Phytostabilization of arsenic, copper and iron by Sphagneticola trilobata (L.) Pruski in contaminated tungsten mine tailings

The sustainable management of contaminated tungsten mine tailings requires plant species that can tolerate potentially toxic elements and reduce their environmental mobility. However, the physiological tolerance and element-partitioning patterns of invasive plants in tungsten tailings remain insufficiently understood, and their potential use must be evaluated cautiously because of ecological risks. In this study, the invasive plant Sphagneticola trilobata was collected from metalliferous areas (M; tailings-impacted) and non-metalliferous areas (NM; non-tailings) in the Lianhuashan tungsten mining area. We compared organ-level accumulation patterns of arsenic (As), copper (Cu), iron (Fe), and other trace elements, together with leaf physiological and biochemical responses. Soil data from the same contaminated zone confirmed severe enrichment of As, tungsten (W), Cu, cadmium (Cd), zinc (Zn) and lead (Pb) in the metalliferous area. S. trilobata showed clear organ- and element-specific partitioning. As tended to accumulate more strongly in aboveground tissues, whereas Cu and Fe showed preferential retention in roots. Bioaccumulation factor (BAF) and translocation factor (TF) analyses further indicated that Cu had the clearest phytostabilization-related pattern, with a root BAF greater than 1 and TF values lower than 1; Fe showed root retention but low BAF values, whereas As showed stronger aboveground translocation. Plants from M areas also showed elevated malondialdehyde content and relative membrane leakage, reduced chlorophyll fluorescence and photosynthetic performance, and enhanced activities of antioxidant enzymes and contents of antioxidant metabolites. These results indicate that S. trilobata can maintain physiological activity under As, Cu and Fe associated stress by activating enzymatic and non-enzymatic antioxidant defenses, although photosynthetic function remains inhibited. Overall, the findings suggest element-specific phytostabilization potential of S. trilobata , especially for Cu, in contaminated tungsten tailings where the species is already established. Field-scale use should nevertheless be evaluated cautiously through long-term monitoring, biomass-based assessment and ecological risk control.