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Metrology for Stable Isotope Reference Standards


Project Objectives

The SIRS project has the following objectives:

1. Develop static and dynamic reference materials for pure CO2 and at 400 µmol/mol in an air matrix with uncertainties (δ13C-CO2 0.1 ‰ and δ18O-CO2 0.5 ‰). Ensure traceability and consistency with VPDB (primary scale) and work towards meeting the WMO compatibility goals (δ13C-CO2 0.01 ‰ and δ18O-CO2 0.05 ‰).

2. Re-measure the absolute CO2 isotope ratios of the reference materials to provide the data necessary for SI traceability.

3. Develop static and dynamic reference materials for pure N2O and at 300 – 1000 nmol/mol in an air matrix. The static and dynamic reference materials should meet the requirements for regionally focussed monitoring studies and have target uncertainties of 1.0 ‰ (δ15Nα and δ15Nβ) and 0.5 ‰ (δ15N, d18O).

4. Develop spectroscopic methods for isotope ratio measurements of CO2 with an uncertainty target of 0.1 ‰ for δ13C-CO2 and 0.5 ‰ for δ18O-CO2, and of N2O, including site specific delta values in real time with a target precision of 0.1 ‰ for δ15Nα, δ15Nβ and δ18O - N2O. Methods will be suitable for use in the field and include spectral line data measurements to improve isotope-specific line parameters. Study the stability and fractionation of CO2 and N2O static reference materials.

5. Facilitate the uptake of the technology and measurement infrastructure developed in the project by industry, by standards developing organisations and end users.