Alaska Sea Grant College Program report ; no. 99-03 : Chapter 18The process of efficient biological pumping with high biological productivity was determined for the Bering Sea by employing a long-term time-series sediment trap deployed during 1990-1995. The present Bering Sea is an effective atmospheric CO2 sink with significant drawdown of the CO2. The high efficiency attributes to markedly high opal content of 69% in total mass flux, which is followed by 13% calcium carbonate content. The nodal location of the Bering Sea, in terms of the Pacific-Arctic-Atlantic gateway connection, makes this marginal sea significantly important for water circulation, balances of heat and salt, and various chemical properties, many of which affect global climate and mass balance. The present situations of the “opal” Pacific Ocean and the “carbonate” Atlantic Ocean were different during the glacial low stands primarily due to closure of the Bering Strait gateway caused by sea level drop. With a longer time scale than the Milankovitch cycles, Beringia (or the Bering land bridge) subsided a number of times due to tectonic movement, allowing intrusion of Atlantic signals. Based on mollusk faunal distribution in northern Japan, the Bering gateway must have been open initially at earlier than 5.1 Ma in the Late Miocene, followed by a number of openings and closures due to tectonics during the Pliocene. Detailed history of such openings and closures must be investigated with scientific drilling in the Bering Sea. The formation of the North Pacific Intermediate Water is established by evidence including stable isotopes, microfossils, and detritus sediments. The Meiji Drift is composed of sediments derived from the past Bering Sea, forming contourite deposits on the flank of the northern Emperor Seamount region just south of Kamchatka Strait
