Effect of different planting years of Vetiveria zizanioides L. on the distribution of heavy metals in coal spoil-heap soil

Vetiveria zizanioides L. were planted on the coal spoil-heaps in Dahe coal mine located at Liupanshui in Guizhou province to improve the vegetation restoration and ecological management in 2002,2005,2007,2009, and 2013,respectively. Soil samples were taken from these different areas to measure the contents of Cu,Zn,Cd,Pb and As for evaluating the effect of different planting years of vetiver on the distribution of heavy metals in coal spoil-heaps. Re- sults show that the contents of five heavy metals are decreasing with the increase of vetiver planting years. The contents of Cu,Zn and Cd in coal spoil-heap soil were higher in 0-10 cm than in 10-20 cm and 20-30 cm (P 10-30 cm>0-10 cm ( P