Phytoaccumulation of heavy metals (Pb, Zn, and Cd) by 10 wetland plant species under different hydrological regimes

Wetland plants have been widely used in constructed wetlands to remove metal contaminants from water and soil. This study aimed to investigate radial oxygen loss (ROL) rate, metal (Pb, Zn, and Cd) uptake, Fe plaque formation, and their relationships in a pot trial with 10 emergent wetland plant species grown in metal-contaminated soil under flooded and non-flooded conditions. The results showed that biomass, ROL rates, metal (Pb, Zn, and Cd) uptake, and Fe plaque formation on root surfaces and in the rhizospheres of the wetland plant species were remarkably higher under flooded conditions than under non-flooded conditions. Generally, flooding mainly increased metal accumulation in the roots and Fe plaque on the root surface of wetland plant species. The wetland plant species with higher ROL rates had higher biomass, Fe plaque formation and metal adsorption on the roots and in the rhizospheres under flooded conditions. These results suggest the wetland plant species with higher ROL rates, biomass and metal accumulation ability, e.g. C. alternifolius, has the potential for use in phytoremediation of metal-contaminated wetlands.