Fe‐impregnated biochar enhances cadmium detoxification and compartmentalization in rice

, water-washed PBC) suggest that I-PBC enhances Cd compartmentalization in aboveground tissues by increasing Cd in the cytosolic fraction while reducing soluble Cd proportions, likely sequestering Cd into less metabolically active compartments (e.g., vesicles). Additionally, I-PBC promoted the conversion of Cd into low-toxicity Cd-oxalate complexes, as evidenced by a significant increase in the HCl-extractable Cd fraction (FHCl, predominantly Cd-oxalate) in stems. These findings demonstrate that impregnation is superior to co-pyrolysis for Fe-modified biochar in inhibiting grain Cd accumulation, with key mechanisms involving enhanced Cd chelation by oxalic acid and subcellular compartmentalization. This study highlights the potential of low-dose I-PBC for practical Cd-contaminated farmland remediation.