雅鲁藏布江河水氢氧同位素时空变化特征

为揭示流域内水汽循环过程变化规律、揭示河水稳定同位素与气象要素及海拔之间的关系，2018年先后采集雅鲁藏布江干流丰、平、枯，水期水样90个，对河水的氢氧同位素组成进行了分析.结果表明：利用δ¹⁸O与纬度和海拔定量关系模型研究了雅江流域降水氢氧同位素空间变化特征，发现降水中δ¹⁸O值变化呈现东西部（雅江上、下游）高中部（雅江中游）低的趋势；建立了雅江丰、平、枯水期河水氢氧同位素方程，研究发现δD与δ¹⁸O的线性方程斜率低于中国大气降水线，河水δD与δ¹⁸O有一定的季节性特征，其受大气降水的影响较大，且丰水期较平水期以及枯水期相比更为明显；雅江河水中δ¹⁸O空间特征表现为，从上游至下游整体表现出先降低再升高的变化趋势.南北空间上表现为河水δD-δ¹⁸O从南至北逐步增高的趋势.δD-δ¹⁸O值与海拔高度具有较弱的负相关关系；受地表蒸发分馏、降水云团迁移以及流域岩石风化的影响，雅江河水d值季节性、空间性变化明显.

Temporal and spatial variation characteristics of hydrogen and oxygen isotopes in Yarlung Zangbo River

In order to reveal the changing law of the water vapor cycle process in the basin, and reveal the relationship between stable isotopes of river water and meteorological elements and altitude. In 2018, 90 water samples were collected from the main stream of the Yarlung Zangbo River in three periods of high, flat, and dry. The hydrogen and oxygen isotope composition of the river water were analyzed and the relationship between stable isotopes of surface water and meteorological elements and altitude was revealed. The main contents and results of the study are as follows:the spatial variation characteristics of hydrogen and oxygen isotopes in precipitation in the Yarlung Zangbo River Basin were studied using the quantitative relationship model of δ¹⁸O with latitude and altitude.It is found that the change of δ¹⁸O value in precipitation showed a trend of low in the east and west (upper and lower reaches of the Yarlung Zangbo River) and the high and middle parts (the middle reaches of the Yarlung Zangbo River). The hydrogen and oxygen isotope equations of the river water during the rich, flat and dry periods of the Yarlung Zangbo River had been established. The study found that the slope of the linear equation of δD and δ¹⁸O was lower than the atmospheric precipitation line in China. River water δD and δ¹⁸O had certain seasonal characteristics, which were more affected by atmospheric precipitation. The high water period was more obvious than the normal water period and the dry period; The spatial characteristics δ¹⁸O in the Yarlung Zangbo River were shown as the overall performance from west to east of the trend of first decreasing and then increasing, the north-south space shows a trend of increasing δD-δ¹⁸O of river water from south to north. The δD-δ¹⁸O value had a weak negative correlation with altitude; Affected by surface evaporation fractionation, precipitation cloud cluster migration and rock weathering in the basin, the water d value of the Yarlung Zangbo River had seasonal and spatial changes significantly.