Abstract:
Brazilian mining ventures aged 30 years or older were studied, revealing historical oversights in environmental planning that have caused substantial environmental liabilities during active mining and decommissioning. Electrical resistivity tomography surveys were conducted in a decommissioning uranium mine in southeast Brazil. The results provided valuable insights into local hydrogeological dynamics, revealing the fow of acid mine drainage in two distinct systems: the porous waste rock pile and the fractured underlying crystalline basement. Geo-electrical sections displayed conductive anomalies indicating hydraulic connectivity between the waste rock pile and the underlying fractured aquifer through crystalline basement fractures. This connection was substantiated by sub-vertical zones of low electrical resistivity interpreted as groundwater infux from the porous system to the fractured aquifer. Consequently, the waste rock pile acted as a localized recharge zone for the regional aquifer, facilitating chemical exchanges between the two systems. Furthermore, the study successfully differentiated less impacted saturated zones (resistivity ≈80 Ω·m) from those associated with acid mine drainage (<40 Ω·m). Preliminary investigations identifed a complex fracture network in the study area, comprising two main fault systems with preferential NE and NW orientations, nearly orthogonal to each other. This fracture network demonstrated continuity, playing a fundamental role in sustaining fow within the local and regional drainage network.
Referência:
MOREIRA, César Augusto; GUIRELI NETTO, Leonides; BUCH, Fernanda Miranda de Siqueira; HANSEN, Marco Antônio Fontoura; MASQUELIN, Henri; LIMA, José Pedro Rebés. Using electrical resistivity tomography to understand the hydrogeological behavior of acid drainge percolation in a fractured aquifer at a uranium mining site. Mine Water and the Enviornment, Sept., 2024.
Acesso ao artigo no site do Periódico:
https://link.springer.com/article/10.1007/s10230-024-00998-y
