东台沟实验流域降水氧同位素特征与水汽来源

A study on oxygen isotope in precipitation of Dongtaigou basin in Chao and Bai river basin

运用环境同位素技术研究水循环中水分子组成发生的微观变化,是兴起于20世纪中期研究宏观、微观水文过程机理的新技术。研究流域降水同位素时间和空间变化规律以及与降水要素的相关关系,对于研究流域水资源属性具有重要的理论与实践意义。本文以北京市怀柔区汤河口镇东台沟实验流域为研究对象,研究了该流域2003年7月至10月降水氧同位素含量及降水的时空变化,分析了降水δ18O与降水量、高程及空气湿度的关系,评估了雨量、高程及空气湿度等因子对降水过程的影响及作用,阐明了其间实验流域降水δ18O的时空分布规律,并得出实验流域在实验期间降水的主要水汽来源为由东南向西北方向。

By applying the isotopic technique on the water circulation study arisen in the middle of the 20th century, which is a new technology through the study on macroscopic changes of water molecules in the water circulation to achieve the combining study of macroscopic and microscopic water circulation mechanism. It is of very interest theoretically and practically for the study on the water resources characteristics in the basin to investigate the temporal and spatial variable rules of isotopes in the precipitation and the correla-tivity of the precipitation elements. Because stable isotopic technologies are being used all over the world to provide better links between the water cycle elements and the water resources characteristics. Much work has been done world-wide on δ18O and δD in rainfall, the best famous work is the precipitation sampling and stable isotope analyzing contribution of IAEA, which offers valid theory basis and practicing experiences to isotopic hydrology study. This paper takes Dongtaigou experimental basin at Tanghekou town Huairou district Beijing city in North China as study object, analyses the spatial and temporal change of the oxygen isotope in the precipitation from July to August in 2003, and then illustrates the correlativity between oxygen isotope ratio δ18O and rainfall, and the correla-tivity between oxygen isotope ratio δ18O and altitude. At last, this study evaluates the influence and effect of rainfall and altitude factors on the precipitation processes, illuminates the spatial and temporal distribution of δ18O in the precipitation during the sampling period, and offer basis for the later on study of water cycle in basin in the study area. This study draw some conclusions as follows: the δ18O spatial gradient in the basin is 0. 58‰/ 100m, the direction of the water vapor moving in the study period of time is from the south-east to the north-west.