A comparative study of the northwest Africa and eastern equatorial Pacific upwelling zones as sources of CO2 during glacial periods based on boron isotope paleo‐pH estimation
A comparative study of the northwest Africa and eastern equatorial Pacific upwelling zones as sources of CO2 during glacial periods based on boron isotope paleo‐pH estimation
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基于硼同位素古 pH 估算的西北非洲和赤道东太平洋上升流区作为冰期 CO2 来源的比较研究
DOI：
10.1029/1999pa900036
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
J. Bijma
中科院分区：
文献类型：
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作者：
A. Sanyal;J. Bijma
基于有孔虫硼同位素组成的古pH重建已被用来估计西北非洲上升流区表层海洋pCO 2的冰川间冰期变化。与赤道东太平洋上升流区的类似研究相比较，可以得出结论，这两个主要的上升流区在冰期的行为与今天相比有很大的不同。虽然非洲西北部海面的pH值在冰期比全新世高0.2±0.07个单位，但赤道太平洋东部海面的pH值没有明显的冰期-间冰期变化。基于估计的pH值变化的碳酸盐化学重建表明，与全新世相比，冰期期间非洲西北部的海洋-大气pCO 2梯度至少低70±40 µatm。相比之下，赤道东太平洋的海洋-大气pCO 2梯度在冰期比全新世至少高出80±40 µatm。因此，赤道东太平洋上升流系统是一个显着更大的来源，CO2的大气，而一个关闭西北非洲是一个显着较小的来源，CO2在末次冰期。pCO 2重建进一步表明，尽管较高的冰川生产力相比，在全新世，这两个地区都没有成为一个汇的CO2。
Paleo-pH reconstructions based on boron isotopic composition of foraminifera have been used to estimate glacial-interglacial changes in surface ocean pCO2 of the northwest African upwelling zone. On comparison with a similar study for the eastern equatorial Pacific upwelling zone, it can be concluded that the two major upwelling zones acted quite differently during the glacial periods as compared to today. While the pH of the surface ocean off northwest Africa was 0.2±0.07 units higher during the glacial period compared to that during Holocene, there was no significant glacial-interglacial change in the surface ocean pH in the eastern equatorial Pacific. Carbonate chemistry reconstructions based on the estimated pH changes suggest that the ocean-atmosphere pCO2 gradient off northwest Africa was lower by at least 70±40 µatm during glacial periods compared to during the Holocene. In contrast, the ocean-atmosphere pCO2 gradient in the eastern equatorial Pacific was higher by at least 80±40 µatm during glacial periods as compared to during the Holocene. Hence the eastern equatorial Pacific upwelling system was a significantly larger source of CO2 to the atmosphere, while the one off northwest Africa was a significantly smaller source of CO2 during the last glacial period. The pCO2 reconstructions further indicate that in spite of higher glacial productivity compared to during the Holocene, neither of the two areas became a sink of CO2.