http://www.bdtd.uerj.br/handle/1/3704 2026-04-16T11:13:00Z http://www.bdtd.uerj.br/handle/1/24934 Título: Previsão da maré meteorológica com rede neural aplicada à estimativa do nível do mar na Baía de Guanabara – RJ Autor: Borba, Eduarda Pinto Primeiro orientador: Filippo, Alessandro Mendonça Abstract: Sea level (SL) in coastal regions is affected by several meteorological and oceanographic factors, especially in the southern and southeastern regions of Brazil. Conventional forecasting, based only on the astronomical tide, disregards variations induced by forcings of non-astronomical origin, which can generate significant deviations from SL. In this study, we propose the use of a recurrent Long Short-Term Memory (LSTM) neural network to predict the Meteorological Tide (MT) in Guanabara Bay - RJ and to estimate the SL from the sum of the astronomical and meteorological components. Wind and Mean Sea Level Pressure data from the ERA5 reanalysis were used at four points on the Brazilian coast, in addition to sea level data provided by the Brazilian Navy. The MT was obtained by the difference between the observed level and the predicted astronomical tide and was subsequently filtered in the 3.1 to 31.5-day band. The model had its architecture and hyperparameters optimized through the Random Search method. The prediction of MT with the LSTM network showed good performance, with a correlation coefficient (r) of 0.84 and RMSE of 6.5 cm. The reconstruction of the entire times series, with the sum of the astronomical tide to the MT predicted by the network, reduced the error by 43% compared with conventional forecast, with an r of 0.97 and RMSE of ~8 cm. The results highlight the potential of LSTM to improve short-term coastal forecasts and enhance forecasting accuracy in higher energy events. Instituição: Universidade do Estado do Rio de Janeiro Tipo do documento: Dissertação 2025-08-27T00:00:00Z http://www.bdtd.uerj.br/handle/1/24903 Título: Elementos-traço (Hg, Ag, Se) em toninhas (Pontoporia blainvillei) do Sudeste do Brasil Autor: Carvalho, Beatriz Lessa Marinho de Primeiro orientador: Brito Junior, José Lailson Abstract: The franciscana (Pontoporia blainvillei) is a small cetacean considered as the most endangered dolphin species in the South Atlantic. Anthropogenic activities, such as contamination by trace elements, contribute intensively and progressively to the population decline and habitat degradation of this species. In this context, the aim of the present study was to measure THg, Ag, and Se concentrations in muscle and liver of 49 Pontoporia blainvillei specimens using the atomic absorption spectrometry method. Additionally, hepatic molar ratios of Se:THg and Se:THg + (0.5 × Ag) were calculated to infer the detoxification processes of Hg and Ag, mediated by Se, an essential element for the performance of physiological activities. Tissue samples were obtained from individuals stranded or incidentally captured along the coasts of Espírito Santo, Rio de Janeiro, and São Paulo, Brazil, between 2015 and 2023. These states host three franciscana populations, classified as Franciscana Management Areas (FMA) Ia, IIa, and IIb, respectively. Liver showed the highest concentrations of THg and Se in all populations and of Ag in FMAs Ia and IIb (Wilcoxon, p < 0.05). Specimens from FMA IIa, a recently monitored and poorly studied population, exhibited significantly higher levels of THg in muscle and liver and of Se in muscle according to the Generalized Linear Model. Conversely, FMA IIa displayed the lowest Ag concentrations in both tissues, while the highest Se concentrations in the liver were recorded in individuals from FMA IIb. The expected molar ratio of Se:THg in the liver of marine mammals for an efficient detoxification process is 1. However, all populations analyzed in this study presented ratios exceeding this agreed value. Notably, individuals from FMA IIb exhibited the highest values, suggesting a substantial excess of Se that could potentially play a role in detoxifying other unknown toxic elements. This study is the first to analyze Ag concentrations in franciscana muscle and provides new insights into the dynamics of toxic element detoxification mediated by Se in this species. Instituição: Universidade do Estado do Rio de Janeiro Tipo do documento: Dissertação 2025-02-25T00:00:00Z http://www.bdtd.uerj.br/handle/1/24813 Título: Variação de curta escala temporal do fitoplâncton no setor leste da Baía de Sepetiba e Canal de Guaratiba (RJ) Autor: Kirsten, Fabiana Vasconcelos Primeiro orientador: Moser, Gleyci Aparecida Oliveira Abstract: Estuarine systems are characterized by transient hydrographical and biological gradients, influenced by both short-term and mesoscale phenomena. Tides generally induce short-term variations, causing both vertical and horizontal water column mixing. Mesoscale processes, such as the intrusion of shelf water masses due to coastal upwelling, may promote phytoplankton development in coastal systems. The study sites, the Eastern Sector of Sepetiba Bay and Barra de Guaratiba Channel, stand for growing eutrophication and lack of studies on phytoplankton community. This study aims to investigate phytoplankton structure and dynamics focusing potentially harmful species in the Eastern Sector of Sepetiba Bay and Barra de Guaratiba channel. The methodological approach assesses phytoplankton community variation considering oceanographic variables in two