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| Titel |
Dissolved greenhouse gas concentrations as proxies for emissions: First results from a survey of 43 Alpine lakes |
| VerfasserIn |
Sylvie Pighini, Georg Wohlfahrt, Franco Miglietta |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250111683
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| Publikation (Nr.) |
 EGU/EGU2015-11824.pdf |
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| Zusammenfassung |
| Up to very recently, freshwater ecosystems were neglected in assessments of the global
carbon cycle and considered merely as passive ‘pipes’ which transport carbon from the land
to the oceans. This view has been challenged by an increasing number of studies showing that
freshwater ecosystems may negate a substantial fraction of the carbon sink through carbon
dioxide (CO2) and in particular methane (CH4) emissions and thus rather should
be viewed as ‘reactors’ which process a large fraction of the terrigenous carbon.
Most of our knowledge on freshwater CO2 and CH4 emissions to date derives from
studies in tropical and boreal regions, while temperate freshwater ecosystems are
understudied.
This study is focused on lakes from the Alpine area and their content in dissolved greenhouse
gases, CH4 and CO2. We mostly aim to assess the content of dissolved methane and carbon
dioxide from the Alpine lakes in order to understand whether Alpine lakes could be potential
CH4 and CO2 emitters. We also would like to relate concentrations to lake characteristics and
potential biotic and abiotic driving forces.
A diverse set of 43 lakes, from Trentino, South Tirol (Italy) and North Tirol (Austria), was
selected resulting in a gradient with respect to elevation (from 240 to 1700 m a.s.l.) and
latitude (from 45.52° to 47.38°). Complementary to dissolved CH4 and CO2 surface water
samples, dissolved oxygen and temperature were measured. Only water surface samples were
considered. Analyses were done with a gas chromatographer equipped with a flame
ionization detector (FID) for CH4 and a thermal conductivity detector (TCD) for CO2
determination.
The first results show that all the sampled lakes were super-saturated in dissolved methane
and carbon dioxide concentrations, at least partly to a degree that in the literature
has been shown to result in substantial emissions to the atmosphere. To estimate
emissions, CO2 and CH4 fluxes will be quantified using the eddy covariance and
floating chamber technique on a subset of the investigated lakes in a next step. Results
will indicate which parameters lead to greenhouse gases emissions in the Alpine
area. |
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