长江流域资源与环境 >> 2005, Vol. 14 >> Issue (5): 665-669.

• 长江流域的发展与区域协调 • 上一篇    下一篇

西南水汽通道上昆明站降水中的稳定同位素

章新平1, 孙维贞2,刘晶淼3   

  • 收稿日期:2005-03-02 修回日期:2005-07-04 出版日期:2005-09-20
  • 通讯作者: 章新平

STABLE ISOTOPES IN PRECIPITATION IN THE VAPOR TRANSPORT PATH IN KUNMING OF SOUTHWEST CHINA

ZHANG Xin-ping1,SUN Wei-zhen2,LIU Jing-miao3   

  • Received:2005-03-02 Revised:2005-07-04 Online:2005-09-20
  • Contact: ZHANG Xin-ping

摘要: 位于西南水汽通道上的昆明站降水中的稳定同位素比率具有显著的季节变化。旱季(11~4月)降水中平均δ18O明显高于雨季(5~10月)。显著的降水量效应说明昆明站降水的水汽主要来源于低纬度海洋。与全球大气水线相比,昆明站大气水线的斜率和常数项均较小。这与雨滴在未饱和大气中降落时重同位素的蒸发富集作用有关。统计分析显示,近地面温度露点差ΔTd与降水中稳定同位素比率存在显著的正相关关系。在旱季,受大陆性气团的影响,空气干燥,降水量小,大气中ΔTd大,因此蒸发强,重同位素的富集作用强,从而降水中稳定同位素比率高;在雨季,受来自海洋水汽的影响,空气湿润,降水量大,大气中ΔTd小,因此蒸发弱,重同位素的富集作用轻,从而降水中稳定同位素比率低。据此推测,降水量效应可能是不同水汽来源对降水中稳定同位素影响的产物。

关键词: 昆明, 水汽通道, 稳定同位素, 降水量效应, 温度露点差

Abstract: The stable isotopic ratios in precipitation have notable seasonal variations in the vapor transport path in Kunming in Southwest China, with a higher mean δ18O in precipitation in dry season (from November to April) than that in rain season (from May to October).The vapor for precipitation in Kunming is originated primarily from low\|latitude oceans. The slope and the constant item in the meteoric water line (MWL), compared to the global MWL, are both smaller in Kunming, and are related to the evaporation enrichment of heavy isotopes as raindrops fall in unsaturated atmosphere. There is a notable positive correlation between the stable isotopic ratios in precipitation and the dewpoint deficit in land ΔTd. In dry season with the dry air, light precipitation, great ΔTd in atmosphere, strong evaporation and thus strong enrichment of heavy isotopes, influenced by continental air-mass, the rainfall in Kunming is characterized with high stable isotopic ratio. In rain season with the moist air, heavy precipitation, small ΔTd in atmosphere, light evaporation and thus light enrichment, influenced by lowlatitude marine vapor, the rainfall is characterized with low stable isotopic ratio. Therefore, it can be deduced that the effect is the outcome of the impact of different vapor origins on stable isotopes in precipitation.

Key words: Kunming, vapor transport path, stable isotopes, amount, dew-point deficit

[1] 周毅, 吴华武, 贺斌, 李静, 段伟利, 王建锋, 童世贤. 长江水δ18O和δD时空变化特征及其影响因素分析[J]. 长江流域资源与环境, 2017, 26(05): 678-686.
[2] 李在军, 张雅倩, 胡美娟, 马志飞, 吴启焰. 基于最低成本-周期模型的昆明市空间形态演变研究[J]. 长江流域资源与环境, 2016, 25(05): 708-714.
[3] 张千千, 缪丽萍, 孙继朝, 刘景涛. 稳定同位素识别水体硝酸盐污染来源的研究进展[J]. 长江流域资源与环境, 2015, 24(05): 742-749.
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