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LU

Emma Hammarlund

Research team manager

LU

Development of Iron Speciation Reference Materials for Palaeoredox Analysis

Author

  • Lewis J. Alcott
  • Alexander J. Krause
  • Emma U. Hammarlund
  • Christian J. Bjerrum
  • Florian Scholz
  • Yijun Xiong
  • Andrew J. Hobson
  • Lesley Neve
  • Benjamin J.W. Mills
  • Christian März
  • Bernhard Schnetger
  • Andrey Bekker
  • Simon W. Poulton
Show all

Summary, in English

The development and application of geochemical techniques to identify redox conditions in modern and ancient aquatic environments has intensified over recent years. Iron (Fe) speciation has emerged as one of the most widely used procedures to distinguish different redox regimes in both the water column and sediments, and is the main technique used to identify oxic, ferruginous (anoxic, Fe(II) containing) and euxinic (anoxic, sulfidic) water column conditions. However, an international sediment reference material has never been developed. This has led to concern over the consistency of results published by the many laboratories that now utilise the technique. Here, we report an interlaboratory comparison of four Fe speciation reference materials for palaeoredox analysis, which span a range of compositions and reflect deposition under different redox conditions. We provide an update of extraction techniques used in Fe speciation and assess the effects of both test portion mass, and the use of different analytical procedures, on the quantification of different Fe fractions in sedimentary rocks. While atomic absorption spectroscopy and inductively coupled plasma-optical emission spectrometry produced comparable Fe measurements for all extraction stages, the use of ferrozine consistently underestimated Fe in the extraction step targeting mixed ferrous–ferric minerals such as magnetite. We therefore suggest that the use of ferrozine is discontinued for this Fe pool. Finally, we report the combined data of four independent Fe speciation laboratories to characterise the Fe speciation composition of the reference materials. These reference materials are available to the community to provide an essential validation of in-house Fe speciation measurements.

Department/s

  • Lithosphere and Biosphere Science
  • Division of Translational Cancer Research

Publishing year

2020-09

Language

English

Pages

581-591

Publication/Series

Geostandards and Geoanalytical Research

Volume

44

Issue

3

Document type

Journal article

Publisher

Wiley-Blackwell

Topic

  • Geology

Keywords

  • ancient sediments
  • iron speciation
  • reference materials
  • sequential extraction
  • total iron
  • water column redox

Status

Published

ISBN/ISSN/Other

  • ISSN: 1639-4488