Technical note: Facilitating the use of low-cost methane (CH₄) sensors in flux chambers – calibration, data processing, and an open-source make-it-yourself logger

• Main Authors: D. Bastviken, J. Nygren, J. Schenk, R. Parellada Massana, N. T. Duc
• Format: Article
• Language: English
• Published: Copernicus Publications 2020-07-01
• Series: Biogeosciences
• Online Access: https://www.biogeosciences.net/17/3659/2020/bg-17-3659-2020.pdf
• ISSN: 1726-4170; 1726-4189

<p>A major bottleneck regarding the efforts to better quantify greenhouse gas fluxes, map sources and sinks, and understand flux regulation is the shortage of low-cost and accurate-enough measurement methods. The studies of methane (<span class="inline-formula">CH₄</span>) – a long-lived greenhouse gas increasing rapidly but irregularly in the atmosphere for unclear reasons, and with poorly understood source–sink attribution – suffer from such method limitations. This study presents new calibration and data processing approaches for use of a low-cost <span class="inline-formula">CH₄</span> sensor in flux chambers. Results show that the change in relative <span class="inline-formula">CH₄</span> levels can be determined at rather high accuracy in the 2–700&thinsp;<span class="inline-formula">ppm</span> mole fraction range, with modest efforts of collecting reference samples in situ and without continuous access to expensive reference instruments. This opens possibilities for more affordable and time-effective measurements of <span class="inline-formula">CH₄</span> in flux chambers. To facilitate such measurements, we also provide a description for building and using an Arduino logger for <span class="inline-formula">CH₄</span>, carbon dioxide (<span class="inline-formula">CO₂</span>), relative humidity, and temperature.</p>