River Inflow Dominates Methane Emissions in an Arctic Coastal System Manning, Cara C.; Preston, Victoria L.; Jones, Samantha F.; Michel, Anna P. M.; Nicholson, David P.; Duke, Patrick J.; Ahmed, Mohamed M. M.; Manganini, Kevin; Else, Brent G. T.; Tortell, Philippe Daniel, 1972-
We present a year‐round time series of dissolved methane (CH₄), along with targeted observations during ice melt of CH₄ and carbon dioxide (CO₂) in a river and estuary adjacent to Cambridge Bay, Nunavut, Canada. During the freshet, CH₄ concentrations in the river and ice‐covered estuary were up to 240,000% saturation and 19,000% saturation, respectively, but quickly dropped by >100‐fold following ice melt. Observations with a robotic kayak revealed that river‐derived CH₄ and CO₂ were transported to the estuary and rapidly ventilated to the atmosphere once ice cover retreated. We estimate that river discharge accounts for >95% of annual CH₄ sea‐to‐air emissions from the estuary. These results demonstrate the importance of resolving seasonal dynamics in order to estimate greenhouse gas emissions from polar systems.
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