包头地区大气降水δD和δ^(18)O变化特征浅析

The variations of stable isotopes(δD and δ^(18)O) in the precipitation in Baotou area

大气降水中氢氧稳定同位素包含着水循环演化过程中的历史信息,对揭示水资源的形成及演化机制具有重要的意义。文中根据包头站大气降水中稳定同位素和气象资料,分析了包头地区(1986-1992年)大气降水的氢氧稳定同位素的变化特征及其与气温和降水之间的关系,发现该区氘盈余值(d)具有冬季高夏季低的特点,且d值接近全球大部分地区降水的d值(10‰)。该区大气降水中δ18O值具有夏季高冬季低,δ18O的温度效应显著,而降水量效应只在夏半年(4-9月)间显著。同时提出了包头地区当地大气降水线方程为δD=6.4δ18O-4.07,与全国及全球降水线方程相比,反映出干旱的气候特征。

Stable isotopes （δD and δ^18O） in the precipitation contain the information of the water cycle, which can be used to identify the mechanism of the formation and evolution of water resource. According to the isotope and meteorological data （1986 -1992） in Baotou station, we discussed the variations of the hydrogen and oxygen stable isotope （δD and δ^18O） in precipitation and the relationships with the temperature and rainfall. The results show that the value of deuterium excess （d） was higher in winter and lower in summer. The weighted mean deuterium excess in the Baotou area closed to the mean value （10%‰） of the global. The value of δ^18O was higher in summer than in winter, and the temperature effect in this area was significant, and the precipitation amount effect was obvious only in the summer period （ April - September）. The equation of the local meteoric water line in Baotou area was δD = 6.4 ＊ δ^18O - 4.07, and the semi -arid climate could be identified by comparing with the local and global meteoric water line.