Adsorption of diuron in black soil amended with biochar can predict its bioavailability to crops and earthworms

Purpose In this study, the adsorption behavior of diuron in a typical black soil and its bioavailability to crops and earthworms were investigated by adsorption and incubation experiments, combined with biochar amendment and aging time. Methods In this study, the adsorption of diuron, and its uptake by corn and earthworms were investigated in black soil with 0.1–5% (w/w) bamboo charcoal. Results Uptake of diuron by corns was reduced by 45% in black soil aged for 0 day in 0.1–5% biochar-amended soil, the concentration of diuron in both roots and stems of corn plants tended to decrease with the increase of aging time, and the enrichment coefficient of diuron in corn also tended to decrease in 0.1–5% biochar-amended soil. When aging time was 0 day and the biochar amendment in black soil was 0.1–5%, the accumulation concentration of diuron in earthworms decreased by 63%; the bioconcentration coefficient of diuron in earthworms in black soil with different levels of biochar decreased continuously with the increase of aging time. Conclusion Biochar is an efficient adsorbent for diuron and could significantly reduce the uptake of diuron by plants and earthworms from contaminated soil. Significant correlations indicated that regression analyses could be constructed between the bioconcentration factor and sorption coefficients to predict the bioavailability of diuron residues in soil to corns and earthworms. Biochar amendment could be used as an option to immobilize diuron in soil and protect non-target organisms from diuron contamination.