GEOESPELEOLOGIA
URI permanente para esta coleçãohttps://bdc.icmbio.gov.br/handle/cecav/2
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Resultados da Pesquisa
Item Uso de traçadores corantes fluorescentes na identificação de rotas de fluxos em sistemas cársticos: panorama de estudos no Brasil(2024) Vieira, Matheus Santiago; Tavares, André Silva; Uagoda, Rogério Elias Soares; Assunção, PedroO transporte de poluentes por condutos cársticos é preocupante, visto que podem ocasionar a perda da biodiversidade aquática na contaminação dos recursos hídricos subterrâneos. Para a identificação e avaliação da origem e destino dos contaminantes e as interações entre fluxos superficiais e subterrâneos os traçadores do tipo corante fluorescente são amplamente usados em todo mundo. Logo, este trabalho teve como objetivo apresentar um panorama sobre a evolução metodológica do uso de traçadores corantes em sistemas cársticos e os principais avanços desses estudos no Brasil. Para isso foi realizada uma pesquisa bibliográfica com o método de análise exploratória quantitativa que contemplou análise de livros, periódicos, teses e dissertações nacionais e internacionais publicadas recentemente nos últimos 10 anos, disponíveis no Portal Periódicos CAPES, Web of Science e Google Scholar. Como resultado, foi possível identificar os avanços de novos instrumentos de campo e laboratoriais, softwares de modelagem específicos e novos traçadores. No Brasil, observou-se um crescimento no número de pesquisas, avanço importante para o melhor entendimento sobre os sistemas cársticos brasileiros. As avaliações sobre as rotas de fluxos subterrâneos permitiram identificar principalmente os limites entre bacias hidrogeológicas cársticas, obter parâmetros mais confiáveis de transporte de contaminantes, e compreender melhor sobre a hidrodinâmica de bacias cársticas no Brasil.Item Natural responses of Neoproterozoic dynamic karst springs to rainfall events, São Miguel Watershed, Minas Gerais, Brazil(2024-03-03) Marques, Tássia; Galvão, Paulo; Assunção, Pedro; Pandolf, Bruno; Marshall, Peter; Paiva, IsabelKarst aquifers consist of complex networks of conduits in which groundwater flows and recharge/discharge processes are generally more dynamic than in other types of aquifers. Due to their intrinsic heterogeneity and anisotropy, monitoring, quantifying, and analysing natural responses of karst springs is an efficient tool. Unlike Cenozoic and Mesozoic rocks, in Neoproterozoic karst systems, groundwater circulates and stores generally in dissolution features known as tertiary porosity, as the rock's primary porosity is recrystallized, considered negligible. This article studies the hydrodynamics of a karst portion of the São Miguel River basin, southwest of the state of Minas Gerais, Brazil. The region is predominantly composed of Neoproterozoic carbonate rocks, dating from about 570 to 540 million years ago. During a hydrological year (2019–2020), three karst springs (S1, S2, and S3) were daily monitored through their natural responses (variations of electrical conductivity, EC, temperature, T, and discharge, Q) to rainfall episodes. The data were interpreted based on the analysis of spring hydrographs, time series, recession curves (seasonal and intra-annual), and statistics of EC, T, and Q variations. The results show the three springs generally exhibit quick flow, typically karstic, in the case of hydrosystems with a well-structured and functional underground drainage network. The time series indicate the hydrosystem drained by S1 presents slower circulation and a lower degree of linearity, resulting from the higher sinuosity of the system, while the hydrosystems of S2 and S3 have similar behaviours, of quick water circulations immediately after a rainy episode. The degrees of karstification classify S1 and S2 as complex and extensive karst systems consisting of several subsystems, and S3 as a system in which the conduit network is more developed at the upper epiphreatic zone than near the outlet.Item Hydrodynamic and hydrodispersive behavior of a highly karstified neoproterozoic hydrosystem indicated by tracer tests and modeling approach(2023-04) Assunção, Pedro; Galvão, Paulo; Lucon, Thiago; Doi, Bruno; Fleming, Peter Marshall; Marques, Tássia; Costa, FelipeBrazilian Neoproterozoic carbonate rocks, dating from about 740–590 million years ago, contain the oldest karst-structured terrains on Earth, resulting in groundwater flow pathways in highly heterogeneous and anisotropic conduit networks. Unlike Paleozoic and Mesozoic rocks, in Neoproterozoic karst systems, groundwater circulates and stores practically through dissolution features characterized as tertiary porosity, as the rock’s primary porosity is recrystallized, considered negligible. However, studies using hydrodispersive equilibrium and non-equilibrium models to estimate flow and transport parameters to base the hydrodynamic behavior of these areas are not common. This paper proposes this, by a set of techniques involving dye tracer tests and the analysis of breakthrough tracer curves (BTCs) in a highly karstified Neoproterozoic terrain. For this, three karst springsheds, in the east, west, and south areas of the São Miguel river watershed, in Alto São Francisco karst region, Brazil, were choose and studied with dye tracer tests using Rhodamine WT and Uranine during dry and wet seasons, associated with regional/local (hydro)geological-structural, geomorphological, and speleological data. The results identified spatial and seasonal variations of water flow and transport parameters, recharge and discharge zones, and water dynamic and speleogenetic evolutions. BTCs models showed the karst systems are very dynamic with seasonal variations, and heterogeneities (bypass, loops and stagnant zones) control the variation of flow and transport parameters. The hydrodispersive parameters (mean flow velocity, and longitudinal dispersion coefficient) and coefficients of non-equilibrium models (partition, β, and mass transfer, ω) show a direct dependence on hydrogeological and speleogenetic contexts. Furthermore, the comparison with other karst systems around the world showed that Neoproterozoic karst has a more stable hydrodynamic behavior under hydrological conditions.