Deglacial upwelling, productivity and CO2 outgassing in the North Pacific Ocean
Deglacial upwelling, productivity and CO2 outgassing in the North Pacific Ocean
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DOI：
10.1038/s41561-018-0108-6
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发表时间：
2018-04
影响因子：
18.3
通讯作者：
W. Gray;J. Rae;Robert C.J. Wills;A. Shevenell;B. Taylor;A. Burke;G. Foster;C. Lear
中科院分区：
文献类型：
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作者：
W. Gray;J. Rae;Robert C.J. Wills;A. Shevenell;B. Taylor;A. Burke;G. Foster;C. Lear
海洋环流和生物生产力之间的相互作用影响大气CO2水平和海洋氧气浓度。在最后一次冰消期的变暖期间，北太平洋经历了生产力的高峰和广泛的缺氧，环流、铁供应和光照限制的变化都被认为是潜在的驱动因素。在这里，我们使用硼同位素组成的南极有孔虫从沉积物芯在西北太平洋重建pH值和溶解CO2浓度从24,000年至8,000年前。我们发现，在14，700年至12，900年前的Bølling-Allerød暖期期间，生产力峰值与近地表pH值的下降和pCO 2的增加有关，因此必须由营养和CO2丰富的沃茨供应的增加驱动。在一个气候模式集合（PMIP 3）中，北美上空大冰盖的存在导致了副极地北太平洋内风驱动的上涌的高速率。我们认为，这一过程，结合崩溃的北太平洋中层水形成的开始时，Bølling-Allerød，导致高速率的上升流的水富含营养物质和CO2，并支持生产力的峰值。这种有机物的呼吸作用，沿着通风不良，可能是造成局部缺氧的原因。我们认为，从北太平洋的CO2释气有助于维持高浓度的大气CO2在Bølling-Allerød，并有助于冰消期CO2上升。
The interplay between ocean circulation and biological productivity affects atmospheric CO2levels and marine oxygen concentrations. During the warming of the last deglaciation, the North Pacific experienced a peak in productivity and widespread hypoxia, with changes in circulation, iron supply and light limitation all proposed as potential drivers. Here we use the boron-isotope composition of planktic foraminifera from a sediment core in the western North Pacific to reconstruct pH and dissolved CO2concentrations from 24,000 to 8,000 years ago. We find that the productivity peak during the Bølling–Allerød warm interval, 14,700 to 12,900 years ago, was associated with a decrease in near-surface pH and an increase inpCO2, and must therefore have been driven by increased supply of nutrient- and CO2-rich waters. In a climate model ensemble (PMIP3), the presence of large ice sheets over North America results in high rates of wind-driven upwelling within the subpolar North Pacific. We suggest that this process, combined with collapse of North Pacific Intermediate Water formation at the onset of the Bølling–Allerød, led to high rates of upwelling of water rich in nutrients and CO2, and supported the peak in productivity. The respiration of this organic matter, along with poor ventilation, probably caused the regional hypoxia. We suggest that CO2outgassing from the North Pacific helped to maintain high atmospheric CO2concentrations during the Bølling–Allerød and contributed to the deglacial CO2rise.