The changing roles of iron and vertical mixing in regulating nitrogen and silicon cycling in the Southern Ocean over the last glacial cycle
The changing roles of iron and vertical mixing in regulating nitrogen and silicon cycling in the Southern Ocean over the last glacial cycle
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末次冰期期间铁和垂直混合在调节南大洋氮和硅循环中的作用变化
DOI：
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Patrick Bedsole
中科院分区：
文献类型：
--
作者：
R. Robinson;M. Brzezinski;C. Beucher;M. Horn;Patrick Bedsole
南大洋通过生物和物理机制在海-气二氧化碳平衡方面发挥着关键作用。深层沃茨的垂直供应将营养物质和二氧化碳返回到表面，并刺激浮游植物生长。南大洋的光合作用受到铁的限制，只有一小部分返回表面的碳和营养物质被消耗，可能被封存在深海中。在这里，我们提出了空间上最广泛的硅和氮同位素测量硅藻壳的数据集，以检查在末次冰期和整个冰川终止在南极和亚南极带的营养下降的控制。新的数据证实了现有的观点，即南极地区不同的硅和硝酸盐消费模式可能是末次冰期最大期（LGM）期间铁添加的结果。然而，在冰川早期，一个更协调的反应，在两个代理记录，都反映了增加的铁积累和出口生产的插曲期间，消费增加，意味着一个不同的系统响应比观察到的末次盛冰期。预期的硅同位素值和氮同位素梯度的收缩，在冰消期向赤道梯度的崩溃表明，营养供应增加，不仅在南极区，但也在Subanabritic，也许是由于增强深层混合当地。增强的深水通风整个南大洋可能增加了模式沃茨的营养物质含量在冰川消退。
The Southern Ocean plays a critical role in the air-sea CO2 balance through biological and physical mechanisms. Vertical supply of deep waters returns nutrients and CO2 to the surface and stimulates phytoplankton growth. Photosynthesis in the Southern Ocean is limited by iron and only a fraction of the carbon and nutrients that return to the surface are consumed for potential sequestration in the deep sea. Here we present the most spatially extensive data set of silicon and nitrogen isotope measurements from diatom frustules to date to examine the controls on nutrient drawdown during the last glacial period and across the glacial termination in both the Antarctic and Subantarctic zones. The new data confirm existing views that differing silicon and nitrate consumption patterns in the Antarctic zone are likely the result, at least in part, of iron addition during the last glacial maximum (LGM). However, earlier in the glacial, a more coordinated response in the two proxy records, with both reflecting enhanced consumption during episodes of increased iron accumulation and export production, implies a different system response than observed for the LGM. A collapse of the expected equatorward gradient in silicon isotope values and contraction of the nitrogen isotope gradient during the deglaciation suggests that nutrient supply increased not only in the Antarctic Zone, but also in the Subantarctic, perhaps due to enhanced deep mixing locally. Enhanced deep water ventilation across the Southern Ocean likely increased the nutrient content of mode waters during the deglaciation.
DOI：
10.1073/pnas.1309345110
发表时间：
2013-12-17
影响因子：
11.1
作者：
Assmy, Philipp;Smetacek, Victor;Wolf-Gladrow, Dieter
通讯作者：
Wolf-Gladrow, Dieter
影响因子：
4
作者：
Hendry, Katharine R.;Brzezinski, Mark A.
通讯作者：
Brzezinski, Mark A.