Lime and pig manure as ameliorants for revegetating lead/zinc mine tailings: a greenhouse study

Abstract

The Lechang lead/zinc mine is located at the north of Guangdong Province in southern China. The residual tailings from the extraction of lead/zinc ores were permanently stored in tailings ponds which required revegetation to reduce their impact on the environment. Therefore, a greenhouse study was conducted to evaluate the effects of lime (0.5, 1.0, 2.0 and 4.0 t ha −1) and pig manure (12.6, 25.2, 37.8, 50.3 and 75.5 t ha −1) amendment on the revegetation of the Pb Zn mine tailings using Agropyron elongatum (tall wheatgrass) and Trifolium repens (clover). The results showed that the applications of lime or pig manure increased pH, reduced electrical conductivity (EC) and DTPA-extractable concentrations of Zn, Pb and Cd in the tailings. Compared with tailings without amendment, application of lime alone (2 t ha −1) did not improve growth of either species. However, using lime with supplemental fertilizer (150 kg ha −1 of N) improved shoot growth of A. elongatum, especially at lime amendment rates of 0.5 and 4.0 t ha −1 + 150 kg ha −1 of N, but it did not improve root growth of either plant species. When compared with the tailings amended with lime (2 t ha −1) only, tailings receiving pig manure (25.2–50.3 t ha −1) and 2 t ha −1 of lime effectively improved shoot and root growth and reduced tailings toxicity to seedlings of T. repens, especially at 50.3 t ha −1 of pig manure. However, only tailings receiving 37.8 t ha −1 of pig manure and 2 t ha −1 of lime significantly increased shoot and root dry weight of A. elongatum. Plant tissue analysis showed that applications of lime and pig manure did not significantly reduce Zn, Pb and Cd uptake and accumulation in A. elongatum. However, higher pig manure amendment rates (> 25.2 t ha −1) significantly reduced Pb content in shoots of T. repens.