Geochemical Characteristics and Their Environmental Implications for the Water Regime of Hulun Lake, Inner Mongolia, China

Abstract

The overall geochemical composition of natural-water regimes reflects the response to long-term interactions between the water and the surrounding environment in the process of its circulation. Their characteristics can reflect both aquatic ecological health and the tracer of the water source, as well as the water budget. In this study, Hulun Lake, a remote lake in a cold and arid area of China, was chosen in order to analyze its geochemical characteristics, including the major ions, stable isotopes (δD and δ18O) and dissolved organic matter (DOM) in its lake water, river water and groundwater. The major ions in the water were dominated by Na+ + Ca2+-CO32− and the concentration of ions in the groundwater was significantly higher than that in the lake and river water, implying a dry climate and relatively little human disturbance. The δD and δ18O values for both the groundwater and the river water were similar and both were close to the global meteoric water line (GMWL), indicating that their sources were mainly supplied by atmospheric precipitation. However, the δD and δ18O values for lake water were below the GMWL, indicating strong evaporation. The concentration of DOM in the lake water was significantly higher than that in the river water and groundwater, which was affected by the growth of aquatic organisms, and the three-dimensional fluorescence spectrum characteristics also proved that the contribution of biomass sources was greater.