Source and Quality of Groundwater Surrounding the Qinghai Lake,NE Qinghai-TibetPlateau

Comprehensive studies on the spatial distribution, water quality, recharge source, and hydrochemical evolution of regional groundwater form the foundation of rational utilization of groundwater resources. In this study, we investigated the water levels, hydrochemistry, and stable isotope composition of groundwater in the vicinity of the Qinghai Lake in China to reveal its recharge sources, hydrochemical evolution, and water quality. The level of groundwater relative to the level of water in the Qinghai Lake ranged from -1.27 to 122.91 m, indicating most of the groundwater to be flowing into the lake. The local evaporation line (LEL) of groundwater was simulated as delta H-2 = 6.08 delta O-18-3.01. The groundwater surrounding the Qinghai Lake was primarily recharged through local precipitation at different altitudes. The hydrochemical type of most of the groundwater samples was Ca-Mg-HCO3; the hydrochemistry was primarily controlled by carbonate dissolution during runoff. At several locations, the ionic concentrations in groundwater exceeded the current drinking water standards making it unsuitable for drinking. The main source of nitrate in groundwater surrounding the Qinghai Lake was animal feces and sewage, suggesting that groundwater pollution should be mitigated in areas practicing animal husbandry in the Qinghai-Tibet Plateau, regardless of industrial and urbanization rates being relatively low in the region. The scientific planning, engineering, and management of livestock manure and wastewater discharge from animal husbandry practices is a crucial and is urgently required in the Tibetan Plateau