Geochemistry of stream water and sediment collected in the vicinity of the Donghae coal mine in the Samchuk coalfied were investigated in order to evaluate the environmental impacts of acid mine drainage. The pH of stream water ranges from 2.85(at 2 km away from the mine) to 7.92(at uncontaminated tributary). The main cation and anion species in the upper stream are Ca2+ and SO42-, respectively. The level of pH and the amount of HCO3- in stream water increase to the downstream and where uncontaminated small tributaries are joining, and in the area covered with limestone. From the results of thermodynamic caculation, the main forms of iron in stream water are estimated as Fe2+ and FeSO0, and most of them could be precipitated as FeO(OH) with increase of pH. The white precipitates in stream sediments particularly found around the coal mine are proved to be Al(OH)3 by XRD and XRF analysis. As a result of investigation for seasonal variation of AMD, the level of pH decreased and conductivity increased in dry season.
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