EGU23-5657, updated on 22 Feb 2023
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Planktonic Foraminiferal δ13Corg as a novel proxy for Carbon Cycling 

Tommaso Paoloni1, Babette Hoogakker1, Helen Grant2, Patrick Keenan2, and Helliot Hamilton3
Tommaso Paoloni et al.
  • 1Heriot Watt University, EGIS - ILES, Lyell Centre, Edinburgh, United Kingdom of Great Britain – England, Scotland, Wales (
  • 2UK Centre For Ecology & Hydrology, Lancaster
  • 3British Geological Survey, Keyworth

It has been hypothesized that lower atmospheric CO2 concentrations and lower temperatures during glacial times caused the enrichment of carbon isotopes of particulate organic material (δ13Corg-POM) produced in the surface ocean. Some downcore measurements of organic carbon isotopes of bulk sediments show such a trend, however, others do not. The lack of a coherent picture could be due to issues relating to the bulk sediments, including diagenetic alteration, the nature of the organic material, input of allochthonous material, and sediment redistribution.

Recent work by Hoogakker et al. (2022) shows that planktonic foraminifera-bound organic carbon δ13C values (δ13CFBOM) are remarkably similar to those of δ13Corg-POM. Here we present the first down-core organic carbon isotope record of planktonic foraminifera-bound organic carbon (δ13CFBOM) from the Southern Ocean (ODP Site 1088), to test for a glacial enrichment in δ13Corg-POM. The samples (Globigerina bulloides, Globorotalia truncatulinoides, and G. inflata) cover the last 20,000 years.

Our δ13CFBOM results show a slight positive trend toward the Last Glacial Maximum (LGM), in accordance with the hypothesized δ13Corg-POM trend, but not to the extent as shown in some bulk sediments from more tropical latitudes. We discuss our results in the context of predicted past δ13Corg-POM using ice core atmospheric pCO2 concentrations, G. bulloides calcification DIC (from inorganic carbon isotopes), and temperature (using Mg/Ca). 

How to cite: Paoloni, T., Hoogakker, B., Grant, H., Keenan, P., and Hamilton, H.: Planktonic Foraminiferal δ13Corg as a novel proxy for Carbon Cycling , EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-5657,, 2023.