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| Titel |
Sediment-water column fluxes of carbon, oxygen and nutrients in Bedford Basin, Nova Scotia, inferred from 224Ra measurements |
| VerfasserIn |
W. J. Burt, H. Thomas, K. Fennel, E. Horne |
| 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 ; 10, no. 1 ; Nr. 10, no. 1 (2013-01-08), S.53-66 |
| Datensatznummer |
250017458
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| Publikation (Nr.) |
 copernicus.org/bg-10-53-2013.pdf |
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| Zusammenfassung |
| Exchanges between sediment pore waters and the overlying water column play a
significant role in the chemical budgets of many important chemical
constituents. Direct quantification of such benthic fluxes requires explicit
knowledge of the sediment properties and biogeochemistry. Alternatively,
changes in water-column properties near the sediment-water interface can be
exploited to gain insight into the sediment biogeochemistry and benthic
fluxes. Here, we apply a 1-D diffusive mixing model to near-bottom
water-column profiles of 224Ra activity in order to yield vertical eddy
diffusivities (KZ), based upon which we assess the diffusive exchange
of dissolved inorganic carbon (DIC), nutrients and oxygen (O2), across
the sediment-water interface in a coastal inlet, Bedford Basin, Nova Scotia,
Canada. Numerical model results are consistent with the assumptions
regarding a constant, single benthic source of 224Ra, the lack of
mixing by advective processes, and a predominantly benthic source and sink
of DIC and O2, respectively, with minimal water-column respiration in
the deep waters of Bedford Basin. Near-bottom observations of DIC, O2
and nutrients provide flux ratios similar to Redfield values, suggesting
that benthic respiration of primarily marine organic matter is the dominant
driver. Furthermore, a relative deficit of nitrate in the observed flux
ratios indicates that denitrification also plays a role in the oxidation of
organic matter, although its occurrence was not strong enough to allow us to
detect the corresponding AT fluxes out of the sediment. Finally,
comparison with other carbon sources reveal the observed benthic DIC release
as a significant contributor to the Bedford Basin carbon system. |
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