DISTRIBUTION PATTERN OF BIOGENIC COMPONENTS IN SURFACE SEDIMENTS OF THE WESTERN ARCTIC OCEAN AND THEIR PALEOCEANOGRAPHIC IMPLICATIONS

Biogenic components in total 66 surface sediments, which were taken in the western Arctic Ocean during the First and Second Chinese National Arctic Expedition cruises, are analyzed for probing into the relationship between surface productivity and water masses in area studied. As a result of the investigation, high organic carbon and biogenic opal percentages appear in the southwestern Chukchi Sea. On the contrary, low organic carbon and biogenic opal percentages occur in several areas, including the central Chukchi Sea, Herald Shoal, seacoast of Alaska, Chukchi Plateau, Northwind Ridge and Canada Basin. High foraminiferal abundance emerges in the Chukchi Plateau, Northwind Ridge and Canada Basin where the planktonic foraminifera dominate. Inversely, low foraminiferal abundance comes on the shelf of the Chukchi Sea where the benthic foraminifera dominate. Distribution patterns of biogenic components are associated obviously with three branches of the Pacific Water from the Bering Strait into the Chukchi Sea and the subsurface Atlantic Water. High surface productivity presents in the area of abundant nutrient Anadyr Water in the western Chukchi Sea. Reversely, low surface productivity appears in the areas influenced by scant nutrient Alaska Coastal Water and terrigenous matter input along northwestern Alaska seacoast. Similarly, low surface productivity in the northern area higher than 75°N and Canada Basin is attributed to the long-term sea ice coverage. High calcareous productivity in the outer side of Chukchi Sea Shelf and high latitude is ascribed to the influence of the subsurface Atlantic Water. The C_org/N ratio in surface sediments and its distribution pattern indicate that the organic carbon in surface sediments of the Chukchi Sea mainly originates from marine source and is controlled by biological pump process. High correlative coefficient between organic carbon and biogenic opal shows a closer relationship between organic carbon and diatom. Primary productivity of diatom and other phytoplankton can control the absorption and release of biological pump for carbon.