Integrated life cycle assessment for sustainable agricultural land remediation: Full-chain analysis of environmental trade-offs and upstream carbon burdens.

Despite increasing attention being paid to the sustainability of agricultural land remediation, narrow system boundaries in existing assessments often lead to underestimation of life cycle environmental burdens, thereby overstating contribution to sustainable development. Here, we developed an integrated life cycle assessment framework that extends beyond the conventional focus on secondary impacts from energy and material use to include primary impacts from residual contaminant exposure and tertiary impacts from supply-chain activities. The framework was employed to evaluate the environmental benefits of four typical remediation strategies applied to a Cd-contaminated paddy field in eastern China. Among the four remediation strategies, phytoextraction and alternative planting achieved net environmental benefits and relatively low tertiary carbon emissions. By adjusting crop structure, alternative planting was the only strategy that maintained relatively stable environmental burdens under higher contamination levels. In contrast, the environmental benefits of biochar stabilization and excavation and elution were constrained by substantial secondary and tertiary impacts, primarily driven by energy-intensive pyrolysis and excavation-transport activities, respectively. Nevertheless, due to the valorization of agricultural residues during biochar production, biochar stabilization retained certain environmental advantages over other stabilizing agents. Off-site carbon emissions were mainly concentrated in the electric power and heat production sector, with notable spillover effects in coal-producing provinces, indicating that reducing reliance on coal in the energy sector could substantially mitigate upstream emissions. Overall, this study provides new insights to support more comprehensive policymaking and informs the future development of sustainable remediation technologies.