Hydrogeochemical characteristics of acid mine drainage along the Daduk creek in the vicinity of the abandoned metal mine, Korea

摘要

Acid mine drainage discharged from the abandoned tailings in the Daduk mine has a pH of 3.3, and concentrations of Al, Mn, Fe, Zn and SO_4 of 18, 41, 45, 38 and 1940 mg/L, respectively. In particular, As concentration in acid mine drainage is 1,000  250L蘥/L. Removing order of metal ions normalized by SO_4 concentration downstream from discharge point is Fe > As > Al > Cu > Zn > Mn > Cd > Pb. This indicates that in the Daduk creek, concentrations of Fe, As and Al are decreased by the formation of precipitates as well as dilution, but concentrations of heavy metals except these ions by mainly dilution. From the results of geo-chemical modeling using the Phreeq C program, goethite (FeOOH) is oversaturated, and schwertmannite (Fe_8O)_8(OH)_(4.5)(SO_4)_(1.75)) is the most stable solid phase at low pH in the Daduk creek. Thus, yellowish red (orange ochre) precipitates occurred in the study area seem either to be goethite or schwertmannite. In case of water samples with white precipitates, the positive saturation indices of gibbsite (Al(OH)_3) and basaluminite (A1_4(SO_4)(OH)_(10)*5H_2O) indicate possible precipitation.