Triple isotopes (δD, δ18O, δ17O) characteristic of river water and groundwater in an arid watershed from Qaidam Basin, Northwestern China: implications for hydrological cycle

Nuan Yang; Guangcai Wang; Enke Hou; Liang Guo; Luoyao Xiong; Xinming Song

doi:10.1016/j.scitotenv.2024.172229

Triple isotopes (δD, δ¹⁸O, δ¹⁷O) characteristic of river water and groundwater in an arid watershed from Qaidam Basin, Northwestern China: implications for hydrological cycle

Sci Total Environ. 2024 Jun 1:927:172229. doi: 10.1016/j.scitotenv.2024.172229. Epub 2024 Apr 4.

Authors

Nuan Yang¹, Guangcai Wang², Enke Hou³, Liang Guo³, Luoyao Xiong², Xinming Song²

Affiliations

¹ College of Geology and Environment, Xi'an University of Science and Technology, Xi'an, Shaanxi 710054, China. Electronic address: yangnuan@xust.edu.cn.
² State Key Laboratory of Biogeology and Environmental Geology and MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing 100083, China; School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, China.
³ College of Geology and Environment, Xi'an University of Science and Technology, Xi'an, Shaanxi 710054, China.

PMID: 38582115
DOI: 10.1016/j.scitotenv.2024.172229

Abstract

Combining traditional stable isotopes (δD and δ¹⁸O) and triple oxygen isotope (δ¹⁷O) is conducive to tracing hydrological cycle processes. The application of triple oxygen isotopes primarily focuses on precipitation, which is lacking in river water and groundwater. In this study, the spatial variations of δD, δ¹⁸O, δ¹⁷O, d-excess and ¹⁷O-excess of river water and groundwater in the Golmud River basin as well as the correlation between them were investigated to elucidate water origin and assess the evaporation influence on water bodies during flood season. Spatial changes in δD, δ¹⁸O and δ¹⁷O of river water exhibit a decrease-increase-stability pattern contrary to that observed for d-excess, ¹⁷O-excess has no distinct trend but is higher at both the source and downstream regions. The results show that river water and groundwater originate from precipitation in the mountainous area, and the meltwater in the source region also contribute to the river water with high d-excess and ¹⁷O-excess during flood season. The combination of d-excess and ¹⁷O-excess reveal that river water is also affected by evaporation and mixing of river water in tributaries. It was found that the river water is recharged in the mountains, undergoes evaporation in the upstream region and leaks into groundwater in the midstream region, which is recharged by the groundwater and evaporated again in the downstream region. This study could provide a more comprehensive understanding of the potential and value of triple oxygen isotopes in the hydrological cycle.

Keywords: (17)O-excess; Arid watershed; Hydrological cycle; River water and groundwater; Stable isotopes.