This paper studies the uranium content and uranium isotopic disequilibria as a tool to identify hydrogeochemical processes from 52 groundwater samples in the province of Granada (Betic Cordillera, southeastern Spain). According to the geological complexity of the zone, three groups of samples have been considered. In Group 1 (thermal waters; longest residence time), the average uranium content was 2.63 ± 0.16 μg/L, and ²³⁴U/²³⁸U activity ratios (AR) were the highest of all samples, averaging 1.92 ± 0.30. In Group 2 (mainly springs from carbonate aquifers; intermediate residence time), dissolved uranium presented an average value of 1.34 ± 0.13 μg/L, while AR average value was 1.38 ± 0.25. Group 3 comes from pumping wells in a highly anthropized alluvial aquifer. In this group, where the residence time of the groundwater is the shortest of the three, average uranium content was 5.28 ± 0.26 μg/L, and average AR is the lowest (1.17 ± 0.12). In addition, the high dissolved uranium value and the low AR brought to light the contribution of fertilizers (Group 3). In the three groups, ²³⁵U/²³⁸U activity ratios were similar to the natural value of 0.046. Therefore, ²³⁵U detected in the samples comes from natural sources. This study is completed with the determination of major ions and physicochemical parameters in the groundwater samples and the statistical analysis of the data by using the Principal Component Analysis. This calculation indicates the correlation between uranium isotopes and bicarbonate and nitrate anions.

本文研究了铀含量和铀同位素不平衡现象，以此作为从格拉纳达省（西班牙东南部的比迪科迪勒拉）的52个地下水样品中识别水文地球化学过程的工具。根据该区域的地质复杂性，已经考虑了三组样品。在第1组（热水；最长停留时间）中，平均铀含量为2.63±0.16μg/ L，²³⁴ U / ²³⁸U活性比（AR）在所有样品中最高，平均为1.92±0.30。第2组（主要来自碳酸盐岩含水层；中间停留时间）中，溶解铀的平均值为1.34±0.13μg/ L，而AR平均值为1.38±0.25。第3组来自在高度人工冲积含水层中抽水井。在这三组中，地下水的停留时间最短，三者的平均铀含量为5.28±0.26μg/ L，而平均AR最低（1.17±0.12）。此外，高的溶解铀值和低的AR使肥料的作用得以显现（第3组）。在这三组中，²³⁵ U / ²³⁸ U活性比与自然值0.046相似。因此²³⁵样品中检测到的U来自自然来源。通过确定地下水样品中的主要离子和理化参数以及使用主成分分析对数据进行统计分析来完成本研究。该计算表明铀同位素与碳酸氢根和硝酸根阴离子之间的相关性。