Dicranopteris pedata improves soil quality by enhancing nutrient deposition, decreasing metal concentration, and boosting microbial diversity on abandoned rare earth elements mining sites

Abstract

Rare earth elements (REEs) mining exerts adverse impacts on soil ecosystems. Attempts to recover REEs-contaminated soils have been made through phytoremediation with Dicranopteris pedata. However, how it improves soil quality is still poorly understood. This study fully investigated the effects of D. pedata-aided phytoremediation on abandoned REEs mining sites, focusing on soil properties, REEs speciation, and microbial diversity. Results showed that D. pedata increased soil TC from 488 to 626 mg kg–1, soil TN from 20.1 to 57.0 mg kg–1, and soil TP from 232 to 259 mg kg–1, while decreased concentrations of soil Fe, Mn, and REEs by 37 %, 62 %, and 43 %, respectively. The plant efficiently removed labile REEs and elevated non-labile fractions. Additionally, D. pedata increased microbial diversity and reshaped microbial composition, with microbial communities such as p_Chloroflexota and p_Acidobacteriota being decreased from 22–47 % to 17–27 % (p < 0.01), and p_Pseudomonadota, p_Acidobacteriota, p_GAL15, and p_Bacteroidota being increased from 0.25–16 % to 5.3–26 % (p < 0.01). Several communities belonging to these phyla significantly correlated to soil properties and metal concentrations, suggesting their roles in improving soil quality. This study provides new insights into soil quality improvement after D. pedata aided-phytoremediation and highlights the beneficial use of phyto-microbial technology for remediating abandoned REEs mining sites.