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| Titel |
Belowground in situ redox dynamics and methanogenesis recovery in a degraded fen during dry-wet cycles and flooding |
| VerfasserIn |
C. Estop-Aragonés, K.-H. Knorr, C. Blodau |
| 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 ; 10, no. 1 ; Nr. 10, no. 1 (2013-01-24), S.421-436 |
| Datensatznummer |
250017480
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| Publikation (Nr.) |
 copernicus.org/bg-10-421-2013.pdf |
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| Zusammenfassung |
| Climate change induced drying and flooding may alter the redox conditions of
organic matter decomposition in peat soils. The seasonal and intermittent
changes in pore water solutes (NO3−, Fe2+, SO42−,
H2S, acetate) and dissolved soil gases (CO2, O2, CH4,
H2) under natural water table fluctuations were compared to the
response under a reinforced drying and flooding in fen peats. Oxygen
penetration during dryings led to CO2 and CH4 degassing and to a
regeneration of dissolved electron acceptors (NO3−, Fe3+ and
SO42−). Drying intensity controlled the extent of the electron
acceptor regeneration. Iron was rapidly reduced and sulfate pools
~ 1 mM depleted upon rewetting and CH4 did not
substantially accumulate until sulfate levels declined to ~ 100 μmol L−1. The post-rewetting recovery of soil methane
concentrations to levels ~ 80 μmol L−1 needed
40–50 days after natural drought. This recovery was prolonged after
experimentally reinforced drought. A greater regeneration of electron
acceptors during drying was not related to prolonged methanogenesis
suppression after rewetting. Peat compaction, solid phase content of
reactive iron and total reduced inorganic sulfur and organic matter content
controlled oxygen penetration, the regeneration of electron acceptors and
the recovery of CH4 production, respectively. Methane production was
maintained despite moderate water table decline of 20 cm in denser peats.
Flooding led to accumulation of acetate and H2, promoted CH4
production and strengthened the co-occurrence of iron and sulfate reduction
and methanogenesis. Mass balances during drying and flooding indicated that
an important fraction of the electron flow must have been used for the
generation and consumption of electron acceptors in the solid phase or other
mechanisms. In contrast to flooding, dry-wet cycles negatively affect
methane production on a seasonal scale, but this impact might strongly depend
on drying intensity and on the peat matrix, of which structure and physical
properties influence moisture content. |
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