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| Titel |
The linkage between methanotrophy and diazotrophy in boreal environments |
| VerfasserIn |
Marja Tiirola, Sanna Leppänen, Tuula Larmola, Eeva-Stiina Tuittila |
| 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 |
250092564
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| Publikation (Nr.) |
 EGU/EGU2014-6919.pdf |
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| Zusammenfassung |
| Many methanotrophic bacterial groups fix nitrogen in laboratory conditions. Furthermore,
nitrogen (N) is a limiting nutrient in many environments where methane concentrations are
highest. Despite these facts, methane-induced N fixation has previously been overlooked,
possibly due to methodological problems. To study the possible link between methanotrophy
and diazotrophy in terrestrial and aquatic habitats, we measured the co-occurrence of these
two processes in boreal forest, peatland and stream mosses using a stable isotope
labeling approach (15N2 and 13CH4 double labeling) and sequencing of the nifH gene
marker.
N fixation associated with forest mosses was dependent on the annual N deposition,
whereas methane stimulate N fixation neither in high (>3 kg N ha-1 yr-1) nor low
deposition areas, which was in accordance with the nifH gene sequencing showing that forest
mosses (Pleurozium schreberi and Hylocomium splendens) carried mainly cyanobacterial N
fixers. On the other extreme, in stream mosses (Fontinalis sp.) methane was actively
oxidized throughout the year, whereas N fixation showed seasonal fluctuation. The
co-occurrence of the two processes in single cell level was proven by co-localizing both N
and methane-carbonfixation with the secondary ion mass spectrometry (SIMS)
approach.
Methanotrophy and diazotrophy was also studied in peatlands of different primary
successional stages in the land-uplift coast of Bothnian Bay, in the Siikajoki chronosequence,
where N accumulation rates in peat profiles indicate significant N fixation. Based on
experimental evidence it was counted that methane-induced N fixation explained over
one-third of the new N input in the younger peatland successional stages, where the highest N
fixation rates and highest methane oxidation activities co-occurred in the water-submerged
Sphagnum moss vegetation. The linkage between methanotrophic carbon cycling and N
fixation may therefore constitute an important mechanism in the rapid accumulation of N
during the primary succession of peatlands. It is still an open issue whether methanotrophy
induces N fixation directly or by enhancing phototrophic or heterotrophic N fixation. |
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