Dissertações em Oceanografia (Mestrado) - PPGOC/IG
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Navegando Dissertações em Oceanografia (Mestrado) - PPGOC/IG por Orientadores "ROLLNIC, Marcelo"
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Item Acesso aberto (Open Access) Desenvolvimento de modelo matemático para simulação de transporte de resíduo plástico em estuário amazônico.(Universidade Federal do Pará, 2024-05-28) SANTIAGO, Matheus Pamplona; BORBA, Thaís Angélica da Costa; http://lattes.cnpq.br/6210073723678433; https://orcid.org/0000-0001-8084-3128; ROLLNIC, Marcelo; http://lattes.cnpq.br/6585442266149471; https://orcid.org/0000-0002-8601-1514The increasing use of plastics has raised environmental concerns due to the persistence of these materials in marine ecosystems. It is estimated that trillions of pieces of plastic debris are currently in the oceans, with millions of additional tons entering annually through rivers and other terrestrial sources. There is a gap between models of plastic input to the oceans and field observations, indicating the need for more accurate approaches and simulations based on in-situ data. The Amazon Coastal Zone (ACZ) emerges as a hotspot for the accumulation of plastic waste, especially in vegetated areas close to large urban centers. Although several numerical models have been developed for the ACZ, none have addressed the transport of plastic waste to date. This pioneering study implemented the first mathematical simulation for plastic transport in an urban estuary on the Amazon coast, specifically in the Guajará Bay, using the urban river (Tamandaré river) as a release site due to the availability of in-situ data for plastic parameterization. The hydrodynamic model (D-Flow), validated by the LAPMAR environmental modeling group, and the water quality module (D-Waq), were implemented using the Delft-3D software. The results show that Guajará Bay is more sensitive to plastic contamination during the dry period, characterized by slow transport of water masses and a reduced capacity for renewal. In contrast, during the rainy season, the tendency is to export plastics, due to the system's greater capacity for renewal. The residence time of the waters of the Tamandaré River in the bay varies from approximately 8.28 days in the period of greatest discharge to 31.76 days in the period of lowest discharge, allowing us to estimate that the waste released by the Tamandaré can reach the Tropical Atlantic Ocean in a range of 36 to 63 days, depending on the seasonal season. The study concludes that Amazon estuaries dominated by positive asymmetric tides favor the import of waste during periods of lower flow and increase exports during periods of higher flow. Temporary plastic retention zones were observed in both seasonal periods for marginal regions of low energy and atypical morphology, such as the coastline close to the port of Belém (BG1) and the mouth of the Guamá River (RG). These retention zones are intensified in the dry season and attenuated in the rainy season, depending on local hydrodynamic variability. Although the study analyzed the dynamics resulting from the input of plastics in a single ebb tide, it did not consider the continuous flow and potential accumulation of plastics over time. This work represents an important initial step towards improving the understanding and methodology of plastics transport in the ACZ.Item Acesso aberto (Open Access) Investigação da influência antrópica na concentração de nutrientes inorgânicos dissolvidos no entorno da cidade de Belém-PA(Universidade Federal do Pará, 2022-08-30) PORTO, Yuri Paixão Santa Rosa; ROLLNIC, Marcelo; http://lattes.cnpq.br/6585442266149471; https://orcid.org/0000-0002-8601-1514Water is one of the most important natural resources, especially in the Amazon context. The disorderly population increase and consequent mismanagement of this resource causes worrying environmental changes in terms of its quality. According to the National Sanitation Information System - SNIS, the northern region of the country treats about 22.0% of the sewage generated and in the Metropolitan Region of Belém, below the national average, with 11.3% of sewage collection. The study area encompasses Guajará Bay and adjacent areas such as the Guamá and Acará rivers. Water collections were carried out during the rainy season (May), in 4 sections divided into left bank (ME), middle (M) and right bank (MD) with surface and bottom collections, every 4 hours for 13 hours to analyze the entire tidal cycle. Parameters were analyzed in situ (Temperature, pH, Eh, electrical conductivity, turbidity, OD, %OD and total dissolved solids) and in the laboratory (Silicate, phosphate, nitrate and nitrite), in addition to determining the intensity, speed and direction of the current. with the aid of an ADCP to obtain the flow and calculate the nutrient flow. The study area has some more remote places with little or no human influence throughout its extension, and others with untreated domestic and industrial effluent discharge points. The objective of this work is to investigate a possible anthropic contribution in the flow of dissolved inorganic nutrients from the water bodies that bathe the city of Belém-PA and surroundings. The Guamá River near the “alça viária” showed the lowest values of dissolved inorganic nutrients, unlike the Acará River which, despite its geographical distance from the RMB, showed the highest values of nutrient concentration. The mouth of the Guamá river had higher nutrient values on its right bank and the Guajará bay in its central portion, due to the influence of domestic and industrial waste. The Guamá river near the “alça viária” is relatively preserved, with a low concentration of dissolved inorganic nutrients, increasing only near its mouth, while the Acará presented higher values mainly due