Observing Seasonal Cycles in Greenhouse Gas Fluxes with Automatic Flushing Chambers in a Low-Arctic Lake

Abstract

The Arctic is warming nearly four times faster than the global average. Greenhouse gases (GHG) are causing a changing climate which is affecting permafrost thaw, sea ice melt, and changing hydrological dynamics. Lakes in the Arctic and sub-Arctic regions are increasingly recognised as important actors in the global carbon budget, acting as both sources and sinks of carbon dioxide (CO₂) and methane (CH₄). Despite their abundance, these lakes remain understudied due to harsh environmental conditions and logistical constraints. This study explores the use of low-cost, Automatic Flushing Chambers (AFCs) equipped with CH₄ and CO₂ sensors for continuous monitoring of GHG fluxes. Over the summer of 2024, four AFCs were deployed on Lake Badesø, located near Nuuk, Greenland, to measure fluxes during the ice-free season. The aims were to test the performance of low-cost sensors in Arctic environments and to evaluate the lake’s role in carbon cycling and assess how environmental drivers impact gas fluxes. Measurements showed that Lake Badesø functions as a consistent source of CO₂ throughout the sampling period. Methane emissions, on the other hand, were minimal across the lake system. Generalised Additive Mixed Models (GAMMs) and linear regression analyses revealed significant correlations between CO₂ fluxes and some environmental parameters. Specifically, freshwater discharge, was positively linked to CO₂ emission at all sampling locations. Methane concentrations were too low for accurate flux estimates using the low-cost CH₄ sensors, as the readings were dominated by humidity-related noise. Future work should include further sensor calibration and electronic nose strategies to improve CH₄ measurements at low concentrations.