Transport Processes of Seafloor Sediment From the Chukchi Shelf to the Western Arctic Basin

The processes of seafloor sediment transport from the Chukchi shelf to the western Arctic basin were investigated using a pan-Arctic sea ice-ocean model and sediment-trap measurements at four mooring stations: North of Barrow Canyon, North of Hanna Canyon, Northwind Abyssal Plain, and Chukchi Abyssal Plain. The available sediment-trap data verified that the sinking flux of lithogenic material (LM) originally resuspended from the seafloor for 2010-2020 was simulated reasonably well in the four mooring areas. The model results were analyzed to quantify the spatiotemporal variability of LM and to reveal its background mechanisms. Analysis indicated that the Barrow Canyon throughflow, Chukchi Slope Current (CSC), and mesoscale eddies played important roles in LM redistribution. The CSC controlled the westward transport of LM from the mouth of Barrow Canyon to the Chukchi Borderland. The mesoscale eddies generated north of Barrow Canyon efficiently transported shelf-origin LM toward the southern Canada Basin. The sinking flux of particulate organic carbon (POC) averaged from September 2010 to August 2020, which was estimated statistically from the simulated LM flux, was 0.13-0.30 gC m(-2) yr(-1) at 200-m depth in the southern Canada Basin. This finding reveals that lateral transport of sediment from the Chukchi shelf bottom has a considerable effect on the sinking flux of POC in the western Arctic basin, and suggests that the western Arctic marine biogeochemical cycle is strongly influenced by shelf-basin exchange that depends on the relative strength of the CSC and mesoscale eddy activity.