| 摘要: |
| 氧同位素异常（Δ17O）常用来衡量氧同位素非质量分馏的程度，也是目前研究大气CO2相关问题的有力手段之一。本文综述大气CO2氧同位素非质量分馏效应的研究进展。首先介绍氧同位素非质量分馏程度的表示方法（Δ17O）和成因；其次概括CO2中Δ17O的测量方法，并对比质谱法和光谱法测量Δ17O的优缺点；最后总结Δ17O在估算平流层向对流层输入的CO2通量、估算全球生产力和示踪CO2不同来源方面的应用，并对Δ17O在CO2未来的研究方向提出展望。 |
| 关键词: CO2 氧同位素非质量分馏 Δ17O 光谱法 示踪研究 |
| DOI：10.7515/JEE231004 |
| CSTR：32259.14.JEE231004 |
| 分类号: |
| 基金项目:国家自然科学基金项目（42173082）；中国科学院战略性先导科技专项（XDA23010302） |
| 英文基金项目:National Natural Science Foundation of China (42173082); Strategic Priority Research Program of the Chinese
Academy of Sciences (XDA23010302) |
|
| Progress on mass independent fractionation of oxygen isotope in CO2 related researches |
|
CAO Jialu, NIU Zhenchuan, LIANG Dan, FENG Xue, LÜ Mengni, WANG Guowei, LIU Wanyu
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1. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710061, China
2. Shaanxi Key Laboratory of Accelerator Mass Spectrometry Technology and Application, Xi’an Accelerator Mass Spectrometry Center, Xi’an 710061, China
3. Xi’an Institute for Innovative Earth Environment Research, Xi’an 710061, China
4. University of Chinese Academy of Sciences, Beijing 100049, China
5. National Observation and Research Station of Regional Ecological Environment Change and Comprehensive Management in the Guanzhong Plain, Shaanxi, Xi’an 710061, China
6. Interdisciplinary Research Center of Earth Science Frontier, Beijing Normal University, Beijing 100875, China
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| Abstract: |
| Background, aim, and scope As an important component in atmosphere and the main greenhouse gas, CO2 has always been a research focus in the field of atmosphere. The concentration of CO2 in the atmosphere has significantly increased in recent decades and still shows an upward trend. In order to control carbon emission and achieve the goals of “carbon peak” and “carbon neutrality” as soon as possible, we must clearly understand the sources of atmospheric CO2 and the global carbon cycle processes. Recently, the development of oxygen isotope anomaly (Δ17O) provides a new tracer for studying CO2 related issues, and now Δ17O is becoming a more and more important tracer. Materials and methods This article provides a review of the research progress on oxygen isotope mass independent fractionation in atmospheric CO2. Firstly, a brief introduction is given to the definition and origin of oxygen isotope mass independent fractionation. Secondly, this article summarizes the measurement methods of Δ17O and compares the advantages and disadvantages between mass spectrometry and spectroscopy for measuring isotopes. Finally, this article summarizes the application of Δ17O in estimating the input of CO2 flux from stratosphere to troposphere and global productivity, as well as tracing CO2 different sources, and proposes prospects for future research directions of Δ17O in CO2. Results The Δ17O produced by the photochemical reaction of stratospheric ozone has become a powerful tool for studying CO2 related issues. As a tracer, it has been applied to estimate the input of CO2 from the stratosphere to the troposphere and global productivity, as well as tracing different sources of CO2. Discussion (1) ∆17O is generated by photochemical reactions of ozone in the stratosphere. At present, both mass spectrometry and spectroscopy can be used to measure ∆17O, with a precision of 0.01‰. (2) The oxygen isotope mass independent fractionation in stratospheric CO2 transports from stratosphere to troposphere through the Brewer-Dobson circulation. Therefore, the Δ17O value in tropospheric CO2 can be used to estimate the input of CO2 flux from stratosphere to troposphere. (3) The efficient isotope exchange between CO2 and leaf water during photosynthesis leads to the close relation between the Δ17O value in troposphere CO2 and the productivity of the biosphere. Therefore, the Δ17O value in troposphere CO2 can be used to estimate global productivity. (4) There is a significant difference between the Δ17O value of CO2 generated by combustion and the Δ17O value in background CO2, and the Δ17O produced in different biochemical processes also varies, so we can utilize the Δ17O value in tropospheric CO2 to distinguish different sources of atmospheric CO2. Due to the influence of fractionation slope λ selection, measurement accuracy and environmental factors impact limitations, there is still room for improvement in the tracing accuracy of Δ17O. Conclusions The production and transportation process of Δ17O is closely related to the biochemical reactions that occur in the atmosphere, such as photosynthesis and combustion reactions. Due to this close correlation, Δ17O has become a new atmospheric tracer to better understand the global carbon cycle process and has been used in multiple fields for tracing research. For examples, Δ17O has been used to estimate the input of CO2 flux from stratosphere to troposphere and global productivity, as well as to trace CO2 sources. Recommendations and perspectives The current usage of Δ17O as a tracer tool has achieved some results, further researches can be strengthened in the following aspects: when establishing a model for estimating the input of CO2 flux from stratosphere to troposphere, estimating global productivity, and tracing CO2 different sources, we should (1) choose a more suitable fractionation slope λ; (2) add more biogeochemistry processes involving CO2 in the model and fully consider the impact of environmental factors. |
| Key words: CO2 oxygen isotope mass independent fractionation Δ17O spectrometry tracing research |
