| 引用本文: | 陶士勇,张翔,夏军强,肖洋,熊兴基,徐晶.鄱阳湖湿地碟形湖-河流水稳定同位素变化特征及其指示意义.湖泊科学,2024,36(2):487-498. DOI:10.18307/2024.0226 |
| Tao Shiyong,Zhang Xiang,Xia Junqiang,Xiao Yang,Xiong Xingji,Xu Jing.Variations of stable isotopic characteristics of shallow lake-river water system and its indicative significance in Lake Poyang wetland, China. J. Lake Sci.2024,36(2):487-498. DOI:10.18307/2024.0226 |
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| 鄱阳湖湿地碟形湖-河流水稳定同位素变化特征及其指示意义 |
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陶士勇1,2, 张翔1,2, 夏军强1, 肖洋3, 熊兴基1,2, 徐晶1,2
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1.武汉大学水资源工程与调度全国重点实验室, 武汉 430072;2.武汉大学海绵城市建设水系统科学湖北省重点实验室, 武汉 430072;3.长江水资源保护科学研究所, 武汉 430051
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| 摘要: |
| 为深入认识鄱阳湖湿地区域水循环过程,于2019年1-12月在鄱阳湖国家级自然保护区对降水、河流水、主要碟形湖水进行系统采集,综合分析碟形湖-河流水稳定同位素的动态变化特征及其指示意义。结果表明,鄱阳湖湿地修河和赣江的同位素组成具有明显的季节性变化规律,4月河水同位素最为富集,5-7月逐渐贫化,之后呈现出不断富集的变化趋势,整体上与降水同位素的时间变化特性相似。在空间分布上,各段河水的同位素组成均具有相对稳定的沿程分布特征,赣江在修河汇入点上、下游的同位素特性在大多数月份没有呈现出明显变化。碟形湖水同位素的年内变化范围比河水大,并且相对富集。主要碟形湖水的δ2H-δ18O关系接近当地大气降水线,具有更小的蒸发线斜率以及系统性偏离的特征,反映碟形湖主要受到当地降水补给,经历了一定程度的蒸发作用。基于指数模型方法估算修河和赣江水体的平均滞留时间(mean residence time,MRT)分别为1.54和0.81年,赣江较短的MRT表明鄱阳湖流域具有不同水体组分相互快速转化的水力条件,修河上游柘林水库的调蓄作用导致其MRT明显大于赣江。通过假定碟形湖水的蒸发过程遵循瑞利分馏模型,全年的同位素监测结果揭示蚌湖、沙湖、大湖池的年平均蒸发损失量分别为15.5%、15.0%、14.1%,不同碟形湖之间蒸发程度的差异可能与地形、植被和水动力条件等因素的综合影响有关。 |
| 关键词: 稳定同位素 平均滞留时间 蒸发 碟形湖-河流水 鄱阳湖湿地 |
| DOI：10.18307/2024.0226 |
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| 基金项目:国家自然科学基金项目(U21A2002, 52109005)资助。 |
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| Variations of stable isotopic characteristics of shallow lake-river water system and its indicative significance in Lake Poyang wetland, China |
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Tao Shiyong1,2, Zhang Xiang1,2, Xia Junqiang1, Xiao Yang3, Xiong Xingji1,2, Xu Jing1,2
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1.State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, P.R. China;2.Hubei Key Laboratory of Water System Science for Sponge City Construction, Wuhan University, Wuhan 430072, P.R. China;3.Changjiang Water Resources Protection Institute, Wuhan 430051, P.R. China
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| Abstract: |
| Lake Poyang is the largest freshwater lake in China and an important wetland ecosystem with international protection significance. Affected by climate change and anthropogenic activities, the hydrological rhythm of Lake Poyang has changed significantly, which seriously threatens the function and stability of the wetland ecosystem. Shallow lakes and rivers are the main natural units in Lake Poyang wetland, which store abundant environmental change information and directly affect the biogeochemical processes of wetlands. In order to further understand the regional hydrological process, a systematic collection of precipitation, river water and main shallow lake water in the Lake Poyang National Nature Reserve was carried out from January to December 2019, and the stable isotopes of shallow lake-river water system were comprehensively analysed for their dynamic change characteristics and indicative significance. Results showed that the isotopic composition of Xiuhe River and Ganjiang River had obvious seasonal variations, which was the most enriched in April, gradually depleted from May to July, and then showed a trend of continuous enrichment, similar to the temporal variation of precipitation isotopes. Spatially, the isotopic composition of each section in Xiuhe River and Ganjiang River had a relatively stable distribution along the distance. The isotopic composition of the lower section of Ganjiang River did not show significant changes in most months after the inflow of Xiuhe River, possibly related to the large discharge difference between Xiuhe River and Ganjiang River. The annual variation range of stable isotopes in shallow lake water was larger than that in river water and was relatively more enriched. The δ2H-δ18O relationships of the shallow lakes were close to the local meteoric water line, and had smaller evaporation line slopes and systematic deviation, indicating that the shallow lakes were mainly recharged by local precipitation and had experienced a certain degree of evaporation. The mean residence time (MRT) of Xiuhe River and Ganjiang River was 1.54 years and 0.81 years respectively based on the exponential flow model. The shorter MRT of Ganjiang River indicates that the Lake Poyang basin had the hydraulic condition conducive to rapid exchange of different water components, and the MRT of Xiuhe River was obviously larger due to the regulation and storage of Zhelin Reservoir upstream. Based on the assumption that the evaporation process of shallow lake water followed the Rayleigh fractionation model, the isotopic monitoring revealed that the average annual evaporation loss of Lake Banghu, Lake Shahu and Lake Dahuchi was 15.5%, 15.0% and 14.1%, respectively. The difference of evaporation degree among different shallow lakes could be associated with the comprehensive influence of terrain, vegetation and hydrodynamic conditions. |
| Key words: Stable isotope mean residence time evaporation shallow lake-river water system Lake Poyang wetland |
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