Identifying the origin and geochemical evolution of groundwater using hydrochemistry and stable isotopes in the Subei Lake basin, Ordos energy base, Northwestern China

Abstract

Abstract. A series of changes in groundwater systems caused by groundwater exploitation in energy base have been of great concern to hydrogeologists. The research aims to identify the origin and geochemical evolution of groundwater in the Subei Lake basin under the influence of human activities. Water samples were collected, and major ions and stable isotopes (δ18O, δD) were analyzed. In terms of hydrogeological conditions and the analytical results of hydrochemical data, groundwater can be classified into three types: the Quaternary groundwater, the shallow Cretaceous groundwater and the deep Cretaceous groundwater. Piper diagram and correlation analysis were used to reveal the hydrochemical characteristics of water resources. The dominant water type of the lake water was Cl-Na type, which was in accordance with hydrochemical characteristics of inland salt lakes; the predominant hydrochemical types for groundwater were HCO3–Ca, HCO3–Na and mixed HCO3–Ca–Na–Mg types. The groundwater chemistry is mainly controlled by dissolution/precipitation of anhydrite, gypsum, halite and calcite. The dedolomitization and cation exchange are also important factors. Rock weathering is confirmed to play a leading role in the mechanisms responsible for the chemical composition of groundwater. The stable isotopic values of oxygen and hydrogen in groundwater are close to the local meteoric water line, indicating that groundwater is of modern local meteoric origin. Unlike significant differences in isotopic values between shallow groundwater and deep groundwater in the Habor Lake basin, shallow Cretaceous groundwater and deep Cretaceous groundwater have similar isotopic characteristics in the Subei Lake basin. Due to the evaporation effect and dry climatic conditions, heavy isotopes are more enriched in lake water than in groundwater. The low slope of the regression line of δ18O and δD in lake water could be ascribed to a combination of mixing and evaporation under conditions of low humidity. Comparison of the regression line for δ18O and δD showed that lake water in the Subei Lake basin contains more heavily isotopic composition than that in the Habor Lake basin, indicating that lake water in the discharge area has undergone stronger evaporation than lake water in the recharge area. Hydrochemical and isotopic information of utmost importance has been provided to decision makers by the present study so that a sustainable groundwater management strategy can be designed for the Ordos energy base.

Groundwater recharge sources in semiarid irrigated mountain fronts

“…However, although hydraulic head data record the groundwater recharge events, the discrimination of different sources of recharge generally requires the use of environmental tracers. Commonly used tracers include stable isotopes and major ions (Ayadi et al, 2018;Gastmans, Hutcheon, Menegário, & Chang, 2016;Guoliang, Chunmiao, & Simmons, 2016;He et al, 2018;Liu et al, 2015;Liu & Yamanaka, 2012;Yang et al, 2012;Zhu, Ren, & Rioual, 2018). The main advantage of using stable isotopes to analyse the mountain-front recharge is that the signature of local rainfall on the plain are likely to significantly vary from the signature of rainfall in the mountains due to rainout effects (Clark & Fritz, 1997;Kalbus, Reinstorf, & Schirmer, 2006;Lambs, 2004;Scanlon, Healy, & Cook, 2002).…”

Identifying evaporation fractionation and streamflow components based on stable isotopes in the Kaidu River Basin with mountain–oasis system in north‐west China

“…Furthermore, due to the widely used drop irrigation technology in the Yanqi Basin, almost no irrigation return flow can infiltrate deep enough to supply the groundwater. The slope and intercept of the local rainwater line were higher than the LMWL, although the Kaidu River is mainly charged by modern precipitation (Liu et al, ), and the waters undergo complex evaporation fractionation and isotope redistribution processes. Winter surface snow isotopes were much more depleted than glacier meltwater in the Kaidu River Basin, with the slopes of their evaporation lines being quite close.…”

Fluoride Levels in the Groundwater and Prevalence of Dental Fluorosis in the Municipality of Santana, in Region Karstic of West Bahia, Brazil

“…In this context, the application of hydrochemical methods and techniques can help the management of water quality. The knowledge about the origin and behavior of major ions (Ca 2+ , Mg 2+ , Na + , K + , CO 3 2− , HCO 3 − , Cl − , SO 4 2− ) in groundwater allows the elucidation of the hydrogeochemical composition [20]. This varies depending on the solubility of the chemical elements from the dissolution of the mineral constituent of the rocks that host the aquifer.…”