Environmental risks related to groundwater contamination from coal mining waste disposal and reuse

摘要

Chemical composition of pore solutions along vertical profiles of coal mining waste dumps could be a problematic due to the generation of Acid Rock Drainage (ARD) containing high concentrations of sulfates. This kinetically defined process induced by sulfide oxidation results in a long-term contamination of the groundwater with high sulfate loads and potentially toxic elements (metal ions) at low pH (mainly Mn<'2+>, Fe<'2+>, Al<'3+>, Ni<'2+>, Zn), lasting for decades. Despite of relatively low concentrations of most trace metals in coal mining waste comparable to the natural concentrations in soils and precipitation of Fe(OH)<,3> in oxidized conditions, the extensive release of sulfate at all pH values and trace elements at acidic pH to the pore solution resulting in the deep deterioration of groundwater down gradient of the studied dumps and polder bank constructed of coal mining waste has been observed.