Geochemical and eco-toxicological characteristics of stream water and its sediments affected by acid mine drainage

In assessing the adverse effects of acid mine drainage (AMD), the chemistry of AMD and stream water (i.e., pH and toxic metal concentrations) has been accounted as important monitoring parameters and its characteristics are regulated in many countries. Yet for the precise evaluation of eco-toxicological effect on AMD receiving streams, a more comprehensive evaluation parameter has to be recognized as a mandatory parameter. In this study, eco-toxicological correlations between chemical properties of water and sediments collected from an AMD receiving stream were investigated at an abandoned mine site in Korea. The stream water in the AMD watercourse near the mine adit that is highly acidic and contains high concentrations of heavy metals, has been neutralized as the AMD became diluted with nearby natural stream water. The toxicity of stream water showed a relatively strong correlation with the pH and dissolved metal concentrations of water implying the toxic effects of stream water on its stream biota. In contrast, the toxicity results obtained from stream sediments hardly showed close correlation with the composition of toxic elements, particularly with enriched arsenic.