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Rebecca Pickering

Rebecca Pickering

Postdoctoral fellow

Rebecca Pickering

Effect of cleaning methods on the dissolution of diatom frustules

Author

  • Emily Saad
  • Rebecca Pickering
  • K Shoji
  • M.I. Hossain
  • T.G. Glover
  • Jeffrey W. Krause
  • Y Tang

Summary, in English

Experimental studies characterizing the reactivity of siliceous materials, such as biogenic silica from the field or laboratory cultures, typically require organic matter removal prior to experimental analysis. Consequently, it is highly desired to develop and optimize a cleaning protocol that imposes minimal alterations to the reactivity of the siliceous substrate and can be robustly employed among laboratories and investigators. This study offers a quantitative comparison of several methods for removing organic matter associated with biogenic silica to assess their efficacy for use in reactivity studies. Five protocols for organic matter removal were assessed, including combinations of chemical treatments and/or baking, along with low temperature ashing with an oxygen plasma. These methods were tested and evaluated using Thalassiosira pseudonana frustules for mass recovery, organic carbon removal, elemental composition, morphology, structural order, relative abundance of silanol (≡Si-OH) groups, and dissolution rate. An additional experiment was conducted over a longer time scale using Thalassiosira weissflogii and a more realistic seawater matrix. Low temperature plasma ashing was found to be the most suitable for organic matter removal in studies seeking to constrain the short-term dissolution of biogenic silica; this method efficiently removed organic carbon while being the least impactful on frustule dissolution compared to the other cleaning methods evaluated. However, if the line of inquiry for an experiment does not require understanding of short-term dissolution rates, commonly used chemical (e.g. mineral acid, peroxide) and high temperature treatments did not appear to affect the long-term trajectory in biogenic silica dissolution.

Publishing year

2020

Language

English

Publication/Series

Marine Chemistry

Volume

224

Document type

Journal article

Publisher

Elsevier

Topic

  • Geochemistry
  • Environmental Sciences

Keywords

  • Diatoms
  • Biogenic silica
  • Thalassiosira
  • Dissolution
  • Sediment cleaning

Status

Published

ISBN/ISSN/Other

  • ISSN: 1872-7581