Soil Metal Pollution Gradients and Cadmium Uptake Responses of Accumulator Plants in Mediterranean Environments

Phytoremediation is one of the most widely used techniques for the removal of heavy metal pollutants from soil. This investigation explored the effect of soil co-contamination on Cd accumulation levels in hemp. To this end, a series of experiments were carried out on Cd-contaminated Mediterranean soils, which were subsequently contaminated with different levels of additional metals (Zn, Cu and their combination). The amount of Cd accumulated in hemp plants grown in the mono- and multi-contaminated soils was determined in each case, along with the Cd distribution in the different plant parts. The results showed that Cd accumulated mainly in the roots of hemp plants, regardless of the presence or absence of Cu and Zn. Co-contamination with Zn at moderate levels resulted in antagonistic effects on Cd uptake, whereas higher Zn concentrations increased hemp’s Cd accumulation capacity. On the other hand, Cu presence resulted in a synergistic increase in Cd uptake, notably at higher levels of contamination. Both Cu and Zn presence did not significantly alter Cd accumulation patterns, suggesting that hemp remains a sustainable candidate for phytoremediation in multi-metal contaminated soils. These findings provide valuable insights regarding the potential of hemp for soil remediation, highlighting its suitability for Cd-contaminated soils, even in complex contaminated environments. In light of the ongoing accumulation of heavy metals in soil environments, the implementation of cost-effective and environmentally sustainable remediation strategies is becoming increasingly necessary and can be regarded as essential.