新疆三工河流域土壤水δD和δ^(18)O特征及其补给来源  

Features of δD and δ^(18)O and origin of soil water in Sangong River Basin,Xinjiang

作　　者：孙芳强[1,2] 尹立河[1,2] 马洪云[1,2] 张俊[1,2] 王晓勇[1,2] 王化齐[1,2] 郭莉[1,2] 

机构地区：[1]中国地质调查局干旱-半干旱区地下水与生态重点实验室,陕西西安710054 [2]中国地质调查局西安地质调查中心,陕西西安710054

出　　处：《干旱区地理》2016年第6期1298-1304,共7页Arid Land Geography

基　　金：国土资源部公益性行业科研专项(201511047)

摘　　要：采用环境同位素示踪技术研究旱区不同土地利用类型下的土壤水来源与运移机理,通过以新疆三工河流域为研究区,对三工河流域四个土壤剖面分层采集了不同土地利用类型的土壤水,测定了其稳定同位素(δD、δ^(18)O)的含量,分析了非饱和带土壤水稳定同位素沿土壤剖面的垂向变化规律。结果表明:区内非饱和带中的土壤水在入渗的同时经历了明显的混合作用,荒地土壤水比耕地受蒸发作用影响更强烈,荒地蒸发影响深度为1.2~1.6 m,耕地蒸发影响深度为0.8~1.2m;荒地与耕地土壤水中氢氧同位素在垂向上呈现旋回变化,每个旋回经历了一次新水入渗补给的过程,即新水入渗与土壤老水混合-土壤水氢氧同位素逐渐变小直到贫化极值-地表入渗补给结束,土壤水向下运移并逐渐与土壤老水混合同时受蒸发作用-同位素逐渐富集直到土壤老水本底值;耕地土壤剖面补给水δD值为-112.93‰^-102.58‰,荒地土壤剖面补给水δD值为-111.07‰^-94.44‰,比地下水、地表水同位素值更贫化,可见土壤水中的补给水主要来源于大气降水;灌溉水入渗地表后,在强烈的蒸发作用下,很难向非饱和带深部运移对地下水补给,节水灌溉方式改变了绿洲内土壤水入渗补给机制。研究结论为进一步厘定绿洲内垂向补给量,准确评价三工河流域水资源量提供重要依据。Origin and infiltration patterns of soil water were investigated using environmental isotopes under different land use types in arid area. Soil water samples were collected from four soil profiles representing different land use types in Sangong River Basin,Xinjiang,China. Vertical variations of stable isotopes of soil water were analyzed based on the values of stable isotopes,i.e. δD and δ^（18）O. The results show that the soil water in uncultivated regions suffers stronger evaporation than that in cultivated areas. The influencing depth of evaporation in uncultivated and cultivated regions are 1.2-1.6 m and 0.8-1.2 m,respectively. The results also show that soil water experiences mixture during infiltration and the isotopes in soil water presents a cyclic variation,i.e.,one infiltration event involved the procedures that the newly infiltrated water and existing soil water mix with each other,causing the values of δD and δ^（18）O deplete to the minimum,which indicates the end of infiltration of recharge water,then the soil water moved downward and further mixes with the old soil water,influenced by evaporation,the isotopes are finally enriched to the values of existing soil water. δD of soil water in uncultivated and cultivated regions vary from-112.93‰ to-102.58‰ and from-111.07‰ to-94.44‰,respectively,which is more depleted than that of groundwater and surface water. This indicates that the soil water mainly originates from precipitation.Under strong evaporation,irrigation water hardly moves downward to recharge groundwater. The infiltration patterns of soil water have changed under the water-saving irrigation method in the oasis. This study lays a solid foundation for estimating vertical recharge in oasis and for assessing accurately water resource in Sangong River Basin.

关 键 词：非饱和带 三工河流域 氢氧同位素 δD峰值 

分 类 号：S152.7[农业科学—土壤学]