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| Titel |
Revisiting the disappearance of terrestrial dissolved organic matter in the ocean: a δ13C study |
| VerfasserIn |
K. Lalonde, A. V. Vähätalo, Y. Gelinas |
| 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 (2014-07-15), S.3707-3719 |
| Datensatznummer |
250117512
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| Publikation (Nr.) |
 copernicus.org/bg-11-3707-2014.pdf |
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| Zusammenfassung |
| Organic carbon (OC) depleted in 13C is a widely used tracer for
terrestrial organic matter (OM) in aquatic systems. Photochemical reactions
can, however, change δ13C of dissolved organic carbon (DOC) when
chromophoric, aromatic-rich terrestrial OC is selectively mineralized. We
assessed the robustness of the δ13C signature of DOC
(δ13CDOC) as a tracer for terrestrial OM by estimating
its change during the photobleaching of chromophoric DOM (CDOM) from 10
large rivers. These rivers cumulatively account for approximately one-third of the
world's freshwater discharge to the global ocean. Photobleaching of CDOM by
simulated solar radiation was associated with the photochemical
mineralization of 16 to 43% of the DOC and, by preferentially removing
compounds depleted in 13C, caused a 1 to 2.9‰ enrichment in
δ13C in the residual DOC. Such solar-radiation-induced
photochemical isotopic shift could bias the calculations of terrestrial OM
discharge in coastal oceans towards the marine end-member. Shifts in
terrestrial δ13CDOC should be taken into account when
constraining the terrestrial end-member in global calculation of
terrestrially derived DOM in the world ocean. |
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