ABSTRACT Glacial and periglacial basins contain the largest reserves of fresh water in the world. These areas are extremely sensitive to global warming and climate change. The dry Andes of South America are characterized by large periglacial areas. This study focuses on the water isotopic composition and hydrochemistry of a typical periglacial environment of the Andes, in the Vallecitos catchment (2400–5500 m a.s.l.), Cordillera Frontal, Argentina. Detailed fieldwork was conducted between 2013 and 2017 with 240 samples collected for major ions and physicochemical parameters, and 67 samples analysed for 2H and 18O. The chemical composition of precipitation is typical Ca-HCO3, while streams and groundwaters are Ca-MgSO4 type. The isotope content of precipitation shows a wide dispersion. The snow samples are in general more depleted than the rainfall. Some springs vary their composition seasonally, associated to the melting of perennial snow patches. In general, all samples from the upper basin present depleted isotope contents related to recharge at higher altitudes, whereas samples from the lower basin show more enriched values. Intermediate compositions reflect the melting of snow and degrading ice-rich permafrost. These results will give a better understanding of the dynamics of water to manage water resources. GRAPHICAL ABSTRACT

中文翻译：

---

冰缘安第斯流域的同位素组成和水文地球化学及其与山区水资源知识的相关性

摘要冰川和冰缘盆地包含世界上最大的淡水储量。这些地区对全球变暖和气候变化极为敏感。南美洲干燥的安第斯山脉的特点是大面积的冰缘地区。本研究的重点是阿根廷 Cordillera Frontal 的 Vallecitos 流域（海拔 2400-5500 米）安第斯山脉典型冰缘环境的水同位素组成和水化学。2013 年至 2017 年期间进行了详细的实地调查，收集了 240 个样品的主要离子和物理化学参数，并分析了 67 个样品的 2H 和 18O。降水的化学成分是典型的 Ca-HCO3，而河流和地下水是 Ca-MgSO4 类型。沉淀的同位素含量表现出广泛的分散性。雪样通常比降雨量更耗尽。一些泉水的成分随季节变化，这与常年积雪的融化有关。一般而言，来自上盆地的所有样品都存在与高海拔补给相关的耗尽同位素含量，而来自下盆地的样品显示出更多的富集值。中间成分反映了雪的融化和富含冰的永久冻土层的退化。这些结果将有助于更好地了解水的动态以管理水资源。图形概要 中间成分反映了雪的融化和富含冰的永久冻土层的退化。这些结果将有助于更好地了解水的动态以管理水资源。图形概要 中间成分反映了雪的融化和富含冰的永久冻土层的退化。这些结果将有助于更好地了解水的动态以管理水资源。图形概要