn, Zn, Cu, Cr, Ni and Pb (ICP-OES). With the exception of turbidity, both the parameters and the ions concentration presented their values below the maximum recommended by the CONAMA resolution 357/2005 for waters class 2. Both evaluated stretches showed medium and fine sand contents as the predominant composition in the bottom sediments, except for RMGua point Guayaramerín-BO, reflecting the higher concentration of metals in this sample. In bottom sediments there was a predominance of quartz, albite, clinochlore, illite, muscovite and microcline in the total fraction of these. The presence of heavy minerals such as andalusite, augite and rutile were viewed in the Solimões / Amazonas stretch where this occurrence may be associated with Içá and Solimões formations. The correlation analysis allowed to evaluate that metals such as Fe, Pb and Ni have high correlation with the mineralogical composition of the Solimões / Amazonas stretch. The high correlation between Zn and Fe with SO42- content indicates their relationship with pyrite deposits, though not rule out the influence of mining activities widespread in the region. In PCA analysis it was observed that the dispersion of data, both in the Solimões / Amazonas stretch and in Madeira / Amazonas, are caused by naturally occurring factors, despite the high incidence of human activities, mainly in the basin of Madeira. / A bacia Amazônica, considerada a maior bacia hidrográfica do mundo, é responsável por aproximadamente 16% da água despejada no oceano e sua ampla extensão resulta na maior sensibilidade dos seus rios às mudanças climáticas globais. A dinâmica e disponibilidade de elementos químicos em um sistema tão complexo dependem de processos naturais como a lixiviação de substâncias químicas contidas nas rochas como também de atividades de fonte antrópica. O objetivo deste estudo foi avaliar a variação espacial de parâmetros físico-químicos (temperatura, turbidez, condutividade, sólidos totais suspensos, pH) e concentração de ânions (F-, Cl-, NO3-, NO2- e SO42-) em trechos que abrangem os principais formadores do rio Amazonas: Rio Solimões e Rio Madeira, além de caracterizar o sedimento de fundo destes sistemas no que se refere à sua granulometria, composição mineralógica (DRX) e concentração dos metais Fe, Mn, Zn, Cu, Cr, Ni e Pb (ICP-OES). Com exceção da turbidez, tanto os parâmetros quanto a concentração de íons apresentaram seus valores abaixo do máximo recomendado pela resolução do CONAMA 357/2005 para águas de classe 2. Ambos os trechos avaliados apresentaram teores de areia fina e média como composição predominante nos sedimentos de fundo, com exceção de um ponto em Guayaramerín-BO (RMGua), refletindo na maior concentração de metais nesta amostra. Nos sedimentos de fundo verificou-se a predominância de quartzo, albita, clinocloro, ilita, muscovita e microclina na fração total. A presença de minerais pesados como a andaluzita, augita e rutilo foram visualizadas no trecho Solimões/Amazonas onde esta ocorrência pode ser associada às formações Içá e Solimões. A análise de correlação permitiu avaliar que metais como Fe, Pb e Ni possuem alta correlação com a composição mineralógica do trecho Solimões/Amazonas. A alta correlação entre o Zn e Fe com o teor de SO42- indica a relação destes com os depósitos de pirita, entretanto não se descarta a influência das atividades mineradoras muito difundidas na região. Na análise de PCA foi possível observar que a dispersão entre os dados, tanto no trecho Solimões/Amazonas quanto no Madeira/Amazonas, são causados por fatores de origem natural, apesar da alta incidência de atividades antrópicas, principalmente na bacia do Rio Madeira.

