ESTIMATING ATMOSPHERIC METHANE EMISSION BY MINERAL CRYOSOLS IN THE ARCTIC REGION USING THE EXPLICIT HIGH AFFINITY METHANOTROPH (XHAM) MODEL

Abstract

Methane is a powerful greenhouse gas that needs to be closely regulated in orderto mitigate its effect on climate change. This is especially important in the permafrostaffectedArctic region that has a large carbon reservoir, which, if thawed, would likely bemineralized into greenhouse gases and increase warming. For this reason, much attentionhas been paid to carbon-rich cryosols and methane emissions in the Arctic region.However, there is a large area of carbon-poor cryosols that may have the potential to bemethane uptaking sites especially due to the activity of high-affinity methanotrophic(HAM) bacteria. Because HAM activity has been reported in carbon-poor cryosols andthe carbon-poor cryosols are 87% of the Arctic region, Arctic will likely be a net sink formethane. To estimate the net methane flux in the Arctic region where HAM have beenfound, the eXplicit High Affinity Methanotroph (XHAM) model was scaled up tosimulate methane fluxes in the Arctic region for 2004, 2006, 2008, 2010, and 2012. Thismodel took the soil moisture and surface temperature and simulated the change inbiomass and activity of both methanogens and methanotrophs down a 1m column foreach year-long period. Methane production and consumption and net fluxes werecomputed for each month of simulation. These values were compared to determineseasonal and inter-annual trends and determine whether the Arctic was an overall sink foratmospheric methane. The hypothesis that the Arctic region was an overall sink foratmospheric methane was not validated through this project.