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在气候变化和人类活动影响下,水资源短缺是干旱区面临的一个严峻问题。解决问题的关键是要深入了解干旱区独特的水循环机理,而分析不同水体中氢氧同位素特征及转化关系,是应用同位素示踪技术研究水循环机理的基础。以呼图壁河流域为研究区,分析了大气降水、河水、地下水和积雪融水氢氧同位素变化特征及不同水体的δD~δ18 O关系,探讨了地表水对地下水的补给关系。结果表明:呼图壁河流域大气降水、河水、地下水和积雪融水中δD、δ18 O的组成和季节变化差异较大,δD值分别为-86.25‰、-66.66‰、-69.82‰和-150.79‰,而δ18 O值依次为-12.42‰、-9.94‰、-10.23‰和-19.42‰;河水受大气降水和冰雪融水的混合补给导致同位素的贫化,积雪融水主要受蒸发的影响导致同位素的富集,而河水和积雪融水对地下水有密切的水力联系,导致地下水同位素的贫化;呼图壁河上游地区河水对地下水的补给仅占到18.45%,而中下游区域的地下水补给占到90%以上。
Under the influence of climate change and human activities, the shortage of water resources is a serious problem facing the arid areas. The key to solve the problem is to understand the unique mechanism of water cycle in arid regions. Analyzing the characteristics of hydrogen and oxygen isotopes and transformation relations in different water bodies is the basis of applying isotope tracing technique to study water cycle mechanism. Taking the Hutubi River Basin as a study area, the variation characteristics of hydrogen and oxygen isotopes in atmospheric precipitation, river water, groundwater and snowmelt meltwater were analyzed. The relationship between δD and δ18O in different water bodies was analyzed, and the relationship between surface water supply and groundwater recharge was discussed. The results show that the composition and seasonal variations of δD and δ18O in the Hutubi River Basin are quite different from those in the atmospheric precipitation, river water, groundwater and snowmelt meltwater. The δD values are -86.25 ‰, -66.66 ‰, -69.82 ‰ and -150.79 ‰, while δ18 O values were -12.42 ‰, -9.94 ‰, -10.23 ‰ and -19.42 ‰, respectively. The river water was depleted in isotopes due to the mixed replenishment of precipitation and snowmelt water, and the snowmelt melt was mainly affected by evaporation Resulting in the enrichment of isotopes. However, river water and snow melt water have close hydraulic connection with groundwater, leading to the depletion of isotopes of groundwater. The supply of groundwater to the upper reaches of the Hutubi River accounts for only 18.45% of the groundwater, while that of the middle and lower reaches Groundwater recharge accounted for more than 90%.