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| Titel |
The impact of elevated CO2 concentrations on soil microbial community, soil organic matter storage and nutrient cycling at a natural CO2 vent in NW Bohemia |
| VerfasserIn |
Martin Nowak, Felix Beulig, Joe von Fischer, Jan Muhr, Kirsten Kuesel, Susan Trumbore |
| 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 |
250100079
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| Publikation (Nr.) |
 EGU/EGU2014-15962.pdf |
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| Zusammenfassung |
| Natural CO2 vents or “mofettes” are diffusive or advective exhalations of geogenic CO2 from
soils. These structures occur at several places worldwide and in most cases they are linked
to volcanic activity. Characteristic for mofette soils are high CO2 concentrations
of up to more than 90% as well as a lack of oxygen, low pH values and reducing
conditions.
Mofette soils usually are considered to be sites of carbon accumulation, which is not only
due to the absence of oxygen, but might also result from lower plant litter quality due to CO2
fertilization of CO2 influenced plants and reduced availability of N and P for the decomposer
community.
Furthermore, fermentation processes and the formation of reduced elements by anoxic
decomposition might fuel chemo-lithoautotrophic or mixotrophic microbial CO2 uptake, a
process which might have important ecological functions by closing internal element cycles,
formation of trace gasses as well as by re-cycling and storing of carbon. Several studies of
microbial community structure revealed a shift towards CO2 utilizing prokaryotes in moffete
soils compared to a reference site.
Here, we use combined stable and radiocarbon isotope data from mofette soils in NW
Bohemia to quantify the contribution of geogenic CO2 to soil organic carbon formation
within mofette soils, either resulting from plant litter or from microbial CO2 uptake. This is
possible because the geogenic CO2 has a distinct isotopic signature (δ13C = -2 o
Δ14C = -1000 ) that is very different from the isotopic signature of atmospheric
CO2. First results show that mofette soils have a high Corg content (20 to 40 %)
compared to a reference site (2 to 20 %) and soil organic matter is enriched in 13C as
well as depleted in 14C. This indicates that geogenic CO2 is re-fixed and stored as
SOM.
In order to quantify microbial contribution to CO2 fixation and SOM storage, microbial
CO2 uptake rates were determined by incubating mofette soils with 13CO2 labelled
gas.
The findings of this study can help to understand interactions of soil, microorganisms and
plants under elevated CO2 concentrations in these special soils. Further, they will help to
quantify the process of autotrophic uptake of CO2 in soils and its influence on subsurface C
cycling. |
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