The accumulation/improper treatment of coal gangue will not only lead to waste of land, but also cause environmental pollution. Especially the impact of radioactive elements on the surrounding ecological environment is widely concerned by many scholars. In this study, the concentration of radioactive elements (uranium (U) and thorium (Th)) of small-scale coal gangue mining site and surrounding soil in the northern region of Xieqiao coal mine were tested, the material composition of coal gangue was analyzed via XRF and XRD, the modes of occurrence of U and Th elements were investigated, and their potential ecological risks and ecological effectiveness were evaluated. The results show that the clay minerals with high content in coal gangue are the key minerals for the adsorption of uranium and thorium in coal gangue. The specific activity of two radioactive elements (U and Th) in soil is much lower than that of coal gangue. With the increase of the distance from the soil collection point to the gangue piles and the depth of the soil profile, the specific activities of the two radioactive elements decrease gradually. On the basis of the concentration curve, the range of the radioactive contamination halo of gangue piles is limited (≤30 m), speculating qualitatively that the gangue dump has no significant influence on the radioactivity of the surrounding water. The modes of occurrence of U and Th in coal gangue and soil are altered. According to the index of geo-accumulation, Th is easier to accumulate in soil environment, but Th and U pollution in soil is not obvious. In contrast to U element, the active state of Th element in soil is generally affected by exogenous (coal gangue) export, which may have a potential environmental effects. This study provides a research idea for the investigation of radioactive element pollution to the surrounding soil in small-scale coal gangue plies.

中文翻译：

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小型矿区煤矸石基本特征及周边土壤放射性元素风险评估

煤矸石堆积/处理不当，不仅会造成土地浪费，还会造成环境污染。尤其是放射性元素对周边生态环境的影响受到众多学者的广泛关注。本研究对谢桥煤矿北部地区小型煤矸石开采场地及周边土壤放射性元素（铀（U）和钍（Th））的浓度进行了检测，分析了煤矸石的物质成分。通过XRF和XRD研究了U和Th元素的赋存方式，评估了它们的潜在生态风险和生态效益。结果表明，煤矸石中含量高的粘土矿物是煤矸石吸附铀和钍的关键矿物。土壤中两种放射性元素（U 和 Th）的比活度远低于煤矸石。随着集土点到矸石堆的距离和土壤剖面深度的增加，两种放射性元素的比活度逐渐降低。根据浓度曲线，矸石堆放射性污染晕范围有限（≤30 m），定性推测矸石堆对周围水体的放射性没有显着影响。改变了煤矸石和土壤中U和Th的赋存方式。从地积累指数来看，Th在土壤环境中更容易积累，但土壤中Th和U污染不明显。与 U 元素相比，土壤中Th元素的活性状态一般受外源（煤矸石）输出的影响，可能具有潜在的环境影响。该研究为小尺度煤矸石层中放射性元素对周围土壤的污染调查提供了研究思路。