Xu Qi, Li Jian-Hong, Sun Ping-An, He Shi-Yi, Yu Shi
National Engineering Research Center for Geographic Information System, Wuhan 430074, China.
Key Laboratory of Karst Dynamics, Ministry of Land and Resources & Guangxi, Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, China.
Huan Jing Ke Xue. 2017 Jun 8;38(6):2308-2316. doi: 10.13227/j.hjkx.201607136.
The H and O isotope composition of the Xijiang water was investigated on 54 samples collected from the mainstreams and main tributaries in June 2014 and January 2015.It was found that in the Xijiang river, there was a remarkable linear relationship between δ O and δD. This relationship was more significant in the dry season. In both seasons, the O and D values distributed along the meteoric water line, which indicated that precipitation was the source of the Xijiang River. Due to the direct water recharge through karst forms (i.e. sinkholes, vertical shaft and funnel) to the underground river, the -excess value was higher in the rainy season. While during the dry season, water recharge came from the storage in fissures and pores. Affected by altitude and evaporation effect, along the mainstream Hongshui River-Xunjiang and tributary Youjiang-Yujiang reach, the δ O and δD values were gradually approaching positive value in general. However, along the short tributary Guijiang reach, the altitude difference was not dramatic, and the discharge was less, the same phenomenon was not observed. By establishing a linear regression model between δ O and altitude, it revealed that the change rate of Xijiang water with altitude was -0.44‰·(100 m) in the rainy season, and -0.45‰·(100 m) in the dry season. The result reflected the height effect of the precipitation, which has a considerable meaning for the study of hydrological cycle in a river basin.
对2014年6月和2015年1月从西江干流和主要支流采集的54个水样的氢氧同位素组成进行了研究。结果发现，西江中δO与δD之间存在显著的线性关系。这种关系在旱季更为显著。在两个季节中，O和D值均沿大气降水线分布，这表明降水是西江的水源。由于通过岩溶形态（即落水洞、竖井和漏斗）直接补给地下水，雨季的过剩值较高。而在旱季，水源补给来自裂隙和孔隙中的蓄水。受海拔高度和蒸发效应的影响，沿红水河—浔江干流及右江—郁江支流河段，δO和δD值总体上逐渐趋近正值。然而，沿桂江短支流河段，海拔差异不显著，流量较小，未观察到相同现象。通过建立δO与海拔高度之间的线性回归模型，结果表明，雨季西江河水随海拔高度的变化率为-0.44‰·(100 m)，旱季为-0.45‰·(100 m)。该结果反映了降水的高度效应，对流域水文循环研究具有重要意义。
