Geochemical Control of Acid Mine Drainage in Abandoned Mines: The Case of Ermioni Mine, Greece

AbstractAcid mine drainage is an extensively documented environmental issue, commonly originated by the weathering of sulfide ores both in active and abandoned mining sites. Even though national and international regulations obliged mining companies to handle this problem in active mines, in the abandoned ones it is usually regarded as a major environmental thread. Natural attenuation is a term that is used to describe a combination of in situ physical, chemical and biological processes that under some specific conditions, act without human interventions in order to reduce the mass, toxicity, mobility and concentration of metals in soil or groundwater” (USEPA, 1999). For those processes, the local lithology may plays a key role, when contributing to an alkaline environment, consequent the precipitation of metals in the form of hydroxides. Despite of the fact that in Ermioni, Greece, a mixed sulfide ore mine had been operational since 1928, it has been abandoned after 1978 and no restoration actions have been implemented. Dispersed ore tailings have been deposited near the galleries, being exposed to atmospheric conditions. Soil and mine-water samples were collected from the region of that abandoned mine. The soil was collected from tailings at superficial points near the mining galleries, while water was sampled from canals, which drain from the mining galleries to the nearby Roros River. The mineralogical composition of the soil samples was studied by X-ray Diffraction Spectroscopy and Scanning Electron Microscopy, while Flame Atomic Adsorption Spectroscopy was applied for the determination of the Fe, Zn, Cd, Cu, Pb, Mn, Ni, Co, Cr and Hg concentrations in the water samples