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Stable isotope and hydrochemistry reveal source and quality of groundwater around Qinghai Lake, NE Qinghai-Tibet Plateau, China
  • +2
  • Dongsheng Li,
  • Buli Cui,
  • Ying Wang,
  • Yaxuan Wang,
  • Baofu Jiang
Dongsheng Li
Ludong University
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Buli Cui
Ludong University
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Ying Wang
Ludong University
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Yaxuan Wang
Ludong University
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Baofu Jiang
Ludong University
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Abstract

The integrated use of isotopic and hydrochemical tracers is an effective approach for investigating complex hydrological processes of groundwater. Thorough understanding of recharge and quality of the groundwater is usually a prerequisite for effective groundwater management. This study investigated the water level, stable isotope and hydrochemistry of groundwater around the Qinghai Lake to reveal the recharge sources, hydrochemical evolution and water quality of groundwater. The relative altitudes of groundwater level ranged from -1.27 to 122.91 m with hydraulic gradient ranging from -6.20 to 43.14‰relative to the water level of Qinghai Lake, indicating most of the groundwater was flowing into the lake. Most of the groundwater points lay close to the local meteoric water line, and the slope of Local Evaporation Line of groundwater (LEL: δ2H = 6.08 δ18O-3.01) was lower than the slopes of the LMWL, indicating that the groundwater were recharged primarily from precipitation at different altitude in the basin, though it had undergone varying degrees of evaporation. The hydrochemical analysis showed that the groundwater was mainly freshwater and its hydrochemical type was Ca-Mg-HCO3. The groundwater chemistry was mainly controlled by carbonate dissolution around Qinghai Lake. Furthermore, high TDS and high concentrations of Na+, Mg2+, Cl-, or SO42- in several groundwater were caused by the recharge source of lake water, the recharge source of fissure water, or by the dissolution of evaporite. The main sources of nitrate (NO3-) in groundwater around Qinghai Lake were animal feces and sewage, suggesting that the pollution of groundwater should be paid more attention in animal husbandry areas on the Qinghai-Tibet Plateau, although the industrial and urbanization rates were relative low on the plateau. The scientific planning and engineering management of livestock manure and wastewater discharge in animal husbandry regions are very necessary to be carried out urgently, which could not only protect water resources for drinking, but also contribute to human health and sustainable development of the ecological environment of the Qinghai-Tibet Plateau.