Impacts of acid mine drainage on a stream in subtropical China during a major flood event

Field and laboratory work was carded out to investigate the chemistry and ecotoxicity of stream water affected by acid mine drainage in a tributary catchment of the Pearl River in subtropical China during a major flood event that corresponded to a return period of 100 years occurred in the study area. The results indicate that stream water was affected by acid mine drainage from the Dabaoshan Mine at least to a distance of 25 km downstream of the mine water discharge point. It appears that sulfide-H^＋ from the waste rock dumps was readily available for discharging and the amount of H^＋ being transported outwards depended on the volume of out-flowing waters. However, there was a lag time for the discharge of the metals. This may be attributed to the slower release of metals, relative to H^＋, because it might take more time for the dissolution of heavy metal-bearing compounds. Fe, Zn and Al were the major metals of potential toxicity contained in the AMD-affected stream water, followed by Mn, Cu, Pb, As, Cd and Ni. Acute toxicity tests show that the AMD-affected stream water at 3.5 km downstream of the discharge point was highly toxic to the test organisms.

Impacts of acid mine drainage on a stream in subtropical China during a major flood event