Nuclear Technique Laboratory, University of Science, Ho Chi Minh City, Vietnam, Vietnam National University, Ho Chi Minh City, Vietnam; Department of Nuclear Physics and Nuclear Engineering, Faculty of Physics and Engineering Physics, University of Science, Ho Chi Minh City, Vietnam, Vietnam National University, Ho Chi Minh City, Vietnam.
Nuclear Technique Laboratory, University of Science, Ho Chi Minh City, Vietnam, Vietnam National University, Ho Chi Minh City, Vietnam.
J Environ Radioact. 2020 May;216:106189. doi: 10.1016/j.jenvrad.2020.106189. Epub 2020 Mar 5.
The effects of moisture content, grain size, temperature, major elemental composition, and the pH of soils on the radon emanation and diffusion coefficients were evaluated in this study. The emanation and diffusion coefficients are strongly influenced by moisture content and grain size. The radon emanation coefficient increased and the diffusion coefficient decreased with decreasing particle size. However, for soils with large particle sizes, the radon emanation and diffusion coefficient remain almost unchanged with variation in grain size. Comparing five different sized soil particles, the emanation coefficient increased and the diffusion coefficient decreased with moisture content. The radon emanation coefficient reached a constant value with different moisture contents depending on the range of grain sizes. The saturation emanation coefficient for less than 0.1, 0.1-0.2, 0.2-0.3, 0.3-0.5, and more than 0.5 mm sized soil grain ranges are 0.47, 0.42, 0.35, 0.26 and 0.23, respectively, with saturation moisture contents of 16%, 14%, 10%, 6% and 4%, respectively. A drastic increase in radon emanation is found at smaller grain sizes with increasing moisture content. Based on the content of major elements and pH of the soils, the multiple regression indicates that the radon emanation coefficient appears to be significantly dependent on iron content and pH. Effective diffusion coefficient values calculated in our study agree with the results calculated by a previous model. Experimental values show that the temperature dependence of the radon diffusion coefficient follows Arrhenius behavior.
本研究评估了含水量、粒度、温度、主要元素组成和土壤 pH 值对氡散发和扩散系数的影响。散发和扩散系数强烈受含水量和粒度的影响。氡散发系数随粒径减小而增加，扩散系数减小。然而，对于大粒径土壤，氡散发和扩散系数随粒径变化几乎保持不变。比较五种不同粒径的土壤，散发系数随含水量增加而增加，扩散系数随含水量增加而减小。氡散发系数随不同含水量达到恒定值，这取决于粒径范围。小于 0.1、0.1-0.2、0.2-0.3、0.3-0.5 和大于 0.5mm 粒径范围的土壤的饱和散发系数分别为 0.47、0.42、0.35、0.26 和 0.23，相应的饱和含水量分别为 16%、14%、10%、6%和 4%。随着含水量的增加，较小的粒径会导致氡散发急剧增加。根据土壤中主要元素的含量和 pH 值，多元回归表明，氡散发系数似乎明显依赖于铁含量和 pH 值。我们研究中计算的有效扩散系数值与之前模型计算的结果一致。实验值表明，氡扩散系数的温度依赖性符合 Arrhenius 行为。
