GEOESPELEOLOGIA
URI permanente para esta coleçãohttps://bdc.icmbio.gov.br/handle/cecav/2
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Resultados da Pesquisa
Item Karst Hydrological Connections of Lakes and Neoproterozoic Hydrogeological System between the Years 1985–2020, Lagoa Santa—Minas Gerais, Brazil(2024-09-12) Pacheco Neto, Wallace; Paula, Rodrigo de; Galvão, PauloThis study focuses on a complex Brazilian Neoproterozoic karst (hydro)geological and geomorphological area, consisting of metapelitic–carbonate sedimentary rocks of ~740–590 Ma, forming the largest carbonate sequence in the country. At the center of the area lies the Lagoa Santa Karst Environmental Protection Area (LSKEPA), located near the Minas Gerais’ state capital, Belo Horizonte, and presents a series of lakes associated with the large fluvial system of the Velhas river under the influence, locally, of carbonate rocks. The hydrodynamics of carbonate lakes remain enigmatic, and various factors can influence the behavior of these water bodies. This work analyzed the hydrological behavior of 129 lakes within the LSKEPA to understand potential connections with the main karst aquifer, karst-fissure aquifer, and porous aquifer, as well as their evolution patterns in the physical environment. Pluviometric surveys and satellite image analysis were conducted from 1984 to 2020 to observe how the lakes’ shorelines behaved in response to meteorological variations. The temporal assessment for understanding landscape evolution proves to be an effective tool and provides important information about the interaction between groundwater and surface water. The 129 lakes were grouped into eight classes representing the hydrological connection patterns with the aquifers in the region, with classes defined for perennial lakes: (1) constantly connected, (2) seasonally disconnected, and (3) disconnected; for intermittent lakes: (4) disconnected during the analyzed time interval, (5) seasonally connected, (6) disconnected, (7) extremely disconnected, and (8) intermittent lakes that connected and stopped drying up. The patterns observed in the variation of lakes’ shorelines under the influence of different pluviometric moments showed a positive correlation, especially in dry periods, where these water bodies may be functioning as recharge or discharge zones of the karst aquifer. These inputs and outputs are conditioned to the well-developed karst tertiary porosity, where water flow in the epikarst moves according to the direction of enlarged karstified fractures, rock foliation planes, and lithological contacts. Other factors may condition the hydrological behavior of the lakes, such as rates of evapotranspiration, intensity of rainfall during rainy periods, and excessive exploitation of water.Item Natural Hydrogeochemical Background Levels in the Carste Lagoa Santa Protection Unit, Minas Gerais, Brazil(2021-01) Aragão, Frederico; Velásquez, Leila Nunes Menegasse; Galvão, Paulo; 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-, SO42, 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.- Natural Hydrogeochemical Background Levels in the Carste Lagoa Santa Protection Unit, Minas Gerais, Brazil(2020-11-05) Aragão, Frederico; Velásquez, Leila Nunes Menegasse; Galvão, Paulo; 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, SO42, Clto 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 indi-cating 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 car-bonate aquifer units from the impure ones.
- Natural Hydrogeochemical Background Levels in the Carste Lagoa Santa Protection Unit, Minas Gerais, Brazil(2021-01) Aragão, Frederico; Velásquez, Leila Nunes Menegasse; Galvão, Paulo; 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−, SO42, 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.