Portable Free Fall Penetrometers (PFFPs) are lightweight tools used for rapid and economic characterization of surficial subaqueous sediments. PFFPs vary in weight, shape and size with options for using add-on units. The different configurations enable deployments in various environments and water depths, including the nearshore zone where conventional methods are challenged by energetic hydrodynamics and limited navigable depth. Moreover, PFFPs offer an opportunity to reduce the high site investigation costs associated with conventional offshore geotechnical site investigation methods. These costs are often a major obstacle for small projects serving remote communities or testing novel renewable energy harvesting machines. However, PFFPs still face issues regarding data analysis and interpretation, particularly in energetic sandy nearshore areas. This includes a lack of data and accepted analysis methods for such environments. Therefore, the goal of this research was to advance data interpretation and sediments characterization methods using PFFPs with emphasis on deployments in energetic nearshore environments. PFFP tests were conducted in the nearshore areas of: Yakutat Bay, AK; Cannon Beach, AK; and the U.S. Army Corps of Engineers' Field Research Facility's beach, Duck, NC. From the measurements, the research goal was addressed by: (1) introducing a methodology to create a regional sediment classification scheme utilizing the PFFP deceleration and pore pressure measurements, sediment traces on the probe upon retrieval, and previous literature; (2) investigating the effect of wave forcing on the sediments' behavior through correlating variations in sediment strength to wave climate, sandbar migration, and depth of closure, as well as identifying areas of significant sediment mobilization processes; and (3) estimating the relative density and friction angle of sand in energetic nearshore areas from PFFP measurements. For the latter, the field data was supported by vacuum triaxial tests and PFFP deployments under controlled laboratory conditions on sand samples prepared at different relative densities. The research outcomes address gaps in knowledge with regard to the limited studies available that investigate the sand geotechnical properties in energetic nearshore areas. More specifically, the research contributes to the understanding of surficial sediment geotechnical properties in energetic nearshore areas and the enhancement of sediment characterization and interpretation methods. / PHD / The increasing demand for energy, fluctuations of oil prices, and the expected reduction in the world’s oil production in addition to concerns associated to the global climate change drive the search for renewable energy sources. Out of the different sources of renewable energy, the reliable availability of waves is an advantage over other sources like solar and wind. However, different challenges are still facing the advancement of generating energy from waves. One important challenge is the reliability of the anchoring or foundation system, and the associated site characterization and data collection. The stability of the systems depends on the sediment strength (ability accommodate loads), sediments susceptibility to scour (removal of the sediments around the foundations), and local morphodynamics (changes in the seabed shape). In fact, the stability of the foundations in the seabed represents a major concern for many nearshore and offshore structures. Accordingly, the site characterization stage of any project is essential to mitigate the risks of failures, as well as to achieve cost-effective designs. Portable Free fall penetrometers (PFFPs) are rapid and economical tools used to characterize uppermost seabed sediments. The variability of such devices in weight, shape and size enables the use in different environments and water depths. However, data of PFFPs in sandy sediments is still limited which contradicts the fact that sand represents the most common soil type on the beaches worldwide. Accordingly, the aim of this research is to investigate the sediment behavior in energetic wave areas, and to advance the methods of interpreting the PFFP data in sandy nearshore zones. A PFFP was used to characterize the sediments in three main areas: Yakutat Bay, AK, Cannon Beach, AK and the U.S. Army Corps of Engineers’ Field Research Facility’s beach, Duck, NC. The results were utilized to introduce a sediment classification scheme and complete an existing sediment distribution map for Yakutat Bay, AK; study the effect of storms on the seabed sediment strength; and to determine sand strength parameters using PFFP measurements. The results of this research will contribute to improve the sediment characterization methods and to understand topmost sediment layers’ properties.

