极地研究

极地研究 ›› 2018, Vol. 30 ›› Issue (2): 210-219.DOI: 10.13679/j.jdyj.20170043

• 研究进展 • 上一篇    

低温冷阱大气水汽收集技术及其在水稳定同位素研究中的应用

胡家权  庞洪喜   

  1. 南京大学地理与海洋科学学院, 江苏 南京 210023
  • 收稿日期:2017-11-09 修回日期:2018-01-14 出版日期:2018-06-30 发布日期:2018-06-30
  • 通讯作者: 庞洪喜
  • 基金资助:

    国家自然科学基金(41622605, 41771031), 南北极环境综合考察与评估专项(CHINARE2017-02-02)和江苏省自然科学基金(BK20151387)资助

Cold trap technique for collecting atmospheric water vapor and its applications in the study of water stable isotopes

Hu Jiaquan, Pang Hongxi   

  • Received:2017-11-09 Revised:2018-01-14 Online:2018-06-30 Published:2018-06-30
  • Contact: Hongxi Pang
  • Supported by:

    National Natural Science Foundation of China;National Natural Science Foundation of China

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摘要：

系统地介绍了低温冷阱大气水汽收集的基本原理、实验方法、实验过程中的误差估计以及该方法在
水稳定同位素研究中的应用。基于低温条件下显著增加水汽凝结面和凝结时间的方法, 使水汽完全凝结; 利
用水分在真空条件下升华/蒸发及其在低温条件下再凝结的原理, 实现对水汽样品的转移收集。收集的水汽
样品中稳定同位素值的误差主要来自两方面: (1)低温条件下玻璃冷阱中部分未冷凝的饱和水汽; (2)样品室
温融化后, 外界大气进入瓶内与融化后的水汽样品发生同位素平衡分馏; 并分别对上述两种误差进行了理
论估计。利用低温冷阱水汽收集和稳定同位素离线测试方法在以下三方面具有较重要的应用: (1)过量17O
是当前水稳定同位素研究的前沿, 实现对大气水汽中过量17O 高精度测试是该方法的重要应用; (2)获取低
水汽浓度地区高精度大气水汽稳定同位素测试数据; (3)验证激光光谱稳定同位素分析仪在线水汽稳定同位
素测试数据。

关键词: 低温冷阱, 水汽收集, 水汽稳定同位素

Abstract:

This study systematically introduces the cold trap technique for use in the collection of atmospheric
water vapor, including its basic principles, experimental methods, error estimates, and applications in the
study of water stable isotopes. Atmospheric water vapor can condense completely in the cold trap by increasing
both the condensation surface area (by filling with small glass beads) and the condensation time
under conditions of cold temperature (−80℃). The condensed water sublimates or evaporates by heating the
cold trap, and then the sublimated or evaporated water vapor re-condenses in a sample bottle under vacuum
conditions and cold temperatures (−80℃). The error of the stable isotopic composition in the collected water
vapor derives mainly from two aspects: the lost saturated vapor during collection and the ambient air in the
bottle mixed with the sampled water. The magnitudes of the above two errors were estimated theoretically in
the study. Water vapor collection using a cold trap has important applications in the study of water stable
isotopes including achieving high-accuracy δ17O data in atmospheric water vapor, obtaining high-accuracy
isotopic composition of atmospheric water vapor in the remote areas of polar ice sheets where vapor concentration
is very low, and verifying the isotopic measurements of atmospheric water vapor by laser absorption
spectrometers.

Key words: cold trap, water vapor collection, water vapor stable isotopes