The decomposition process of uranium-accumulating plant litter: secondary release of uranium and its impact on soil microbial communities

Eco-friendly phytoremediation technologies offer unique advantages in the remediation of uranium-contaminated soil. However, these uranium-accumulating plants may still release uranium back into the soil through decomposition, thereby increasing environmental risks. Currently, the decomposition characteristics and uranium release of uraniferous plants are still exploring. This study investigated the decomposition characteristics of uraniferous litter of Syngonium podophyllum in different parts and states, the migration and transformation patterns of uranium between litter and soil environment, and the effects of uraniferous litter decomposition on soil microbial communities. Results indicate that both litter decomposition rate and nutrient release rate of litter exhibited a similar pattern: an initial rapid release followed by a gradual decline in rates over time. The presence of uranium affects the decay and nutrient release of litter. Decomposition of uraniferous litter releases uranium into the soil, significantly increasing uranium bioactivity and bioavailability, posing substantial environmental threats. Concurrently, decomposition of uraniferous litter alters soil microbial communities, with dominant bacterial groups including Proteobacteria, Actinobacteria, Firmicutes, and Chloroflexi, while Ascomycota being predominant among fungi. This research provides a scientific theoretical basis and rationale for the phytoremediation practices of uranium-contaminated soils and the disposal management for uraniferous plants.