桂西北喀斯特峰丛洼地降水氢氧稳定同位素的季节变化特征  

Characteristics of seasonal variation of deuterium and oxygen-18 isotope composition of precipitation in karst peak-cluster depression area,northwest Guangxi of China

作　　者：胡可[1,2,3] 陈洪 聂云鹏[1,2] 杨静[1,2,3] 王克林[1,2] 

机构地区：[1]中国科学院亚热带农业生态研究所亚热带农业生态过程重点实验室,长沙410125 [2]中国科学院环江喀斯特生态系统观测研究站,环江547100 [3]中国科学院大学,北京100049

出　　处：《农业工程学报》2013年第5期53-62,共10页Transactions of the Chinese Society of Agricultural Engineering

基　　金：中国科学院西部行动计划项目(KZCX2-XB3-10);国家自然科学基金项目(41171187和31100294);国家科技支撑计划课题(2010BAE00739-02)

摘　　要：喀斯特地区特殊的二元水文地质结构增加了水文过程研究的难度。大气降水是流域水循环的重要输入因子,研究降水氢氧稳定同位素的季节变化规律及其影响因素,有利于探讨该地区水汽来源、径流划分、水分滞留时间等水文过程。该文以桂西北环江地区典型喀斯特峰丛洼地为例,基于2009年4月-2011年8月的降雨、温度资料以及月降水氢氧稳定同位素组成数据,分析了降水分布及其氢氧稳定同位素组成的季节变化规律,并探讨了各种环境因素的影响。结果表明,当地大气水线与全球大气水线存在一定的偏离,表明研究区降水云气形成过程中汽、液两相同位素分馏不平衡的程度偏大。过量氘年平均值为14.21‰,旱雨季不同,反映了水汽来源的差异。降水氢氧稳定同位素季节变化呈现正弦波动的特性,波动周期和振幅受纬度及季节因素的影响明显大于降水量及温度,表明大尺度环境因素的影响占主导地位。该研究为基于氢氧稳定同位素技术的喀斯特地区流域尺度水文过程研究奠定了基础,对深入分析该地区植被恢复与重建的生态水文效应提供参考。The specific double hydrogeological structure increases the difficulty of study on hydrological processes in karst area. As an important input of water cycle in the basin, to study the seasonal variation of deuterium and oxygen-18 in precipitation and their influencing factors are necessary for discussing hydrological processes, such as origin of water vapor, separation of runoff and mean residence time of water. Studies on stable deuterium and oxygen-18 isotope composition of precipitation in China have been focused a lot, but little is known about seasonal variation especially in karst area. Based on the monthly data of precipitation, temperature and deuterium and oxygen-18 isotope compositions in precipitation determined by using liquid water isotope analyzer （DLT-100） from April in 2009 to August in 2011, the distribution of rainfall and seasonal variation of stable isotopes in precipitation and their influencing factors was analyzed in the typical karst peak-cluster depression areas in Huanjiang of northwest Guangxi. Rainfall amount displayed an obviously seasonal variation in this study area, rainy season start from Mar and end to September. The rainfall amount gets a big increase shift in Mar in comparison to April. The average monthly rainfall amounts of rainy and dry season are 142.5 mm and 44.0 mm. The totally rainfall amount of rainy season contributed about 75% of whole year precipitation. The local meteoric water line is obtained from linear relationship between deuterium and oxygen-18 isotope compositions in monthly weighted precipitation. The discrepancy between local and global meteoric water lines is appealed. The local meteoric water line characterized by larger gradient and intercept relative to global meteoric water line, demonstrates that the level of unbalanced in isotopic fractionation between gas and liquid is higher than normal during the formative process of rainfall mass and evaporation give some influences. Deuterium excess range from 2.23‰ to 19.95‰ and mean annual value is 14

关 键 词：同位素 降水 水文 季节变化 桂西北喀斯特地区 峰丛洼地 

分 类 号：P426.61[天文地球—大气科学及气象学]