ABSTRACT Changes in groundwater evolutionary processes due to aquifer overexploitation show a world-wide increase and have been of growing concern in recent years. The study aimed to improve the knowledge of groundwater evolutionary processes by means of stable water isotopes and hydrochemistry in a representative lake basin, Ordos energy base. Groundwater, precipitation, and lake water collected during four campaigns were analysed by stable isotopes and chemical compositions. Results showed that temperature effect predominated the isotope fractionation in precipitation, while evaporation and inadequate groundwater recharge were the key factors explaining high salinity and isotopic enrichment in lake water. Additionally, the Kuisheng Lake was a preferential area of groundwater recharge, while the Subei Lake received less sources from underlying aquifer due to the combined effects of low permeable zone and upstream groundwater captured by the production wells. The homogeneous isotope signatures of groundwater may be ascribed to the closely vertical hydraulic connectivity between the unconfined and the confined aquifers. Isotopically enriched groundwater pumping from well field probably promoted isotopic depletion in groundwater depression cone. These findings not only provide the conceptual framework for the inland basin, but also have important implications for sustainable groundwater management in other groundwater discharge basins with arid climate.

中文翻译：

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鄂尔多斯能源基地苏北湖盆水和水化学稳定同位素对地下水演化过程的洞察

摘要 由于含水层过度开发引起的地下水演化过程的变化在世界范围内呈上升趋势，近年来受到越来越多的关注。该研究旨在通过具有代表性的湖盆——鄂尔多斯能源基地的稳定水同位素和水化学，提高对地下水演化过程的认识。通过稳定同位素和化学成分分析了四次活动期间收集的地下水、降水和湖水。结果表明，温度效应在降水中同位素分馏占主导地位，蒸发和地下水补给不足是造成湖水中高盐度和同位素富集的关键因素。此外，奎升湖是地下水补给的优先地区，而由于低渗透带和生产井捕获的上游地下水的共同影响，苏北湖从下伏含水层获得的水源较少。地下水的同质同位素特征可能归因于非承压含水层和承压含水层之间密切的垂直水力连通性。从井场抽取的同位素富集地下水可能促进了地下水洼地锥体中同位素的消耗。这些发现不仅为内陆盆地提供了概念框架，而且对其他干旱气候的地下水排放盆地的可持续地下水管理具有重要意义。地下水的同质同位素特征可能归因于非承压含水层和承压含水层之间密切的垂直水力连通性。从井场抽取的同位素富集地下水可能促进了地下水洼地锥体中同位素的消耗。这些发现不仅为内陆盆地提供了概念框架，而且对其他干旱气候的地下水排放盆地的可持续地下水管理具有重要意义。地下水的同质同位素特征可能归因于非承压含水层和承压含水层之间密切的垂直水力连通性。从井场抽取的同位素富集地下水可能促进了地下水洼地锥体中同位素的消耗。这些发现不仅为内陆盆地提供了概念框架，而且对其他干旱气候的地下水排放盆地的可持续地下水管理具有重要意义。