The Significance of Hydrogen and Oxygen Stable Isotopes in the Water Vapor Source in Dingxi Area

Abstract

Deuterium excess and stable oxygen isotopes in precipitation have been widely applied to trace the source of water vapor. In this study, hydrogen and oxygen isotope analyses of samples were collected on seven sampling stations in Dingxi area from April 2019 to April 2020. The seasonal variation of hydrogen and oxygen stable isotopes as well as the d-excess indicate that the source of water vapor in Dingxi area is mostly from a single source. However, there are different sources of water vapor in the summer. Meanwhile, water vapor sources were analyzed using the Lagrange algorithm, indicating two different principal water vapor sources for precipitation in the area: some locally recycled water vapor in summer and autumn, and most water vapor from the westerly belt. Further studies using the PSCF and CWT analysis methods show that the locally recycled water vapor contributes more to its precipitation in the northwest of Dingxi area.

Ocean air masses from the East Asian monsoon dominate the land‐surface atmospheric water cycles in the coastal areas of Liaodong Bay, Northeast China

“…Apparently, the rainfall process was one of the main factors contributing to the diurnal dynamics of atmospheric water vapour δ 2 H, δ 18 O and d‐excess (Figure 4). The isotopic fractionation caused by the sub‐cloud secondary evaporation enriches the residual rainfall, which in turn can make the enrichment of atmospheric isotopes during small rainfall events (Vuille et al, 2003; Wu et al, 2021). However, the rainout effects of rainfall would result in the continuous depletion of atmospheric isotopes according to the Rayleigh distillation mechanisms (Gat, 1996; Lee et al, 2005; Wen et al, 2010).…”

Characteristics of hydrogen and oxygen isotopes and their differences of different water bodies in the subalpine shrubland of the eastern Qilian Mountains in China

“…The lowest values of δD (-99.48‰) and δ 18 O (-15.59‰) were found on October 6. In study area, the precipitation concentrates in July-August (Figure 3), when the relative humidity of the atmospheric is higher and the kinetic fractionation due to sub-cloud evaporation is weak (Wu et al 2021). In addition, the stable isotope is constantly depleted for long-distance transport of the westerly vapor (Ma et al 2012;Ma et al 2018;.…”

“…This was related to precipitation sources that were more complex due to the influence of westerly moisture, local circulation water vapor and sub-cloud evaporation (Wu et al 2011). Many scholars have proved the precipitation process in northwest China undergoes certain sub-cloud evaporation and local water vapor mixing (Liu et al 2008;Ma et al 2020;Wu et al 2021). Except for July 30, the d-excess values showed an obvious decrease trend from early of July to August (from 22.34‰ to 3.91‰), which may be influenced by higher precipitation and monsoon moisture during this period.…”

Characteristics of hydrogen and oxygen isotopes and their differences of different water bodies in the subalpine shrubland of the eastern Qilian Mountains in China

“…In study area, the precipitation concentrates in July-August (Fig. 3), when the relative humidity of the atmospheric is higher and the kinetic fractionation due to sub-cloud evaporation is weak (Wu et al 2021). In addition, the stable isotope is constantly depleted for long-distance transport of the westerly vapor (Ma et ).…”