The Role of Some Plants in Improving the Properties of Soil Contaminated with Heavy Elements

The effects of cadmium (Cd), lead (Pb), and zinc (Zn) pollution on soil physicochemical characteristics, including pH, cation exchange capacity (CEC), electrical conductivity (EC), and organic matter (OM), are examined in greater detail in this study. We used soils exposed to increasing concentrations of heavy metals, two ornamental plant species (Acacia and Nerium), and unplanted controls in our three-month-long trials. The results showed a distinct trend of soil acidification with increasing metal concentrations, particularly in the presence of cadmium stress. While Pb and Zn caused minor decreases in CEC values that were not statistically significant, we saw a considerable decline in CEC values in soils polluted with Cd, especially in the unplanted groups. With no discernible variations, EC values increased slightly across all treatments but remained within acceptable bounds. Similarly, when metal levels increased over time, the amount of organic matter reduced, but this impact was more noticeable in soils that were polluted with Cd. Nerium continuously fared better than Acacia among the plant species in preserving greater CEC and OM levels. However, only the CEC under Cd contamination (Table 4) exhibited significant variations across treatments, whereas the remaining metrics showed no statistical significance, according to our statistical analyses using the LSD test (P<0.05). These findings highlight the need of carrying out long-term phytoremediation studies to get a deeper comprehension of the sustainable function of ornamental plants in heavy metal-contaminated soils.