Yan Xun, Luo Xuegang
College of Life Science, Northeast Forestry University, Harbin, Heilongjiang 150040, China; College of Chemistry and Chemical Engineering, Qiqihar University Qiqihar, Heilongjiang 161006, China.
Southwest University of Science and Technology Mianyang, Sichuan 621010, China.
J Environ Radioact. 2015 Jan;139:85-90. doi: 10.1016/j.jenvrad.2014.09.019. Epub 2014 Oct 25.
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.
收集中国东南部铀矿尾矿环境修复的放射性污染数据。
根据铀浓度将采样区域分为高、中、低浓度区。每个区域分别在0 - 15厘米、15 - 30厘米和30 - 45厘米深度采集3份土壤样品，每份重复5次。共采集45份（3×5×3）土壤样品。按照参考文献所述方法测定土壤的理化性质和酶活性。采用高纯锗γ射线能谱仪测定土壤中放射性核素（²³⁸）U、（²³²）Th、（²²⁶）Ra和（⁴⁰）K的浓度。通过变性梯度凝胶电泳（DGGE）分析土壤微生物多样性。
土壤样品均呈酸性。土壤的理化性质，如pH值、全氮/有效氮、磷和钾含量以及酶活性均随铀浓度降低而增加。（²³²）Th浓度随铀浓度降低而升高，且不受采样点深度影响。然而，铀浓度和采样深度对（²²⁶）Ra和（⁴⁰）K的浓度无显著影响。（²³²）Th浓度与（²²⁶）Ra和（⁴⁰）K浓度显著相关，而（²²⁶）Ra和（⁴⁰）K浓度也显著相关。然而，（²³⁸）U与其他放射性核素之间的皮尔逊相关系数不显著。不同浓度区域的微生物种群不同，低浓度区有四个门类菌株，中高浓度区均为两个门类。此外，根据GenBank数据库，在每个采样点，变形菌门是最主要的菌群，环境样品菌次之。而且，变形菌门的沙雷氏菌属是优势菌株。
铀矿尾矿中放射性核素分布对土壤性质和微生物多样性有深远影响。本初步研究可能为进一步了解中国东南部铀矿尾矿放射性污染提供有价值的数据。
