Fate and bioavailability of heavy metals in biosolids during phytoextraction using the short rotation coppice trees Salix reichardtii and Populus balsami f era

摘要

Continuous monitoring of heavy metals in biosolids solution (pore water) by in situ sampling from an one-year phytoextraction experiment was employed to determine the bioavailability of heavy metals in biosolids from Melbourne Water's Western Treatment Plant, Werribee. The results showed that heavy metals (Cd, Cu, Ni and Zn) in biosolids solution increased significantly with depth and showed a tendency to decrease over time. However, during the summer (Dec. 2005 to Feb. 2006), concentrations of heavy metals increased significantly in the plant treatments. Arsenic, Cr, Hg and Pb concentrations in biosolids solution were below the detection limit of ICP-OES. The pH of biosolids solution temporary decreased over phytoextraction periods. In Feb 2006, the concentrations of heavy metals in the columns with plants were higher than the control treatments, especially for S. reichardtii. Concentrations (mg·kg<'- 1> dry matter) of Cd, Ni and Zn in leaves and stems of both species increased significantly over time. These results indicated that S. reichardtii had a significant influence on the bioavailability of heavy metals and the pH of the biosolids during phytoextraction.