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| Titel |
Anaerobic oxidation of methane in sediments of two boreal lakes |
| VerfasserIn |
Antti J. Rissanen, Anu Karvinen, Hannu Nykänen, Promise Mpamah, Sari Peura, Marja Tiirola, Paula Kankaala |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250089266
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| Publikation (Nr.) |
 EGU/EGU2014-3462.pdf |
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| Zusammenfassung |
| Anaerobic oxidation of methane (AOM) is a considerable sink for methane (CH4) in marine
systems, but very little is known about the occurrence and importance of the process in
freshwater systems. In addition, much about the microbial communities involved in AOM is
unclear. AOM coupled with sulfate reduction is the dominant AOM process in marine
systems but the scarce existing data suggest that, in freshwater systems, AOM coupled with
reduction of alternative electron acceptors (nitrate/nitrite, manganese, iron) is more
important. In this study, potential for AOM coupled with metal reduction was studied in
boreal lake sediments.
Slurries of sediment samples collected from two sites in southeastern Finland, i.e. from
Lake Orivesi, Heposelkä, an vegetated littoral site, dominated by Phragmites australis
(Sample Sa, sediment layer 0 – 25 cm) and from the profundal zone of a mesotrophic Lake
Ätäskö (Aa, 0 – 10 cm; Ab, 10 – 30 cm; Ac, 90 - 130 cm), were incubated in laboratory
in anaerobic conditions at in situ temperatures for up to 5 months. The samples
were amended either 1) with 13CH4, 2) 13CH4 + manganese(II) oxide (MnO) or
3) 13CH4 + iron(III) hydroxide (Fe(OH)3), and the processes were measured by
following the 13C transfer to the carbon dioxide (CO2) pool and by concentration
measurements of CH4 and CO2. Changes in microbial communities were studied
from DNA extracted from sediment samples before and after incubation period by
next-generation sequencing (Ion Torrent) of polymerase chain reaction (PCR) - amplified
bacterial and archaeal 16S rRNA and methyl coenzyme-M reductase gene (mcrA)
amplicons.
Increase in 13C of CO2 gas confirmed that AOM took place in sediments of both study
lakes. In general, 13CO2 - production was significant both at the beginning (0 - 21 days) and
at the end (84 - 151 days) of incubation period. Potential AOM rates (calculated based on
13CO2 - production) varied considerably and were much lower in deep sediment (Sample
Ac), 0.1 - 0.2 nmol CH4 d-1gwetsediment-1, than in surface sediment samples (Samples Aa,
Ab and Sa), 0.2 – 12.3 nmol CH4 d-1gwetsediment-1. AOM took place without
metal additions in every sample type. Addition of MnO increased potential AOM
rates in surface sediment samples but not in deep sediment samples. Addition of
Fe(OH)3increased AOM significantly only in Aa samples. Molecular microbiological
analyses are currently in progress and the results will be shown in the poster presentation. |
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