Water-soluble chitosan enhances phytoremediation efficiency of cadmium by Hylotelephium spectabile in contaminated soils.

Water-soluble chitosan (WSC) was used to enhance cadmium (Cd) phytoextraction by Hylotelephium spectabile, a promising accumulator. The effect of WSC on Cd forms and functional groups in contaminated soils was determined to clarify the internal mechanism of WSC affecting phytoremediation. Results showed that WSC significantly increased the water-soluble and acid-extractable Cd in contaminated soils by 20.3 %-143.5 % and 2.4 %-39.5 %, respectively. Fourier transform infrared spectra analysis showed that amino and hydroxyl groups in soils were significantly increased in the presence of WSC. The coordination of Cd with increased amino and hydroxyl groups may play important roles in formation of Cd complexes and mobilizing Cd in soils. WSC significantly increased the Cd phytoextraction of H. spectabile by 56.1 %-115.7 % without obvious growth inhibition, which was further confirmed under field trial conditions. Therefore, it is feasible to apply WSC as a soil amendment to Cd-contaminated soils during remediation with H. spectabile.