Hydro-chemical Characteristics and Ion Origin Analysis of Surface Groundwater at the Shengjin Lake and Yangtze River Interface

Abstract

The interface between Shengjin Lake and Yangtze River was selected as the study area. The water chemical composition and hydrogen and oxygen isotope values of different types of water bodies were tested, and their seasonal variation characteristics were analyzed to explore the sources of chemical ions in the surface and groundwater. Finally, the contribution of mixed water sources to chemical ions in groundwater was estimated. The results show the following ① The concentration of chemical ions in the surface and groundwater of the study area is higher than that of atmospheric precipitation, and the physical and chemical parameters exhibit seasonal variation. ② Surface water mainly belongs to the Ca-HCO3 type, but the proportion of the Ca-SO4 type in summer is significantly lower than that in other seasons; Groundwater primarily belongs to Ca-HCO3 and Ca-SO4 types, with proportions of 46% and 27%, respectively, and the seasonal difference is not significant. ③ Ca2+ and Mg2+ in the surface and groundwater mainly come from the dissolution of carbonate rocks, carbonic acid and sulfate ions participate in the dissolving process of carbonate minerals. Na+and Cl- are partly derived from atmospheric precipitation and partly sourced from agricultural fertilization and manure sewage. ④ Mixed water sources is also an important source of chemical ions in groundwater, with the average contribution 28% to Cl-, showing a seasonal trend.