Monitub: A Low-Cost Real-Time System for Long-Term Methane Emissions Monitoring from Inland Waterbodies

Inland waterbodies are a significant emitter of greenhouse gases, especially methane. They contribute 15.2% of all anthropogenic methane emissions. Major uncertainties are still present in emissions estimates for these systems; as a result, more in situ measurements are required to constrain them, especially when ebullition, a direct release of methane, is present. The Monitub Automated Floating Chamber (AFC) was developed to address existing challenges in floating chamber deployments, a common emissions measurement method, through the use of a custom floating chamber, datalogger, and generic calibration of the TGS2611-E00 sensor. This system is able to perform long-term, real-time monitoring of methane emissions from waterbodies at a low cost. This allows for the correlation of environmental drivers to further constrain uncertainties related to emissions, due to its high temporal frequency, and help to answer questions about the spatial heterogeneity of emissions, as more systems can be deployed at a lower cost. The Monitub AFC was deployed to an urban lake for testing, showing its ability to differentiate between diffusion and ebullition, and its capabilities as a long-term monitoring system.