洞庭湖流域不同水体中同位素研究

在洞庭湖流域内的长沙、汨罗、怀化对大气降水、地表水（河水）、地下水（泉水、井水）进行了取样,分析了流域内不同水体中稳定水同位素的变化特征以及它们之间的转化关系。研究发现地处亚热带季风区的洞庭湖流域,地表水、地下水中同位素继承了降水同位素冬半年富集、夏半年贫化的特征,但存在不同程度的滞后。同时,降水同位素的变化幅度及波动性明显大于地表水及地下水,而地表水、地下水中同位素较降水中要富集。流域内河水中同位素大致表现出随纬度升高而贫化的趋势,这主要受降水同位素场的影响。流域内长沙河水、井水、泉水中同位素组成均位于大气水线附近且分别大致位于一直线上,这说明大气降水是这3种水体的主要补给源。不同季节河水、井水、泉水中同位素组成与大气水线的比较则进一步反映出了不同水体在不同季节的转化关系。

Stable Water Isotopes of Different Water Bodies in the Dongting Lake Basin

In this study, stable water isotope compositions of different water bodies (such as precipitation, river waterfor surface water, spring and well water for ground water) were collected to reveal the characteristics of stable isotopes of different water bodies and conversion among them in Dongting Lake Basin, which located in the south of China. The results show that isotopes of surface and ground water inherit isotopes of precipitation’s rich in winter half year and depleted in the summer half year, and the variation trend of isotopes having been delayed in time. Referring to variation range and fluctuation of different water bodies’ isotope, precipitation’sisotope is more significant than surface and ground water’s. Generally, isotopes of river water is depleted with increasing latitude, which decided by the distribution of precipitation’s isotopes in space. Stable water isotope compositions of river, well and spring water distribute near the local meteoric water line suggests that precipitation is the main recharge source of the three water bodies. Furthermore, comparison of isotopic composition of surface and ground water with local meteoric water line in different season can reflect conversion of different water bodies.