The Connection Between Deep Eastern Equatorial Pacific Ocean Oxygenation and Atmospheric CO2 Over the Past 180 KYR

• Main Author: Hostak, Ryan Michael
• Other Authors: Marcantonio, Franco, Belanger, Christina, Roark, Brendan, Zhang, Yige
• Format: Thesis
• Language: English
• Published: 2019
• Subjects: Eastern Equatorial Pacific; Authigenic Uranium; Deep Ocean Respired Carbon Storage; Southern Ocean; Pacific
• Online Access: https://hdl.handle.net/1969.1/185090

Ventilation of carbon stored in the deep ocean is thought to play an important role in atmospheric COv2 increases associated with the Pleistocene deglaciations. The presence of this respired carbon has been recorded by an array of palaeoceanographic proxies in broad swaths of the global ocean, including the Eastern Equatorial Pacific (EEP). Today, the Eastern Equatorial Pacific is a significant source of COv2 to the atmosphere and accounts for a significant proportion of global export productivity. Here we present a new, 180,000-year sediment core from the EEP and reconstruct ^230Th derived fluxes of ^232Th and barium, along with redox-sensitive uranium concentrations to examine past variations in Fe-bearing dust delivery, export productivity, and bottom-water oxygenation, respectively. We compare these to similar records from the equator in order to infer changes in local atmospheric circulation and bottom-water oxygenation over the past 95,000 years. We then discuss these EEP uranium records in the context of similar, global records, highlighting the importance of the deep EEP and Southern Ocean in deep-ocean respired carbon storage.