The shoots of common reed grown in the tailings that received higher amounts of manure compost and sewage sludge had significantly lower (p ⩽ 0.05) Cu and Pb contents than those grown in control tailings ( Table 7). Concentrations of Cu and Pb in the roots of common reed also showed a significant decrease (p ⩽ 0.05) after the application of manure compost or sewage sludge, except for the treatment with 10% manure compost (PZM10) ( Table 7). Common reed accumulated significantly higher Zn in its shoots when grown in PZS10, PZM + F, and PZS10 + F substrata than that of grown in control tailings (PZ)( Table 7). In general, the addition of manure compost or sewage sludge to tailings reduced the uptake of Cu and Pb in the shoots and roots of both plant species.
Concentrations of Cu, and Zn in the shoot and root tissues of both plant species grown in Cu tailings that were amended with manure compost were similar (Table 8). Vetiver tended to accumulate higher concentrations of Zn and Cu in shoots when treated with higher amounts of sewage sludge. The shoots of vetiver and common reed that were grown in the tailings that received more than 10% of sewage sludge (CuS10) had significantly higher (p ⩽ 0.05) Cu and Zn concentrations than those grown in tailings with 2.5% of sewage sludge (CuS2.5).