Controlling Factors of Surface Water Ionic Composition Characteristics in the Lake Genggahai Catchment, NE Qinghai–Tibetan Plateau, China

Abstract

This study has determined the major ion compositions of surface waters within the basin of Lake Genggahai, northeastern Qinghai–Tibetan Plateau, China. The results showed that the anions in the groundwater and river water of Genggahai Lake are mainly HCO3−, and the cations are mainly Ca2+ + Na+. Evaporite, carbonate, and silicate in the basin all have an impact on the chemical composition of river water and groundwater. Among them, carbonate weathering has a relatively larger contribution. The grazing activities of herdsmen in the basin have had a certain degree of impact on the water quality of river basins and groundwater. The anion of lake water is dominated by Cl−, and the cation is mainly Na+. The content change is mainly affected by the change of corresponding ion content in groundwater coming into the lake and the evaporation of lake water. Among them, Cl− in lake water is more affected by the change of Cl− content in the groundwater coming into the lake, while Na+ in lake water is more affected by evaporation. More specifically, the low concentrations of Ca2+ and HCO3− in lake water were determined to be related to the photosynthesis of aquatic plants in the lake.