Decomposition of Uranium-Containing Plant Residues and Impact on the Surrounding Environment

As plants gradually age and die, uranium-rich plant residues are at risk of migration and diffusion of accumulated uranium to the surrounding environment under the action of monsoon and rainfall. In this study, we collected roots and stems of Macleaya cordata from restored uranium-rich soils to simulate the decomposition of M. cordata residues under rainfall drenching. We analyzed the characteristics of uranium release, microbial community composition, and functional group changes during the decomposition of residues. The results showed that after 36 days of decomposition, the stems of the plant residues decomposed faster than the roots, whereas the uranium release rate from the stems (65.09%) was greater than that from the roots (59.09%). On the basis of microbial community analysis and infrared spectroscopy, our results show that Galactomyces, Proteobacteria, and Firmicutes (Ascomycota phylum) play critical roles in the degradation of cellulose, hemicellulose, and lignin in M. cordata residues. These results suggest that after the uranium-rich plant residues migrate and disperse with the monsoon, the uranium in the plant is released into the water body under the action of rain, and migrates and disperses with the water body, causing pollution to the surrounding environment.