DEGEO - Departamento de Geologia
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/8
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Resultados da Pesquisa
Item Natural hydrogeochemical background levels in the carste Lagoa Santa protection unit, Minas Gerais, Brazil.(2021) Cardoso, Frederico Aragão; Velásquez, Leila Nunes Menegasse; Galvão, Paulo Henrique Ferreira; Vieira, Luísa CostaThe identification of hydrogeochemical anomalies in karst water resources represents a crucial step in Brazil’s water management plans. Accelerated urban and industrial development occurs in the region that includes the Carste Lagoa Santa Protection Unit, State of Minas Gerais, which may negatively impact its water quality. This paper establishes Natural Background Levels (NBL) of waters collected from deep tubular wells and springs for Si4+, Ca2+, Mg2+, Na+, K+, HCO3 − , SO4 2 , Cl− to understand sources of possible geogenic and anthropogenic anomalies. Areas with surpassed thresholds were compared with geological, hydrogeochemical, and land use data. Every parameter, except for chloride, showed elevated concentrations due to lithologic origin. The NBLs for waters of wells and springs are, respectively, 17.9 and 12.7 mg/L (silica), 97.0 and 91.5 mg/L (calcium), 4.9 and 2.9 mg/L (magnesium), 6.2 and 3.8 mg/L (sodium), 1.0 and 0.3 mg/L (potassium), 285.5 and 254.6 mg/L (bicarbonate), 9.4 and 13.6 mg/L (sulfate). Chloride, analyzed only in groundwater, presented 6.7 mg/L indicating a possible influence of upstream urban areas of Lagoa Santa and Pedro Leopoldo municipalities. Volatile and Semivolatile Organic Compounds were also analyzed, but all of them were below the detection limit. This work is important to comprehend the NBL of major elements, reveal geogenic anomalies, and distinguish carbonate aquifer units from the impure ones.Item An approach to map karst groundwater potentiality in an urban area, Sete Lagoas, Brazil.(2020) Gomes, Rafael Magnabosco de Almeida; Galvão, Paulo Henrique Ferreira; Carvalho, Ana Maciel deDue to complex hydrogeological contexts, mapping groundwater potential zones in karst regions is a difficult task. This study was conducted on a karst terrain in Sete Lagoas, Brazil, where rapid urban growth without adequate water resources management resulted in the drilling of unproductive wells and possible aquifer over-exploitation due to the concentration of wells. The objective was to develop a method for mapping groundwater potentiality for karst aquifers, serving as water resources management tool, based on 3D geological modelling, field work and pumping test data, remote sensing, geophysics analysis and production of thematic maps, resulting in the hydrogeological conceptual model. The groundwater potentiality map showed that most potential zones are on the central area, limited by grabens, where limestones are in contact with unconsolidated sediments, on areas with higher density of morphostructural and geophysical lineaments, mainly in east–west and north–east directions, near karst surface features, on thicker karstified zones, with higher recharge rates.Item Recharge sources and hydraulic communication of karst aquifer, São Miguel watershed, MG, Brazil.(2020) Lucon, Thiago Nogueira; Costa, Adivane Terezinha; Galvão, Paulo Henrique Ferreira; Leite, Mariangela Garcia Praça; Madeira, Thiago José Augusto; Nogueira, Leonardo BrandãoThe main public water supply in the São Miguel watershed (MG, Brazil) comes from a well-developed karst region, where information about hydraulic communications between caves entrances, sinkholes, recharge and discharge areas are still unknown. The study aims to identify regional hydrogeological processes describing groundwater hydrochemical evolution, interactions between meteoric, surface and ground waters, recharge and discharge sources, and possible hydraulic communications for proper management of water resources. Geophysical data were analyzed and water samples (meteoric, surface, and groundwater) throughout the watershed were collected for stable isotopes (18O and 2 H) and major ions analyzes. Results indicated strong influences of regional geological structures in the karst water flow directions; high concentrations of major ions in the central region of the watershed are common; karstification processes and aquifer recharge are more active during the rainy season, while in the dry season the watershed is supplied by groundwater.Item Natural background levels and validation of the assessment of intrinsic vulnerability to the contamination in the Carste Lagoa Santa Protection Unit, Minas Gerais, Brazil.(2020) Cardoso, Frederico Aragão; Velásquez, Leila Nunes Menegasse; Galvão, Paulo Henrique Ferreira; Tayer, Thiaggo de Castro; Lucon, Thiago Nogueira; Azevedo, Úrsula Ruchkys deThe contamination of karst aquifers by anthropogenic activities causes a major issue regarding environmental policies, since they present high sensitivity, influenced by unique features such as dolines, swallow holes, and conduits. This paper is focused on the Carste Lagoa Santa Protection Unit, MG, Brazil, and presents three main objectives: to determine the natural background levels of chloride, nitrate, sulfate, and phosphate; to indicate the locations where the concentrations of those parameters exceed the natural background levels in the existing vulnerability map and, finally, to determine the proportion of the areas (in percentage) where this surpassing occurs, according to the vulnerability classes (high, moderate and low). Results have shown values (90th percentile) of 2.4 mg/L, 1.0 mg/L, 5.3 mg/L, and 0.1 mg/L, for Cl−, NO3−, SO4−2, and PO4−3, respectively, indicating that for all four parameters, there were areas (mainly distributed within moderate vulnerability portions) where the values were surpassed, which suggests anthropogenic activity due to the presence of urban settlements and agricultural activities. Therefore, the proposal of natural background levels was essential to understand the hydrochemistry of the studied region.