Analysis of heavy metal content and microbial characteristics in the pioneer plant soil system of typical manganese tailing ponds in Guangxi

Ecological restoration of mine tailing ponds plays a crucial role in managing heavy metal pollution and enhancing biodiversity. This study aimed to investigate the ecological restoration potential of pioneer plants under high manganese metal pollution, as well as the microbial community composition and functional characteristics of their rhizosphere soil.

Sampling and analysis were conducted on seven plants of Neyraudia reynaudiana (LL), Pueraria montana (GT), Bidens pilosa (GZC), Buddleja asiatica (BBF), Pogonatherum crinitum (JSC), Crotalaria albida (XND), Thysanolaena maxima (ZYL) and their rhizosphere soil in Daxin manganese tailing ponds of Guangxi Province.

Pioneer plants improved the physicochemical properties of rhizosphere soil, and increase soil enzyme activity and the abundance and diversity of microbial communities, and reduce soil available metal content. The BTF values of GZC, GT, BBF, and XND are close to or greater than 1 for Mn, Cd and Cu, indicating their strong ability to absorb and transfer heavy metals from underground to above-ground. Proteobacteria, Actinobacteria, and Bacteroidetes are the bacterial communities with the dominant abundance, showing a significant positive correlation with the BTF value and promoting the absorption of heavy metals by plants. FAPROTAX function prediction revealed that chemoheterotrophy, aerobic chemoheterotrophy, and chloroplasts were the main metabolic modes.

GZC, GT, BBF, and XND can be utilized as habitat improvement plants in the preliminary ecological restoration of manganese tailing ponds. Rhizosphere soil microorganisms of pioneer plants respond to heavy metal pollution by regulating community structure and influencing metabolic function.