太行山区典型植被下降水入渗的稳定同位素特征分析  

Stable Isotopes Characters in the Process of Precipitation and Infiltration in Taihang Mountainous Region

作　　者：侯士彬[1] 宋献方[1] 于静洁[1] 刘鑫[1] 张广英[2] 

机构地区：[1]中国科学院地理科学与资源研究所陆地水循环及地表过程重点实验室 [2]河北省保定市水土保持实验站,保定071000

出　　处：《资源科学》2008年第1期86-92,共7页Resources Science

基　　金：国家自然科学基金资助项目:“基于环境同位素与水化学的太行山流域水循环研究”(编号:40671034);中国科学院知识创新工程方向性项目:“华北地区水循环与水资源安全研究”(编号:KZCX-SW-317)

摘　　要：本研究以位于太行山区北部的河北易县崇陵流域为对象,对流域内三种典型植被(荒草、刺槐林、侧柏林)下不同深度土层的土壤水及流域内降水进行同步观测及取样,室内进行稳定同位素氘和氧-18含量测定,以18O为例对降水入渗过程中的稳定同位素变化进行了研究。通过对2004年的数据进行分析,获得崇陵流域当地大气降水线(δD=6.2441δ8O-7.158,R2=0.7727,n=55),其降水中稳定同位素时间变化波动较大且缺少规律性,降水中稳定同位素含量同降水量呈二次相关关系,大于15mm的降水雨量效应较显著。土壤水中的稳定同位素较降水普遍富集,其中荒草地土壤水中稳定同位素值较刺槐林地和侧柏林地整体偏高,表现出较强的蒸发分馏作用。土壤水中的δ18O的时间变化波动较大,表层10cm土壤水1δ8O受降水中的δ18O直接影响,呈现一定的响应关系,深层次土壤水中δ18O变化则有一定滞后性。不同植被覆盖下δ18O的时间变化的活跃层深度不同,同其土壤特征和植被覆盖类型有关。δ18O的剖面垂向空间变化上有两种类型,随深度增加基本都呈富集的趋势。土壤水中稳定同位素的时间变化和垂向空间分布,反映了一种降水入渗和蒸散发的平衡关系,其垂向空间变化很好地记录了降水从地表向下入渗的过程。This study was conducted in Chongling catchment in Yixian of Hebei provinces. Soil with three typical vegetations （weeds, acacia and arborvitae） was sampled and soil water at different depth and infiltration of precipitation were analyzed through hydrogen and oxygen isotopes composition test. The stable isotopes variation characters in the process of precipitation-infiltration were studied. Based on the data in 2004, the Local Meteoric Water Line （LMWL） was obtained： δD = 6.244δ^18O - 7. 158, R^2 = 0. 773, n = 55. The seasonal effect of environmental isotopes of precipitation is not so obvious. The content of stable isotopes of precipitation fluctuates greatly with the time. The quadratic correlation exists between the content of stable isotopes and daily rainfall, and rainfall effect is significant under condition of heavy precipitation over 15mm. The stable isotopes in soil water are much more enriched, and the isotopic fractionation caused by evaporation in weeds field is more intensive than that in acacia filed and arborvitae filed. Since soil water is mainly originated from precipitation, the stable isotopes in soil water vary greatly with time, responding to the variation of isotopic variation in rainwater. The results show that content of δ^18O in soil water in upper layer （10cm depth） are affected by content of δ^18O of precipitation. The stable isotopes variation is closely related to depth of soil, soil traits, and vegetation types. The stable isotopescontent in soil profiles increases with the depth. The change of stable isotopes content in soil reflects a balance between rainfall infiltration and evapotranspiration, and fairly recorded the process of precipitation infiltration. Therefore, it is preferable to study the process of precipitation infiltration using stable isotopes technique.

关 键 词：太行山区 典型植被 降水 入渗 土壤水 稳定同位素 

分 类 号：S152[农业科学—土壤学]