O Rio Paraíba do Sul é considerado um dos mananciais mais importantes da região sudeste, uma vez que está localizado entre as duas maiores capitais brasileiras: São Paulo e Rio de Janeiro. A qualidade das águas deste manancial encontra-se bastante comprometida devido ao desmatamento, mau uso e ocupação do solo em áreas urbanas e rurais, uso de insumos agrícolas e pelo lançamento diário de aproximadamente um bilhão de litros de efluentes domésticos. Esta situação é agravada uma vez que apenas 21% do efluente lançado na Bacia do Rio Paraíba do Sul são tratados. O descarte de efluentes, ricos em nutrientes como fósforo e nitrogênio, pode contribuir diretamente no processo de eutrofização. O objetivo deste trabalho foi avaliar a qualidade da água e do sedimento no trecho paulista do Rio Paraíba do Sul, entre os municípios de Aparecida, Guaratinguetá, Lorena e Cachoeira Paulista, frente às variáveis físicas, químicas, biológicas e ecotoxicológicas, além de determinar a ocorrência de cianobactérias potencialmente tóxicas. Coletas de água e sedimento foram realizadas à jusante e montante de cada município nos meses de agosto/13, novembro/13, fevereiro/14, maio/14 e agosto/14. As variáveis avaliadas foram pH, temperatura, condutividade, turbidez, OD, DBO, DQO, fósforo total, nitrogênio total, série de sólidos, coliformes termotolerantes, clorofila-a e testes de toxicidade utilizando Daphnia similis e Pseudokirchneriella subcapitata para a água. Para o sedimento foram realizadas granulometria, matéria orgânica, fósforo total e testes de toxicidade utilizando D. similis e Chironomus xanthus. Foram calculados Índice de Qualidade das Águas (IQA) e Índice de Estado Trófico (IET) das águas do manancial. Análises estatísticas foram aplicadas: Grupamento de Cluster, Correlação de Spearman e Análise dos Componentes Principais (ACP). Os resultados mostraram que as variáveis OD, fósforo total e coliformes termotolerantes não estão de acordo com o estabelecido pela resolução CONAMA 357/05. Toxicidade aguda e crônica foi determinada nas amostras de água, sobretudo nos períodos chuvosos, novembro/13 e fevereiro/14. Observou-se uma redução ao longo do período avaliado de fósforo total, DBO e sólidos totais na água e fósforo total e matéria orgânica no sedimento. Estes valores podem estar relacionados a implantação de estações de tratamento de esgoto nos municípios de Aparecida e Cachoeira Paulista no final do ano de 2013. O IQA foi classificado como \'Boa\', exceto nos pontos referentes à jusante dos municípios de Aparecida e Guaratinguetá, classificados como \'Regular\'. O IET mostrou que a maioria dos pontos pôde ser classificada como \'Mesotrófico\', exceto pelo ponto referente ao final do trecho, jusante de Cachoeira Paulista, que foi classificado com \'Oligotrófico\'. Os principais gêneros de cianobactérias encontrados foram Borzia sp., Hapalosiphon sp., Johannesbaptistia sp., Leptolyngbya sp., Lyngya sp., Oscillatoria sp., Synechocystis sp. e Phormidium sp. A partir das análises estatísticas observouse que a precipitação pluviométrica obteve grande influência sobre os principais parâmetros avaliados. Além disso, observou-se a influência de parâmetros relacionados ao lançamento de efluentes sobre a qualidade da água. Os resultados sugerem que o Rio Paraíba do Sul demanda maiores ações que promovam a melhoria da qualidade de suas águas, sobretudo quanto ao lançamento de efluentes. / The Paraíba do Sul River is considered one of the most important rivers of the Brazilian Southeast. It is located between the two major Brazilian cities: São Paulo and Rio de Janeiro. The water quality from this source is significantly impaired due to deforestation, misuse and occupation of the soil in urban and rural areas, use of agricultural inputs and the daily release of approximately one billion liters of domestic sewage. This situation is aggravated because only 21% of the effluent released in the basin is treated. The discharge of effluents rich in nutrients such as phosphorus and nitrogen, can contribute directly to the eutrophication process. The aim of this study was to evaluate the water and sediment quality, and determine the occurrence of potentially toxic cyanobacteria in the São Paulo stretch of the Paraíba do Sul River, between the cities of Aparecida, Guaratinguetá, Lorena and Cachoeira Paulista. Water and sediment samples were