Glacial to Interglacial Changes in the Isotopic Gradients of Southern Ocean Surface Water
Glacial to Interglacial Changes in the Isotopic Gradients of Southern Ocean Surface Water
复制标题
南大洋表层水同位素梯度的冰期至间冰期变化
DOI：
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发表时间：
1990
期刊：
影响因子：
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通讯作者：
R. Fairbanks
中科院分区：
文献类型：
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作者：
C. Charles;R. Fairbanks
南大洋的大西洋部分是一个地表水性质（包括稳定同位素含量）水平梯度强烈的区域。这些梯度对气候敏感，只要有记录其变化的方法，就可以用于古海洋学目的。在这里，我们展示了浮游有孔虫物种 Neoghboquadrina pachderma l.c. 中 δ 18O 和 δ 13C 的核心最高值。遵循方解石与地表水平衡沉淀的预期结果。地表水的 δ 18O 方解石从赤道到极地的梯度大约为 6‰，而核心顶部厚皮猪笼草的 δ 18O 记录了该梯度的一半，在南纬 41° – 60° 的纬度范围内增加了 3‰。同时，核心顶部厚皮猪笼草δ 13O 的地理格局与观察到的表面ΣCO2 δ 13C 的趋势相似。最高值出现在目前的南极极锋 (APF) 附近，那里的气体交换率最高；较低的值出现在南部的威德尔环流和北部的副热带辐合附近。因此，第四纪沉积物中厚皮猪笼草的同位素组成可以作为南大洋表层水古化学的有效示踪剂。
The Atlantic sector of the Southern Ocean is a region characterized by intense horizontal gradients in surface water properties, including the stable isotopic content. These gradients are climatically sensitive and can be exploited for paleoceanographic purposes, provided there is a means of recording their variability. Here we show that core top values of δ 18O and δ 13C in the planktic foraminiferal species Neoghboquadrina pachyderma l.c. follow those expected for calcite precipitated in equilibrium with surface waters. The entire equator-to-pole gradient in δ 18Ocalcite for surface waters is roughly 6‰, and the δ 18O of core top N. pachyderma records fully half of this gradient, increasing by 3‰ over a latitudinal range of 41° – 60°S. Meanwhile, the geographic pattern of δ 13O of core top N. pachyderma is similar to observed trends in δ 13C of surface ΣCO2. Highest values are recorded near the present Antarctic Polar Front (APF), where gas exchange rates are the highest; lower values occur both to the south, in the Weddell Gyre, and to the north, near the Subtropical Convergence. Thus, the isotopic composition of N. pachyderma from Quaternary sediments may serve as an effective tracer of the paleochemistry of Southern Ocean surface waters.