Mechanism study of Chromium influenced soil remediated by an uptake-detoxification system using hyperaccumulator, resistant microbe consortium, and nano iron complex.

A soil heavy metal decontamination system was developed based on the immobilization of bioavailable metal fraction by iron-biochar nano-complex (BC@Fe3O4) and the uptake by Chromium (Cr) hyperaccumulator Leersia hexandra (L. hexandra) under the assistance of metal resistant microbe consortium (MC). In this system, L. hexandra was able to accumulate 485.1–785.0 mg kg−1 in root and 147.5–297.2 mg kg−1 of Cr in its aerial part. With MC assistance, more Cr could be translocated to the aerial part of L. hexandra, which dramatically improved its remediation potential. Meanwhile, BC@Fe3O4 application decreased bioavailable Cr in soil and reduced soil toxicity, which contributed to soil microbial community adaption and L. hexandra performance under high level of Cr concentration (elevated microbial activity, decreased plant stress response, enhanced L. hexandra growth and accumulation) without negative influence on accumulation efficiency. Moreover, details of the possible mechanistic insight into metal removal were discussed, which indicated a negative correlation of the extractable Cr with soil microecology and hyperaccumulator performance. Furthermore, the resistant bacteria successfully altered soil microbial community, enhanced its diversity, which was in favor of the soil quality improvement.