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Abstract Arctic coastlines are known to be rapidly eroding, but the fate of this material in the coastal ocean (and the sedimentary dynamics of Arctic continental shelves in general) is less well‐constrained. This study used summertime mooring data from the Alaskan Beaufort Shelf to study sediment‐transport patterns which are dominated by waves and wind‐driven currents. Easterly wind events account for most of the seasonal sediment transport, and serve to focus sediment on the inner shelf. This is a key finding because it means that sediment is readily available for wave‐driven resuspension and sea‐ice entrainment during fall storms. Sediment‐ice entrainment has been previously implicated as a major mechanism for Arctic Shelf erosion—and so the summertime focusing of sediment observed in this study may actually serve to enhance shelf erosion rather than promote shelf sediment accumulation. In a pan‐Arctic context, the Alaskan Beaufort Shelf is somewhat similar to the Laptev Sea Shelf, where previous work has shown that sediment is also focused during the summer months (but for different reasons related to estuarine‐like circulation under the Laptev plume). The Alaskan Beaufort Shelf example contrasts with previous work on the Canadian Beaufort Shelf, where dominant winds from the opposite direction (northwest) likely promote strong seaward dispersal of sediment rather than inner‐shelf convergence. This study thus highlights the importance of understanding dominant wind patterns when considering seasonal and inter‐annual storage, transport, and erosion of sediments from Arctic continental shelves.
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Arctic Continental-Shelf Sediment Dynamics
Sediments covering Arctic continental shelves are uniquely impacted by ice processes. Delivery of sediments is generally limited to the summer, when rivers are ice free, permafrost bluffs are thawing, and sea ice is undergoing its seasonal retreat. Once delivered to the coastal zone, sediments follow complex pathways to their final depocenters—for example, fluvial sediments may experience enhanced seaward advection in the spring due to routing under nearshore sea ice; during the open-water season, boundary-layer transport may be altered by strong stratification in the ocean due to ice melt; during the fall storm season, sediments may be entrained into sea ice through the production of anchor ice and frazil; and in the winter, large ice keels more than 20 m tall plow the seafloor (sometimes to seabed depths of 1–2 m), creating a type of physical mixing that dwarfs the decimeter-scale mixing from bioturbation observed in lower-latitude shelf systems. This review summarizes the work done on subtidal sediment dynamics over the last 50 years in Arctic shelf systems backed by soft-sediment coastlines and suggests directions for future sediment studies in a changing Arctic. Reduced sea ice, increased wave energy, and increased sediment supply from bluffs (and possibly rivers) will likely alter marine sediment dynamics in the Arctic now and into the future.
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- PAR ID:
- 10549015
- Publisher / Repository:
- Annual Reviews of Marine Science
- Date Published:
- Journal Name:
- Annual Review of Marine Science
- ISSN:
- 1941-1405
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1146/annurev-marine-040423-023827
