The effects of Leifsonia sp. on bioavailability and immobilization mechanism of uranium in soil

• Published in: Journal of soils and sediments 2020-03, Vol.20 (3), p.1599-1608
• Main Authors: Tan, Wenfa, Guo, Feng, Deng, Qinwen, Li, Jiaxiang, Wang, Liang
• Format: Article
• Language: English
• Subjects: Bioaccumulation; Bioavailability; Biological magnification; Cell surface; Control; Earth and Environmental Science; Environment; Environmental Physics; Environmental protection; Experiments; Immobilization; Mine tailings; Moisture content; Sec 5 • Soil and Landscape Ecology • Research Article; Soil; Soil bacteria; Soil chemistry; Soil contamination; Soil microorganisms; Soil pollution; Soil remediation; Soil Science & Conservation; Soil testing; Soil water; Soils; Toxicity; Transfer factor; Uranium; Water content; X ray photoelectron spectroscopy
• ISSN: 1439-0108; 1614-7480
• DOI: 10.1007/s11368-019-02494-1

Purpose The remediation of uranium (U)-contaminated soil has become one of the most challenging problems in the field of environmental protection. U immobilization in soil via bacteria is supposed as a promising approach. This study seeks to determine the bioavailability of U and the potential mechanism under the experiment of Leifsonia sp. by pot experiment. Materials and methods Each pot was filled with sterilized soil of the same concentration of U (200 mg/kg) and the same amount of water (500 ml) to simulate the wetland environment around the uranium tailings. Four treatments were performed on different pots (control group, add Leifsonia sp. group, add plants group, and add both plants and Leifsonia sp. group), via comparing the content changes of U in soil, water and plants in each pot during the experimental period to study the influence of Leifsonia sp. on the transfer of U. In addition, MINEQL and sequential extraction procedures were used to calculate and analyze the various forms of U. In order to further explore the mechanism of Leifsonia sp. affecting the bioavailability of U, modern detection technologies (SEM-EDS, FTIR, and XPS) were used to test soil samples. Results and discussion The results showed that bioconcentration factor (BCF), bioaccumulation factor (BAF), and transfer factor (TF) of U in Leifsonia sp. experimental groups were lower than those in the control groups. Moreover, the residual U (46.46%) in pots with Leifsonia sp. was higher than that of the control pots (6.72%). This indicates that Leifsonia sp. may facilitate the immobilization efficiency of U in soil by converting part of reducible and oxidizable fraction of uranium into residual fraction. SEM-EDS showed that the peak of U appeared on the surface of Leifsonia sp. after the pot experiment. A possible explanation for this, supported by FTIR, is that –OH, –NH, and –C=O on the cell surface were involved in the process. XPS measurements indicate that part of U(VI) was transformed into U(IV). Conclusions These findings imply that Leifsonia sp. can, to some extent, prevent the bioavailability of U in soil by changing the chemical states into less toxicity and less risky forms. The results have guiding significance for the site application of Leifsonia sp. in soil.