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首页> 外文期刊>Paleoceanography >Reconciling down core anticorrelation of diatom carbon and nitrogen isotopic ratios from the Southern Ocean
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Reconciling down core anticorrelation of diatom carbon and nitrogen isotopic ratios from the Southern Ocean

机译：调和来自南大洋的硅藻碳和氮同位素比率的核心反相关

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摘要

Oceanic nutrient cycling in the Southern Ocean is supposed to have an important impact on glacial-interglacial atmospheric CO_2 changes and global climate. In order to characterize such nutrient cycling over the last two climatic cycles we investigated carbon and nitrogen isotopic ratios of diatom-bound organic matter (δ~(13)C_(diat) and δ~(15)N_(diat), respectively) in two cores retrieved form the Atlantic and Indian sectors of the Antarctic Ocean. The two cores show the same isotopic patterns. The δ~(13)C_(diat) values are depleted during glacial periods and enriched during interglacial period,s indicating lower productivity during cold times. The δ~(15)N_(diat) values are enriched during glacial periods and depleted during interglacial periods, arguing for greater nitrate utilization during cold times. Taken at face value, this apparent contradiction leads to opposite conclusions on the role of the Southern Ocean biological pump on the atmospheric CO_2 changes. However, he two sets of data can be reconciled by a "sea ice plus mixing rate scenario" that calls upon a balance between the effect of cutting off gas transfer at the ocean-atmosphere boundary and the effect of reducing vertical transport of nutrients through the pycnocline.
机译：据推测，南大洋的海洋养分循环对冰川-冰川间的大气CO_2变化和全球气候具有重要影响。为了表征在最近两个气候周期中的这种养分循环，我们研究了硅藻结合有机物的碳和氮同位素比（分别为δ〜（13）C_（diat）和δ〜（15）N_（diat））。从南极的大西洋和印度部分获得了两个岩心。这两个核心显示出相同的同位素模式。 δ〜（13）C_（diat）值在冰期消减，在冰间期富集，表明在寒冷时期生产力较低。 δ〜（15）N_（diat）值在冰川期富集，而在间冰期则枯竭，这表明在寒冷时期硝酸盐利用率更高。从表面上看，这种明显的矛盾导致有关南大洋生物泵对大气CO_2变化的作用的相反结论。但是，通过“海冰加混合速率方案”可以调和两组数据，该方案要求在切断海洋-大气边界处的气体转移的效果与减少通过营养层的垂直养分运输的效果之间取得平衡。碧萝oc。

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