Trace element availability and plant growth in a mine-spill-contaminated soil under assisted natural remediation: II. Plants

In this second part, we evaluated the effects of different amendments on plant growth (Agrostis stolonifera L.), and trace element accumulation and removal by plants in a trace element (As, Cd, Cu, Pb and Zn) contaminated soil. Description of the various treatments is given in Part I of this work. The plants were grown for consecutive periods (2002, 2003, 2004), 5 months each and harvested twice in each period. Results showed that plant growth was enhanced and trace element concentrations in plant were reduced in SL, MWC, BC and LEO treatments in the first period. No significant differences were observed in subsequent periods. This seemed to be related with changes in soil pH. Removal of trace elements was higher in SL, MWC, BC and LEO treatments due to higher biomass production in the first period. In following years no significant differences between treatments were found. Data from Part I of this study were also used to compare trace element bioavailable concentrations extracted with 0.01 M CaCl2 and 0.05 M EDTA with trace elements in plant. We observed that 0.01 M CaCl2 was more suitable for determination of bioavailable concentrations and that extraction with EDTA overestimated biovailability of trace elements in amended treatments, especially in those where composts were added.