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TitleCoastal Erosion of Permafrost Soils along the Yukon Coastal Plain and Fluxes of Organic Carbon to the Canadian Beaufort Sea
AuthorCouture, N JORCID logo; Irrgang, A; Pollard, W; Lantuit, H; Fritz, M
SourceJournal of Geophysical Research, Biogeosciences vol. 123, issue 2, 2018 p. 406-422, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20170202
Mediapaper; on-line; digital
File formatpdf
ProvinceYukon; Northwest Territories
NTS107B; 117A; 117D
AreaYukon Coastal Plain
Lat/Long WENS-141.0000 -138.0000 69.6667 69.0000
Subjectssurficial geology/geomorphology; coastal studies; coastal erosion; coastal environment; carbon; organic carbon; permafrost; ground ice; ice wedges; ice-wedge polygons; sedimentation rates
Illustrationslocation maps; tables
ProgramGSC Northern Canada Division
Released2018 02 17
AbstractReducing uncertainties about carbon cycling is important in the Arctic where rapid environmental changes contribute to enhanced mobilization of carbon. Here we quantify soil organic carbon (SOC) contents of permafrost soils along the Yukon Coastal Plain and determine the annual fluxes from coastal erosion. Different terrain units were assessed based on surficial geology, morphology, and ground ice conditions. To account for the volume of wedge ice and massive ice in a unit, SOC contents were reduced by 19% and sediment contents by 16%. The SOC content in a 1 m2 column of soil varied according to the height of the bluff, ranging from 30 to 662 kg, with a mean value of 183 kg. Forty-four per cent of the SOC was within the top 1 m of soil and values varied based on surficial materials, ranging from 30 to 53 kg C/m3, with a mean of 41 kg. Eighty per cent of the shoreline was erosive with a mean annual rate of change of ?0.7 m/yr. This resulted in a SOC flux per meter of shoreline of 132 kg C/m/yr, and a total flux for the entire 282 km of the Yukon coast of 35.5 × 106 kg C/yr (0.036 Tg C/yr). The mean flux of sediment per meter of shoreline was 5.3 × 103 kg/m/yr, with a total flux of 1,832 × 106 kg/yr (1.832 Tg/yr). Sedimentation rates indicate that approximately 13% of the eroded carbon was sequestered in nearshore sediments, where the overwhelming majority of organic carbon was of terrestrial origin.
Summary(Plain Language Summary, not published)
The oceans help slow the buildup of atmospheric CO2 because they absorb much of it. However if carbon from other sources is added to the oceans, it reduces their ability to absorb CO2. We examine the organic carbon (OC) added to the Beaufort Sea from eroding permafrost along the Yukon coast. Understanding carbon cycling is important because environmental changes in the Arctic such as longer open water seasons, rising sea levels, and warmer temperatures can increase coastal erosion and thus carbon fluxes to the sea. We measured the OC in soils and applied corrections to account for the volume taken up by ground ice. By determining how quickly the coast is eroding, we assessed how much OC is being transferred to the ocean. Our results show that 35 million kilograms of carbon is added annually from this section of the coast. If we extrapolate these results to other coastal areas along the Canadian Beaufort Sea, the flux of organic carbon is nearly three times what was previously thought.

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