Freudenthal, T. University of Bremen, freuden@allgeo.uni-bremen.de
Neuer, S. University of Bremen, susanne@allgeo.uni-bremen.de
Wefer, G. University of Bremen, gwefer@allgeo.uni-bremen.de

 
NITROGEN ISOTOPES OF SINKING PARTICULATE MATTER ALONG A PRODUCTIVITY GRADIENT IN THE CANARY BASIN
 
The stable nitrogen isotope ratio of sinking particulate matter is affected by the fractionation during nitrate assimilation by phytoplankton. Thus the nitrogen isotope ratio can be used as tracer for nutrient utilization by phytoplankton. Here we present stable nitrogen isotope ratios of sinking particulate matter in the Canary Basin recorded by three sediment trap moorings along a productivity gradient from the Moroccan upwelling region to the oligotrophic gyre. At the mooring in the Eastern Boundary Current (EBC) high organic carbon fluxes and low nitrogen isotope ratios were observed during winter bloom conditions as well as during summer due to coastal upwelling. Nutrient depletion in late summer was documented by low organic carbon fluxes and higher nitrogen isotope ratios. The upper traps of two moorings north of Gran Canaria (ESTOC, 700 and 1000m) and La Palma (LP, 1000m) both showed typical oligotrophic sedimentation patterns: higher organic carbon fluxes during the winter bloom were accompanied by initially low nitrogen isotope ratios which increased during the bloom. Higher total fluxes at the 3000m traps at ESTOC and LP are indicative for an additional allochtonous particle source. Low nitrogen isotope ratios point to the upwelling region as possible source.
 
Day: Tuesday, Feb. 2
Time: Poster
Location: Sweeney Center
 
Code: SS32TU0675S