石油汚染土壌の生物修復におけるバイオ炭媒介の微生物機能経路の窒素形態依存的シフト

Petroleum leakage from agricultural machinery and storage facilities threatens soil health and crop safety. Pyrolysis of agricultural residues into biochar provides a sustainable soil remediation strategy. However, its efficacy is often limited by nitrogen availability. We applied biochar to petroleum-contaminated soil along with different N sources (nitrate, ammonium or organic N) and used multilevel analyses (soil chemistry, enzyme assays, 16S sequencing and PICRUSt/KEGG inference) to track degradation mechanisms. Co-amendment of biochar with N fertilizers enhanced petroleum removal (81.0-83.6% vs 50.4% in control). Integrated analysis revealed form-specific mechanisms: ammonium accelerated early degradation kinetics, nitrate was associated with nitrogen-transforming microbial taxa and nitrate reductase, while organic nitrogen sustained urease activity and long-chain alkane oxidation. Distinct microbial community shifts were associated with changes in predicted metabolic pathways. These findings elucidated the coupled mechanism between nitrogen forms and microbial functional profiles, providing a scientific basis for optimizing nutrient-assisted remediation strategies.