Solid-waste-derived reconstructed soil drives synergistic restoration of abandoned polymetallic mining sites: Evidence from soil properties and microbial network.

Mining activities have generated extensive areas of degraded land worldwide, particularly in polymetallic mining regions where severe heavy-metal contamination and poor soil structure constrain ecological restoration. To overcome the limitations of conventional restoration-such as high cost, long duration, and secondary pollution-We have innovatively proposed a soil restoration technology derived from solid waste. A reconstructed soil matrix was prepared by precisely blending fly ash, blast furnace slag, desulfurization gypsum, municipal sludge, and rice straw. Combined with mineral-functional bacteria, soil conditioners, and site-adapted vegetation, this strategy established a "structure rebuilding-metal stabilization-function recovery" model. Field trials demonstrated that the all-waste reconstruction treatment markedly elevated soil pH, organic matter content, available nitrogen, available phosphorus, and available potassium levels, while transforming the acid-soluble, reducible, and oxidizable fractions of Pb and As into residual forms with minimal bioavailability, thereby mitigating heavy-metal risk. Moreover, the integrated restoration strategy increased vegetation cover and biomass and was associated with concurrent improvements in microbial diversity, bacterial community structure, and changes in microbial co-occurrence networks. Partial least squares path modeling suggested that soil physicochemical properties may play a central mediating role linking heavy-metal speciation, plant diversity, and microbial diversity, thereby potentially influencing soil multifunctionality (R² = 0.93). This work offers theoretical insight and technical support for cost-effective, environmentally friendly restoration of polymetallic mine tailings, and pioneers a novel pathway for waste valorization and holistic ecosystem restoration.