Abstract
Ventilation of carbon stored in the deep ocean is thought to play an important role in atmospheric CO2 increases associated with Pleistocene deglaciations. The presence of this respired carbon has been recorded by an array of paleoceanographic proxies from various locations across the global ocean. Here we present a new sediment core from the Eastern Equatorial Pacific (EEP) Ocean spanning the last 180,000 years and reconstruct high-resolution 230Th-derived fluxes of 232Th and excess barium, along with redox-sensitive uranium concentrations to examine past variations in dust delivery, export productivity, and bottom-water oxygenation, respectively. Our bottom-water oxygenation record is compared to other similar high-resolution records from across the Pacific and in the Southern Ocean. We suggest that the deep Pacific is a site of respired carbon storage associated with periods of decreased global atmospheric CO2 concentration during the LGM, confirming the conclusions from a wealth of previous studies. However, our study is the first to show a similar relationship beyond the last glacial, extending to at least 70,000 years.
Highlights
The dominant signal in global climate over the last 800,000 years is the 100-kyr co-variation of air temperature and atmospheric CO2 concentrations observed in the EPICA Antarctica ice core[1]
We conclude that our eastern equatorial Pacific Ocean (EEP) high resolution aU records generally reflect changes in bottom water oxygenation that waxes and wanes with the extent and reach of a deep-Pacific respired carbon pool that mirrors variations in
There are times during which differences between the authigenic uranium records in the EEP may be explained by changes in local export production and/or changes in the depth interval of the respired carbon pool
Summary
The dominant signal in global climate over the last 800,000 years is the 100-kyr co-variation of air temperature and atmospheric CO2 concentrations observed in the EPICA Antarctica ice core[1]. One prevalent hypothesis is that there is an increased storage of respired carbon in the deep ocean during glacial maxima that is isolated from interaction with the atmosphere[3,4,5,6,7]. The sedimentation rate at site 8JC varies from 1.3 to 6.8 cm/kyr, giving a sub-millennial age resolution of ~300–900 yr during MIS 1–4 and a millennial age resolution of ~750–2000 yr during MIS 5 and 6 for our sampling resolution of 2 cm Through these records of 232Th flux, xsBa flux, and aU concentrations, we aim to better understand the relationship between changes in dust deposition, export production, and bottom water oxygenation in the glacial EEP. There are times during which differences between the authigenic uranium records in the EEP may be explained by changes in local export production and/or changes in the depth interval of the respired carbon pool
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
