Changes in deep Pacific circulation and carbon storage during the Pliocene-Pleistocene transition
Changes in deep Pacific circulation and carbon storage during the Pliocene-Pleistocene transition
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DOI：
10.1016/j.epsl.2023.118020
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发表时间：
2023-03
影响因子：
5.3
通讯作者：
Z. Jian;H. Dang;Jimin Yu;Qiong Wu;X. Gong;C. Stepanek;C. Colin;Lili Hu;G. Lohmann;Xiaoli Zhou;S. Wan
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文献类型：
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作者：
Z. Jian;H. Dang;Jimin Yu;Qiong Wu;X. Gong;C. Stepanek;C. Colin;Lili Hu;G. Lohmann;Xiaoli Zhou;S. Wan
从上新世晚期到更新世早期（约310 - 250万年前，Ma），全球气候逐渐变冷，并以北半球冰川作用（NHG）的强化为间歇。大气中二氧化碳的减少被认为是NHG的先决条件，但相关的碳循环过程仍然难以捉摸。本文结合有孔虫钕同位素和硼钙比的记录，以及地球系统模型的模拟，研究了NHG期间太平洋深海水质量组成和碳酸盐离子浓度的变化。我们的代理记录显示，在NHG期间，南源水域显著扩张，吸入的碳储量增加，进入太平洋深处。正如我们的模式实验和亚南极地区的证据所表明的那样，这些变化可能是由于南极海冰增长导致南大洋深水形成和生物泵效率增强所导致的。这些结果为量化太平洋深水溶解无机碳含量在NHG期间调节大气co2的作用提供了关键线索。
The global climate has been gradually cooling over the Cenozoic and is punctuated by the intensification of Northern Hemisphere Glaciation (NHG) from the latest Pliocene to earliest Pleistocene (∼3.1–2.5 millions of years ago, Ma). A decline of atmospheric CO2is supposed as a prerequisite for the NHG, but the associated carbon-cycle processes remain elusive. Here we combine foraminiferal records of neodymium isotope and boron-calcium ratio, and simulations of an Earth system model, to investigate changes in the water-mass composition and carbonate-ion concentration of the deep Pacific Ocean during the NHG. Our proxy records have revealed a significant expansion of southern-sourced waters with increased respired carbon storage into the deep Pacific during the NHG. These changes may be explained by strengthened deep-water formation and biological-pump efficiency in the Southern Ocean due to Antarctic sea-ice growth, as suggested by our model experiments and evidence from the Sub-Antarctic region. These results provide key clues for quantifying the role of the dissolved inorganic carbon content of deep Pacific waters in modulating atmospheric CO2during the NHG.