Seasonal variability of oxygen and hydrogen isotopes in a wetland system of the Yunnan-Guizhou Plateau, southwest China: a quantitative assessment of groundwater inflow fluxes
Seasonal variability of oxygen and hydrogen isotopes in a wetland system of the Yunnan-Guizhou Plateau, southwest China: a quantitative assessment of groundwater inflow fluxes
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DOI：
10.1007/s10040-017-1635-8
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发表时间：
2018-02
影响因子：
2.8
通讯作者：
Xingxing Cao;Pan Wu;Shaoqi Zhou;Z. Han;Han Tu;Shui Zhang
中科院分区：
文献类型：
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作者：
Xingxing Cao;Pan Wu;Shaoqi Zhou;Z. Han;Han Tu;Shui Zhang
草海湿地是云贵高原重要的生态系统，也是中国国家重点候鸟自然保护区。本研究采集了地表水、地下水和湿地水的环境同位素，以揭示氧和氢同位素(δ18O，δD)、水源和地下水入渗通量的季节变化。结果表明，地表水和地下水均为大气降水来源。湿地水样中的同位素在丰水期(9月)和枯水期(4月)垂直混合良好，但存在明显的季节和空间变化。丰水期湿地表层水的同位素组成变化范围为−97.13~−41.73‰(δD)和−13.17~−4.70‰(δ18O)。该湿地东部的稳定同位素组成低于西部。这可能是受水生植被分布引起的不均匀蒸发的影响。枯水期，水生植被枯死的开阔水域的δD和δ18O分别为−37.11~−11.77‰和−4.25~−0.08‰。这可能是因为这个季节的蒸发率高，大气湿度最低。利用质量传输法和同位素质量平衡法计算了草海湿地的地下水通量，结果表明，丰水期草海湿地的水源主要来自地下水，枯水期地下水对湿地水的贡献较小。
The Caohai Wetland serves as an important ecosystem on the Yunnan–Guizhou Plateau and as a nationally important nature reserve for migratory birds in China. In this study, surface water, groundwater and wetland water were collected for the measurement of environmental isotopes to reveal the seasonal variability of oxygen and hydrogen isotopes (δ18O, δD), sources of water, and groundwater inflow fluxes. Results showed that surface water and groundwater are of meteoric origin. The isotopes in samples of wetland water were well mixed vertically in seasons of both high-flow (September) and low-flow (April); however, marked seasonal and spatial variations were observed. During the high-flow season, the isotopic composition in surface wetland water varied from −97.13 to −41.73‰ for δD and from −13.17 to −4.70‰ for δ18O. The composition of stable isotopes in the eastern region of this wetland was lower than in the western region. These may have been influenced by uneven evaporation caused by the distribution of aquatic vegetation. During the low-flow season, δD and δ18O in the more open water with dead aquatic vegetation ranged from −37.11 to −11.77‰, and from −4.25 to −0.08‰, respectively. This may result from high evaporation rates in this season with the lowest atmospheric humidity. Groundwater fluxes were calculated by mass transfer and isotope mass balance approaches, suggesting that the water sources of the Caohai Wetland were mainly from groundwater in the high-flow season, while the groundwater has a smaller contribution to wetland water during the low-flow season.