Variation of Cu and Zn Fractionation and Mobility in Mine Tailing Soil Due to Experimental Leaching

The aims of this paper were to assess the variation of heavy metal (Cu and Zn) fractions and mobility in abandoned metal mine soil due to batch experimental leaching. Four solutions with different pH levels were used in the experiments. The total and fractional concentrations of heavy metals in untreated and leached soils were determined. The Kruskal–Wallis test was applied to verify the differences in the Cu and Zn distribution in soils before and after leaching. In order to assess the mobility of heavy metals, mobility factors (MFs) were calculated. The research results showed that the original/untreated soil was mainly of a sandy texture and acidic in character. After batch leaching for 7 days, the distribution of heavy metals was dominant in the residual fraction (F5). Heavy metal fractions in F1, F2, F3, and F5 showed a decreasing trend, but an increasing trend in F4 was observed. Among the solutions applied having different pH values, HCl (pH 3) illustrated the strongest effect on decreasing heavy metals in short-term mobile fractions (F1 and F2). The MF of Zn decreased more than that of Cu after 7-day batch leaching.