Implications of repetitive amendment additions for in situ phytostabilization of trace elements in contaminated soils

Abstract

Phytostabilization is a non-invasive remediation technique that combines the utilization of amendments and plants to enhance natural attenuation mechanisms (adsorption, precipitation and complexation) that immobilize trace elements in soil (Adriano et al., 2004). In addition, phytostabilization might reduce soil erosion and run-off transport of contaminated particles. While this low-cost technique has potential for in situ treatment of extensive areas moderately contaminated, it has been argued that repetitive amendment additions are necessary to prevent reversability of treatments associated with changes in soil pH or organic matter mineralization (Azevedo-Silveira et al., 2003). However, there is insufficient information concerning the longevity and stability of treatments in field experiments, particularly in semiarid areas, characterised by low vegetation density and low organic matter content (usually less than 1-2%). In the present study, we evaluate the mid-term effects of repetitive vs single amendment applications on wild vegetation growing in a soil with residual As, Cd, Cu, Pb and Zn contamination, formerly affected by the Aznalcóllar mine accident