collected upstream and downstream in each municipality on August/13, November/13, February/14, May/14 and August/14. The variables evaluated were pH, temperature, conductivity, turbidity, DO, BOD, COD, total phosphorus, total nitrogen, solid series, fecal coliforms, chlorophyll-a and toxicity tests using Daphnia similis and Pseudokirchneriella subcapitata in the water. For the sediment, granulometry, organic matter, total phosphorus and toxicity tests were performed using D. similis and Chironomus xanthus. Water Quality Index (WQI) and Trophic State Index (TSI) of the water were calculated. Statistical analyses were applied: Grouping Cluster Analysis, Spearman Correlation and Principal Component Analysis (PCA). The results showed that DO, total phosphorus and fecal coliforms were not in accordance with the CONAMA resolution 357/05. Acute and chronic toxic effect were determined in water samples, during the rainy season, November/13 and February/14. A reduction of total phosphorus, total solids and BOD in the water, and total phosphorus and organic matter in the sediment was observed during this study. These reduced values can be related to implementation of sewage treatment plants in the cities of Aparecida and Cachoeira Paulista at the end of year 2013. The WQI was classified as \'Good\', except at downstream point of the municipalities of Aparecida and Guaratinguetá, classified as \'Regular\'. The TSI has shown that most of the points could be classified as \'mesotrophic\', except for the point downstream of Cachoeira Paulista, classified as \'oligotrophic\'. The main genera of cyanobacteria found were Borzia sp., Hapalosiphon sp., Johannesbaptistia sp., Leptolyngbya sp., Lyngya sp., Oscillatoria sp., Synechocystis sp. and Phormidium sp. From the statistical analysis, it was observed that rainfall had strong influence on the main parameters evaluated. Furthermore, the influence of parameters related to the discharge of effluents on water quality was observed. The results suggest that the Paraíba do Sul River demands more actions to promote the improvement of the quality of its waters, especially regarding the discharge of effluents.

O Rio Paraíba do Sul é considerado um dos mananciais mais importantes da região sudeste, uma vez que está localizado entre as duas maiores capitais brasileiras: São Paulo e Rio de Janeiro. A qualidade das águas deste manancial encontra-se bastante comprometida devido ao desmatamento, mau uso e ocupação do solo em áreas urbanas e rurais, uso de insumos agrícolas e pelo lançamento diário de aproximadamente um bilhão de litros de efluentes domésticos. Esta situação é agravada uma vez que apenas 21% do efluente lançado na Bacia do Rio Paraíba do Sul são tratados. O descarte de efluentes, ricos em nutrientes como fósforo e nitrogênio, pode contribuir diretamente no processo de eutrofização. O objetivo deste trabalho foi avaliar a qualidade da água e do sedimento no trecho paulista do Rio Paraíba do Sul, entre os municípios de Aparecida, Guaratinguetá, Lorena e Cachoeira Paulista, frente às variáveis físicas, químicas, biológicas e ecotoxicológicas, além de determinar a ocorrência de cianobactérias potencialmente tóxicas. Coletas de água e sedimento foram realizadas à jusante e montante de cada município nos meses de agosto/13, novembro/13, fevereiro/14, maio/14 e agosto/14. As variáveis avaliadas foram pH, temperatura, condutividade, turbidez, OD, DBO, DQO, fósforo total, nitrogênio total, série de sólidos, coliformes termotolerantes, clorofila-a e testes de toxicidade utilizando Daphnia similis e Pseudokirchneriella subcapitata para a água. Para o sedimento foram realizadas granulometria, matéria orgânica, fósforo total e testes de toxicidade utilizando D. similis e Chironomus xanthus. Foram calculados Índice de Qualidade das Águas (IQA) e Índice de Estado Trófico (IET) das águas do manancial. Análises estatísticas foram aplicadas: Grupamento de Cluster, Correlação de Spearman e Análise dos Componentes Principais (ACP). Os resultados mostraram que as variáveis OD, fósforo total e coliformes termotolerantes não estão de acordo com o estabelecido pela resolução CONAMA 357/05. Toxicidade aguda e crônica foi determinada nas amostras de água, sobretudo nos períodos chuvosos, novembro/13 e fevereiro/14. Observou-se uma redução ao longo do período avaliado de fósforo total, DBO e sólidos totais