Nanbiochar for Synergistic Mitigation of Heavy Metal Pollution and Carbon Emissions in Agricultural Ecosystems: Mechanisms and Applications

Nanobiochar (NBC) has emerged as a promising material for mitigating carbon emissions and heavy metal contamination within agricultural ecosystems. This review synthesizes recent advances in NBC research, with emphasis on its dual function in immobilizing heavy metals and enhancing soil carbon sequestration through molecular interactions, rhizosphere processes, and long-term stabilization mechanisms. At the molecular level, the high specific surface area and abundant functional groups of NBC facilitate heavy metal adsorption, complexation, and redox transformations. Within the rhizosphere, NBC interacts with root exudates and microbial communities, thereby reducing metal bioavailability while simultaneously promoting plant growth and improving soil health. NBC also contributes to carbon sequestration by stabilizing soil organic carbon and modulating microbial metabolism, thereby reducing greenhouse gas emissions. Despite these advantages, critical challenges persist, including inconsistencies in large-scale NBC production, uncertainties regarding ecological risks, and a limited understanding of its long-term environmental fate. Future research priorities should include optimizing NBC synthesis pathways, conducting comprehensive ecological risk assessments, and developing strategies to integrate NBC into sustainable agricultural systems. By bridging disciplinary gaps among environmental chemistry, microbiomics, and agricultural engineering, this review underscores the potential of NBC as a multifunctional material that can advance climate-smart agriculture and soil remediation.