地理科学进展 ›› 2013, Vol. 32 ›› Issue (11): 1712-1720.doi: 10.11820/dlkxjz.2013.11.014

• 气候与环境变化 • 上一篇    

基于氢氧同位素的中国东南部降水局地蒸发水汽贡献率

马潜, 张明军, 王圣杰, 汪宝龙   

  1. 西北师范大学地理与环境科学学院, 兰州 730070
  • 收稿日期:2013-02-01 修回日期:2013-10-01 出版日期:2013-11-25 发布日期:2013-11-25
  • 通讯作者: 张明军(1974- ),男,教授,博士生导师,主要从事冰川与环境研究。E-mail: mjzhang2004@163.com E-mail:mjzhang2004@163.com
  • 作者简介:马潜(1987- ),男,甘肃兰州人,硕士研究生,主要研究方向为同位素地球化学。E-mail: maqian0516@126.com
  • 基金资助:
    国家自然科学基金项目(41161012,41240001);甘肃省高等学校基本科研业务费项目。

Contributions of moisture from local evaporation to precipitations in Southeast China based on hydrogen and oxygen isotopes

MA Qian, ZHANG Mingjun, WANG Shengjie, WANG Baolong   

  1. College of Geography and Environment Sciences, Northwest Normal University, Lanzhou 730070, China
  • Received:2013-02-01 Revised:2013-10-01 Online:2013-11-25 Published:2013-11-25

摘要: 中国东南部地区由于临近太平洋,常年受到季风水汽的影响,应用降水等各种水体中的氢氧稳定同位素信息来追踪大气水循环路径,已成为近年来较为常用的方法。本文根据中国东南部地区15 个站点夏季风盛行期间(6-9 月)的氢氧同位素资料,运用瑞利分馏理论,并结合水汽贡献率模型,对当地6-9 月大尺度水汽循环模式、下垫面水体对高空大气的水汽贡献率以及云下二次蒸发效应进行了探讨。基于模拟结果和实测结果的对比分析显示,水汽的运行模式符合瑞利分馏理论。从沿海向内陆,水体的蒸发补给作用在逐步增强。应用水汽贡献率模型计算下垫面水体蒸发的水汽对上风向水汽的补给率,结果表明,东南部地区不同区域的水汽贡献率介于1.4%~4.1%之间,平均水汽贡献率为2.2%。通过计算所有数据的平均过量氘值(d),并与全球水循环平均状态下的d值(10‰)进行对比后发现,水体蒸发的补给作用与二次蒸发效应同时存在,且呈现此消彼长的趋势,越靠近内陆,二次蒸发作用的影响越微弱。

关键词: 二次蒸发作用, 氢氧稳定同位素, 水汽贡献率, 中国东南部地区

Abstract: Stable isotopes are considered as a diagnostic tool which has been utilized in different media and widely used in geosciences and environmental studies, including use of hydrogen and oxygen isotopes in rivers, lakes and groundwater to investigate the circulation mechanism as well as the surface runoff composition in drainage basins, and use of isotopic data from speleothems, tree rings and ice cores to reconstruct paleoclimate. Precipitation is a main input factor in atmospheric water cycle and contains two natural tracers (18O and 2H) with strong signals for tracking the trajectories of water vapor. Rayleigh model is a popular model used in the methods to investigations the changes in moisture sources. Many investigators have used the model to simulate the variations of δ values in different study areas and got better results. In this paper, the study area in Southeast China is mainly influenced by summer monsoon during the period from June to September. However, with depletion of moisture in clouds, the impact of monsoon moisture changes from coast to inland. Based on Rayleigh theory and an evaporative model used by many researchers to calculate the contribution rate in different areas, we investigated the atmospheric water cycle mechanism, the contribution rate of evaporative vapor and the effect of secondary evaporation in Southeast China during the summer monsoon. (1) The comparison between the modeled values and the observed values indicated that the movement of water vapor abided by Rayleigh theory. (2) It was found that the supply of evaporative vapor from surface increased from coast to inland. The contribution rate of evaporative vapor, varying from 1.4% to 4.1% in the area, was 2.2% on average. (3) By comparison of the observed d excess to the global average d excess (10‰), it was inferred that the supply of evaporative vapor from surface and the effect of secondary evaporation both existed in this area. However, the effect of secondary evaporation decreased from coast to inland, suggesting that the decrease of the secondary evaporation may have been compensated by the supply of evaporative vapor from land. Based on the results in this research, it was concluded that the supply of evaporative vapor from surface area and the effect of secondary evaporation both had influences on water circulation in the study area. However, the value of the supply of evaporative vapor and the impact of the secondary evaporation could only be roughly estimated. Related investigations on the supply of evaporative vapor and the effect of secondary evaporation are few and far between in the area. If the problems above can be comprehensively solved, it will be of great significance not only studying the regional water cycle, but also providing basic data for agriculture, meteorology and other purposes. Thus, more sampling sites should be built in this area for detailed studies.

Key words: contribution of moisture, effect of secondary evaporation, Southeast China, stable isotopes of hydrogen and oxygen