Iron and manganese reduction-oxidation

Martin Pentrák, Linda Pentráková, Joseph W. Stucki

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

The natural state of wetland soils is a rich environment for cycling oxidation and reduction (redox) reactions, which can be properly characterized and evaluated only if the methods of analysis do everything possible to preserve the redox balance during sampling and analysis. Iron and Mn are highly susceptible to redox cycling in such natural systems. The purpose of this chapter is to review known methods for handling redox-sensitive samples, for measuring the amount of the respective oxidation states of these two elements, and sample preparation methods for various types of characterizations. The primary oxidation states for Fe in minerals are II or III, whereas Mn in minerals may exist in oxidation states of II, III, or IV. Proper sample handling to minimize redox transformations depends on the use of a septum-sealed inert-atmosphere reaction centrifuge tube (IRT) in which the sample can be reacted and then separated from suspension without being opened to the atmosphere. The fluids can then be removed and replaced without opening the IRT by using a controlled-atmosphere liquid exchanger. An inert-atmosphere glove box, with a freeze-dryer inside, is also used. The Fe oxidation state is quantitatively determined using an HF-H2SO4 digestion, with 1,10-phenanthroline monohydrate as the colorimetric indicator. Semiquantitative results may be obtained by Mössbauer spectroscopy. Manganese oxidation states are more difficult to discern, and many methods have been used and are summarized in this chapter. Methods and sample holders are also described by which further analyses of the samples can be made.

Original languageEnglish (US)
Title of host publicationMethods in Biogeochemistry of Wetlands
PublisherWiley
Pages701-712
Number of pages12
ISBN (Electronic)9780891189619
ISBN (Print)9780891189602
DOIs
StatePublished - Jan 1 2015

Keywords

  • Iron
  • Manganese
  • Redox reaction
  • Sample handling
  • Sample preparation method
  • Sampling method
  • Wetland soils

ASJC Scopus subject areas

  • Engineering(all)
  • Agricultural and Biological Sciences(all)

Fingerprint

Dive into the research topics of 'Iron and manganese reduction-oxidation'. Together they form a unique fingerprint.

Cite this