On the Late Pleistocene ocean geochemistry and circulation

作者：Robin S. Keir · 发表于：Paleoceanography · 年份：1988 · DOI：10.1029/pa003i004p00413 · 被引用次数：207 · 研究领域：Geology and Paleoclimatology Research、Isotope Analysis in Ecology、Marine and coastal ecosystems

A box model of the atmosphere and ocean was developed to investigate how geochemical distributions extant during the late Pleistocene may have come about. The model simulates the regional distribution of calcium carbonate dissolution as well as the chemical oceanography and atmospheric CO2, δ13C, and radiocarbon. If the downward biological flux of particulate carbon increases by a factor of 2 to 3 in the Antarctic and if this increase is combined with a relative increase of the Atlantic sector Antarctic Bottom Water (AABW) versus North Atlantic Deep Water (NADW) source ratio from 1∶3 to about 2∶1, then the model predicts several changes that seem to be recorded in the sedimentary record, as follows: (1) A global redistribution of nutrients and 12C from the intermediate to deep water takes place with the Atlantic intermediate water phosphate decreasing 0.6 µmole kg−1 and the δ13C increasing 0.3 to 0.5‰. (2) The dissolved oxygen level of the deep sea is reduced from an average of about 180 to 70 µmole kg−1, but the intermediate water oxygen declines only a small amount. (3) The decrease in intermediate water nutrient concentration results in lower average organic carbon and calcium carbonate production in the warm surface ocean. (4) The atmospheric CO2 decreases by 90 to 110 ppm. (5) Initially, a global increase in calcium carbonate dissolution occurs, which is followed by a relaxation toward better preservation than exists for the present ocean. In the model in this paper the ...