Séminaire
Le devenir du carbone organique dissous terrestre dans l'Océan Arctique
Date
le 25-05-2011 à 10:45Lieu Salle Stendhal, DGO, Bâtiment B18
Intervenant(s) Céline GUEGUEN, Département de Chimie, Université de Trent, Canada |
Résumé
Though only about 1% of global ocean volume, the Arctic Ocean receives almost 10% of global river discharge. As a consequence, organic carbon transported by arctic rivers has the potential to strongly impact the chemistry and biology of the Arctic Ocean. The main objective of our project is to track colored dissolved organic matter (CDOM), the optically active fraction of organic matter, across the shelf-basin interfaces in western Arctic. CDOM profiles showed distinctive features well correlated with hydrographic characteristics. CDOM fluorescence was particularly high at depths between 40 and 200 m (up to 3 fluorescence units) in East Siberian Sea, Chukchi Sea and Beaufort Sea transects. Penetration of the high CDOM signal, formed on the shelves, into the Canada Basin was confined to the upper halocline layer (salinity of ~33.1). This layer had distinctive fingerprints in fluorescence spectra, showing a marked terrestrial humic signature. The presence of CDOM in the halocline layer likely resulted from two main processes: the brine rejection during sea ice formation and transport across the sediment-water interface during early diagenesis.