na água e fósforo total e matéria orgânica no sedimento. Estes valores podem estar relacionados a implantação de estações de tratamento de esgoto nos municípios de Aparecida e Cachoeira Paulista no final do ano de 2013. O IQA foi classificado como \'Boa\', exceto nos pontos referentes à jusante dos municípios de Aparecida e Guaratinguetá, classificados como \'Regular\'. O IET mostrou que a maioria dos pontos pôde ser classificada como \'Mesotrófico\', exceto pelo ponto referente ao final do trecho, jusante de Cachoeira Paulista, que foi classificado com \'Oligotrófico\'. Os principais gêneros de cianobactérias encontrados foram Borzia sp., Hapalosiphon sp., Johannesbaptistia sp., Leptolyngbya sp., Lyngya sp., Oscillatoria sp., Synechocystis sp. e Phormidium sp. A partir das análises estatísticas observouse que a precipitação pluviométrica obteve grande influência sobre os principais parâmetros avaliados. Além disso, observou-se a influência de parâmetros relacionados ao lançamento de efluentes sobre a qualidade da água. Os resultados sugerem que o Rio Paraíba do Sul demanda maiores ações que promovam a melhoria da qualidade de suas águas, sobretudo quanto ao lançamento de efluentes. / The Paraíba do Sul River is considered one of the most important rivers of the Brazilian Southeast. It is located between the two major Brazilian cities: São Paulo and Rio de Janeiro. The water quality from this source is significantly impaired due to deforestation, misuse and occupation of the soil in urban and rural areas, use of agricultural inputs and the daily release of approximately one billion liters of domestic sewage. This situation is aggravated because only 21% of the effluent released in the basin is treated. The discharge of effluents rich in nutrients such as phosphorus and nitrogen, can contribute directly to the eutrophication process. The aim of this study was to evaluate the water and sediment quality, and determine the occurrence of potentially toxic cyanobacteria in the São Paulo stretch of the Paraíba do Sul River, between the cities of Aparecida, Guaratinguetá, Lorena and Cachoeira Paulista. Water and sediment samples were collected upstream and downstream in each municipality on August/13, November/13, February/14, May/14 and August/14. The variables evaluated were pH, temperature, conductivity, turbidity, DO, BOD, COD, total phosphorus, total nitrogen, solid series, fecal coliforms, chlorophyll-a and toxicity tests using Daphnia similis and Pseudokirchneriella subcapitata in the water. For the sediment, granulometry, organic matter, total phosphorus and toxicity tests were performed using D. similis and Chironomus xanthus. Water Quality Index (WQI) and Trophic State Index (TSI) of the water were calculated. Statistical analyses were applied: Grouping Cluster Analysis, Spearman Correlation and Principal Component Analysis (PCA). The results showed that DO, total phosphorus and fecal coliforms were not in accordance with the CONAMA resolution 357/05. Acute and chronic toxic effect were determined in water samples, during the rainy season, November/13 and February/14. A reduction of total phosphorus, total solids and BOD in the water, and total phosphorus and organic matter in the sediment was observed during this study. These reduced values can be related to implementation of sewage treatment plants in the cities of Aparecida and Cachoeira Paulista at the end of year 2013. The WQI was classified as \'Good\', except at downstream point of the municipalities of Aparecida and Guaratinguetá, classified as \'Regular\'. The TSI has shown that most of the points could be classified as \'mesotrophic\', except for the point downstream of Cachoeira Paulista, classified as \'oligotrophic\'. The main genera of cyanobacteria found were Borzia sp., Hapalosiphon sp., Johannesbaptistia sp., Leptolyngbya sp., Lyngya sp., Oscillatoria sp., Synechocystis sp. and Phormidium sp. From the statistical analysis, it was observed that rainfall had strong influence on the main parameters evaluated. Furthermore, the influence of parameters related to the discharge of effluents on water quality was observed. The results suggest that the Paraíba do Sul River demands more actions to promote the improvement of the quality of its waters, especially regarding the discharge of effluents.

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