Reducing Chromium Mobility and Toxicity in Agricultural Soils Using Cerium Oxide Nanoparticles-Assisted Biochar

Anthropogenic activities have increased chromium contamination in soils, posing risks to environmental quality, food safety, and human health due to its high mobility and accumulation in crops. This study evaluated cerium oxide nanoparticles (CeO₂ NPs) and CeO₂ NP modified biochar (CeMBC) for reducing Cr toxicity in wheat grown under contaminated conditions. Two Cr levels were established using 12.5% and 25% contaminated wastewater. Chromium stress reduced plant growth and biomass, while the combined application of CeO₂ NPs and CeMBC significantly improved plant performance. The mitigation of Cr toxicity was primarily driven by a dual mechanism: CeMBC immobilized Cr in the soil and reduced its bioavailability at the root level, while foliar-applied CeO₂ NPs limited Cr translocation and enhanced physiological resilience in shoots. This integrated effect reduced oxidative damage, improved antioxidant defense, and enhanced photosynthetic efficiency, leading to better growth and biomass accumulation. Adsorption analysis confirmed higher Cr retention in CeMBC treated soils, and life cycle assessment indicated reduced environmental impacts. These findings demonstrate that combining nanoparticle assisted biochar with foliar nanomaterials provides an effective strategy for controlling Cr mobility and improving crop performance in contaminated soils.