Critical Contribution of Biomass-Based Amendments in Mine Ecological Restoration: Properties, Functional Mechanisms, and Environmental Impacts

Mining activities have caused widespread land degradation and contamination, affecting millions of hectares worldwide and posing persistent ecological risks. However, reclamation substrates are constrained by limited availability and compromised quality, which restricts their ability to fully support mine ecological restoration. Among various amendment materials, biomass-based amendments have been widely applied due to their broad availability, renewability, biodegradability, and low cost. In recent years, their role has expanded beyond simple nutrient supplementation to encompass multiple functions, including structural optimization, pollutant stabilization, and microbial regulation. This review highlights the valorisation of biomass-derived solid wastes as multifunctional amendments for mine ecological restoration. By converting agricultural and industrial wastes into green materials, these amendments improve substrate structure, stabilize heavy metals and organic pollutants, enhance nutrient cycling, and stimulate microbial activity. Potential risks, including nutrient leaching, secondary pollution, and greenhouse gas emissions, are critically assessed, with emphasis on their variability under different environmental conditions. By integrating functional benefits with ecological risks, this work underscores the critical role of biomass-based amendments as waste-to-resource strategies in advancing sustainable mine reclamation, contributing to circular economy goals, and supporting environmental engineering practices.