Characteristics of hydrochemical variations and contaminant load during rainfall in an acid mine drainage-impacted watershed, Korea

Abstract

Acid mine drainage (AMD) refers to the outflow of acidic water from usually abandoned metal mines. Since AMD is closely related to the rainfall-runoff process, it is important to monitor rainfall events for its characterization. This work aims to study the characteristics of hydrochemical variations of metals during rainfall in the Geopung Mine Watershed, Korea. Eleven dry-weather and five rainfall event monitorings were conducted in 2010 at two locations (GP-1 and GP-2). At GP-1, concentrations significantly increased during the fifth event, which was the largest one (As from 0.0003 to 0.0046mg/l; Cd from 0.0114 to 0.2188mg/l; Cu from 0.0206 to 3.1512mg/l; Pb from 0.0006 to 0.1857mg/l; Zn from 0.5823 to 15.9194mg/l; Ni from 0.0011 to 0.0294mg/l). Similar though less-marked trend of increase in metal concentration was found at GP-2 during the fifth rainfall event. As for the load, as much as 62-97% of the annual metal loads were accounted for by rainfall at GP-1 and GP-2. This pattern implies that most of the metals in AMD are brought into the stream by rainfall.