Wetland restoration and methanogenesis: the activity of microbial populations and competition for substrates at different temperatures
Ljubljana marsh in Slovenia is a 16 000 ha area of partly drained fen, intended to be flooded to restore its ecological functions. The resultant water-logging may create anoxic conditions, eventually stimulating production and emission of methane, the most important greenhouse gas next to carbon dio...
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2009-06-01
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doaj-b141a66961bb4dd793f5bc3c7f63f0982020-11-24T23:34:43ZengCopernicus PublicationsBiogeosciences1726-41701726-41892009-06-016611271138Wetland restoration and methanogenesis: the activity of microbial populations and competition for substrates at different temperaturesV. JermanM. MetjeI. Mandić-MulecP. FrenzelLjubljana marsh in Slovenia is a 16 000 ha area of partly drained fen, intended to be flooded to restore its ecological functions. The resultant water-logging may create anoxic conditions, eventually stimulating production and emission of methane, the most important greenhouse gas next to carbon dioxide. We examined the upper layer (~30 cm) of Ljubljana marsh soil for microbial processes that would predominate in water-saturated conditions, focusing on the potential for iron reduction, carbon mineralization (CO<sub>2</sub> and CH<sub>4</sub> production), and methane emission. Methane emission from water-saturated microcosms was near minimum detectable levels even after extended periods of flooding (>5 months). Methane production in anoxic soil slurries started only after a lag period of 84 d at 15&deg;C and a minimum of 7 d at 37&deg;C, the optimum temperature for methanogenesis. This lag was inversely related to iron reduction, which suggested that iron reduction out-competed methanogenesis for electron donors, such as H<sub>2</sub> and acetate. Methane production was observed only in samples incubated at 14–38&deg;C. At the beginning of methanogenesis, acetoclastic methanogenesis dominated. In accordance with the preferred substrate, most (91%) <i>mcrA</i> (encoding the methyl coenzyme-M reductase, a key gene in methanogenesis) clone sequences could be affiliated to the acetoclastic genus <i>Methanosarcina</i>. No methanogens were detected in the original soil. However, a diverse community of iron-reducing <i>Geobacteraceae</i> was found. Our results suggest that methane emission can remain transient and low if water-table fluctuations allow re-oxidation of ferrous iron, sustaining iron reduction as the most important process in terminal carbon mineralization. http://www.biogeosciences.net/6/1127/2009/bg-6-1127-2009.pdf |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
V. Jerman M. Metje I. Mandić-Mulec P. Frenzel |
spellingShingle |
V. Jerman M. Metje I. Mandić-Mulec P. Frenzel Wetland restoration and methanogenesis: the activity of microbial populations and competition for substrates at different temperatures Biogeosciences |
author_facet |
V. Jerman M. Metje I. Mandić-Mulec P. Frenzel |
author_sort |
V. Jerman |
title |
Wetland restoration and methanogenesis: the activity of microbial populations and competition for substrates at different temperatures |
title_short |
Wetland restoration and methanogenesis: the activity of microbial populations and competition for substrates at different temperatures |
title_full |
Wetland restoration and methanogenesis: the activity of microbial populations and competition for substrates at different temperatures |
title_fullStr |
Wetland restoration and methanogenesis: the activity of microbial populations and competition for substrates at different temperatures |
title_full_unstemmed |
Wetland restoration and methanogenesis: the activity of microbial populations and competition for substrates at different temperatures |
title_sort |
wetland restoration and methanogenesis: the activity of microbial populations and competition for substrates at different temperatures |
publisher |
Copernicus Publications |
series |
Biogeosciences |
issn |
1726-4170 1726-4189 |
publishDate |
2009-06-01 |
description |
Ljubljana marsh in Slovenia is a 16 000 ha area of partly drained fen, intended to be flooded to restore its ecological functions. The resultant water-logging may create anoxic conditions, eventually stimulating production and emission of methane, the most important greenhouse gas next to carbon dioxide. We examined the upper layer (~30 cm) of Ljubljana marsh soil for microbial processes that would predominate in water-saturated conditions, focusing on the potential for iron reduction, carbon mineralization (CO<sub>2</sub> and CH<sub>4</sub> production), and methane emission. Methane emission from water-saturated microcosms was near minimum detectable levels even after extended periods of flooding (>5 months). Methane production in anoxic soil slurries started only after a lag period of 84 d at 15&deg;C and a minimum of 7 d at 37&deg;C, the optimum temperature for methanogenesis. This lag was inversely related to iron reduction, which suggested that iron reduction out-competed methanogenesis for electron donors, such as H<sub>2</sub> and acetate. Methane production was observed only in samples incubated at 14–38&deg;C. At the beginning of methanogenesis, acetoclastic methanogenesis dominated. In accordance with the preferred substrate, most (91%) <i>mcrA</i> (encoding the methyl coenzyme-M reductase, a key gene in methanogenesis) clone sequences could be affiliated to the acetoclastic genus <i>Methanosarcina</i>. No methanogens were detected in the original soil. However, a diverse community of iron-reducing <i>Geobacteraceae</i> was found. Our results suggest that methane emission can remain transient and low if water-table fluctuations allow re-oxidation of ferrous iron, sustaining iron reduction as the most important process in terminal carbon mineralization. |
url |
http://www.biogeosciences.net/6/1127/2009/bg-6-1127-2009.pdf |
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