水库与城市建设对湟水河流域氢氧同位素特征的影响

Effects of reservoir and urban construction on hydrogen and oxygen isotope characteristics in Huangshui River Basin

水利工程和城市建设改变了流域的天然属性和下垫面特征,进而影响了流域水循环过程。以湟水河流域为研究对象,基于不同的土地利用格局和水库特征划分河段,分别采集水样,分析了湟水河水的氢氧同位素组成及其沿程分布特征。结果表明:水库水和城区水的氢氧同位素(δ^(18) O和δD)相较于入库水和非城区水有明显的偏正现象。为了探究该现象的普遍性,广泛搜集了以往研究中水库水和城区水的氢氧同位素数据。研究发现:在水库影响区域,入库水和水库水的稳定同位素差异与水库的表面积和平均滞留时间有较强的正比关系;在城市影响区域,非城区水和城区水的稳定同位素差异与河段两岸的不透水域面积占比有较强的正比关系。这表明水库建设和城市化都促进了河水氢氧同位素的蒸发分馏。研究成果对从微观尺度探究人类活动影响下的水循环特征具有一定的参考意义。

Reservoirs and urban construction have changed the natural attributes and underlying surface characteristics of river basins,thus affecting the water cycle of basins.Taking the Huangshui River Basin as the research object,the river sections were divided based on different land use patterns and reservoir characteristics,and water samples were collected respectively,and the hydrogen and oxygen isotopic compositions of the Huangshui River water and their distribution characteristics were analyzed.The results showed that the hydrogen and oxygen isotope(δD and δ^(18) O)values of river water in urban areas and reservoir were significantly higher than those in non-urban areas and inflowing water.In order to explore the universality of the phenomenon,the isotopes data of reservoirs and urban areas in previous studies were extensively collected.The study found that in the reservoir-affected area,the difference between the stable isotope values of the reservoir water and the inflowing water was positively correlated with the reservoir surface area and retention time;in the urban impact areas,the difference between the stable isotope values of the urban water and the non-urban water was positively correlated with the proportion of artificial surface area around the river.This indicates that reservoir and urban construction have promoted the evaporation and fractionation of hydrogen and oxygen isotopes in the river water.This study used the stable isotope method to analyze the impact of reservoir and urbanization on the river water cycle,which has reference significance for studying the characteristics of water cycle under influence of human activities at the micro scale.