to the intense agricultural activity in the surroundings of its basin. The Guajará Bay, despite receiving discharges from the Acará and Guamá rivers, has lower nutrient values than the two locations, demonstrating its capacity for self-purification and dilution.Item Acesso aberto (Open Access) Modelagem tridimensional da hidrodinâmica e transporte sedimentar de um lago amazônico urbano(Universidade Federal do Pará, 2025-04-17) CALLADO, Marco Antônio Vieira; ROLLNIC, Marcelo; http://lattes.cnpq.br/6585442266149471; https://orcid.org/0000-0002-8601-1514Lakes are critical environments for sustaining human well-being, as they regulate local climate conditions, supply potable water, and underpin a wide range of ecosystem services. The continuous monitoring of these systems is essential for elucidating their metabolic processes and for informing effective management strategies for natural resources. This study aims to develop an environmental diagnosis and prognosis for a shallow Amazonian lake located in an urban area—Lago Água Preta—through the application of a three-dimensional numerical model of hydrodynamics and sediment transport. Numerical simulations were performed using the Delft3D-FLOW model, encompassing the region’s seasonal periods: wet and dry seasons. The simulations were driven meteorological variables and physical parameters of the lake, such as air temperature, humidity, cloud cover, solar radiation, bathymetry, water temperature, current velocity, and the inflow/outflow rates. This comprehensive dataset allowed for the construction of a computational environment capable of accurately representing the hydro-sedimentary processes within the lake Model calibration was performed using a one-month time series of water temperature from February (wet season), while validation was carried out with current data and vertical temperature profiles over four months (December, February, April, and June). The simulations presented good statistical indicators, demonstrating the model's reliability. The greatest discrepancies between simulation and observation occurred at points closer to the urban center. These differences are associated with the influence of anthropogenic activities, such as the discharge of domestic effluents, or with the narrow morphology of the lake in these areas, which can generate thermal shadow zones. The analysis of circulation and temperature patterns between seasonal periods revealed relatively small differences. Notably, there was an average increase of up to 2 °C in water temperature and approximately 0.02 m/s in current velocity during the warmer period. The most significant differences in average temperature occurred in the lake's daily cycle, varying by about 3°C, with a maximum variation of up to 10°C. Since the lake is fed by an artificial water inflow, this inflow is characterized by an intense discharge with a high sediment load. As it is a shallow lake with a maximum depth of up to 4 meters, this discharge is capable of influencing the lake’s entire metabolism by promoting the resuspension of bottom sediments and redistributing nutrients into the water column. Upon entering the lake, the inflow currents are rapidly decelerated, intensifying sedimentation near the inflow point. This process increases water turbidity and alters the local biotic dynamics, resulting in an environment dominated by phytoplankton and prone to eutrophication processes, which consequently reduce water quality. Therefore, based on the diagnosis provided by the modeling of Lago Água Preta, this study highlights the need for ongoing monitoring and control of anthropogenic influences to prevent the progressive degradation of the lake's metabolism. It also underscores the importance of lakes in general, especially when located in urban contexts.Item Acesso aberto (Open Access) Variabilidade sazonal e espacial da qualidade de água em dois lagos amazônicos: Água Preta e Bolonha, Belém, Pará, Brasil(Universidade Federal do Pará, 2025-04-04) ROMÃO, Cryssia da Costa; ROLLNIC, Marcelo; http://lattes.cnpq.br/6585442266149471; https://orcid.org/0000-0002-8601-1514Located in the Utinga State Park (PEUt), the Bolonha and Água Preta lakes are the main bodies of water that supply the Metropolitan Region of Belém (RMB) with drinking water through the Companhia de Saneamento do Pará (COSANPA), which is responsible for 75% of the supply to this population. Studying and understanding the hydrochemistry of these lakes is of fundamental importance, as environmental conditions and ecosystem services are directly related to the quality of the water in the lakes. The sources of input, such as pumping from the Guamá River, in natura effluent discharges and continental runoff from rainfall, require an enhanced sampling effort throughout the system. Therefore, the aim of this study was to analyze the water quality of the Bolonha and Água Preta lakes in order to identify sources of contamination and their effects on the ecosystem and public health. In order to understand and identify the physical-chemical processes and their interactions with anthropogenic activities, hydrodynamics and climate, monthly measurements were taken over 12 months at 20 points in Água Preta Lake and 4 points in Bolonha Lake. Samples were taken at 2 depths (surface and bottom) to obtain water temperature, pH, electrical conductivity, dissolved oxygen (DO), turbidity and total dissolved solids (TDS) using a HORIBA multi-parameter probe. Aliquots were separated for laboratory determination of the following parameters: ammonium, nitrite, nitrate, phosphate, nitrogen and total phosphorus, biochemical oxygen demand, thermotolerant coliforms, chlorophyll-a and total alkalinity. The measured data was statistically analyzed between points and seasonal stations, and the Trophic State Index (TSI) and Water Quality Index (WQI) were calculated.