THE ROLE OF THE LARGE-SCALE ARCTIC-OCEAN CIRCULATION IN THE TRANSPORTOF CONTAMINANTS

The key features of the large-scale circulation of the Arctic Ocean ar e reviewed based on distributions of hydrographic parameters and natur al and anthropogenic trace substances. Salinity and mass balances, as well as a combination of the tracers tritium and delta(18)O, suggest a mean residence time of the shelf waters in the Siberian seas of about 3 years. Potential pathways of pollutants released to the Siberian sh elf seas from the dumpsites or from river runoff are inferred from the distributions of delta(18)O and salinity. Transit times needed for di ssolved contaminants to cross the central Arctic basins (several years to one or two decades in near-surface waters) and mean residence time s of contaminants in the intermediate (several decades) and deep water s (several centuries) are estimated from the distribution of transient tracers (tritium and its radioactive decay product, He-3) and ''stead y-state'' tracers (C-14 and Ar-39).