Radionuclides distribution, properties, and microbial diversity of soils in uranium mill tailings from southeastern...

To collect the radioactive contamination data for environmental rehabilitation in uranium mill tailings in southeastern China.

The sample areas were divided into high, moderate and low concentration areas, according to the uranium concentration. For every area, 3 soil samples were collected at 0-15 cm, 15-30 cm and 30-45 cm depth respectively, with 5 repetitions for each. Total 45 (3 × 5 × 3) soil samples were collected. Physicochemical properties and enzyme activities of soils were determined as described by references. The concentrations of the radionuclides (238)U, (232)Th, (226)Ra and (40)K in soils were determined by using HPGe gamma-ray spectrometer. Soil microbial diversity was analyzed via denaturing gradient gel electrophoresis (DGGE).

Soil samples were all acidic. Physicochemical properties, like pH, content of total/available N, P and K, as well as enzyme activities were all increased along with decreased uranium concentration. The (232)Th concentration was increased with the decreased uranium concentration and was not influenced by the depth of sample sites. However, uranium concentration and depth of sample showed no significant influence on the concentrations of (226)Ra and (40)K. The concentration of (232)Th was significantly correlated with that of (226)Ra and (40)K, while the concentrations of (226)Ra and (40)K were significantly correlated. However, Pearson correlation coefficients between (238)U and other radionuclides were not significant. The microbial population in different concentration areas was different with four domain strains in low area, and two for both moderate and high areas. Furthermore, in each sample site, Proteobacteria was the most dominant flora, while environmental samples were the second according to GenBank database. Moreover, Serratia sp. of Proteobacteria was the dominant strain.

Radionuclides distribution in the uranium mill tailing showed a profound influence on soil properties and microbial diversity. This primarily study might provide valuable data for further research towards a better understanding of the radioactive contamination in uranium mill tailings in southeast China.