Biological Removal Efficiency of Different Plants of Copper and Cadmium in Contaminated Soil

In order to select heavy metal-enriched plants, Pennisetum sinese, Sesamum indicum, Sorghum, Sedum plumbizincicola, Elsholtzia splendens, and Setaria pumila were planted in a copper (Cu) and cadmium (Cd) contaminated soil in Jiangxi Province. This study investigated the biomass and heavy metal accumulation characteristics of the six plant species, compared the extraction amount and biological removal efficiency of heavy metals by the plants. The results reveal that the total concentrations of Cu and Cd in the soil were 560.0 mg·kg^-1 and 0.80 mg·kg^-1, respectively, which were 10.20 times and 1.67 times higher than the soil risk screening values for agricultural land (GB 15168-2018, pH≤5.5, Cu 50 mg·kg^-1, Cd 0.3 mg·kg^-1), respectively. The biomass of Pennisetum was the highest (41.40 t·hm^-2), which is 11.82 times that of Sedum plumbizincicola. Only Elsholtzia splendens had a bioconcentration factor (BCF) over 1 for Cu, and Sedum plumbizincicola had the highest BCF for Cd (46.16), significantly higher than those of the other plants (1.47-9.69). The extraction amount for Cu was the highest in Pennisetum sinese (7.7 kg·hm^-2) and Elsholtzia splendens (6.9 kg·hm^-2), but their biological removal efficiencies were only 0.61% and 0.55%, respectively. The extraction amount for Cd in Pennisetum sinese (156.17 g·hm^-2) and Sedum plumbizincicola (122.32 g·hm^-2) were the highest, with biological removal efficiencies of 8.68% and 6.80%, respectively. Pennisetum sinese can be used for biomass power generation, while the heavy metal content of Sesamum indicum seeds meets the national food safety standards (GB 2762-2022, Cd < 0.5 mg·kg^-1) and offers certain economic benefits. Therefore, a Sedum plumbizincicola-Sesamum indicum rotation or monocropping mode of Pennisetum sinese is recommended for the remediation of contaminated soils, providing good biological removal effect and potential economic benefits.