北太平洋の深海底コアから推測される最終氷期の世界

抄録

Comparing mutually the records of several deep-sea cores from the North Pacific, it is concluded that glacial ages had high accumulation rate of organic carbon and weak carbonate dissolution rate than interglacial ages. However, the increase of biological productivity in surface water generally causes the drop of the pH of the underlying water and leads to high carbonate dissolution. A key to solve this contradiction is probably carbonate particles in aeolian dust which were extensively supplied to the entire ocean during glacial ages. By dissolving the carbonate particles in water column, the alkalinity of the sea water increased. Hence the atmospheric CO₂ was absorbed by the upwelling water with high alkalinity, as well as by the photosynthesis of marine plankton increased during glacial ages. The variation of atmospheric CO₂ concentration is not related to the deep water circulation but to the conditions of the surface and middle layers in the ocean.