Biochar Reduces Nanoplastics Uptake by Lettuce and Alleviates Its Toxicity to the Plant

The accumulation of micro- and nanoplastics (MPs/NPs) in croplands
threatens food quality and human health. This study investigates the
effectiveness of pristine biochar (BC) and iron-doped biochar (Fe-BC),
produced from pine sawdust via one-step pyrolysis, in reducing NPs
uptake by lettuce (Lactuca sativa L. var. adela).
Fe-BC exhibited greater porosity, higher surface area, and a slightly
positive surface charge compared to BC. Using Pd-doped NPs, we confirmed
that NPs can penetrate roots and translocate to leaves, accumulating
more in older tissues. Soil application of 3 wt % BC or Fe-BC significantly
lowered leaf NPs concentrations, with Fe-BC showing a greater reduction,
by approximately 60% (from 0.90 to 0.36 mg/kg). While both BC and
Fe-BC demonstrated a capacity for alleviating NPs-induced metabolic
disturbances and partially restoring soil enzyme activities, Fe-BC
presents a more promising amendment for mitigating NPs contamination
and protecting crop quality.