Stable isotope characteristics of different water bodies in the Lhasa River Basin

Abstract

Stable hydrogen and oxygen in different water bodies were investigated to understand the isotopic characteristics in the Lhasa River Basin. A total of 73 water samples were collected from the river, well and spring in this study. The stable isotopic compositions of different water bodies are influenced by evaporation, and the slope of the local meteoric water line deviates slightly from that of the global meteoric water line. The slopes of the surface water, groundwater and spring water lines are smaller than that of the global meteoric water line. The surface water originates from not only atmospheric precipitation but also glacial/snow meltwater, especially in the Dang River, the upper reaches of the Lhasa River and the Duilong River. The groundwater is derived from meteoric water, and there are certain differences between the source and the cyclic process of groundwater at different locations and depths. Spring water is conjunctively recharged by groundwater, surface water and precipitation, but groundwater is the main source of spring water. The altitude effect of hydrogen and oxygen isotopes in river water is not obvious in the whole basin, but it is noticeable in some areas due to the effect of climate and temperature. Surface water, groundwater and spring water have a relationship of reciprocal recharge, and the miscibility of groundwater is the strongest, with recharge from multiple water sources.