Simultaneous Measurement of Nitrous Oxide, Carbon Dioxide and Methane Using a Closed-Path Fourier Transform Infra-Red Multi-Component Gas Analyzer.

Soils are important contributors to global greenhouse gas (GHG) emissions; with N₂O, CH₄, and CO₂ being the predominant soil-derived GHGs. The measurement of GHG emissions from soils often involves the collection of discrete gas samples from chamber-based sampling systems, with the gas samples subsequently analyzed in a laboratory setting using gas chromatography. In recent years, however, there has been a push to deploy gas analysis systems in the field, especially in remote locations. Field-based measurements include micrometeorological techniques (e.g., Eddy covariance) and chamber-based systems that employ gas chromatographic analysis of discrete gas samples or in situ measurement using infrared gas analysis (IRGA), photoacoustic spectroscopy (PAS) or Fourier transform infrared (FTIR) spectroscopy. Whereas IRGA systems are well established for the detection and quantification of CO₂ fluxes from soils, both the PAS and FTIR methods are capable of the simultaneous measurement of N₂O, CH₄, and CO₂. In this poster, we evaluate the performance of both new and 3-yr old FTIR-multi-gas analyzers in terms of their response (including accuracy, precision, linearity and detection limits) to N₂O, CH₄, and CO₂; the effects of water vapor and temperature on gas concentration measurements; and comparison of gas fluxes measured using FTIR and GC techniques.