长江下游湿润流域不同水源的同位素组成对台风雨响应

鉴于不同水源对降水事件的响应,对于深入理解流域产流机理及地下水补给有重要意义,通过对长江下游和睦桥小流域台风雨事件的林外降水、贯穿降水、土壤水、河水采样,分析其氢氧稳定同位素组成,探究不同水体同位素组成对降水事件的响应。结果表明,最小二乘法求得的和睦桥流域台风降水的林外和贯穿降水线的斜率和截距均小于全球大气水线;由于植被截留和蒸发共同影响,贯穿降水相对于林外降水稳定同位素更加富集;降水事件中土壤水的δ18 O时程波动最大,主要与真空蒸馏采样方法及事件前水的存在有关,雨强和气温也可能会对土壤水同位素的组成带来很大影响;河水同位素的相对丰度时程变化最小,可能由于其主要补给来源是降水事件发生前储存在流域的水,降水事件对河水的δ18 O影响较小。

Response of Isotopic Composition of Various Water Sources to Typhoon Rainfall Events in a Small Humid Watershed in Lower Reaches of Yangtze River

The response of various water sources to rainfall events is important for understanding the runoff generation mechanism and groundwater discharge.In this study,the data of stable isotopic(δ18 O andδ2 H)of precipitation,throughfall,soil water and streamflow were collected in Hemuqiao watershed during the plum rainfall events in order to study the response of various water sources to typhoon rainfall events.The least square method were used to establish the local precipitation line and local throughfall line,the slope and intercept of these equation were small when compare with that of the Global Material Water Line.The isotopic composition of throughfall were more enriched than that of precipitation,because of the vegetation interception and effect of evaporation fractionation.The main factors of the greatest fluctuation ofδ18 O of soil water included the methods of vacuum distillation sampling,the mixing effect with pre-event water,rain intensity and temperature.The isotopic composition of streamflow was stable,which indicated that the streamflow was recharged from pre-event water and the response of streamflow to rainfall event was not obvious.