Evaluation of low-cost sensors for measurement of CO2 and CH4 fluxes at a Finnish wetland

Northern wetlands are an important sink of atmospheric CO₂ and source of methane (CH₄) to the atmosphere but many uncertainties remain in the magnitude of fluxes due to high spatial, temporal, and methodological variability. Chamber measurements are an important method to link CO₂ and CH₄ fluxes to underlying soil processes. While high-frequency laser gas analyzers have been crucial for improving the number and quality of flux measurements, costs for purchase and maintenance of these systems are still cost-prohibitive for widespread applications of this method for quantification of fluxes.

In the MISO project, we test a low-cost NDIR-based portable sensor for flux measurements at a wetland site in Finland. We deployed the new MISO sensor in a two existing automated chambers (one transparent, one opaque) and evaluated the performance of the low-cost sensor for quantifying fluxes of CO₂ and CH₄ during a three-week period in July 2025. The results indicate that CO₂ fluxes can be measured well with the sensor setup. Methane fluxes show strong variability in the raw signal; calibrated values are highly dependent on methods used to correct for interference from water vapor and temperature. These findings indicate that this method is promising for applications in wetlands and would provide an important step forward in enabling widespread flux monitoring networks.