Chin J Plant Ecol ›› 2018, Vol. 42 ›› Issue (2): 143-152.DOI: 10.17521/cjpe.2017.0206

Special Issue: 稳定同位素生态学 生态学研究的技术和方法

• Review •     Next Articles

A review of the calibration methods for measuring the carbon and oxygen isotopes in CO2 based on isotope ratio infrared spectroscopy

Jia-Ping PANG1,2,Xue-Fa WEN1,3,*()   

  1. 1 Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
    2 Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
    3 College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
  • Online:2018-02-20 Published:2018-04-16
  • Contact: Xue-Fa WEN
  • Supported by:
    Supported by the National Key Research and Development Project of China (2016YFC0500102)(2016YFC0500102);the National Natural Science Foundation of China(31470500)

Abstract:

With the development of isotope ratio infrared spectroscopy (IRIS) technology, it is now possible for the in situ high temporal resolution and high precision measurement of carbon isotopic composition (δ 13C) and oxygen isotopic composition (δ 18O) of atmospheric CO2, which overcomes the low temporal resolution and labor intensive shortcoming of traditional isotope ratio mass spectrometry (IRMS). The dependence of δ 13C and δ 18O on CO2 concentration (termed as concentration dependence) and the drift due to sensitivity to changing environmental conditions (termed as instrumental drift) are the two main sources of error affecting the IRIS measurements. Therefore, it is important to obtain precise measurements by constructing a proper calibration strategy to solve the concentration dependence and instrumental drift. In this study, we briefly discussed the definition and related theoretical principle of concentration dependence, and elaborated the theoretical and empirical calibration methods of concentration dependence. Moreover, we introduced the calibration methods of instrumental drift, and reviewed the state of the art of calibration methods and its application of IRIS technology. Additionally, we briefly discussed the definition and method of data traceability to the international standard, and reviewed its application of IRIS technology. Finally, we recommend that concentration dependence is corrected by using three standards or above with known CO2 concentration and its δ 13C and δ 18O, bracketing the CO2 concentration of samples. The instrumental drift is corrected by setting appropriate calibration frequency and all dataset are traceable to the international standard. In the future, the comparative study of different IRIS instruments and calibration methods should be enhanced, and the similar methods should be used for measuring CH4, N2O and H2O isotopes by IRIS technique. The IRIS technology combined with other technology will provide a new opportunity for ecological research.

Key words: isotope ratio infrared spectroscopy, concentration dependence, instrumental drift, traceability to the international standard, calibration frequency