Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

An Improved Cleaning Protocol for Foraminiferal Calcite: HyPerCal – A New Practice for Micropaleontological and Paleoclimatic Proxies

Version 1 : Received: 11 November 2020 / Approved: 12 November 2020 / Online: 12 November 2020 (18:19:29 CET)

How to cite: Zarkogiannis, S.D.; Kontakiotis, G.; Gkaniatsa, G.; Kuppili, V.S.C.; Marathe, S.; Wanelik, K.; Lianou, V.; Besiou, E.; Makri, P.; Antonarakou, A.A. An Improved Cleaning Protocol for Foraminiferal Calcite: HyPerCal – A New Practice for Micropaleontological and Paleoclimatic Proxies. Preprints 2020, 2020110361 (doi: 10.20944/preprints202011.0361.v1). Zarkogiannis, S.D.; Kontakiotis, G.; Gkaniatsa, G.; Kuppili, V.S.C.; Marathe, S.; Wanelik, K.; Lianou, V.; Besiou, E.; Makri, P.; Antonarakou, A.A. An Improved Cleaning Protocol for Foraminiferal Calcite: HyPerCal – A New Practice for Micropaleontological and Paleoclimatic Proxies. Preprints 2020, 2020110361 (doi: 10.20944/preprints202011.0361.v1).

Abstract

Paleoclimatic and paleoceanographic studies routinely rely on the usage of foraminiferal calcite through faunal, morphometric and physico-chemical proxies. The application of such proxies presupposes the extraction and cleaning of these biomineralized components from ocean sediments in the most efficient way, a process which is often labor intensive and time consuming. In this respect, in this study we performed a systematic experiment for planktonic foraminiferal specimen cleaning using different chemical treatments and evaluated the resulting data of a Late Quaternary gravity core sample from the Aegean Sea. All cleaning procedures adopted here were made on the basis of their minimum potential bias upon foraminiferal proxies, such as the faunal assemblages, degree of fragmentation, stable isotope composition (δ18O and δ13C) and/or Mg/Ca ratios that are frequently used as proxies for surface-ocean climate parameters (e.g., sea surface temperature, sea surface salinity). Six different protocols were tested, involving washing, sieving, and chemical treatment of the samples with hydrogen peroxide and/or sodium hexametaphosphate (Calgon ®). Single species foraminifera shell weighing was combined with high-resolution Scanning Electron Microscopy (SEM) and synchrotron X-ray Microtomography (SμCT) of the material processed by each of the cleaning protocols, in order to assess the decontamination degree of specimen’s ultrastructure and interior. It appeared that a good compromise between time and cleaning efficiency is the simultaneous treatment of samples with a mixed hydrogen peroxide and Calgon solution, while the most effective way for an almost complete decontaminate of the calcareous components from undesirable sedimentary material is a two-step treatment - initially with hydrogen peroxide and subsequently with Calgon solutions.

Subject Areas

Cleaning protocol; shell weight; climate reconstruction; synchrotron X-ray microtomography (SμCT); foraminiferal-based proxies

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