Percentage of As, Co, Cr, Cu, Fe, Mn, Ni, and Zn extracted in each step of the sequential extraction procedure. Fraction 1: exchangeable and associated with carbonates; Fraction 2: associated with easily and moderately reducible iron and manganese oxyhydroxides; Fraction 3: associated with SOM and sulfides; Fraction 4: aqua-regia extractable residual fraction. Locations: 1 and 2 in Tailings (T); 3, 4, 5, 6, 7, and 8 in Near area of the mine (N); 9, 10, 11, and 12 in Far area of the mine (F)