重庆酉阳龙潭槽谷和毛坝向斜大气降水氢氧稳定同位素变化特征  

Variation characteristics of stable hydrogen and oxygen isotopes in precipitation of Longtan trough valley and Maoba syncline in Youyang,Chongqing

作　　者：孙婷婷 杨琰[1,2] 姜修洋 罗振宇[1,2] 唐越尔 SUN Tingting;YANG Yan;JIANG Xiuyang;LUO Zhenyu;TANG Yueer(Chongqing Key Laboratory of Karst Environment,School of Geographic Sciences,Southwest University,Chongqing 400715,China;National Observation and Research Station of Karst Ecosystem in Jinfo Mountain of Chongqing,Chongqing 400715,China;School of Geographical Sciences,Fujian Normal University,Fuzhou,Fujian 350007,China)

机构地区：[1]岩溶环境重庆市重点实验室,西南大学地理科学学院,重庆400715 [2]重庆金佛山喀斯特生态系统国家野外科学观测研究站,重庆400715 [3]福建师范大学地理科学学院,福建福州350007

出　　处：《中国岩溶》2024年第4期796-809,共14页Carsologica Sinica

基　　金：国家自然科学基金项目(42277048);国家重点研发计划子课题(2016YFC050230205)。

摘　　要：为深入探究重庆市东南部武陵山龙潭槽谷和毛坝向斜两个相邻地形区大气降水中δ^(18)O、δD的特征及其影响因素,文章基于两个水文年(2 020.06-2 022.05)在重庆市酉阳县龙潭槽谷(海拔333 m)和毛坝向斜(海拔1 140 m)降水δ^(18)O和δD的采样数据,建立了两地的大气降水线,分析两地大气降水氢氧稳定同位素的变化特征及影响因素。结果表明:(1)龙潭槽谷和毛坝向斜大气降水线的斜率和截距均大于全球大气降水线。大气降水δ^(18)O和δD具有明显的季节变化,雨季(5-10月)偏负,旱季(11月至次年4月)偏正。两地大气降水δ^(18)O表现出显著的降水量效应,温度效应的影响较弱。(2)龙潭槽谷大气降水线的斜率和截距小于毛坝向斜,两地大气降水线的差异主要受控于水汽凝结时的温度和蒸发条件。(3)龙潭槽谷大气降水中的δ^(18)O和δD的平均值较毛坝向斜偏正。d-excess的结果表明,龙潭槽谷δ^(18)O和δD存在微弱的云下二次蒸发。同次降水过程中龙潭槽谷大气降水δ^(18)O总体上较毛坝向斜降水δ^(18)O偏正,这表明龙潭槽谷和毛坝向斜两地的大气降水δ^(18)O受高程效应影响。(4)年际变化上,龙潭槽谷和毛坝向斜两地大气降水δ^(18)O的变化主要受印度洋水汽输送比例的影响。2020年夏季,印度洋水汽到达研究区的比例为76%,降水δ^(18)O偏负;2021年夏季,印度洋水汽到达研究区的比例为52%,降水δ^(18)O偏正。研究结果对增进西南岩溶槽谷区水循环过程的认识和今后展开龙潭槽谷和毛坝向斜两地生态水文过程的研究具有重要的意义。This study aims to explore the characteristics and influencing factors ofδ^(18)O andδD in precipitation in two adjacent topographic areas of Longtan trough valley and Maoba syncline in Wuling mountain,southeastern Chongqing.Based on the sampling data aboutδ^(18)O andδD in precipitation of Maoba syncline(altitude of 1,140 m)and Longtan trough valley(altitude of 330 m)in Youyang county of Chongqing in two hydrological years from June 2020 to May 2022,the meteoric water lines of the two studies areas were established,and the variation characteristics and influencing factors of hydrogen and oxygen stable isotopes in precipitation in these areas were also analyzed.The results show as follows.(1)The slopes and intercepts of meteoric water lines in Longtan trough valley and Maoba syncline exceeded those of the global meteoric water lines.The values ofδ^(18)O in precipitation in these two study areas show a significant effect of precipitation,while the influence of temperature effect is relatively weak.(2)The slope and intercept of the meteoric water line in Longtan trough valley were smaller than those in the Maoba syncline.The difference between the meteoric water lines in these two study areas was mainly controlled by the temperature and evaporation conditions during water vapor condensation.(3)The average values ofδ^(18)O andδD in precipitation in Longtan trough valley were more positive than those in Maoba syncline. The results of d-excess showed that there was a weak sub-cloud secondary evaporation of δ^(18)O and δD in Longtan trough valley. The values of δ^(18)O and δD in precipitation in Longtan trough valley and Maoba syncline exhibited significant seasonal changes, with negative values during the rainy season (May to October) and positive values during the dry season (November to the following April). (3) The values of δ^(18)O in precipitation in Longtan trough valley and Maoba syncline showed a significant precipitation effect, while the influence of temperature effect is weak. During the same prec

关 键 词：大气降水 氢氧稳定同位素 局部地形 龙潭槽谷 毛坝向斜 武陵山 

分 类 号：P426.612[天文地球—大气科学及气象学]