摘要：
Radon in the household water (especially groundwater) which is an important source of indoor radon, has become a potential health hazard to residents. In this study, radon concentrations in groundwater sampled from five villages near Dongpo W-polymetallic metallogenic region were measured using RAD-7 detector with RAD H2O accessory, and the effect of regional geology and mineralization on radon concentration in groundwater was studied. In addition, we also estimated the radiation doses received by people via ingestion of radon in water and inhalation of the radon from the indoor air while using water. The results show that the radon concentration in groundwater samples varies from 1.29 Bq L(-1) to 31.31 Bq L(-1) with 10.47 Bq L(-1) on average, and about 31.3% of the groundwater samples analyzed have a higher radon concentration than the maximum contaminant level of 11.1 Bq L(-1) recommended by United States Environmental Protection Agency (USEPA). The relatively high radon level in groundwater can be attributed to a relatively high uranium background produced by the magmatic activity and magmatic-hydrothermal system. The values of annual effective dose (AEDing) due to ingestion of radon in groundwater range from 0.002mSv y(-1) to 0.055mSv y(-1), 0.005mSv y(-1) to 0.11mSv y(-1) and 0.008mSv y(-1) to 0.188mSv y(-1) for adult, child and infant respectively. The values of annual effective dose due to the inhalation of radon released from water are 63.6, 15.4 and 3.8 times of those through the ingestion of radon in groundwater by the adults, children and infants, respectively. In addition, the values of estimated total annual effective doses are 0.020-0.480mSv y(-1), 0.017-0.406mSv y(-1) and 0.020-0.484mSv y(-1) for adult, child and infant, respectively. These values are much lower than the reference dose level of 1mSv y(-1) recommended by World Health Organization (WHO) and United Nations Scientific Committee on the Effect of Atomic Radiation (UNSCEAR).
作者机构：
[李春光; 谭凯旋] School of Nuclear Resources Engineering, University of South China, Hengyang, 421001, China;[夏良树] School of Nuclear Science and Technology, University of South China, Hengyang, 421001, China;[刘振中] School of Environmental Protection and Safety Engineering, University of South China, Hengyang, 421001, China
摘要：
<jats:p>
In order to study the fractal dynamic properties of uranium leach mining and discuss the influence of ore crushing on the dynamics of leach mining, uranium mine ore rocks in southern China were selected as the research object and an acid leaching experiment was performed on the ore samples with different fractal dimensions of 1.1, 1.4, 1.7, 2.0, 2.3 and 2.6. In the column leaching experiment, a PVC pipe with an inner diameter of 112 mm and a height of 1500 mm was used. The uranium content was determined by using titanium trioxide that was placed into a 0.1 mg ml
<jats:sup>−1</jats:sup>
standard uranium solution, and a sampling rate of once daily with a 5 ml volume of leaching solution was adopted after 8 h drenching time. The results show that the flow rate of the leaching solution depends on the distribution of the ore's particle size, that is, a larger fractal dimension results in a smaller flow rate. The concentration of the uranium leaching solution reaches a maximum value which subsequently decreases with time on the third day of the experiment, and it seems that the changes in the uranium concentration tend to be stable at around 15 days. Moreover, the concentration seems to increase with the increasing fractal dimension, and the fractal dimension of the ore particle size has a significant impact on the leaching kinetics. When the fractal dimension is between 1.1 and 2.6, the uranium dissolution rate,
<jats:italic>K</jats:italic>
, increases with the increasing fractal dimension. The kinetic reaction of the uranium leaching is a liquid–solid one, which is controlled by chemical reactions in the earlier phase. While the middle reaction phase is mainly chemical-diffusion reaction coupling, and the latter part of the reaction is controlled by diffusion. As the fractal dimension increases, the liquid–solid reaction controlled by diffusion appears at earlier phases. When the fractal dimension is greater than 2.0, the time of entering the diffusion control phase only changed little with the increasing of the fractal dimension. At last, a fractal dimension of 2.0 is suggested for the acid leaching of uranium ore crushing.
</jats:p>
摘要：
土壤氡浓度分布具有双分形特征,其分维值分别为 D 1=0.079 4和 D 2=1.465 4,分形临界值为2 167.7 Bq/m 3.低于临界值的分形其分维值 D 1很小,代表了区域背景分布,其背景值为1 088.16 Bq/m 3.高于临界值的分形其分维值 D 2显著增大,反映该区发生了较强的成矿作用的叠加.分形临界值可以作为异常下限值.金狮岭地区土壤氡浓度异常区分布范围较大,表明具有较好的成矿远景.
作者机构：
[谭凯旋; 李春光; 谭婉玉] School of Nuclear Resources Engineering, University of South China, Hengyang, 421001, China;[刘振中] School of Environmental Protection and Safety Engineering, University of South China, Hengyang, 421001, China;[夏良树] School of Nuclear Science and Technology, University of South China, Hengyang, 421001, China
通讯机构：
School of Nuclear Resources Engineering, University of South China, Hengyang, China
作者机构：
[Xia, Yiqun; Zheng, Weina; Li, Reirei; Xia, Liangshu] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.;[Xia, Yiqun] China Inst Atom Energy, Dept Radiochem, POB 275-26, Beijing 102413, Peoples R China.;[Tans, Kaixuan] Univ South China, Sch Nucl Resource & Nucl Fuel Engn, Hengyang 421001, Peoples R China.
通讯机构：
[Xia, Liangshu] U;Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.
摘要：
Basic aspects of uranium adsorption by rice husk have been investigated. The influences of various experimental parameters such as pH, time, adsorbent dosage, rice husk size, temperature and various concentrations of uranium on uptake were evaluated. The thermodynamics and kinetics of adsorption were analyzed by FT-IR and SEM. The adsorption capacity for uranium on rice husk increased upon increasing initial concentration of uranium and temperature, while decreased with the increase of the amount of rice husk. Maximum uranium adsorption was observed at pH = 3 and particle size between 120 μm and 150 μm. Adsorption equilibrium was achieved within 60 min. At 25 °C, the saturated adsorption capacity qmax was up to 15.14 mg/g when the initial concentration of uranium ranged from 10 to 400 mg/dm<sup>3</sup>. The adsorption of uranium followed Langmuir adsorption isotherm and according to quasi-second order kinetic equation. The calculated values of δH<sup>o</sup>, δS<sup>0</sup>, and δG<sup>o</sup>indicated that the biosorption process was endothermic and spontaneous. Based on FT-IR spectra it may be concluded that hydroxyl, carbonyl, P-O and Si=O groups are the main active sites.<br/>
摘要：
Radon diffusion and transport through different media is a complex process affected by many factors. In this study, the fractal theories and field covering experiments were used to study the fractal characteristics of particle size distribution (PSD) of six kinds of geotechnical materials (e.g., waste rock, sand, laterite, kaolin, mixture of sand and laterite, and mixture of waste rock and laterite) and their effects on radon diffusion. In addition, the radon diffusion coefficient and diffusion length were calculated. Moreover, new formulas for estimating diffusion coefficient and diffusion length functional of fractal dimension d of PSD were proposed. These results demonstrate the following points: (1) the fractal dimension d of the PSD can be used to characterize the property of soils and rocks in the studies of radon diffusion behavior; (2) the diffusion coefficient and diffusion length decrease with increasing fractal dimension of PSD; and (3) the effectiveness of final covers in reducing radon exhalation of uranium tailings impoundments can be evaluated on the basis of the fractal dimension of PSD of materials.
