To study the impact of changes in groundwater flow and chemistry on acidity export from sediments in acid mine drainage (AMD) polluted lakes, a column experiment was carried out. Schwertmannite rich sediment was subjected to three different flow rates (0, 5, and 20 L m(-2) a(-1)), two percolate chemistries (1/1 mmol L(-1) vs 10/15 mmol L(-1) sulfate/ferrous iron, pH 5), and DOC input (approxima...