Productivity in the Southern Ocean Antarctic Zone during the Northern Hemisphere Glaciation(NHG)and its link to atmospheric pCO2

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外文摘要：A decrease in atmospheric CO2 partial pressure(pCO2)is considered an important prerequisite for the onset and intensification of Northern Hemisphere Glaciation(NHG).However,how the ocean sequestered missing CO2 during the NHG is still uncertain.Changes in surface productivity and deep ventilation in the Southern Ocean(SO)have been proposed to explain the variations in atmospheric pCO2 over the last eight glacial cycles,but it is unclear whether these mechanisms contributed to the decrease in atmospheric pCO2 during the NHG.Using titanium-normalized contents and mass accumu-lation rates of biogenic opal and total organic carbon from the International Ocean Discovery Program(IODP)Expedition 374 Site U1524A,we reconstruct the productivity in the Ross Sea,Antarctica,from 3.3 Ma to 2.4 Ma.The productivity records exhibit a long-term decreasing trend and several distinct phased evolutionary features.Specifically,the local productivity fluctuated dramatically during 3.3-3.0 Ma,decreased gradually during 3.0-2.6 Ma,and remained relatively constant during 2.6-2.4 Ma.By comparing productivity with its potential influences,we infer that the phased and long-term evolutions of productivity were mainly controlled by changes in deep ocean ventilation.Sea ice expansion might have decreased productivity during 3.3-3.0 Ma by light attenuation.Changes in eolian dust input have little effect on productivity.Further analysis revealed no coupling linkage between productivity and atmospheric pCO2,indicating that the productivity in the SO Antarctic Zone(AZ)was not the main factor controlling the atmospheric CO2 decrease during the NHG.To improve our understanding of the role of SO processes in the NHG,further studies should focus on the potential influences of deep ocean ventilation on atmospheric pCO2 in the AZ,and similar studies should also be extended to the sea area in the Subantarctic Zone.

外文关键词：

Ross SeaBiogenic opalTotal organic carbonDeep ocean ventilationSea iceOcean carbon cycle

作者：

Yiming WU、Jingteng GUO、Xiangyu ZHAO、Wenshen XIAO、Heng LIU、Zhifang XIONG、Tiegang LI

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作者单位：

Key Laboratory of Marine Geology and Metallogeny,First Institute of Oceanography,Ministry of Natural Resources,Qingdao 266061,China

Laboratory for Marine Geology,Laoshan Laboratory,Qingdao 266237,China

School of Oceanography,Shanghai Jiao Tong University,Shanghai 200030,China

Key Laboratory of Polar Ecosystem and Climate Change,Shanghai Jiao Tong University,Ministry of Education,Shanghai 200030,China

State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China

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基金：

National Natural Science Foundation of ChinaImpact and Response of Antarctic Seas to Climate Change ProgramTaishan Scholars Projects Funding

项目编号：

42076232 &42006075IRASCC2020-2022-01-03-02TS20190963 & TSQN202211265

出版年：

2024

DOI：

10.1007/s11430-024-1346-2

中国科学:地球科学(英文版)

中国科学院

中国科学:地球科学(英文版)

影响因子：1.002

ISSN：1674-7313

年,卷(期)：2024.67(7)