闪电河流域“三水”季节变化特征

Seasonal Change of δD and δ^(18)O in Surface Water,Groundwater and Precipitation in the Lightning River Basin

分析水体中氢(H)、氧(O)稳定同位素(δD、δ^(18)O)的变化,可以判断出不同水体的变化特征及相互关系。通过2014年5、8、10月对内蒙古正蓝旗境内闪电河流域地表水、浅层地下水及大气降水等样品的连续采集,得到地表水样21个、地下水样69个、大气降水样21个,在对"三水"样品δD、δ^(18)O值测试分析的基础,进一步讨论了"三水"变化特征及相互关系,结果显示:1闪电河流域"大气降水线"表达式为:δD=8.01δ^(18)O+6.83‰(r=0.962 1),反映了研究区蒸发量远大于降水量的气候特征。而不同月份d(氘盈余参数)出现差异,降水最多的8月d值最低,降水最少的10月d值最高,显示了大气降水次数或强度对二次蒸发作用产生了一定程度的影响。2闪电河流域地下水与地表水中δD、δ^(18)O值,不仅位于"大气降水线"之下,而且不同月份地表水与地下水中δD、δ^(18)O值的变化区间也出现差异。5月,各断面地下水与地表水中δD、δ^(18)O值差异不大,说明地下水与地表水得到充分混合;8月和10月,地表水中δD、δ^(18)O值比地下水明显偏重且各断面中大气降水所占比例较高,显示了大气降水过程对地表水H、O同位素变化的影响。此外,闪电河流域自上游到下游地表水中δD、δ^(18)O值在8月相近,而在10月逐渐出现偏大,指示了10月强烈蒸发作用对地表水中δD、δ^(18)O值变化的影响。

Basing on analyzing the changes of values of δD and δ^18O in surface water,groundwater and precipitation,the relationships among the different kinds of water and their characteristics were discussed. In May,August and October 2014,the samples of surface water,groundwater and precipitation were collected from the Lightning River Basin in Shuluun Huh of Inner Mongolia. The collected 21 surface water samples,69 groundwater samples and 21 precipitation samples as well as the values of δD and δ^18O were analyzed. The results are as follows： 1 The local precipitation line could be expressed by δD = 8. 01δδ^18O ＋ 6. 83‰（ r = 0. 962 1）,which showed that the evaporation was much higher than precipitation in the Lightning River Basin. The value of d was the lower in August than in other two months,which showed that the second evaporation process during rainfall was affected by rainfall intensity to a certain degree; 2 The relationship between surface water and groundwater was different in these three months,and variation of the values of δD and δ^18O in surface water and groundwater was different from different months. In May,the values of δD and δ^18O in both surface water and groundwater were similar,which showed that surface water and groundwater mixed well. Moreover,both the values of δD and δ^18O in surface water were heavier than those in groundwater,which showed that the precipitation affected surface water visibly in August and October. In addition,the strong evaporation in October affected the variation of the values of δD and δ^18O in the Lightning River Basin.