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Sediment cores from the Northwind Ridge north of the Arctic Chukchi-Alaskan margin were analyzed for a suite of stratigraphic and provenance proxies. Based on the correlation to previously studied regional records, cores under study present sedimentary environments of Marine Isotope Stages (MIS) 1–11 (∼0.4 Ma) on millennial time scales. Contrasting glacial-interglacial conditions and provenance were characterized by means of clay-mineral and geochemical (elemental and isotopic) proxies along with grain size. Interglacial environments are interpreted as sea-ice dominated, with pre-Holocene sediment transported mostly from the East Siberian to Chukchi-Alaskan margin. In comparison with the recent conditions, this pattern suggests a stronger Transpolar Drift expanding into the Canada Basin at the expense of the Beaufort Gyre, or stronger along-shelf currents. Glacial intervals prior to MIS4 have a predominantly North American signature with carbonaceous or terrigenous source rocks. Carbonaceous inputs marked by Ca peaks are tracked to the western Canadian Arctic Archipelago eroded by the Laurentide Ice Sheet (LIS). Terrigenous sources (Zr peaks) are likely related to areas impacted by the Innuitian Ice Sheet and/or the LIS Mackenzie ice stream. MIS 4 and 2 intervals have a different composition with the Siberian/Chukchi rather than North American provenance. A stronger winnowing indicated by grain size in the glacial intervals suggests a stronger mid-depth circulation. Study results provide new boundary conditions for modeling paleocirculation and glaciations in the western Arctic Ocean. • Contrasting glacial-interglacial conditions and provenance were characterized. • Pre-Holocene interglacials have sea-ice dominated depositional environment, margin provenance and a stronger TPD. • Glacial intervals prior to MIS4 have a predominantly North American signature with carbonaceous or terrigenous rocks. • MIS4 and 2 intervals have more interglacial compositions with the Siberian/Chukchi rather than North American source. [ABSTRACT FROM AUTHOR]

During the 6th (2014) and 7th (2016) Chinese Arctic Expedition (CHINARE), samples of suspended particulate matter (SPM) were collected from both surface (depth: <1.0 m) and subsurface (depth: approximately between 10 and 150 m) waters over the northern shelf of the Bering Sea and in the western Arctic Ocean. To investigate the distribution and sources of organic matter in both the surface water and the vertical profile, the concentration and stable carbon isotopic composition of SPM, particulate organic carbon (POC), and particulate nitrogen (only in surface water samples) were determined, and some particle samples were selected for examination using scanning electron microscopy. Results showed apparent geographical partitioning and temporal variation in both the concentration and the composition of SPM. Higher SPM concentrations were observed in nearshore, shelf break, and sea ice edge areas; the distribution of POC concentration displayed a similar pattern, with higher values found from the northern part of the Bering Shelf to southern parts of the Chukchi Shelf. In surface water, SPM mainly comprised clay and detrital minerals with higher POC contents, lighter δ13C values, and higher POC/PN ratios, indicating organic matter predominantly derived from terrestrial sources in areas south of St. Lawrence Island and north of 73°N. The downward trend of heavier δ13C values, together with reduction in clay and detrital minerals, suggests that vertical transport of SPM is hindered by stratification, resulting in transport of terrestrial materials toward northern basin areas. In the Chukchi Slope and Canada Basin areas, extremely light δ13C values (as low as −33.41‰ PDB) were mainly observed at depths of 20–60 m, where the Polar Mixed Layer (PML) intersects with the Upper Halocline Layer (UHL). Under the condition of low sea ice extent in 2016, the POC-δ13C values were heavier in the PML than in the UHL in the Chukchi Slope and Canada Basin areas. These findings provide insights into the sources, transport, and fate of organic matter in the Pacific Arctic region, which have important implications for understanding the biogeochemical cycles and ecosystem dynamics in this remote and rapidly changing environment. • Significant geographical partition and temporal variation in suspended particles. • Extremely negative POC-δ13C values at high latitudes. • Links between POC concentration and composition. [ABSTRACT FROM AUTHOR]