Stable Isotope Composition in Surface Water in the Upper Yellow River in Northwest China
Although stable isotopes of hydrogen and oxygen in surface waters (especially in river waters) are useful tools to understand regional hydrological processes, relevant information at some upper reaches of large rivers in western China is still limited. During 2016–2017, we focused on the Liujiaxia Reservoir along the upper Yellow River, where we collected surface water samples at two locations, above and below the dam (identified as “lake water” and “river water”). The results show that the heavy isotopes in lake and river waters are enriched during the warm months, when the river discharge is large, and depleted during the cold months. The slopes of the water line (δ2H versus δ18O) for both the lake and river waters were lower than that of the global mean, due to evaporation. The different d values of the lake and river water reflect the regional evaporation and water sources.