Insights into moisture sources and evolution from groundwater isotopes (2H, 18O, and 14C) in Northeastern Qaidam Basin, Northeast Tibetan Plateau, China

Nuan Yang; Guangcai Wang; Fu Liao; Xueya Dang; Xiaofan Gu

doi:10.1016/j.scitotenv.2022.160981

Insights into moisture sources and evolution from groundwater isotopes (²H, ¹⁸O, and ¹⁴C) in Northeastern Qaidam Basin, Northeast Tibetan Plateau, China

Sci Total Environ. 2023 Mar 15:864:160981. doi: 10.1016/j.scitotenv.2022.160981. Epub 2022 Dec 17.

Authors

Nuan Yang¹, Guangcai Wang², Fu Liao¹, Xueya Dang³, Xiaofan Gu³

Affiliations

¹ 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.
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. Electronic address: wanggc@pku.edu.cn.
³ Xi'an Center, China Geological Survey, Xi'an 710054, China; Key Laboratory for Groundwater and Ecology in Arid and Semi-arid Areas, China Geological Survey, Xi'an 710054, China.

PMID: 36539094
DOI: 10.1016/j.scitotenv.2022.160981

Abstract

Knowledge of moisture sources is of great significance for the understanding of groundwater recharge and hydrological cycle. However, it is often difficult to identify the moisture sources and evolution especially in the areas with complex climate system. Isotopes in groundwater that acts as a climate archive provide a unique perspective on the moisture sources and evolution. In this study, the stable isotopes (²H, ¹⁸O) of precipitation and groundwater, radioactive isotope (¹⁴C) of groundwater, water vapor trajectory modeling (HYSPLIT models) and d-excess based on mass balance model were employed to reveal the groundwater origin, moisture source and evolution in the northeastern Qaidam Basin, northeast Tibetan Plateau, China. The stable isotopic compositions indicate that the precipitation in the mountainous areas is the main origin of groundwater. The spatiotemporal variation of groundwater d-excess together with HYSPLIT modeling suggest that the moisture sources in the northeastern Qaidam Basin have been controlled by the Westerlies and did not alter obviously with time, whereas Delingha with relatively low elevation is influenced by both the Westerlies and local recycled moisture. More than 80 % water vapor derives from the northwest of study area for the plain and mountainous area, except for the mountainous area of Delingha, where approximately 23 % water vapor originates from the surface water evaporation in the plain area. The water vapor with high d-excess formed in the plain area is transported to the mountainous area and mixed with advected water vapor, resulting in the large d-excess of groundwater in Delingha. The moisture recycling fraction in precipitation for the mountainous area of Delingha is estimated to be about 2.0 % by using d-excess-based mass balance model. The results of the study could be helpful to the understanding of hydrological cycle of the area and elsewhere.

Keywords: D-excess; Groundwater stable isotopes; HYSPLIT modeling; Moisture sources; Recycled moisture.