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https://doi.org/10.5194/bg-2019-102
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2019-102
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Technical note 02 Apr 2019

Technical note | 02 Apr 2019

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Biogeosciences (BG).

Technical note: Interferences of volatile organic compounds (VOC) on methane concentration measurements

Lukas Kohl1,2, Markku Koskinen1,2,3, Kaisa Rissanen2,4, Iikka Haikarainen1,2, Tatu Polvinene1,2, Heidi Hellén3, and Mari Pihlatie1,2,5 Lukas Kohl et al.
  • 1Department of Agricultural Sciences, University of Helsinki, Helsinki, 00790, Finland
  • 2nstitute for Atmospheric and Earth System Research / Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Finland
  • 3Finnish Meteorological Institute, P.O. Box 503, 00101 Helsinki, Finland
  • 4Department of Forest Sciences, University of Helsinki, Helsinki, 00790, Finland
  • 5ViPS - Viikki Plant Science Center, University of Helsinki, Helsinki, 00790, Finland

Abstract. Studies that quantify plant methane (CH4) emission rely on the accurate measurement of small changes CH4 concentrations that coincide with much larger changes in the concentration of volatile organic compounds (VOCs). Here, we assessed if 11 commonly occurring VOCs (e.g., methanol, α- and β-pinene, ∆3-carene) interfered with CH4 concentrations measurements by five laser absorption spectroscopy and Fourier-transformed infrared spectroscopy (FTIR) based CH4 analysers, and quantified the interference of seven compounds on three instruments. Our results showed widespread interfere of 5 VOCs with FTIR based CH4 analysers, but only minimal interference with laser absorption spectroscopy based analysers. VOCs not included in the spectral library exerted a strong strong (64–1800 ppb apparent CH4/ppm VOC) bias on FTIR based measurements, which can lead to substancial over- and underestimations of CH4 fluxes. Minor (0.7–126 ppb/ppm) interferences with FTIR based measurements where also detected when the spectrum of the interfering VOC was included in the library. In contrast, we detected only minor (< 20 ppb/ppm) and transient (< 1 minute) VOC interferences with on laser absorption spectroscopy based analysers. Our results thus suggest that FTIR based instruments are not well suited for quantifying plant CH4 emissions. However, our results also suggest that FTIR can provided precisely quantify VOC concentrations, and could therefore provide a method complementary to proton-transfer-reaction mass spectrometry (PTR-MS).

Lukas Kohl et al.
Interactive discussion
Status: final response (author comments only)
Status: final response (author comments only)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Lukas Kohl et al.
Data sets

Technical note: Interferences of volatile organic compounds (VOC) on methane concentration measurements - Raw Data L. Kohl, M. Koskinen, K. Rissanen, I. Haikarainen, T. Polvinen, H. Hellén, and M. Pihlatie https://doi.org/10.5281/zenodo.2597716

Model code and software

Technical note: Interferences of volatile organic compounds (VOC) on methane concentration measurements - Raw Data L. Kohl, M. Koskinen, K. Rissanen, I. Haikarainen, T. Polvinen, H. Hellén, and M. Pihlatie https://doi.org/10.5281/zenodo.2597716

Lukas Kohl et al.
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Latest update: 15 Jun 2019
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Short summary
Plants emit small amounts of methane and large amounts of volatile organic compounds (VOC). Measurements of plant methane emissions therefore require analysers that can provide accurate measurements of CH4 concentrations in the presence of changing amounts of VOCs. We therefore quantified to which degree various VOCs bias methane concentration measurements on different analysers. Our results show that some analysers are more sensitive to the presence of VOCs than others.
Plants emit small amounts of methane and large amounts of volatile organic compounds (VOC)....
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