TY - JOUR
T1 - Oxygen depletion recorded in upper waters of the glacial Southern Ocean
AU - Lu, Zunli
AU - Hoogakker, Babette A.A.
AU - Hillenbrand, Claus Dieter
AU - Zhou, Xiaoli
AU - Thomas, Ellen
AU - Gutchess, Kristina M.
AU - Lu, Wanyi
AU - Jones, Luke
AU - Rickaby, Rosalind E.M.
N1 - Funding Information:
Z.L. thanks NSF OCE 1232620. B.A.A.H. is supported by Natural Environment Research Council (NERC) grant NE/I020563/1. C.-D.H. is supported by NERC. Z.L. and R.E.M.R. were supported by NERC NE/E018432/1 during the initial development of the I/Ca proxy. We thank the captains, officers, crews and shipboard scientists of expeditions JR179 and ANT-XI/3 for recovering cores TC493 and PS2547
PY - 2016/3/31
Y1 - 2016/3/31
N2 - Oxygen depletion in the upper ocean is commonly associated with poor ventilation and storage of respired carbon, potentially linked to atmospheric CO2 levels. Iodine to calcium ratios (I/Ca) in recent planktonic foraminifera suggest that values less than ∼2.5 μmol mol-1 indicate the presence of O2-depleted water. Here we apply this proxy to estimate past dissolved oxygen concentrations in the near surface waters of the currently well-oxygenated Southern Ocean, which played a critical role in carbon sequestration during glacial times. A down-core planktonic I/Ca record from south of the Antarctic Polar Front (APF) suggests that minimum O2 concentrations in the upper ocean fell below 70 μmol kg-1 during the last two glacial periods, indicating persistent glacial O2 depletion at the heart of the carbon engine of the Earth's climate system. These new estimates of past ocean oxygenation variability may assist in resolving mechanisms responsible for the much-debated ice-age atmospheric CO2 decline.
AB - Oxygen depletion in the upper ocean is commonly associated with poor ventilation and storage of respired carbon, potentially linked to atmospheric CO2 levels. Iodine to calcium ratios (I/Ca) in recent planktonic foraminifera suggest that values less than ∼2.5 μmol mol-1 indicate the presence of O2-depleted water. Here we apply this proxy to estimate past dissolved oxygen concentrations in the near surface waters of the currently well-oxygenated Southern Ocean, which played a critical role in carbon sequestration during glacial times. A down-core planktonic I/Ca record from south of the Antarctic Polar Front (APF) suggests that minimum O2 concentrations in the upper ocean fell below 70 μmol kg-1 during the last two glacial periods, indicating persistent glacial O2 depletion at the heart of the carbon engine of the Earth's climate system. These new estimates of past ocean oxygenation variability may assist in resolving mechanisms responsible for the much-debated ice-age atmospheric CO2 decline.
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U2 - 10.1038/ncomms11146
DO - 10.1038/ncomms11146
M3 - Article
AN - SCOPUS:84962866723
SN - 2041-1723
VL - 7
JO - Nature Communications
JF - Nature Communications
M1 - 11146
ER -