Hydrochemical and Isotope (18O, 2H and 3H) Characteristics of Karst Water in Central Shandong Province: A Case Study of the Pingyi-Feixian Region

Chunhua Liu,Guanghui Zhang,Yan Guo,Jingjing Wang,Wei Wang,Henghua Zhu

doi:10.3390/min12020154

Chunhua Liu, Guanghui Zhang + Show 4 more

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https://doi.org/10.3390/min12020154

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Abstract

Karst water serves as an important water supply source in northern China. Hydrochemical and isotope (18O, 2H, and 3H) characteristics are invaluable tools to identify water–rock interaction activities in karst water systems. In this study, the investigation of hydrogeological conditions, hydrogeochemistry, and hydrogen and oxygen isotopes of karst water revealed: (1) HCO3-Ca-type water is widely distributed throughout the study area, while HCO3-Ca·Mg-type water appears in the direct recharge areas and the discharge areas; karst water of the HCO3−·Cl−, Cl−·HCO3−, and Cl− types is scattered in low-land areas; (2) karst water has high δ18O, which may be due to the dissolution and exchange of 18O from the surrounding carbonate rocks in the western discharge zone; and (3) the 3H concentration of karst water is strongly correlated with the content of major ions (Ca2+, Mg2+, HCO3−, SO42−, and Cl−) and it increases along the flow path. It was also revealed that the karst water in the discharge areas is mixed with lateral recharge (infiltration recharge from surface water).

Highlights

Each karst water system has its own storage, transport, and regulatory functions and constantly exchanges water with other system components, resulting in changes in water quantity and quality as the entire system interacts with the external environment [1–14]
The hydrochemistry of karst water is generally focused on the distribution of major ions (K+, Na+, Ca2+, Mg+, HCO3−, SO42−, and Cl−). 2H and 18O are stable isotopes that are widely used to retrieve information about the sources, areas, and times of karst water recharge
A large number of karst water studies have explored the structures, hydrodynamic processes, and hydrochemical evolution patterns of karst water systems based on analyses and measurements of major ions and isotopes (18O, 2H, and 3H), especially in the karst water areas of northern China [25–39]

Summary

Introduction

Each karst water system has its own storage, transport, and regulatory functions and constantly exchanges water with other system components, resulting in changes in water quantity and quality as the entire system interacts with the external environment [1–14]. 2H and 18O are stable isotopes that are widely used to retrieve information about the sources, areas, and times of karst water recharge. Due to atmospheric nuclear tests in the 1950s and in the early 1960s, the 3H concentration in precipitation increased sharply; it peaked at 1868 TU in 1963 [24] and declined every year until reaching 32 TU in 2001 (from the precipitation monitoring station of IAEA in Shijiazhuang), identifying 3H as a good indicator of whether the recharge sources of karst water formed before or after these nuclear tests (1952). A large number of karst water studies have explored the structures, hydrodynamic processes, and hydrochemical evolution patterns of karst water systems based on analyses and measurements of major ions and isotopes (18O, 2H, and 3H), especially in the karst water areas of northern China [25–39]

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