Interpreting Source of Lingshui Spring by Hydrogeological, Chemical and Isotopic Methods

Abstract

Lingshui spring produced excellent drinking water. However there was no protection area for the spring. The goal of the study was to determine source of the spring and give suggestions for protection. Limestone with total thickness of more than 1 km composes the karst aquifer. There was siliceous rock as aquiclude in upper Permian. Lingshui spring was in a syncline. The syncline was covered by mudstone at the center, making the karst aquifer partially confined. Rainfall was the source of surface rivers and groundwater. Groundwater usually recharges to rivers. There were no obvious watersheds between Lingshui and other springs. It is important to know the relation among springs. The hydrochemical results showed that springs in front of mountains were recharged by allogenic rivers. Anthropogenic related contaminants such as K⁺, Na⁺, Cl^-, SO ^2-₄ and NO ^-₃ were higher in shallow aquifer than deep aquifer. This helped to determine that Lingshui spring came from the deep aquifer and had no allogenic source. The hydrogen and oxygen isotopes of springs, wells and rivers were all near the local meteoric water line. Karst springs including Linshui had similar concentrations of D and ¹⁸O and exhibited much less isotopic variability than others. They came from the same karst aquifer.