Sulfur speciation in soil by S K -edge XANES spectroscopy: Comparison of spectral deconvolution and linear combination fitting

Jörg Prietzel, Anna Botzaki, Nora Tyufekchieva, Mareike Brettholle, Jürgen Thieme, Wantana Klysubun

Research output: Contribution to journalArticlepeer-review

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Abstract

Defined, quartz-diluted mixtures of sulfur (S) compounds with different oxidation state (OS) were analyzed by K-edge XANES spectroscopy using linear combination fitting (LCF) and spectrum deconvolution by fitting several Gaussian and arctangent functions (GCF). Additionally, for different soils the S speciation as calculated by both methods was compared with results of a wet-chemical S speciation. For mixtures of FeS, l-cysteine, and Na 2SO4, the S speciation was recovered with satisfactory accuracy and precision by both methods at the 2 and 0.2 mg S g-1 level. For GCF, white-line peaks must be normalized with respect to their OS-specific absorption cross-section. LCF must be conducted with dilute reference compounds to avoid self-absorption effects. For mixtures of FeS, FeS2, S°, and l-cysteine, both procedures showed poor accuracy. For the soils, similar percentages of reduced inorganic S, organic S, and sulfate were calculated by LCF, GCF, and wet chemical S speciation. GCF allows a fair estimation of S species groups with different OS (inorganic reduced S, organic reduced S, organic intermediate S, oxidized S) in soils without standards. If dilute standards of all S compounds assumed to be present in a sample are available, LCF is more objective and allows a more detailed S speciation.

Original languageEnglish
Pages (from-to)2878-2886
Number of pages9
JournalEnvironmental Science and Technology
Volume45
Issue number7
DOIs
StatePublished - 1 Apr 2011

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