River Inflow Dominates Methane Emissions in an Arctic Coastal System

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Manning, Cara C.
Preston, Victoria Lynn
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 D.
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Greenhouse gases
Arctic coastal waters
Biogeochemical sensing
Seasonal cycles
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.
Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 47 (2020): e2020GL087669, doi:10.1029/2020GL087669.
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Manning, C. C., Preston, V. L., Jones, S. F., Michel, A. P. M., Nicholson, D. P., Duke, P. J., Ahmed, M. M. M., Manganini, K., Else, B. G. T., & Tortell, P. D. (2020). River inflow dominates methane emissions in an arctic coastal system. Geophysical Research Letters, 47, e2020GL087669.
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