Influence of Miscanthus floridulus on Heavy Metal Distribution and Phytoremediation in Coal Gangue Dump Soils: Implications for Ecological Risk Mitigation

Coal gangue dumps, a byproduct of coal mining, contribute significantly to heavy metal contamination, impacting soil and water quality. In order to assess the levels of heavy metal contamination in soils at different stages of abandonment, this study investigated the role of <i>Miscanthus floridulus</i> (<i>M. floridulus</i>) in the spatial distribution and remediation of six heavy metals (Cd, Cr, Mn, Ni, Cu, and Pb) in coal gangue dump soils abandoned for 0, 8, and 12 years in Pingxiang City, Jiangxi Province, China. Fieldwork was conducted at three sites operated by the Pingxiang Mining Group: Anyuan (active, barren), Gaokeng (8 years, natural vegetation), and Qingshan (12 years, partially remediated). Anyuan remains largely barren, while Gaokeng supports natural vegetation without formal remediation. In contrast, Qingshan supports diverse plant species, including <i>M. floridulus</i>, due to partial remediation. Using a randomized design, root exudates, heavy metal concentrations, and soil properties were analyzed. The results showed that Cd poses the highest ecological risk, with concentrations of 64.56 mg kg^-1 at the active site, 25.57 mg kg^-1 at the 8-year site, and 39.13 mg kg^-1 at the 12-year site. Cu and Pb showed accumulation, while Cr and Mn decreased over time. Root exudates from <i>M. floridulus</i> enhanced metal bioavailability, influencing Cd, Cr, and Ni concentrations. These findings highlight the importance of rhizosphere processes in metal mobility and inform sustainable remediation strategies for post-mining landscapes.