The effect of species on lacustrine δ18Odiatom and its implications for palaeoenvironmental reconstructions

Hannah L. Bailey, Andrew C.G. Henderson, Hilary J. Sloane, Andrea Snelling, Melanie J. Leng, Darrell S. Kaufman

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

The oxygen isotope composition of diatom silica (δ18Odiatom) is increasingly being used to reconstruct climate from marine and lacustrine sedimentary archives. Although diatoms are assumed to precipitate their frustule in isotopic equilibrium with their surrounding water, it is unclear whether internal processes of a given species affect the fractionation of oxygen between the water and the diatom. We present δ18Odiatom data from two diatom size fractions (3-38 and >38μm) characterized by different species in a sediment core from Heart Lake, Alaska. Differences in δ18Odiatom between the two size fractions varies from 0 to 1.2‰, with a mean offset of 0.01‰ (n=20). Fourier transform infrared spectroscopy confirms our samples consist of pure biogenic silica (SiO2) and δ18Odiatom trends are not driven by contamination. The maximum offset is outside the range of error, but the mean is within analytical error of the technique (±1.06‰), demonstrating no discernible species-dependent fractionation in δ18Odiatom. We conclude that lacustrine δ18Odiatom measurements offer a reliable and valuable method for reconstructing δ18Owater. Considering the presence of small offsets in our two records, we advise interpreting shifts in δ18Odiatom only where the magnitude of change is greater than the combined analytical error.

Original languageEnglish (US)
Pages (from-to)393-400
Number of pages8
JournalJournal of Quaternary Science
Volume29
Issue number4
DOIs
StatePublished - May 2014

    Fingerprint

Keywords

  • Diatom
  • Fractionation
  • Lake
  • Oxygen isotopes
  • Palaeoclimate

ASJC Scopus subject areas

  • Arts and Humanities (miscellaneous)
  • Earth and Planetary Sciences (miscellaneous)
  • Palaeontology

Cite this