RECENT SEDIMENT ACCUMULATION, ORGANIC-CARBON BURIAL AND TRANSPORT IN THE NORTHEASTERN NORTH-SEA

Organic carbon and nitrogen and sedimentation rate determinations were made of boxcores from the Norwegian Channel, North Sea. The geographi cal distribution of recent sedimentation areas were defined by analysi s of published data and 3.5 kHz penetrating echo sounder data. The ann ual dry bulk sediment accumulation in the northeastern North Sea is es tablished at 74 x 10(6) tons. As the average organic carbon content fo r the Norwegian Channel and Skagerrak/Kattegat sediments is 0.6 and 1. 8%, respectively, the organic carbon accumulation rate in the northeas tern North Sea could be calculated. The total organic carbon accumulat ion in the Norwegian Channel and Skagerrak/northern Kattegat is 0.17 x 10(6) tons . yr(-1) and 0.83 x 10(6) tons . yr(-1), respectively. Les s than 10% of this is accounted for by local primary production. This means that more than 90% of the organic carbon buried in the sediments of the northeastern North Sea must have been supplied from different sources. Terrigenous sources supply 20% of the organic carbon. The rem ainder is marine organic matter produced elsewhere in the North Sea, o r imported from the Atlantic Ocean, Norwegian Sea and the Baltic Sea. Storm wave and -current induced (near) bottom nepheloid layers are the main likely mechanism to transport fine grained sediments and associa ted organic matter from the North Sea plateau into the Kattegat, Skage rrak and Norwegian Channel.