Deglacial diatom production in the tropical North Atlantic driven by enhanced silicic acid supply
Deglacial diatom production in the tropical North Atlantic driven by enhanced silicic acid supply
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DOI：
10.1016/j.epsl.2016.01.016
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发表时间：
2016-03
影响因子：
5.3
通讯作者：
K. Hendry;X. Gong;G. Knorr;J. Pike;I. Hall
中科院分区：
文献类型：
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作者：
K. Hendry;X. Gong;G. Knorr;J. Pike;I. Hall
海洋环流的重大变化被认为是最后一次冰消期温度和大气CO2突然变化的原因，与赤道热传输和深海碳储存的变化有关。还有广泛的证据表明，在这些冰消期二氧化碳上升的时期，生物生产发生了变化，包括热带大西洋等地区硅藻产量的增加。然而，目前还不清楚这种硅藻生产是否是由增强的风驱动的上升流或密度驱动的垂直混合，或由温跃层浓度升高的以恒定速率提供给表面的藻酸。在这里，我们表明，在东北大西洋深处的磷酸供应增强在冰川消退的突然气候事件。我们使用海洋沉积物档案表明，在气候突变期间硅藻产量的增加只能发生在东北大西洋的深层供应的海藻酸可以到达表面的地区。相关的变化是增强区域风驱动的上升流和/或减弱层结由于在减弱大西洋纬向翻转阶段的环流变化的指示。全球近同步脉冲的硅藻生产和增强温跃层浓度的藻酸表明，广泛的冰消表面驱动的分层，连接到大气环流的变化，有重大后果的生物生产力和碳循环。
Major shifts in ocean circulation are thought to be responsible for abrupt changes in temperature and atmospheric CO2during the last deglaciation, linked to variability in meridional heat transport and deep ocean carbon storage. There is also widespread evidence for shifts in biological production during these times of deglacial CO2rise, including enhanced diatom production in regions such as the tropical Atlantic. However, it remains unclear as to whether this diatom production was driven by enhanced wind-driven upwelling or density-driven vertical mixing, or by elevated thermocline concentrations of silicic acid supplied to the surface at a constant rate. Here, we demonstrate that silicic acid supply at depth in the NE Atlantic was enhanced during the abrupt climate events of the deglaciation. We use marine sediment archives to show that an increase in diatom production during abrupt climate shifts could only occur in regions of the NE Atlantic where the deep supply of silicic acid could reach the surface. The associated changes are indicative of enhanced regional wind-driven upwelling and/or weakened stratification due to circulation changes during phases of weakened Atlantic meridional overturning. Globally near-synchronous pulses of diatom production and enhanced thermocline concentrations of silicic acid suggest that widespread deglacial surface-driven breakdown of stratification, linked to changes in atmospheric circulation, had major consequences for biological productivity and carbon cycling.