Unlocking the Saponite Potential in Aided Phytostabilisation of Multi-Metal-Contaminated Soils

Human activities have significantly impacted the environment, resulting in a need to restore degraded areas through various remediation techniques. This study aimed to evaluate the effectiveness of saponite in the aided phytostabilisation technique for heavy-metal-contaminated soil. The research was conducted on soil from a post-industrial site characterised by high metal content (Cu, Ni, Cd, Pb, Zn, and Cr) surpassing the established regulatory limits. Saponite was added to the contaminated soil at a ratio of 3% (w/w). The experiment was performed using Lolium perenne L. and Festuca rubra L. due to their adaptability to harsh soil conditions and rapid growth. The results demonstrated that saponite application significantly increased soil pH, which is beneficial for phytostabilisation of heavy metals. Saponite has been found to selectively enhance Ni accumulation in roots while not affecting Pb accumulation in above-ground parts, implying that saponite can effectively regulate heavy metal accumulation in plant biomass. Furthermore, saponite has been observed to significantly decrease soil Cd, Zn, and Cr levels with no impact on Cu, Ni, and Pb levels. Overall, saponite shows promise as an effective and scalable solution for large-scale phytostabilisation projects, contributing to the restoration of degraded soils and the protection of environmental and human health.