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| Titel |
Role of sediment denitrification in water column oxygen dynamics: comparison of the North American East and West Coasts |
| VerfasserIn |
L. Bianucci, K. Fennel, K. L. Denman |
| 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 ; 9, no. 7 ; Nr. 9, no. 7 (2012-07-24), S.2673-2682 |
| Datensatznummer |
250007192
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| Publikation (Nr.) |
 copernicus.org/bg-9-2673-2012.pdf |
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| Zusammenfassung |
| Low oxygen concentrations, either natural or anthropogenically driven, can
severely affect coastal marine ecosystems. A deeper understanding of oxygen
dynamics is required in order to improve numerical models, eventually to
predict the timing and severity of hypoxia. In this study we investigate the
effect of sediment denitrification on oxygen concentrations in bottom waters
over the continental shelf. We used two coupled physical-biological models
based on the Regional Ocean Modelling System (ROMS) to compare summer
simulations with and without denitrification within the sediments for two
North American shelves: the Middle Atlantic Bight (MAB) and the Vancouver
Island Shelf (VIS). These regions belong to western and eastern boundary
current systems, respectively, and are characterized by different physical
and biological dynamics. Both models assume coupled
nitrification-denitrification within the sediments. Denitrification
represents a loss of bioavailable nitrogen through the production of
dinitrogen gas, with the potential to affect biogeochemical cycles. In our
MAB model, this loss of regenerated nutrients through denitrification within
the sediments significantly affects primary production, since recycled
nitrogen supports most of the primary production in that region. The
diminished primary production and consequent decrease of organic matter flux
to the seafloor leads to less sediment oxygen consumption and higher oxygen
concentrations in bottom waters. However, changes in regenerated nitrogen on
the VIS barely affect primary production due to the efficient supply of new
nutrients through wind-driven upwelling during summer and the nutrient-rich
coastal current. We recommend that modelling experiments focusing on
oxygen dynamics (as well as oxygen budget calculations) should include
sediment denitrification in coastal regions where regenerated primary
production dominates productivity. |
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