Foraminifera-bound nitrogen isotope data from eastern equatorial Pacific cores ME-24 and ME-27 back to the last ice age

DOI

Previous paleoceanographic applications of the N isotopes in the eastern equatorial Pacific have used the N isotopic composition of the bulk sediment, which can be biased by diagenetic alteration or foreign N input. To avoid these biases, we measured foraminifera shell-bound d15N (FB-d15N) on the two species Neogloboquadrina dutertrei and Neogloboquadrina incompta in two sediment cores extending back to the last ice age. The datafile contains FB-d15N data measured on the two sediment cores ME0005-24JC (0°1.3' N, 86°27.8' W, 2941m) and ME0005-27JC (1°51.2' S, 82°47.2'W, 2203m) from the eastern equatorial Pacific, as well as updated age models for the two sediment cores. Moreover, it contains estimated changes in Pacific oxygen concentration from the LGM to the Holocene.The age models for both sediment cores have been updated by Dubois et al. (2014) and are based on (1) radiocarbon ages measured on the planktonic foraminifera N. dutertrei by accelerator mass spectrometry, (2) correlation of benthic foraminifera oxygen isotopes to the LR04 stack and (3) the identification of the Los Chocoyos Ash Layer in the sediment cores. In core ME0005-27JC, three additional 14C dates on N. dutertrei from Mekik (2014) were included. All radiocarbon ages were calibrated with Calib 7.1. and the marine calibration curve MARINE13, assuming a reservoir age of 467 years as given in Dubois et al. (2014). Ages were linearly interpolated between the stratigraphic tie points.Foraminifera-bound d15N (FB-d15N) was measured with the “persulfate-denitrifier” technique (Ren et al., 2009; Straub et al., 2013). In short, ~3-5 mg of foraminifera (N. dutertrei and N. incompta from the 300-600µm size fraction) were picked, cut open with a scalpel and underwent a chemical cleaning. The organic N bound within the calcite was then released by dissolution with HCl and converted to nitrate in a basic potassium persulfate solution. The nitrate concentration of the solution was determined by chemiluminescence, and an aliquot of the nitrate solution equivalent to 5nmol of N was converted to nitrous oxide (N2O) by denitrifying bacteria. The N isotopic composition of the N2O was measured with a custom continuous-flow system for N2O extraction and purification on-line to a Thermo MAT253 stable isotope mass spectrometer and referenced to air N2 using the international nitrate standards IAEA-N3 and USGS-34. The FB-d15N data were then corrected for the contribution of the oxidation procedural blank with an in-house aminocaproic acid standard of known isotopic composition. Changes in Pacific oxygen concentration from the LGM to the Holocene were calculated based on solubility changes as well as CYCLOPS box model results of Hain et al., (2010). Changes in oxygen saturation result from changes in temperature and salinity; changes in oxygen utilization result from a glacial shoaling of the Atlantic Meridional Overturning Circulation, enhanced nutrient consumption due to Subantarctic iron fertilization, reduced Antarctic surface-to-deep exchange and more complete Antarctic nutrient consumption. Oxygen utilization is calculated using O2:Pregenerated of -170:1 (Anderson and Sarmiento, 1994).

Identifier
DOI https://doi.org/10.1594/PANGAEA.925339
Related Identifier IsSupplementTo https://doi.org/10.1029/2020PA004063
Related Identifier IsDocumentedBy https://doi.org/10.1029/93GB03318
Related Identifier IsDocumentedBy https://doi.org/10.1016/j.epsl.2014.04.008
Related Identifier IsDocumentedBy https://doi.org/10.1029/2010GB003790
Related Identifier IsDocumentedBy https://doi.org/10.1002/2013PA002532
Related Identifier IsDocumentedBy https://doi.org/10.1126/science.1165787
Related Identifier IsDocumentedBy https://doi.org/10.1038/nature12397
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.925339
Provenance
Creator Studer, Anja S ORCID logo; Mekik, Figen; Ren, Haojia Abby ORCID logo; Hain, Mathis P ORCID logo; Oleynik, Sergey; Martínez-García, Alfredo; Haug, Gerald H; Sigman, Daniel M ORCID logo
Publisher PANGAEA
Publication Year 2020
Rights Creative Commons Attribution 4.0 International; https://creativecommons.org/licenses/by/4.0/
OpenAccess true
Representation
Resource Type Bundled Publication of Datasets; Collection
Format application/zip
Size 4 datasets
Discipline Earth System Research
Spatial Coverage (-86.463W, -1.853S, -82.787E, 0.022N)