Paleoproductivity and deep-sea oxygenation in Cosmonaut Sea since the last glacial maximum: impact on atmospheric CO2

The paleoproductivity in the Southern Ocean plays a crucial role in controlling the atmospheric CO 2 concentration. Here, we present the sediment record of gravity core ANT37-C5/6-07, which was retrieved from the Cosmonaut Sea (CS), Indian Ocean sector of the Southern Ocean. We found that the change...

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Bibliographic Details
Published in:Frontiers in Marine Science
Main Authors: Hu, Liangming, Zhang, Yi, Wang, Yizhuo, Ma, Pengyun, Wu, Wendong, Ge, Qian, Bian, Yeping, Han, Xibin
Format: Article in Journal/Newspaper
Language:unknown
Published: Frontiers Media SA 2023
Subjects:
Ocean Engineering
Water Science and Technology
Aquatic Science
Global and Planetary Change
Oceanography
Antarctic
Cape Ann
Indian
Southern Ocean
Antarc*
Cosmonaut sea
Online Access:http://dx.doi.org/10.3389/fmars.2023.1215048
https://www.frontiersin.org/articles/10.3389/fmars.2023.1215048/full
Description
Summary:The paleoproductivity in the Southern Ocean plays a crucial role in controlling the atmospheric CO 2 concentration. Here, we present the sediment record of gravity core ANT37-C5/6-07, which was retrieved from the Cosmonaut Sea (CS), Indian Ocean sector of the Southern Ocean. We found that the change in the oxygen concentration in the CS bottom water is strongly correlated with the atmospheric CO 2 fluctuations since the Last Glacial Maximum (LGM). Based on the change in the export production, we reconstructed the evolution history of the deep-water ventilation/upwelling in the study area. During the LGM, a large amount of respiratory carbon was stored in the deep Southern Ocean due to the effect of the low export productivity and restricted ventilation. The oxygen concentration was also low at this time. Despite the increase in paleoproductivity, the biological pump efficiency remained at a low level during the Last Deglaciation. Vast quantities of CO 2 were released into the atmosphere through enhanced upwelling. The recovery of ventilation during this period facilitated the supply of oxygen-rich surface water to the deep ocean. Moreover, signals were identified during the transitions between the Heinrich Stage 1 (HS1), Antarctic Cold Reverse (ACR), and Younger Drays (YD) periods. During the Holocene, the productivity increased overall, and the oxygen in the bottom water was consumed but still remained at a high level. This may have been caused by the enhanced ventilation and/or the prevalence of East Cosmonaut Polynya (ECP) near Cape Ann.

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