Abstract
AbstractDetailed organic geochemical and carbon isotopic (δ13C and Δ14C) analyses are performed on permafrost deposits affected by coastal erosion (Herschel Island, Canadian Beaufort Sea) and adjacent marine sediments (Herschel Basin) to understand the fate of organic carbon in Arctic nearshore environments. We use an end‐member model based on the carbon isotopic composition of bulk organic matter to identify sources of organic carbon. Monte Carlo simulations are applied to quantify the contribution of coastal permafrost erosion to the sedimentary carbon budget. The models suggest that ~40% of all carbon released by local coastal permafrost erosion is efficiently trapped and sequestered in the nearshore zone. This highlights the importance of sedimentary traps in environments such as basins, lagoons, troughs, and canyons for the carbon sequestration in previously poorly investigated, nearshore areas.
Highlights
Arctic permafrost soils are an important terrestrial carbon reservoir and currently store about 1,300 PgC (Hugelius et al, 2014)
Detailed organic geochemical and carbon isotopic (δ13C and Δ14C) analyses are performed on permafrost deposits affected by coastal erosion (Herschel Island, Canadian Beaufort Sea) and adjacent marine sediments (Herschel Basin) to understand the fate of organic carbon in Arctic nearshore environments
We investigate the sources of OC to Herschel Basin, a sedimentary basin situated between Herschel Island and the Mackenzie Delta in the southern Canadian Beaufort Sea (Figure 1)
Summary
Arctic permafrost soils are an important terrestrial carbon reservoir and currently store about 1,300 PgC (Hugelius et al, 2014). Arctic coastal waters are believed to receive increasing OCterr fluxes from rivers draining permafrost terrain and from eroding permafrost coasts (Fritz et al, 2017). Such increase would result in drastic impacts on global carbon fluxes and their climate feedbacks, on nearshore food webs, and on local communities. The fate of the released material in the nearshore zone is quantitatively not well assessed. It may (i) degrade into greenhouse gases (Tanski et al, 2019), (ii) fuel marine primary production, (iii) be buried in nearshore sediments, or (iv) be transported offshore (Fritz et al, 2017; Vonk & Gustafsson, 2013)
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