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| Titel |
Biogeochemical fluxes along the Storfjorden continental slope (Svalbard Islands, Arctic) impacted by dense shelf water cascading: one-year mooring deployment |
| VerfasserIn |
Oriol Veres, Anna Sanchez-Vidal, Antoni Calafat, Miquel Canals, Leonardo Langone, Serge Heussner, Xavier Durrieu de Madron, Antonio Pusceddu, Jürgen Mienert, Joan Grimalt |
| 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 |
250073957
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| Zusammenfassung |
| Biogeochemical fluxes have been monitored for one year off Storfjorden (Svalbard Islands,
Arctic Ocean) where dense, Brine-enriched Shelf Water (BSW) forms seasonally.
BSW is generated by strong winter cooling that enhances ice formation and brine
rejection forming dense water that sinks to the bottom of the fjord, flows over the outer
fjord sill and sinks towards Fram Strait. This process may entrain large amounts of
sediments, including organic carbon and other components, and may also alter seafloor
sediment geochemistry and affect the deep-sea ecosystem as observed in other
continental margins. The western continental margin of the Svalbard islands is also
influenced by the warm West Spitsbergen Current (WSC) that carries relatively
warm (6-8Ë C) and salty (35.1-35.3) Atlantic Water north into the Arctic Ocean.
Therefore, atmospheric and oceanographic forcings are expected to influence deep
biogeochemical fluxes. To investigate particle fluxes, including C export to the deep, and the
near-bottom current flow along the presumable pathway of cascading waters, 4 mooring
lines equipped with sediment traps, current meters, and temperature and salinity
recorders were deployed along the continental slope from July 2010 to July 2011 at
1000,1250,1500 and 2000 m of water depth. Seabed sediment sampling was also performed
to characterize the sediment and its geochemical properties along the path of BSW and
WSC.
While the mean total mass flux (TMF) between August and December 2010 was quite
low (0.25 to 0.5 g m-2 d-1), in February-March 2011 a marked increase was recorded at all
stations, with values up to 11.6 g m-2 d-1 at 1000 m, increasing at the near bottom and
decreasing northwestward along the slope. Particles were mainly lithogenic. After, TMF
decreases to values slightly higher than those recorded during the previous year (1.5 to 5.5 g
m-2 d-1). When mass fluxes peaked, water masses were warmer (-0.5Ë C to 1Ë C) and
more saline. Currents were maxima (up to 40 cm s-1), directed toward NW. All
findings converge to highlight that the mechanism of particle delivery was by laterally
advection of resuspended material from the seabed triggered by dense BSW cascading.
Because of the cold plume of cascading dense waters entrains and mixes with the
relatively warm intermediate Atlantic Water, it appears as a heat source for the bottom
ambient Norwegian Sea Deep Water, while is still driven by its salinity excess. |
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