三峡库区典型支流氢氧同位素时空分布特征研究

定量分析三峡水库支流库湾中水体组成,研究支流库湾水循环过程,有助于分析支流库湾的环境问题。对三峡水库内的草堂河及其毗邻干流进行了连续1 a的观测,分析了水体中氢氧同位素特征,阐述了在干支流相互作用下,三峡水库支流库湾的水团来源及其组成,探讨了三峡水库蓄水后支流库湾水循环的变化。研究表明:长江干流和支流库湾中δD/δ~(18)O与区域降水线十分接近,表明其水团主要来源为大气降水;同时长江和支流库湾中的氘盈余与建库前有明显不同,说明三峡水库蓄水之后长江干流和支流库湾水体组分发生了一定改变;支流库湾中水体混合比存在明显的时空变化,长江干流水团占的比例为76. 9%~99%。

Spatial and temporal distribution characteristics of hydrogen and oxygen isotope in typical tributary estuary of Three Gorges Reservoir

Quantitative analysis on the water body composition in the tributary of the Three Gorges Reservoir and the water circulation process are helpful to solving the environmental problems of tributary estuary. The isotopic characteristics of hydrogen and oxygen in water masses were analyzed based on a one-year observation in the Caotang River and adjacent mainstream. Under the interaction of the mainstream and tributary, the source and compositions of the water masses of the tributary estuary were described and the water circulation variation in the tributary estuary after the Three Gorges Reservoir impoundment was discussed. The results show that: δD/δ18O in the Yangtze River mainstream and the tributary estuary were very close to the regional precipitation line, indicating that the main source of water mass is precipitation. The deuterium-surpluses in the Yangtze River and the tributary estuary are obviously different from those before the construction of the reservoir, which indicated that the water body composition of the Yangtze River main stream and the tributary reservoir estuary have changed to some extent after the Three Gorges Reservoir impounded. There are obvious spatiotemporal variations in the mixing ratio of the water body, the proportion of the water mass in the main stream of the Yangtze River ranges from 76.9% to 99%.