Advances in reference materials and measurement techniques for greenhouse gas atmospheric observations

Abstract

We present the global research landscape which aims to deliver a measurement infrastructure to underpin atmospheric observations of key greenhouse gases governing changes in the Earth's climate. These measurements present a significant challenge to the metrological community, analytical laboratories and major producers of reference materials. The review focuses on the progress made in the Gas Analysis Working Group of the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology (CCQM-GAWG) in establishing the primary realisation of the amount-of-substance fraction for carbon dioxide, methane and nitrous oxide in an air matrix. It also focuses on the importance of providing traceable measurements of isotopic composition of these components for commutability of reference materials and for isotope ratio measurements for greenhouse gas source attribution. Metrologia 56 (2019) 034006 (29pp) P J Brewer et al 2 of the World Meteorological Organization (WMO) for providing the framework for the development and implementation of integrated greenhouse gas observations, which is vital for understanding the global carbon cycle and the role greenhouse gases play in climate change. The developments in analytical techniques are also discussed which have shaped the direction of the metrology required to meet the evolving and future needs of stakeholders.

What can we learn from N2O isotope data? – Analytics, processes and modelling

“…Preliminary isotopic composition measurements of USGS51 and USGS52 revealed relatively large differences between the two standard materials with regard to δ 15 N SP , but not so much for δ 15 N bulk and δ 18 O. To implement a two‐point isotope calibration also for the bulk parameters, however, additional gases with differences in δ 15 N bulk and δ 18 O values are required, and these will probably become available within the framework of the ongoing European metrology project SIRS 59 . These primary N 2 O reference materials can then be applied to establish secondary N 2 O isotope laboratory standards with similar N 2 O and trace gas mole fractions and matrix gases to the sample gas, considering the “identical treatment principle” 22,49 .…”

Absolute isotope ratios of carbon dioxide – a feasibility study

“…It is commonly agreed that for a robust d scale, the absolute ratio R 13 C/ 12 C of the zero point (VPDB) must be known with a relative uncertainty of 0.01& or lower. 23 This means that also the relative uncertainty associated with the absolute isotope ratio of material A 0 must be less than 0.01&.…”

“…A relative uncertainty of 0.01& or better would be required. 23 NBS19 has now been exhausted. Therefore, the International Atomic Energy Agency (IAEA) in Vienna has managed, with much effort, to prepare a new reference material, IAEA-603, 24 realizing the VPDB scale.…”

“…These drawbacks can be eliminated by making the scale traceable to the SI, requiring an uncertainty low enough to achieve d 13 C values with uncertainties of 0.01& or lower. 23 The issues which arose with the use of NBS19 and LSVEC (or any other not SI-traceable anchor) illustrate clearly why a method of obtaining SI-traceable isotope ratios of carbon dioxide is highly desirable. One potential way of achieving this is the so-called gravimetric isotope mixture approach, which has been developed by Nier.…”

Successive and automated stable isotope analysis of CO2, CH4 and N2O paving the way for unmanned aerial vehicle‐based sampling

“…In addition to the compound concentration, the stable isotopic composition enables identification of GHG sources and sinks 5–9 . However, the inclusion of isotopic analysis requires different considerations and an appropriate analyzer, such as an isotope ratio mass spectrometer, or optical devices based on tunable diode laser adsorption spectroscopy or Fourier transform infrared spectroscopy 10 . While optical devices are customized to analyze specific compounds only (e.g.…”