ARCTIC RIVER-RUNOFF - MEAN RESIDENCE TIME ON THE SHELVES AND IN THE HALOCLINE

The mean residence time of river-runoff on the shelves and in the halo cline of the Arctic Ocean is estimated from salinity and tracer data ( tritium, He-3 and the O-18/O-16 ratio). These estimates are derived fr om comparison of apparent tracer ages of the halocline waters using a combination of tracers that yield different information: (1) the triti um ''vintage'' age, which records the time that has passed since the r iver-runoff entered the shelf; and (2) the tritium/He-3 He age, which reflects the time since the shelf waters left the shelf. The differenc e between the ages determined by these two methods is about 3-6 years. Correction for the initial tritium/He-3 age of the shelf waters (abou t 0.5-1.5 years) yields a mean residence time of the river-runoff on t he shelves of the Siberian Seas of about 3.5 +/- 2 years.