Ice-out and Freshet Fluxes of CO2 and CH4 Across the Air–water Interface of the Channel Network of a Great Arctic Delta, the Mackenzie

Resource type
Date created
2020-06-26
Authors/Contributors
Abstract
Carbon dioxide (CO2) and methane (CH4) were monitored at five sites spanning the upstream–downstream extent of the Mackenzie Delta channel network during May 2010, capturing the historically under-sampled ice-out period that includes the rising freshet, peak water levels and the early falling freshet (flood recession). Unexpectedly, partial pressures of CO2 in the Mackenzie River were undersaturated during the rising freshet before water levels peaked, indicating net CO2 invasion at instantaneous CO2 flux rates (F-CO2) ranging from –112 to –258 mg-C m-2 d-1. Net CO2 invasion was also observed around the time of peak water levels at sites in the middle and outer delta. Following peak water levels, the Mackenzie River switched to saturation and net CO2 evasion (F-CO2 from 74 to 177 mg-C m-2 d-1). Although the Peel River (which flows into the west side of the Mackenzie Delta) was a strong emitter of CO2 (F-CO2 from 373 to 871 mg-C m-2 d-1), overall, the Mackenzie River and Delta were weak emitters of CO2 during the 2010 ice-out period. All sites were strong emitters of CH4 during ice-out, however, with the highest evasive fluxes observed in the outer delta when the extent of flooded delta landscape was greatest. Estimated aerial fluxes from Mackenzie Delta channel surfaces during May 2010 ranged from 2.1 to 4.8 Gg-C as CO2, and 186 to 433 Mg-C as CH4. These results provide critical information that can be used to refine gas flux estimates in high-latitude circumpolar river deltas during the relatively under-studied ice-out period.
Document
Identifier
DOI: 10.33265/polar.v39.3528
Published as
Gareis, J. A. L., & Lesack, L. F. W. (2020). Ice-out and freshet fluxes of CO2 and CH4 across the air–water interface of the channel network of a great Arctic delta, the Mackenzie. Polar Research, 39. https://doi.org/10.33265/polar.v39.3528.
Publication title
Polar Research
Document title
Ice-out and Freshet Fluxes of CO2 and CH4 Across the Air–water Interface of the Channel Network of a Great Arctic Delta, the Mackenzie
Date
2020
Volume
39
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Copyright is held by the author(s).
Scholarly level
Peer reviewed?
Yes
Language
Member of collection