A multidisciplinary characterization of a tailings pond in the Linares-La Carolina mining district, Spain

Abstract Geochemical and geophysical techniques have been applied to investigate the potential environmental impact of the abandoned La Aquisgrana mine tailings, one of the most important sulfide-bearing tailings ponds of the Linares-La Carolina mining district (Spain). The geometry of the pile has been defined through geological field work and electrical resistivity imaging (ERI) surveys. The ERI profiles revealed the position of the bedrock surface below the tailings central area (more than 40 m in thickness) and helped in placing drill core sampling for geochemical analysis and a piezometer installation. In the 21 extracted samples, the total content of Pb, Zn, Cu, Fe, Mn, Sr, Rb and As were determined, with significant values being found for Pb and Zn (> 2000 mg kg − 1 ), Mn (> 700 mg kg − 1 ) and As (> 170 mg kg − 1 ). Although AMD has not been identified, water samples from the saturated zone of the tailings are characterized by elevated dissolved sulfate (2495 mg L − 1 ), Fe (20 mg L − 1 ), Mn (16 mg L − 1 ) and Zn (7 mg L − 1 ) contents, with an E.C. value of 3.3 mS cm − 1 and pH from 5.6 to 6.9, suggesting a process of metal mobilization. Physical and chemical data obtained from drill core and groundwater samples were combined with the electrical resistivity profile of the tailings to characterize areas with higher metal concentrations. A central low resistivity area (