海拉尔盆地地下水铀的分布特征及富集规律

通过采集海拉尔盆地地表水样品12件,地下水样品67件,运用Durov图、等值线图和铀形态计算理论,结合数理统计方法,分析研究区域地下水铀的分布特征和赋存形态,结果表明:海拉尔盆地赫尔洪德凹陷地区主要为HCO₃-Ca·Na型,蹉岗隆起、乌尔逊凹陷和贝尔凹陷地区主要为Cl-Na型和HCO₃-Na型,巴彦山隆起地区主要为HCO₃-Na型,红旗牧场和新宝力格凹陷主要为Cl-Na型.研究区域铀的分布范围为17~425μg/L,平均值为80μg/L,标准偏差为70μg/L,引发了区域地源性地下水铀污染问题.地下水中以UO₂(CO₃)₃^4-和UO₂(CO₃)₂^2-的主要形式存在,与Eh表现的氧化还原环境具有一致性,其中呼伦贝尔湖东南部属于地下水铀成矿有利区域.潜在铀成矿范围属于重碳酸铀酰占优势的HCO₃型含铀地下水,铀酰碳酸盐复合物应占主导地位,铀的溶解与HCO₃^-的增加有关,地下水中的铀存在参与碳酸盐岩和硫酸盐岩的混合溶滤作用的可能性,UO₂(CO₃)₃^4-、UO₂(CO₃)₂^2-、U₄O₉和沥青铀矿等处于饱和状态,总Fe和(Ca²⁺+Mg²⁺)浓度较低,各种水化学指标对铀富集具有指示意义,因此可将其视为潜在铀源的参考依据.

The distribution and enrichment of Uranium in groundwater of Hailar Basin

12 surface water samples and 67 groundwater samples were collected from the Hailar Basin. The distribution characteristics and occurrence patterns of uranium in groundwater of samples were analyzed using Durov diagrams, contour maps, uranium form calculation theory, as well as mathematical statistics. Results show that the Helhongde sag area of the Hailar Basin is mainly HCO₃-Ca·Na type, the Wagang uplift, Wuerxun sag and Beier sag area are mainly Cl-Na type and HCO₃-Na type, and the Bayanshan uplift area was mainly HCO₃-Ca·Na type. Hongqi Ranch and Xinbaolige depression were mainly Cl-Na type. The distribution of uranium in the study area ranged from 17 to 425μg/L, with an average of 80μg/L and a standard deviation of 70μg/L, which may indicate a regional groundwater uranium pollution. UO₂(CO₃)₃^4- and UO₂(CO₃)₂^2- are the dominate forms of uranium in groundwater, which is consistent with the redox environment of Eh, indicating a favorable environment for uranium mineralization in groundwater in the southeast of Hulunbuir Lake. Uranium mineralization prefers HCO₃^-type uranium-containing groundwater where uranyl bicarbonate is dominant, and the uranyl carbonate complex should be the dominate form. The dissolution of uranium is related to the increase of HCO₃^-. Uranium in groundwater may have participated in the mixed leaching of carbonate rock and sulfate rock. UO₂(CO₃)₃^4-, UO₂(CO₃)₂^2-, U₄O₉and bituminous ore are in a saturated state, while the concentrations of total Fe and (Ca²⁺+Mg²⁺) were low. Various water chemical indicators are indicative of uranium enrichment, so they can be regarded as references for potential uranium sources.