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托来河流域不同海拔降水稳定同位素的环境意义
摘要点击 330  全文点击 82  投稿时间:2017-08-11  修订日期:2017-11-28
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中文关键词  大气降水  稳定同位素  海拔  托来河流域  δ18O  δD
英文关键词  precipitation  stable isotopes  altitude  Tuolai River Basin  δ18O  δD
作者单位E-mail
李永格 中国科学院西北生态环境资源研究院(筹), 内陆河流域生态水文重点实验室/甘肃省水文水资源工程技术中心, 兰州 730000
中国科学院大学, 北京 100049 
18354950235@163.com 
李宗省 中国科学院西北生态环境资源研究院(筹), 内陆河流域生态水文重点实验室/甘肃省水文水资源工程技术中心, 兰州 730000 lizxhhs@163.com 
冯起 中国科学院西北生态环境资源研究院(筹), 内陆河流域生态水文重点实验室/甘肃省水文水资源工程技术中心, 兰州 730000  
肖莲桂 青海省天峻县气象局, 天峻 817200  
吕越敏 中国科学院西北生态环境资源研究院(筹), 内陆河流域生态水文重点实验室/甘肃省水文水资源工程技术中心, 兰州 730000
中国科学院大学, 北京 100049 
 
桂娟 西北师范大学地理与环境科学学院, 兰州 730070  
袁瑞丰 西北师范大学地理与环境科学学院, 兰州 730070  
张百娟 兰州理工大学能源与动力工程学院, 兰州 730050  
中文摘要
      为了探讨祁连山中段托来河流域不同海拔降水稳定同位素的环境意义,依据该流域托勒站(3367 m)和嘉峪关站(1658 m)的降水样品和气象数据,分析了降水稳定同位素的时间变化、局地大气水线、海拔变化,讨论了降水稳定同位素与温度、降水量、平均水汽压和相对湿度的关系.结果表明,研究时段内托勒站和嘉峪关站降水稳定同位素具有一定的季节变化特征,托勒站表现为夏秋较高值,冬春季为较低值,与托勒不同的是,嘉峪关站春季较高,其他季节较低.嘉峪关站降水δ18O和d-excess值展现出显著的反向变化趋势,托勒站则不显著,随海拔升高对应的相关系数呈下降趋势,反映了内陆河流域低海拔地区存在较强的云下蒸发,同时高海拔地区受局地水汽再循环的强烈影响;从嘉峪关到托勒站大气降水线的斜率和截距都明显升高,表现出从低海拔到高海拔的增加趋势;处于高海拔地区托勒站的温度效应比低海拔地区的嘉峪关站更显著,对于气温在10℃以上的降水事件而言,托勒站δ18O与气温呈显著正相关,嘉峪关站则表现出相反的变化趋势,可能是嘉峪关站云下蒸发对高降水量事件稳定同位素的富集作用减弱,使得呈现降水量效应;从托勒站到嘉峪关站,δ18O和d-excess与平均水汽压的正相关关系减弱,变化幅度也明显减小,原因可能是从高海拔到低海拔地区,水汽压升高,饱和水汽压升高,降水难以形成,降水量较小,降水稳定同位素受云下蒸发影响作用明显,δ18O和δD偏正,高海拔地区受局地水汽再循环的作用明显,δ18O和δD偏负;嘉峪关站降水δ18O与平均相对湿度呈不显著正相关,托勒站则相反.研究结果为托来河流域同位素水文过程研究提供了理论依据.
英文摘要
      Precipitation samples and meteorological data were collected simultaneously during individual precipitation events at Tuole station (3367 m a.s.l.) and Jiayuguan station (1658 m a.s.l.) in the Tuolai River Basin. A study of temporal variation, Local Meteoric Water Lines, and altitude change on precipitation stable isotopes was conducted. The relationships between precipitation stable isotopes and temperature, precipitation, average vapor pressure, and relative humidity were determined in order to explore the environmental significance of the stable isotopes at different altitudes in the middle reaches of the Qilian Mountains. The analysis indicated that the stable isotopes of the precipitation in Tuole and Jiayuguan station were characterized by pronounced seasonal variation, with Tuole having higher δ18O values in summer and autumn and lower δ18O values in spring and winter, while Jiayuguan displays higher δ18O values in spring and lower in other seasons. The d-excess was correlated negatively with δ18O, and the correlation coefficients between δ18O and d-excess decreased with increasing altitude due to weakening sub-cloud evaporation. The slope and intercept of the Local Meteoric Water Lines from Jiayuguan to Tuole rose significantly, showing an increasing trend from low altitude to high altitude. For the precipitation events above 10℃, δ18O of Tuole was positively correlated with the temperature, but the Jiayuguan results indicated the opposite. Sub-cloud evaporation weakened with high precipitation events in Jiayuguan. δ18O and d-excess were positively correlated with the average vapor pressure, which declined from Tuole to Jiayuguan. Since the water vapor pressure and saturated water vapor pressure increased, it was difficult to form precipitation with decreasing altitude. The local strong sub-cloud evaporation caused δ18O and δD was positive at low altitude, while the effect of moisture recycling is obvious, such that δ18O and δD are negative in high altitude areas. There is no significant positive correlation between the δ18O and the relative humidity of the precipitation in Jiayuguan, while Tuole displays an opposite pattern. The results of the study will provide a scientific basis for further study of precipitation isotopes in the Tuolai River basin.

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