陕北煤矸石路基重金属释放与迁移特性OA

To study the release and migration characteristics of heavy metals from coal-gangue sub-grades in northern Shaanxi under rainfall conditions,and to elucidate the attenuation and buffering effects of subgrade structures on heavy-metal transport,a coal gangue subgrade in the Yulin region was used as the study object to test the static leaching and dynamic percolation behaviors of heavy metals in coal gangue.Environmental risks were evaluated using the single-factor pollution index and geo-accu-mulation index,the leaching patterns and accumulation characteristics of Pb,Cr,Ba,Fe,and Al were analyzed,and vertical migration in a typical subgrade was simulated using the Hydrus-1D model to de-termine the relationships among heavy-metal concentrations,soil depth,and migration time.The results show that:Although the overall pollution level of the coal gangue is low,Fe and Al exhibit relatively high pollution indices,indicating potential environmental risks.Pb and Fe are rapidly released during the initial leaching stage,subsequently,the concentrations of the five elements tend to stabilize.Heavy-metal migration displays pronounced spatiotemporal attenuation,even after 300 days of continuous rain-fall,the maximum migration depth does not exceed 4.63 m,suggesting minimal impact on the surround-ing soil environment and a low migration risk.Under the situation where the compactness of the sub-grade on the first-class highway reaches＞90％,heavy-metal release and migration within coal-gangue subgrades remain controllable,demonstrating good environmental adaptability.The findings confirm that subgrade structures effectively retard and buffer the migration of heavy metals,providing scientific guid-ance for environmental risk management and practical application of coal-gangue subgrades.