3He and chlorofluorocarbons (CFC) in the Southern Ocean

The distribution of 3He across the Southern Ocean is depicted on the basis of a meridional section between Antarctica and South Africa measured during the INDIGO-3 survey (1988). A core of δ3He values above 10% is observed south of the Polar Front, associated with very low CFC concentrations. This 3He enriched layer is documented from the GEOSECS and INDIGO 3He data in the Southern Ocean. It is found at a density level around θσ=27.8 in all the waters close to Antarctica (i.e. south of 50 degS). Its zonal distribution suggests that it is likely that it originates from the central/eastern Pacific. Hence, it provides an indication of the deep Pacific waters in the Antarctic Circumpolar Current, which are not easily detectable from the standard hydrographic parameters. (author). 19 refs.; 8 figs