ORIGIN, DISTRIBUTION AND ACCUMULATION OF ORGANIC-CARBON IN THE SKAGERRAK

Organic carbon contents have been determined in grain-size fractions of sediments from the Skagerrak southern slope and basin. C(ORG) concentrations were generally inversely related to grain size. The > 63 mum fraction in surface sediments from deeper waters had higher contents attributable to agglutination of fine material by tube forming benthic organisms. Especially in the clay and fine silt fractions C(ORG) increased with increasing fraction content presumably as a result of higher ''grazing pressure'' on fine material in coarse sediments. A comparison of high resolution age (Pb-210), porosity and grain-size composition profiles indicates that deviations in the Pb-210 curves are due both to bioturbation and sedimentation events. Porosity profiles also show high regional variability on a small scale. When primary production, C(ORG) vertical fluxes and accumulation rates are compared an excess of organic carbon stored in Skagerrak sediments becomes apparent. Potential sources for this carbon such as river input, dumping or sea-floor erosion are examined.