SIRS: Metrology for Stable Isotope Reference Standards

Scientist Empa: Sarah Eggleston (Postdoc), Dr. Longfei Yu (Postdoc)

Collaboration between twelve European partner institutions. Project lead by Dr. P. Brewer (NPL, UK)


Climate change is accepted as one of the greatest risks to society worldwide. The rise in temperature, due to increasing greenhouse gas concentrations in the atmosphere, is predominantly driven by human produced (i.e. anthropogenic) emissions; two thirds of which are CO2 and N2O. However, to distinguish between anthropogenic and natural emissions, a more robust metrological infrastructure, including stable isotope reference standards, is needed to underpin measurements of CO2 and N2O. Such an infrastructure would allow improved source apportionment of emissions, and validation of emission inventory data. It will also support the verification of nationally determined emission targets and allow pledges of emissions reductions made by governments to be demonstrated.

The targets of the SIRS project are:

  • To develop static and dynamic reference standards for pure CO2 and at 400 μmol/mol in an air matrix with uncertainties of δ13C-CO2 0.1 ‰ and δ18O-CO2 0.5 ‰. To ensure traceability and consistency with the Vienna Pee Dee Belemnite (VPDB) primary standard and to work to meet the WMO compatibility goals (δ13C-CO2 0.01 ‰ and δ18O-CO2 0.05 ‰).
  • To re-measure the absolute CO2 isotope-ratios of the reference materials (including the 47 mass peak), in order to provide the data necessary for SI traceability.
  • To develop static and dynamic reference standards for pure N2O and at (300 – 1000) nmol/mol in an air matrix. The static and dynamic reference standards should meet the requirements for regionally focused monitoring studies and have target uncertainties of 1.0 ‰ (δ15Nα and δ15Nβ) and 0.5 ‰ (δ18O).
  • To develop spectroscopic methods for isotope ratio measurements of CO2 with a target uncertainty of 0.1 ‰ for δ13C-CO2, δ18O-CO2 and N2O, including site specific delta values in real time with a target precision of 0.1 ‰ for δ15Nα, δ15Nβ and δ18O-N2O.
  • To facilitate the take up of the technology and measurement infrastructure developed in the project by industry, by standards developing organizations (such as ISO/TC158 and CENTC/264) and by end users (WMO-GAW, UPAC CIAAW, IAEA).

The ENV06 project “Metrology for Stable Isotope Reference Standards” is supported by the European Metrology Programme for Innovation and Research (EMPIR) jointly funded by the EMPIR participating countries within EURAMET and the European Union.

Related publications

Harris, S. J., Liisberg, J., Xia, L., Wei, J., Zeyer, K., Yu, L., … Mohn, J. (2020). N2O isotopocule measurements using laser spectroscopy: analyzer characterization and intercomparison. Atmospheric Measurement Techniques, 13(5), 2797-2831.
Detailed Record

Brewer, P. J., Kim, J. S., Lee, S., Tarasova, O. A., Viallon, J., Flores, E., … Griffith, D. W. T. (2019). Advances in reference materials and measurement techniques for greenhouse gas atmospheric observations. Metrologia, 56(3), 034006 (29 pp.).
Detailed Record

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