| 摘要: |
| 氢氧稳定同位素被广泛用于水文循环过程的研究。本文观测了2015年太湖湖水H2HO和H218O组分，分析了它们的时空变化规律及其控制因子，探讨亚热带大型浅水湖泊的同位素富集机制；基于稳定同位素质量守恒法计算太湖蒸发量；评价了动力分馏学系数的传统湖泊算法与海洋算法的适用性；重点分析了H2HO和H218O示踪湖泊蒸发的效果，对比二者之间的差异。研究结果表明，在空间上，太湖湖水和河水的氢氧同位素在南部特别是东南部较为富集但在北部区域较为贫化，这主要是受水流方向的控制，东南部湖水经历的蒸发时间较长，因此湖水中同位素累积较多；在季节上，冬季湖水同位素较贫化、春夏季较富集。对于2015年太湖的年蒸发量，用氢同位素示踪的结果与观测值较一致，为880mm；氧同位素的示踪结果略低，为690mm。使用传统湖泊研究中对动力学分馏系数的取值，会导致蒸发被显著低估，而氧稳定同位素的示踪结果对动力学分馏系数的取值更为敏感，同时氢稳定同位素在同位素分馏过程中主要是平衡分馏效应占主导，因此H2HO在动力学分馏系数的参数化方案中影响较小，在实际应用中更为稳定。本文的研究结果表明了稳定同位素水文学研究中使用合适的动力学分馏系数的重要性。 |
| 关键词: 太湖 蒸发 H2HO H218O 同位素质量守恒模型 动力学分馏系数εk |
| DOI：10.11693/hyhz20180300064 |
| 分类号:X142 |
| 基金项目:国家自然科学基金项目，41475141号；国家自然科学基金项目，41505005号；国家自然科学基金项目，41575147号；江苏省高校优势学科建设工程项目（PAPD）；教育部长江学者和创新团队发展计划项目（PCSIRT）。 |
附件 |
|
| COMPARISON OF USING HYDROGEN AND OXYGEN ISOTOPES IN TRACING WATER EVAPORATION IN TAIHU LAKE |
|
XIE Cheng-Yu1, XIAO Wei1,2, XU Jing-Zheng3, ZHU Shan-Xian4, HU Yong-Bo1, LI Xu-Hui1
|
|
1.Yale-NUIST Center on Atmospheric Environment, Nanjing University of Information Science and Technology, Nanjing 210044, China;2.Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science and Technology, Nanjing 210044, China;3.Jiangsu Radio Scientific Institute Co., LTD, Wuxi 214073, China;4.Department of Earth System Science, Tsinghua University, Beijing 100084, China
|
| Abstract: |
| Hydrogen and oxygen isotopes are widely used in the studies on the hydrologic cycle. In this study, we compared the performance of using H2HO and H218O compositions to track water evaporation in Taihu Lake and its tributary rivers, analyzed the spatial pattern and temporal variability and their controlling factors, and investigated the isotopic enrichment mechanism. Based on the isotopic mass balance model, we simulated the evaporation over the lake and evaluated the appropriateness of kinetic fractionation factors. The results show that, in space, the hydrogen and oxygen isotopes of Taihu Lake water and river water are more concentrated in the south, especially in the southeast, but are more depleted in the northern region, which is controlled mainly by the direction of water flow, because the southeastern part of the lake experienced longer and stronger evaporation so more isotopes were accumulated there; in the season, lake water isotope is more depleted in the winter but more abundant in spring and summer. The evaporation of Lake Taihu in 2015 was better estimated using hydrogen isotope as the tracer (880 mm) than oxygen isotope tracer (690 mm) that underestimated. Traditional studies on lake water evaporation using a kinetic fractionation factor may lead to a significant underestimation of evaporation, and oxygen stable isotope is more sensitive to determine the kinetic fractionation factor. In hydrogen stable isotope fractionation, the equilibrium fractionation effect is dominant, so H2HO has less influence on the parameterization scheme of the kinetic fractionation factor and is more stable in practical application. The results of this study demonstrate the importance of using appropriate kinetic fractionation factors in stable-isotope hydrology studies. |
| Key words: Taihu Lake evaporation H2HO H218O isotopic mass balance model kinetic fraction factor εk |
