Exploring the application of TEX86 and the sources of organic matter in the Antarctic coastal region

Ana Lúcia L. Dauner*, B David A Naafs, Richard Pancost, César C Martins*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

28 Downloads (Pure)

Abstract

Isoprenoidal glycerol dialkyl glycerol tetraethers (isoGDGTs) are archaeal biomarkers. In many settings, the degree of cyclization of isoGDGTs is correlated with temperature, forming the basis of the TEX86 paleothermometer that is widely used to reconstruct sea surface temperature (SST) across a range of time scales. However, the application of TEX86 to the polar regions is relatively limited and there is currently no consensus on which calibration is best suited for polar environments. In addition, application of TEX86 to the polar regions is complicated by uncertainty regarding the source of organic matter input in coastal polar environments. We tested five different calibrations for TEX86 in marine sediments from the Antarctic coastal region of Admiralty Bay near King George Island, using four short cores that span the second half of the 20th century. We also explored the possible sources of organic matter in these cores using sterol biomarkers. Best results for TEX86 were obtained using a quadratic calibration. The TEX86 signal presented a strong seasonal signal and best matched reanalysis temperatures of the austral spring season (Oct/Nov/Dec). The most abundant compounds observed in the sediments were the sterols cholest-5-en-3β-ol and 24-ethylcholest-5-en-3β-ol, the fatty alcohols C16 and phytol, and isoGDGT-0, indicating a dominant marine origin of the organic matter.
Differences in their vertical distributions suggests that some compounds (such as cholest 5-en-3β-ol and phytol) may have had different sources over the evaluated period. Together our results indicate that TEX86 can be used to reconstruct SSTs in the Antarctic coastal region.
Original languageEnglish
Article number104288
JournalOrganic Geochemistry
Volume160
Early online date24 Jul 2021
DOIs
Publication statusPublished - 1 Oct 2021

Bibliographical note

Funding Information:
The work was supported by the Antarctic Brazilian Program (PROANTAR), Secretaria da Comissão Interministerial para os Recursos do Mar (SECIRM), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, 550014/2007-1 and 442692/2018-8 ) and Coordenação de Aperfeiçoamento de Pessoal de Ensino Superior (CAPES, 88887.314458/2019-00 ). The authors wish to thank the ‘Comandante Ferraz’ Brazilian Antarctic Station staff for support during the sampling activities and G. N. Inglis, J. M. Williams and M. Slowakiewicz for their assistance with chemical analysis. B.D.A. Naafs acknowledges funding through a Royal Society Tata University Research Fellowship. NERC (Reference: CC010) and NEIF ( www.isotopesuk.org ) are thanked for funding and maintenance of the GC–MS and LC–MS instruments at the University of Bristol used for this work. C.C. Martins and A.L.L. Dauner thank CAPES for personal grant support (BEX 5366/12-7 and 88887.362846/2019-00, respectively). Finally, this work is part of CARBMET project (The multiple faces of organic CARBon and METals in the sub-Antarctic ecosystem) sponsored by CNPq, CAPES and Brazilian Ministry of Science, Technology, Innovation and Communication. We would also like to acknowledge the contribution of J.K. Volkman, S. Schouten and two anonymous reviewers who provided helpful comments on the manuscript..

Funding Information:
The work was supported by the Antarctic Brazilian Program (PROANTAR), Secretaria da Comiss?o Interministerial para os Recursos do Mar (SECIRM), Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq, 550014/2007-1 and 442692/2018-8) and Coordena??o de Aperfei?oamento de Pessoal de Ensino Superior (CAPES, 88887.314458/2019-00). The authors wish to thank the ?Comandante Ferraz? Brazilian Antarctic Station staff for support during the sampling activities and G. N. Inglis, J. M. Williams and M. Slowakiewicz for their assistance with chemical analysis. B.D.A. Naafs acknowledges funding through a Royal Society Tata University Research Fellowship. NERC (Reference: CC010) and NEIF (www.isotopesuk.org) are thanked for funding and maintenance of the GC?MS and LC?MS instruments at the University of Bristol used for this work. C.C. Martins and A.L.L. Dauner thank CAPES for personal grant support (BEX 5366/12-7 and 88887.362846/2019-00, respectively). Finally, this work is part of CARBMET project (The multiple faces of organic CARBon and METals in the sub-Antarctic ecosystem) sponsored by CNPq, CAPES and Brazilian Ministry of Science, Technology, Innovation and Communication. We would also like to acknowledge the contribution of J.K. Volkman, S. Schouten and two anonymous reviewers who provided helpful comments on the manuscript.

Publisher Copyright:
© 2021 Elsevier Ltd

Keywords

  • GDGT
  • sterol
  • Sea surface temperature
  • Organic Matter
  • Admiralty Bay

Fingerprint

Dive into the research topics of 'Exploring the application of TEX86 and the sources of organic matter in the Antarctic coastal region'. Together they form a unique fingerprint.

Cite this