Studer, Anja S; Mekik, Figen; Ren, Haojia Abby; Hain, Mathis P; Oleynik, Sergey; Martínez-García, Alfredo; Haug, Gerald H; Sigman, Daniel M (2020): Foraminifera-bound nitrogen isotope data from eastern equatorial Pacific cores ME-24 and ME-27 back to the last ice age [dataset bundled publication]. PANGAEA, https://doi.org/10.1594/PANGAEA.925339
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Abstract:
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).
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Studer, Anja S; Mekik, Figen; Ren, Haojia Abby; Hain, Mathis P; Oleynik, Sergey; Martínez-García, Alfredo; Haug, Gerald H; Sigman, Daniel M (2021): Ice age‐Holocene similarity of foraminifera‐bound nitrogen isotope ratios in the eastern equatorial Pacific. Paleoceanography and Paleoclimatology, e2020PA004063, https://doi.org/10.1029/2020PA004063
Further details:
Anderson, L A; Sarmiento, Jorge L (1994): Redfield ratios of remineralization determined by nutrient data analysis. Global Biogeochemical Cycles, 8(1), 65-80, https://doi.org/10.1029/93GB03318
Dubois, Nathalie; Kienast, Markus; Kienast, Stephanie S; Timmermann, Axel (2014): Millennial-scale Atlantic/East Pacific sea surface temperature linkages during the last 100,000 years. Earth and Planetary Science Letters, 396, 134-142, https://doi.org/10.1016/j.epsl.2014.04.008
Hain, Mathis P; Sigman, Daniel M; Haug, Gerald H (2010): Carbon dioxide effects of Antarctic stratification, North Atlantic Intermediate Water formation, and subantarctic nutrient drawdown during the last ice age: Diagnosis and synthesis in a geochemical box model. Global Biogeochemical Cycles, 24(4), https://doi.org/10.1029/2010GB003790
Mekik, Figen (2014): Radiocarbon dating of planktonic foraminifer shells: A cautionary tale. Paleoceanography, 29(1), 13-29, https://doi.org/10.1002/2013PA002532
Ren, Haojia Abby; Sigman, Daniel M; Meckler, Anna Nele; Plessen, Birgit; Robinson, Rebecca S; Rosenthal, Yair; Haug, Gerald H (2009): Foraminiferal Isotope Evidence of Reduced Nitrogen Fixation in the Ice Age Atlantic Ocean. Science, 323(5911), 244-248, https://doi.org/10.1126/science.1165787
Straub, Marietta; Sigman, Daniel M; Ren, Haojia Abby; Martínez-García, Alfredo; Meckler, Anna Nele; Hain, Mathis P; Haug, Gerald H (2013): Changes in North Atlantic nitrogen fixation controlled by ocean circulation. Nature, 501(7466), 200-203, https://doi.org/10.1038/nature12397
Coverage:
Median Latitude: -0.915825 * Median Longitude: -84.624985 * South-bound Latitude: -1.853350 * West-bound Longitude: -86.463300 * North-bound Latitude: 0.021700 * East-bound Longitude: -82.786670
License:
Creative Commons Attribution 4.0 International (CC-BY-4.0)
Size:
4 datasets
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Datasets listed in this bundled publication
- Studer, AS; Mekik, F; Ren, HA et al. (2020): Age model tie points for sediment cores ME-24 and ME-27. https://doi.org/10.1594/PANGAEA.925309
- Studer, AS; Mekik, F; Ren, HA et al. (2020): Foraminifera-bound nitrogen isotopes of sediment core ME0005-24JC. https://doi.org/10.1594/PANGAEA.925301
- Studer, AS; Mekik, F; Ren, HA et al. (2020): Foraminifera-bound nitrogen isotopes of sediment core ME0005-27JC. https://doi.org/10.1594/PANGAEA.925302
- Studer, AS; Mekik, F; Ren, HA et al. (2020): Estimated changes in Pacific oxygen concentration (LGM-Holocene). https://doi.org/10.1594/PANGAEA.925311