Paleoenvironment and Paleoproductivity Variations in the Bering Sea Since the Last Deglacial

Paleoenvironment and paleoproductivity variations were constructed, combined with radiocarbon dating, based on 17 geochemical elements, TOC and CaCO3, since 13.7 ka in the Bering Sea. The results show that the sedimentation rate was 34.2 cm/ka and the climate signals such as Younger-Dryas (YD), Bolling-Allerod (BA), and meltwater pulse were also reflected in the B5-4 core. The accumulation of terreginous sediments is controlled by many factors, including climate condition in the sediments source, sea level change and biogenic material dilution. The obvious features are the high paleoproductivity and hypoxia in the bottom water in the Bering Sea during the last deglacial period. The high paleoproductivity are attributed to the meltwater pulse event and the input of warmer Pacific water with the increased temperature. Hypoxia in the bottom water is caused by high productivity in the surface water and subsurface waterbody stratification due to saline gradient. However, the potential factors caused hypoxia in the bottom water also include the decreasing Pacific intermediate water ventilation and bottom-current speed in the Pacific Ocean. In the Holocene, the paleoenvironment and productivity of the Bering Sea were mainly controlled by the Alaskan stream. There are no obvious changes for productivity and paleoenvironment in the Holocene.