祁连山南坡水体氢氧稳定同位素特征研究

Hydrogen and oxygen isotope characteristics of water bodies on the southern slope of the Qilian Mountains

水体氢氧稳定同位素是表征水体运移和水分转化的重要指示剂,可为地区水文循环过程的研究提供判断依据。基于稳定同位素技术,分析祁连山南坡不同水体的氢氧同位素组成特征,探讨其影响因素。结果表明:(1)祁连山南坡不同水体的氢氧稳定同位素特征存在差异,降水的稳定同位素值波动范围大于河水、地下水及冰川融水;(2)河水与地下水稳定同位素关系点接近,两者水力联系较强;(3)研究区冰川融水蒸发线方程为y=6.331x+1.756(n=8,R2=0.98),河水蒸发线方程为y=4.467x-11.716(n=75,R2=0.80),地下水蒸发线方程为y=4.889x-7.481(n=19,R2=0.76),各水体氢氧稳定同位素值之间均具有较好的线性关系,河水与地下水补给源关系较复杂;(4)冰川融水、河水与地下水氢氧稳定同位素的环境效应均不显著,而降水则具有较明显的高程效应、纬度效应和大陆效应。

Hydrogen-oxygen stable isotope composition of water is an important indicator for characterizing water migration and transformation processes and can provide a basis for studying regional hydrological cycle processes.On the basis of the stable isotope technique,this paper analyzes the hydrogen and oxygen isotope composition and influencing factors of different water bodies on the southern slope of the Qilian Mountains.The results are as follows.(1)Hydrogen and oxygen stable isotope characteristics of different water bodies on the southern slope of the Qilian Mountains are different,the fluctuation range of stable isotope values of precipitation is larger than river water,groundwater and glacier meltwater.(2)The relationship between the stable isotope of river water and groundwater is close,and the hydraulic connections are strong.(3)The evaporation line equation of glacier meltwater in the study area is y=6.331 x+1.756(n=8,R2=0.98),and the evaporation line equation of river water is y=4.467 x-11.716(n=75,R2=0.80).The evaporation line equation of groundwater is y=4.889 x-7.481(n=19,R2=0.76).There is a good linear relationship between the hydrogen and oxygen isotope values of water.The values ofδ18O andδD in water mostly deviate from the atmospheric precipitation line.The deviation degree ofriver water and groundwater is greater than that of glacier meltwater,and the source of supply is more complicated.(4)The environmental effects of hydrogen and oxygen stable isotopes of glacier meltwater,river water,and groundwater are not significant,whereas precipitation has obvious elevation,latitude,and continental effects.