complete tidal cycles. Two campaigns (summer and winter) were performed, considering mesoscale processes, such as the presence of the South Atlantic Central Water (SACW). Sampling was carried out in two moorings simultaneously, one in the Eastern Sector of Sepetiba Bay (BS) and another in Barra de Guaratiba Channel (BGC). The occurrence of SACW was already reported in literature from the main entrance of Sepetiba Bay to Guaíba Island, however its presence in CBG was recently reported in the studies coming from the research projects in which this dissertation is included. The SACW lead to changes in the phytoplankton community structure, increasing diatom contribution in the CBG associated with the intrusion of this water mass, while dinoflagellates and flagellates were associated with the Coastal Water (CW). Considering the Intermediate Disturbance Hypothesis (IDH), episodes of higher disturbances occurred in CBG with SACW intrusion and tidal currents reversals during summer campaign; and with rainfall events and higher current speeds in the winter sampling. Intermediate disturbance situations with greater species richness and diversity occurred in both BS and BGC, associated with temperature variations and suspended particulate matter (SPM) supply, influenced by tidal channels. The potentially harmful species Prorocentrum lima and diatoms of the complex Pseudonitzschia delicatissima were observed in low densities in CBG, during tidal currents inversions, while the dinoflagellate D. acuminata occurred in BS during both campaigns. The occurrence of potentially harmful algae in the study area, related to CW influenced by the tidal channels, is note worth and deserves a monitoring program for this area of fishing, mariculture and recreation activities. Instituição: Universidade do Estado do Rio de Janeiro Tipo do documento: Dissertação 2016-03-28T00:00:00Z http://www.bdtd.uerj.br/handle/1/24683 Título: Histórico das fontes da matéria orgânica através da determinação de hidrocarbonetos e esteróis em testemunho sedimentar do manguezal da lagoa de Itaipu, Niterói – RJ Autor: Ferreira, Tatiane Vidal Primeiro orientador: Farias, Cássia de Oliveira Abstract: On the coast of the state of Rio de Janeiro, mangrove forests are found associated with major coastal systems, which have been influenced by diverse human activities. Mangroves are considered deposition environments where there is naturally high organic matter production, and conditions favor its preservation regardless of its allochthonous and/or autochthonous origin. The pressures of urban occupation combined with rapid economic development are responsible for potential alterations in the flows of natural or non-natural organic material in this environment. Therefore, monitoring the quality of this environment is necessary given its significant ecological and socioeconomic importance. One way to determine the presence of pollution in these environments is through geochemical organic markers, such as hydrocarbons and fecal sterols. This study aims to evaluate the origin of organic matter through the distribution of molecular markers, polycyclic aromatic hydrocarbons (PAHs), and fecal sterols (EFs), as well as the elemental composition of carbon (Corg) and total nitrogen (NT) in a sediment core from the mangrove adjacent to Itaipu lagoon. One sediment core was collected from the mangrove of Itaipu lagoon (Niterói, RJ) for the determination of elemental markers (carbon and nitrogen) and molecular markers (PAHs and sterols). Another core was used for determining the fines content and dating using 210Pb gamma spectrometry. Identification and quantification were performed using gas chromatography coupled with mass spectrometry (EPA 8270D). The concentrations of Corg and NT were determined using dry combustion in an elemental analyzer. The use of the CRS model resulted in an average sedimentation rate of 0.55 cm per year, indicating an increase in sedimentation rate in the 1980s and late 2000s. The Corg concentration ranged from 1.4% to 14.5%, and NT from 0.15% to 1.05% along the sediment core, with a median fines content of 77%. The C/N ratio showed variability along the core, with values oscillating between 6 and 20. The results indicate that the sediment in the Itaipu mangrove is composed of organic matter of terrestrial and marine origin, suggesting that its distribution may result from the hydrodynamics of the Itaipu-Piratininga lagoon system, river and stream runoff in the region, and mangrove forest production. Analyzing the diagnostic ratios of PAHs, a predominance of combustion sources and/or mixed sources is observed for this system. Fecal sterols, on the other hand, showed concentrations ranging from 0.22 to 6.30 μg.g-1 (median of 1.51 μg.g-1). There is evidence of low to moderate fecal contamination, probably due to the significant influx of domestic effluents from the expansion of urban density in the coastal region, where sewage treatment infrastructure does not reach informal settlements. Additionally, the profile demonstrated an increase in anthropogenic organic matter sources from the 1970s, the year of the construction of the Rio-Niterói bridge. Thus, a more significant influx of these compounds was observed in recent decades, reflecting the increase in PAH concentrations and the presence of compounds from domestic sewage. Instituição: Universidade do Estado do Rio de Janeiro Tipo do documento: Dissertação 2023-08-28T00:00:00Z