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首页> 外文期刊>Global Biogeochemical Cycles >Carbon dioxide effects of Antarctic stratification, North Atlantic Intermediate Water formation, and subantarctic nutrient drawdown during the last ice age: Diagnosis and synthesis in a geochemical box model
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Carbon dioxide effects of Antarctic stratification, North Atlantic Intermediate Water formation, and subantarctic nutrient drawdown during the last ice age: Diagnosis and synthesis in a geochemical box model

机译：在最后一个冰期中，南极分层，北大西洋中层水的形成和南极营养物质的减少对二氧化碳的影响：地球化学盒模型的诊断和合成

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摘要

In a box model synthesis of Southern Ocean and North Atlantic mechanisms for lowering CO_2 during ice ages, the CO_2 changes are parsed into their component geochemical causes, including the soft-tissue pump, the carbonate pump, and whole ocean alkalinity. When the mechanisms are applied together, their interactions greatly modify the net CO_2 change. Combining the Antarctic mechanisms (stratification, nutrient drawdown, and sea ice cover) within bounds set by observations decreases CO_2 by no more than 36 ppm, a drawdown that could be caused by any one of these mechanisms in isolation. However, these Antarctic changes reverse the CO_2 effect of the observed ice age shoaling of North Atlantic overturning: in isolation, the shoaling raises CO_2 by 16 ppm, but alongside the Antarctic changes, it lowers CO_2 by an additional 13 ppm, a 29 ppm synergy. The total CO_2 decrease does not reach 80 ppm, partly because Antarctic stratification, Antarctic sea ice cover, and the shoaling of North Atlantic overturning all strengthen the sequestration of alkalinity in the deepest ocean, which increases CO_2 both by itself and by decreasing whole ocean alkalinity. Increased nutrient consumption in the sub-Antarctic causes as much as an additional 35 ppm CO_2 decrease, interacting minimally with the other changes. With its inclusion, the lowest ice age CO_2 levels are within reach. These findings may bear on the two-stepped CO_2 decrease of the last ice age.
机译：在南冰洋和北大西洋在冰河时期降低CO_2的机理的盒式综合中，将CO_2的变化解析为它们的成分地球化学原因，包括软组织泵，碳酸盐泵和整个海洋的碱度。当这些机制一起应用时，它们的相互作用极大地改变了净CO_2的变化。在观测设定的范围内结合南极机制（分层，营养物下降和海冰覆盖），会使CO_2减少不超过36 ppm，这可能是这些机制中的任何一种孤立引起的下降。但是，这些南极变化逆转了观测到的北大西洋覆冰冰期浅滩的CO_2效应：孤立地，浅滩使CO_2升高了16 ppm，但与南极洲变化相比，它又使CO_2降低了13 ppm，产​​生了29 ppm的协同作用。总的CO_2减少量未达到80 ppm，部分原因是南极分层，南极海冰覆盖以及北大西洋的俯冲作用都强化了最深海的碱度螯合，从而增加了CO_2本身并通过降低整个海洋碱度。在南极洲，养分消耗量的增加导致额外的35 ppm CO_2减少，与其他变化的相互作用最小。包括在内，最低冰河时期的CO_2含量是可以达到的。这些发现可能与最后一次冰期的两步式CO_2减少有关。

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