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| Titel |
Microbial reduction of iron and porewater biogeochemistry in acidic peatlands |
| VerfasserIn |
K. Küsel, M. Blöthe, D. Schulz, M. Reiche, H. L. Drake |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 5, no. 6 ; Nr. 5, no. 6 (2008-11-12), S.1537-1549 |
| Datensatznummer |
250002921
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| Publikation (Nr.) |
 copernicus.org/bg-5-1537-2008.pdf |
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| Zusammenfassung |
| Temporal drying of upper soil layers of acidic methanogenic peatlands might
divert the flow of reductants from CH4 formation to other
electron-accepting processes due to a renewal of alternative electron
acceptors. In this study, we evaluated the in situ relevance of Fe(III)-reducing
microbial activities in peatlands of a forested catchment that differed in
their hydrology. Intermittent seeps reduced sequentially nitrate, Fe(III),
and sulfate during periods of water saturation. Due to the acidic soil
conditions, released Fe(II) was transported with the groundwater flow and
accumulated as Fe(III) in upper soil layers of a lowland fen apparently due
to oxidation. Microbial Fe(III) reduction in the upper soil layer accounted
for 26.7 and 71.6% of the anaerobic organic carbon mineralization in the
intermittent seep and the lowland fen, respectively. In an upland fen not
receiving exogenous Fe, Fe(III) reduction contributed only to 6.7%.
Fe(II) and acetate accumulated in deeper porewater of the lowland fen with
maximum concentrations of 7 and 3 mM, respectively. Both supplemental
glucose and acetate stimulated the reduction of Fe(III) indicating that
fermentative, incomplete, and complete oxidizers were involved in Fe(II)
formation in the acidic fen. Amplification of DNA yielded PCR products
specific for Acidiphilium-, Geobacter-, and Geothrix-,
but not for Shewanella- or Anaeroromyxobacter-related sequences. Porewater
biogeochemistry observed during a 3-year-period suggests that increased
drought periods and subsequent intensive rainfalls due to global climate
change will further favor Fe(III) and sulfate as alternative electron
acceptors due to the storage and enhanced re-oxidation of their reduced
compounds in the soil. |
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