基于氢氧同位素的平原湖荡地表水与地下水转化研究

地表水与地下水间的相互转化以及量化地下水补给量是湖泊水循环研究的重要内容。本文采集了元荡湖区域湖水、地下水样品，测试了其氢氧稳定同位素组成和水化学组成，运用Piper三线图分析其水化学类型、通过钻孔实测的地下水埋深绘制元荡湖区域旱季(2022年12月)和雨季(2023年6月)的地下水水位等值线图，结合电导率(EC)和溶解性总固体(TDS)定性分析地表水-地下水之间的转化关系，利用同位素水量平衡方程、线性端元混合模型定量评价了湖水、地下水、河水和降水之间的转化量。结果表明，研究区湖水和地下水的水化学类型均为HCO₃^-·SO₄^2-·Ca²⁺·Na⁺·Mg²⁺，旱季和雨季湖水均受到地下水的补给，拟合得到的湖水旱季、雨季氢氧稳定同位素线性回归方程表明雨季斜率较小，蒸发更为强烈。湖水主要由河水、地下水和降水补给，其三者在旱季的补给比例分别为59%、26%和15%，在雨季的补给比例分别为23%、39%和38%。本文成果为元荡湖区域以及太湖流域的综合治理提供了科学依据。

Hydrogen and oxygen isotope based transformation studies of surface water and groundwater in plains lakes and swamps

The interconversion between surface water and groundwater and the quantification of groundwater recharge are important elements in the study of lake water cycle.In this paper，we collected lake water and groundwater samples from Yuandang Lake，tested their stable isotope compositions of hydrogen and oxygen and hydrochemical compositions，analyzed their hydrochemical types using Piper’s trilinear diagrams，and obtained the groundwater flow fields of Yuandang Lake during the dry season(December 2022) and the rainy season(June 2023) from the measured groundwater in the boreholes，and analyzed the transformation relationship between surface water and groundwater qualitatively with the combination of the electrical conductivity(EC) and total dissolved solids(TDS)，and quantified the amount of recharge from the isotope water balance equations.Qualitatively analyzed the transformation relationship between surface water-groundwater，and quantitatively evaluated the amount of transformation between lake water，groundwater，river water and precipitation by combining isotopic water balance equations and linear end-element mixing models.The results showed that the hydrochemistry types of lake water and groundwater in the study area were both of the HCO₃^-·SO₄^2-·Ca²⁺·Na⁺·Mg²⁺ type，and the lake water was recharged by groundwater in both the dry and rainy seasons,and linear regression equations were derived for the stable isotopes of lake water for hydrogen and oxygen in the dry and rainy seasons,with smaller slopes in the rainy season indicating that evaporation was more intense.The lake is mainly recharged by the inlet river water，shallow groundwater and precipitation，whose three recharge ratios are 59%，26% and 15% in the dry season and 23%，39% and 38% in the rainy season，respectively.The results of this paper provide a scientific evidence for the rational development and protection of the Yuandang Lake area and the Taihu Lake basin.