Microscale characterization of sulfur speciation in lake sediments

Teng Zeng, William A. Arnold, Brandy M. Toner

Research output: Contribution to journalArticlepeer-review

62 Scopus citations


Prairie pothole lakes (PPLs) are naturally sulfur-enriched wetlands in the glaciated prairie region of North America. High sulfate levels and dynamic hydrogeochemistry in combination render PPLs a unique environment to explore the speciation of sedimentary sulfur (S). The goals of this research were to define and quantify the solid-phase S pools in PPL sediments and track seasonal dynamics of S speciation. A quantitative X-ray microprobe method was developed based on S 1s X-ray absorption near-edge structure (XANES) spectroscopy and multienergy X-ray fluorescence mapping. Three S pools-pyritic S, reduced organic S (organic mono- and disulfide), and oxidized S (inorganic sulfate, ester sulfate, and sulfonate)-were identified in PPL sediments. No significant seasonal variation was evident for total S, but S speciation showed a seasonal response. During the spring-summer transition, the reduced organic S decreased from 55 to 15 mol %, with a concomitant rise in the oxidized S. During the summer-fall transition, the trend reversed and the reduced organic S grew to 75 mol % at the expense of the oxidized S. The pyritic S, on the other hand, remained relatively constant (∼22 mol %) over time. The seasonal changes in S speciation have strong potential to force the cycling of elements such as mercury in prairie wetlands.

Original languageEnglish (US)
Pages (from-to)1287-1296
Number of pages10
JournalEnvironmental Science and Technology
Issue number3
StatePublished - Feb 5 2013
Externally publishedYes

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry


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