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| Titel |
Old carbon contributes to aquatic emissions of carbon dioxide in the Amazon |
| VerfasserIn |
L. E. Vihermaa, S. Waldron, M. H. Garnett, J. Newton |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 13 ; Nr. 11, no. 13 (2014-07-04), S.3635-3645 |
| Datensatznummer |
250117507
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| Publikation (Nr.) |
 copernicus.org/bg-11-3635-2014.pdf |
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| Zusammenfassung |
| Knowing the rate at which carbon is cycled is crucial to understanding the
dynamics of carbon transfer pathways. Recent technical developments now
support measurement of the 14C age of evaded CO2 from fluvial
systems, which provides an important "fingerprint" of the source of C. Here
we report the first direct measurements of the 14C age of effluxed
CO2 from two small streams and two rivers within the western Amazonian
Basin. The rate of degassing and hydrochemical controls on degassing are also
considered. We observe that CO2 efflux from all systems except for the
seasonal small stream was 14C-depleted relative to the contemporary
atmosphere, indicating a contribution from "old" carbon fixed before
~ 1955 AD. Further, "old" CO2 was effluxed from the perennial
stream in the rainforest; this was unexpected as here connectivity with the
contemporary C cycle is likely greatest. The effluxed gas represents all
sources of CO2 in the aquatic system and thus we used end-member
analysis to identify the relative inputs of fossil, modern and
intermediately aged C. The most likely solutions indicated a contribution
from fossil carbon sources of between 3 and 9% which we interpret as
being derived from carbonate weathering. This is significant as the currently
observed intensification of weather has the potential to increase the future
release of old carbon, which can be subsequently degassed to the atmosphere,
and so renders older, slower C cycles faster. Thus 14C fingerprinting of
evaded CO2 provides understanding which is essential to more accurately model the
carbon cycle in the Amazon Basin. |
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