Influence of Heavy Metals and Soil Amendments on Vetiver (Chrysopogon zizanioides) Grown in Zinc Mine Soil

Abstract

Soil amendments, such as compost and chelating agents, are often required to improve phytoremediation efficiency. In this study, the Ratchaburi vetiver ecotype was grown in soil uncontaminated by heavy metal and in zinc mine soil amended with compost and chelating agents (EDTA and DTPA). It was found that the concentration of Zn in the mine soil was about 5.6 times higher than the toxic level in soil. It inhibited vetiver growth as well as causing leaf chlorosis which was a symptom of either Zn toxicity or iron deficiency. The application of compost had no influence on growth performance, primary nutrient uptake and heavy metal uptake. EDTA could enhance the concentration and uptake of Zn, Mn and Cu, but not Fe, while DTPA increased the concentration of these heavy metals, but not their uptake. The compost and chelating agents did not affect Mn or Zn translocation. However, they could elevate Fe and Cu translocation, especially when compost was applied together with chelating agents of which EDTA and DTPA gave significantly-different results. In summary, EDTA was superior for soil amendment in a zinc mine soil with high concentrations of multi-heavy metals.