Synergistic ecological remediation of tailings in high altitude ecologically fragile areas by ryegrass ( Lolium perenne L.) and activated carbon

The ecological vulnerability and extreme physicochemical properties of tailings in high-altitude mining areas pose challenges to the ecological restoration of tailings. Therefore, the aims of the current study were to remediate tailings in high-altitude mining areas by combining ryegrass (Lolium perenne L.) and activated carbon. Ryegrass potting experiments with Cu and Pb-Zn tailings and the two tailings amended with activated carbon. The effects of synergistic treatment of ryegrass and activated carbon on the physicochemical properties, heavy metal content, and enzyme activity of Cu tailings and Pb-Zn tailings were studied. Compared with planting ryegrass group, activated carbon significantly improved the water holding capacity of the two tailings. After restoration, the water holding capacity of Cu tailings and Pb-Zn tailings were 47.33% and 47.67%, respectively. In addition, the combination of ryegrass and activated carbon improved the quality of tailings, effectively increasing the organic carbon and available phosphorus content of tailings. Ryegrass and activated carbon synergistically activate tailings enzyme activity. The decrease in heavy metals in the tailings was mainly attributed to uptake by ryegrass rather than immobilization by activated carbon. The synergistic remediation of ryegrass and activated carbon is a potential ecological restoration treatment for tailings in high-altitude ecologically fragile areas.