Rare Earth Elements concentrations measured in sediment leachates from samples collected during the IN2017-V01 voyage of the RV Investigator

Brief description

Sediment cores were collected from the East Antarctic margin, aboard the Australian Marine National Facility R/V Investigator from January 14th to March 5th 2017 (IN2017_V01; (Armand et al., 2018). This marine geoscience expedition, named the “Sabrina Sea Floor Survey”, focused notably on studying the interactions of the Totten Glacier with the Southern Ocean through multiple glacial cycles. The cores were collected using a multi-corer (MC), sliced every centimetre, wrapped up in plastic bags, and stored in the fridge.

Back at the home laboratory (IMAS, UTAS, Hobart, Australia), sediment samples were dried in an oven at 40°C. Three hundred mg of dry sediment was then homogenised and vortexed for 10-sec with 12 mL of a reductive solution of 0.005M hydroxylamine hydrochloride (HH) / 1.5% Acetic Acid (AA) / 0.001M Na-EDTA / 0.033M NaOH, at pH 4 (Huang et al., 2021). This reductive leaching solution was designed to target Fe-Mn oxides phases, with chelating ligand to avoid re-adsorption of leached REE onto the sediment. The leach mixture was then centrifuged, and 6 mL of the supernatant solution was collected into a Teflon vial. This solution was taken to dryness, oxidized with 1 mL HNO3 + 100 µL H2O2, and redissolved in 4 mL of 7.5M HNO3.

A 0.5 mL aliquot was separated from the 4 mL solution for rare earth elements (REE) analysis by Sector Field Inductively Coupled Mass Spectrometry (SF-ICP-MS, Thermo Fisher Scientific, Bremen, Germany) at the Central Science Laboratory (UTAS, Hobart, Australia). Element quantification was performed via external calibration using multi-element calibration solutions (MISA-5, QCD Analysts, Spring Lake, NJ, USA). Samples were introduced to the instrument using an Aridius® II desolvating nebulizer (CETAC Technologies, USA). The DSN was tuned daily, and oxide formation for a range of test analytes (Ba, Ce, U etc) was always less than 0.05%. Isotopes 137Ba, 139La, 140Ce, 141Pr, 146Nd, 150Nd, 147Sm, 153Eu, 158Gd, 159Tb, 163Dy, 165Ho, 166Eu, 169Tm, 172Yb and 175Lu were monitored in low resolution mode. Raw intensities were blank and dilution corrected.

References
- Armand, L. K., O’Brien, P. E., Armbrecht, L., Baker, H., Caburlotto, A., Connell, T., … Young, A. (2018). Interactions of the Totten Glacier with the Southern Ocean through multiple glacial cycles (IN2017-V01): Post-survey report. ANU Research Publications
- Huang, H., Gutjahr, M., Kuhn, G., Hathorne, E. C., and Eisenhauer, A. (2021). Efficient Extraction of Past Seawater Pb and Nd Isotope Signatures From Southern Ocean Sediments. Geochemistry, Geophysics, Geosystems, 22(3), 1–22.

Lineage

Progress Code: completed

Statement: At least 2 standards and a blank were included in every digestion batch, which typically involved 24 samples. Samples were analysed in batches of 10 and bracketed by blanks and a Quality Control (Standard, 1 ppb).

Notes

Purpose
These data were collected in order to determine the geochemistry of the sediment leachates, i.e., of the ‘authigenic’ fraction of the sediment.