Isotopic composition and hydrogeochemistry of a periglacial Andean catchment and its relevance in the knowledge of water resources in mountainous areas

SILEO, NOELIA R.; DAPEÑA, CRISTINA; TROMBOTTO LIAUDAT, DARIO

ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES

TAYLOR & FRANCIS LTD

Año: 2020 p. 1 - 15

1025-6016

Glacial and periglacial basins contain the largest reserves of freshwater in the world. These areas are extremely sensitive to globalwarming and climate change. The dry Andes of South America arecharacterized by large periglacial areas. This study focuses on thewater isotopic composition and hydrochemistry of a typicalperiglacial environment of the Andes, in the Vallecitos catchment(2400?5500 m a.s.l.), Cordillera Frontal, Argentina. Detailedfieldwork was conducted between 2013 and 2017 with 240samples collected for major ions and physicochemical parameters,and 67 samples analysed for 2H and 18O. The chemicalcomposition of precipitation is typical Ca-HCO3, while streams andgroundwaters are Ca-MgSO4 type. The isotope content ofprecipitation shows a wide dispersion. The snow samples are ingeneral more depleted than the rainfall. Some springs vary theircomposition seasonally, associated to the melting of perennialsnow patches. In general, all samples from the upper basinpresent depleted isotope contents related to recharge at higheraltitudes, whereas samples from the lower basin show moreenriched values. Intermediate compositions reflect the melting ofsnow and degrading ice-rich permafrost. These results will give abetter understanding of the dynamics of water to manage waterresources.