Effect of goethite-loaded montmorillonite on immobilization of metal(loid)s and the micro-ecological soil response in non-ferrous metal smelting areas.

In this work, the immobilization stabilization and mechanism of heavy metal(loid)s by goethite loaded montmorillonite (GMt) were investigated, and the soil microbial response was explored. The simulated acid rain leaching experiment showed that GMt had a higher acid tolerance and the more stable heavy metal(loid)s fixation ability. The soil incubation demonstrated that GMt significantly decreased the available Cd, Zn, Pb and As concentration. Interestingly, higher immobilization of heavy metals was observed by GMt in highly acid leached and acidic soils. The richness and diversity of bacterial communities improved after the addition of GMt. GMt induced the enrichment of the excellent functional bacteria of the phylum Proteobacteria as well as the genus Massilia and Sphingomonas. The main immobilization mechanisms of heavy metal(loid)s by GMt include electrostatic interaction, complexation, precipitation and oxidation. The addition of the GMt also optimizes the soil bacterial community structure, which further facilitates the immobilization of heavy metal(loid)s. Our results confirm that the novel GMt has a promising application in the immobilization and stabilization of heavy metal(loid)s contaminated soils in non-ferrous metal smelting areas.