Hydrogeochemistry of mine, surface and groundwaters from the Sanggok mine creek in the upper Chungju Lake, Republic of Korea

The Sanggok mine used to be one of the largest lead-zinc mines in the Hwang gangri mining district, Republic of Korea. The present study characterizes the heavy metal contamination in the abandoned Sanggok mine creek on the ba sis of physico-chemical properties of various kinds of water samples (mine, surface and groundwater). Hydrochemistry of the water samples is character ized by the relatively significant enrichment of Ca2+, HCO3-, NO3- and Cl- in the surface and groundwater, whereas the mine water is relatively enrich ed in Ca2+, Mg2+, heavy metals, and HCO3- and SO42-. The more polluted mine water has a lower pH and higher Eh, conductivity and TDS values. The conce ntrations of some toxic elements (Al, As, Cd, Cu, Fe, Mn, Pb, Se, Sr, Pb an d Zn) are tens to hundreds of times higher in the mine water than in the un polluted surface and groundwaters. However, most immobile toxic pollutants from the mine drainage were quickly removed from the surface water by the p recipitation of Al and Fe oxyhydroxides. Geochemical modeling showed that p otentially toxic heavy metals might exist largely in the forms of MSO42- an d M2+ in the mine water. These metals in the surface and groundwaters could form M2+, CO32- and OH- complex ions. Computer simulation indicates that t he saturation indices of albite, alunite, anhydrite, chlorite, fluorite, gy psum, halloysite, and strontianite in the water samples are undersaturated and have progressively evolved toward the saturation condition. However, ba rite, calcite, chalcedony, dolomite, gibbsite, illite and quartz were in eq uilibrium, and only clay minerals were supersaturated. Ground and mine wate rs seemed to be in -equilibrium with kaolinite field, but some surface wate r were in equilibrium with gibbsite and seceded from the stability field of quartz. This indicates that surface water samples in reaction with carbona te rocks would first equilibrate with carbonate minerals, then gibbsite to kaolinite. Investigations on water quality and environmental improvement of the severely polluted Sanggok creek, as well as remediation methods on the possible future pollution of the groundwater by the acid mine drainage fro m the abandoned metal mines, are urgently required.