School of Resources and Environment Engineering, Henan Polytechnic University, 454000 Jiaozuo, China.
Henan Yuzhong Geological Exploration Engineering Co., LTD., Zhengzhou, Henan 450016, China.
Sci Total Environ. 2023 Jan 20;857(Pt 3):159666. doi: 10.1016/j.scitotenv.2022.159666. Epub 2022 Oct 24.
With the gradual increase of the coal mining depth, the mixing of multiple water sources intensifies and the activity of radium and radon in groundwater increases. Identifying the source of mine water inrush by using radium and radon isotopes is a new choice. In this paper, the mathematical statistics method, radioactive isotope decay theory, the mass conservation principle, and the numerical simulation method are used to analyze the influence of total dissolved solids (TDS), pH, and the hydrochemical ion content in groundwater on the isotope activity of radium, radon, uranium, thorium, and lead. The activity of thorium and lead is lower than the detection limit of the instrument, and the influence of coal mining activities on it is small. The simulation of the radium-radon mass balance in groundwater shows that the greater the adsorption coefficient (k) of solid particles in groundwater is, the more obvious the adsorption effect and the greater the influence on the radium-radon activity balance are. The radium-radon dating method is used to calculate the groundwater age. Results show that the groundwater age in the closed pit coal mining area is generally older than that in the mining coal mining area. Combined with the Rn, Ra, and U radioactive isotopes and temperature, a mixing water source identification model of limestone in the coal seam floor is constructed. The model shows that the radium activity and temperature of the groundwater are inversely proportional to the mixing ratio of the Permian sandstone water. From the closed pit coal mining area to the mining coal mining area, the radium radon activity of the groundwater increases gradually, the groundwater age decreases significantly, the water cycle is accelerated, the mixing ratio of the Permian sandstone water decreases gradually, the mixing ratio of the Ordovician limestone water increases gradually, and the risk of coal mine water inrush increases. The research results prove the feasibility of the new method for accurately discriminating the mixing water sources in coal mine areas, which is of great significance to the improvement of the theory of coal mine water disaster prevention and control.
随着煤矿开采深度的逐渐增加，多种水源的混合加剧，地下水镭和氡的活度增加。利用镭和氡同位素识别矿井突水水源是一种新的选择。本文采用数理统计方法、放射性同位素衰变理论、质量守恒原理和数值模拟方法，分析了总溶解固体（TDS）、pH 值和地下水水化学离子含量对镭、氡、铀、钍和铅同位素活度的影响。钍和铅的活度低于仪器的检测极限，受煤矿开采活动的影响较小。地下水镭-氡质量平衡模拟表明，地下水固相颗粒的吸附系数（k）越大，吸附效果越明显，对镭-氡活度平衡的影响越大。利用镭-氡定年法计算地下水年龄。结果表明，露天煤矿区地下水年龄普遍大于开采煤矿区。结合 Rn、Ra 和 U 放射性同位素及温度，构建了煤层底板灰岩混合水水源识别模型。该模型表明，地下水镭活度与温度与二叠系砂岩水的混合比例成反比。从露天煤矿区到开采煤矿区，地下水镭-氡活度逐渐增加，地下水年龄显著减小，水循环加速，二叠系砂岩水混合比例逐渐减小，奥陶系灰岩水混合比例逐渐增加，矿井突水风险增大。研究结果证明了利用新方法准确判别矿区混合水源的可行性，对提高矿井水害防治理论具有重要意义。
