CARBON-DIOXIDE CHARACTERISTICS OF WATER MASSES IN THE NORTHERN NORTH-ATLANTIC OCEAN

Accurate measurements of total dissolved carbon dioxide (TCO2) togethe r with other tracers (Theta, S, O-2, and nutrients) have been carried out during a hydrographic survey of a zonal section between Ireland an d Greenland and a number of sections in the Iceland Basin. The resulti ng data, with > 1300 TCO2 data points, have allowed the determination of the TCO2 signature of the water masses in the northern North Atlant ic Ocean in terms of seven water types. The structure of TCO2 and diss olved phosphate and nitrate appears to be well correlated with the app arent oxygen utilization. This indicates that ageing of the water type s, by mineralization of organic matter, is more important for the obse rved TCO2 structure than differences in the preformed TCO2 when the wa ter types were formed. The overturning of water in the ''oceanic conve yor belt'' will support meridional TCO2 transport. This transport was estimated at 0.16 . 10(6) mol s(-1) (-0.06 Gt a(-1) C) from the differ ences of TCO2 content between the northward flowing Surface and Sub-Po lar Mode water and the southward flowing deep Iceland-Scotland and Den mark Strait Overflow Waters.