Sustainable Management Approaches to Heavy Metal Pollution in Arid Soils Using Soil Amendments and Plant-Based Remediation

This study examined the effect of sulfur, ethylenediaminetetraacetic acid (EDTA), olive mill wastewater (OMW), and their mixtures in remediating metal-polluted soils by implementing both leaching trials and a greenhouse experiment with sunflower (Helianthus annuus). In the leaching study, soils were subjected to five discharge volumes (V1–V5). EDTA significantly improved metal mobility of Cd (221.4) mg·kg−1 in V2, Pb (340.8) mg·kg−1 in V3, and Zn (1.01) mg·kg−1 in V3, while OMW moderately mobilized Cd and Mn. However, sulfur mitigated leaching by buffering soil pH and metal immobilization. Mixed treatments revealed moderate leaching behavior. EDTA lowered soil pH (5.3) and raised EC (1763) µS/cm, while sulfur maintained stable chemical environments. In the greenhouse experiment, amendments significantly influenced biomass and metal uptake. Sunflower roots accumulated the highest Cd under sulfur (733.5) mg·kg−1 and Mn under EDTA (743.3) mg·kg−1. EDTA restricted Cd translocation (TF = 0), while OMW enhanced Cr movement to shoots (TF = 17.6). EDTA also reduced Cd bioavailability, whereas OMW raised Pb and Mn availability. Overall, EDTA improved metal solubility for potential removal and sulfur in stabilized metals, while OMW acted as a moderate mobilizer. Sunflower demonstrated selective metal uptake, indicating its potential in phytoremediation strategies tailored to specific contaminants.