Geochemical control of Acid Mine Drainage in abandoned mines: The case of Ermioni Mine, Greece

Acid mine drainage is an extensively documented environmental issue, commonly originated by the weathering of sulfide ores both in active and abandoned mining sites. Despite regulations mandating mining companies to manage this problem, the situation in abandoned mines poses a significant environmental threat. This study investigates the natural attenuation processes that occur in the abandoned Ermioni Mine in Greece, operational since 1928 and abandoned in 1978. Soil and mine-water samples were collected near the mining galleries, where dispersed ore tailings are exposed to atmospheric conditions. We assessed the mineralogical composition of the soil samples using X-ray Diffraction Spectroscopy and Scanning Electron Microscopy to understand the impact of local lithology on alkalinity and consequent metal precipitation. The results indicate that the local lithology plays a crucial role in contributing to an alkaline environment, which promotes the precipitation of metals as hydroxides. The findings highlight the environmental risks associated with abandoned mines and emphasize the importance of understanding natural attenuation to mitigate acid mine drainage effects.