Remediation of metal toxicity and alleviation of toxic metals-induced oxidative stress in Brassica chinensis L using biochar-iron nanocomposites

Introduction Soil pollution caused by toxic elements such as lead (Pb) and cadmium (Cd) induces environmental stress on vegetable plants and soil microbial communities, reducing crop yield and disrupting ecosystem functions.Methodology In this study, nanoscale zerovalent iron supported with eggshell biochar and activated carbon (nZVI-ESB/AC) was synthesized using carbothermal reduction synthesis and evaluated the effectiveness in minimizing the toxicity of lead and cadmium in soil and alleviating the toxic effects of these metals on Brassica chinensis L. and soil microbial communities.Results The nZVI-ESB/AC immobilized Pb and Cd in the soil more than ordinary eggshell biochar, resulting in their lower bioaccumulation in the edible part of Brassica chinensis L. The nZVI-ESB/AC treatments were significantly more effective than biochar treatments in enhancing plant growth, reducing oxidative stress indicators by 1.5-2 folds, and increasing the relative abundance level of Bacilli and Clostridia by 52-67% and 10-15%, respectively. The presence of iron in nZVI-ESB/AC enhanced the activities of antioxidant enzymes, leading to the decreased generation of reactive oxygen species and lipid peroxidation in the plants.Conclusions This study demonstrates the potential of nZVI-ESB/AC as an effective adsorbent for soil remediation, alleviating stress induced by toxic metals on vegetable plants and promoting bacterial community diversity. The successful application of nZVI-ESB/AC presents promising prospects for sustainable agriculture, mitigating the environmental impact of lead and cadmium pollution and improving crop yield.