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| Titel |
Seasonal variation in methane consumption and in the diversity of methanotrophs in the littoral zone of a boreal lake |
| VerfasserIn |
H. Siljanen, A. Saari, L. Bodrossy, P. J. Martikainen |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250030078
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| Zusammenfassung |
| The atmospheric concentration of methane (CH4) has increased by approximately
150% since pre-industrial times because of increased CH4 emissions and decreased
CH4consumption. Methane oxidizing bacteria, methanotrophs, consume CH4 for their carbon
and energy needs and thus play a significant role in reducing CH4 emissions and decelerating
global warming. In wetlands, for example, methanotrophs can consume as much as 90% of
the CH4 produced.
In freshwater lakes, even 70% of the total release of CH4 from the lakes can originate
from the littoral wetland. Globally, wetlands are responsible for 44% of methane emissions.
In boreal region, where lakes are abundant in landscape, it is important to understand how
different seasons affect CH4 oxidation activity and are there changes in the diversity
of methanotrophs over seasons? This study belongs to the research consortium
METHECO (Eurodiversity programme of European Science Foundation), where the
activity and diversity of methane oxidising bacteria are studied in various European
ecosystems.
The activity and diversity of methanotrophs were studied in a littoral wetland of the
shallow hyper-eutrophic Lake Kevätön in east-central Finland. The study area has
a gradient with moisture and vegetation. Sediment sampling for CH4 oxidation
activity and diversity studies of methanotrophs were performed over four seasons:
autumn, winter, spring and summer. Samples were taken from three sampling points
with different distance from the shoreline (2m; 8m; 17m) and sediment cores were
separated to layers 0-2cm, 2-10cm, 10-20cm and 20-30cm. Methane oxidation
potential was analyzed with flask experiments and diversity of methanotrophs with
pmoA-microarray.
Methane was oxidized in all seasons. In the wettest area (nearest to the shoreline) the
highest activity occurred in autumn, while in drier areas CH4 oxidation was most active in
spring time. In winter time the activity of methanotrophs was not significantly decreased.
Methane oxidation activity was always the highest in the organic surface layer (0-10
cm) and the activity decreased with depth. According to the first pmoA-microarray
results, methanotroph community structure is significantly changing over seasons. |
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