Impact of mine pit lake on metal mobility in groundwater

Abstract

Open pit mines are potential source of metal contamination. Three types of open pit mines, i.e. copper, quartzite and granite were selected to understand the mobility and behaviour of metals. Metal contamination due to abandoned open pit copper mines (Average Cu = 64.57 ± 90 µg/L) is observed more comparative to quartzite (Average Cu = 20.42 ± 34.39 µg/L) and granite mines (Average Cu = 9.67 ± 7.94 µg/L). Acid mine drainage (AMD) from copper mines result in dissolution of metals and contaminates groundwater in the downstream direction. Correlation used for source assessment confirms the influence of anthropogenic or abandoned pit mine on metal concentration in groundwater. It is observed that the impact of abandoned pit mine is more compared to tailings and overburden dumps. Dissolution and precipitation process control the metal abundance in downstream groundwater. Precipitation dominates dissolution process with distance and results in decrease in metal concentration. It also confirms the self-neutralisation and self-attenuation capacity of the aquifer. The study recommends restoration of abandoned open pit mines to their natural conditions to avoid metal contamination in downstream.