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| Titel |
Linking terrestrial and aquatic organic carbon in boreal lake sediments |
| VerfasserIn |
Cristian Gudasz, Chiara Cerli, Sabine Fiedler, Karsten Kalbitz, Jan Karlsson, Yvonne Oelmann, Marc Ruppenthal |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250082890
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| Zusammenfassung |
| The coupling of terrestrial and aquatic carbon cycling has been well-recognized, but often
difficult to characterize. The quantification of the aquatic versus terrestrial organic carbon
(OC) sources plays an essential part in our understanding of the fate of the OC. Lake
sediments, and boreal lake sediments in particular are well-recognized sites for the
sequestration of OC, comparable to soils and living biomass. However, a clear picture about
the extent of the aquatic versus terrestrial OC sources in lake sediments is currently
lacking. Measurements of the non-exchangeable δ2Hn of the organic matter have
become increasingly used to trace OC sources. Difficulties in measuring δ2Hn in
bulk sediments, largely due to mineral matrix interference, are still hampering the
implementation of this approach. Moreover, the separation of the terrestrial versus aquatic
end members is not well established. We sampled surface sediment layers from
15 lakes, from the alpine subarctic and across the boreal forest zone, spanning a
wide range, along the gradient of aquatic - terrestrial OC sources. The organic soil
layer, groundwater dissolved organic carbon (DOCG) as well as algae, were also
sampled and analyzed for δ2Hn as a measure of terrestrial and aquatic end members,
respectively. Moreover, the δ2Hn of soil water-extract (DOCS) was also used to assess the
contribution to the terrestrial end member. Soil, sediment and DOCS samples were
demineralized based on the implementation of a recently described method using
a stepwise hydrofluoric - hydrochloric acid treatment, and in combination with
solid-phase extraction of solubilized OC, to achieve high OC recovery. All samples
were water-steam equilibrated prior to measurement of δ2Hn. We show that the
removal of the mineral matrix implemented here opens new insights not possible
before. We discuss the use of δ2Hn in tracing the contribution of terrestrial versus
aquatic OC sources as a new tool in linking terrestrial and aquatic carbon cycling. |
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