Ventilation rates of the waters in the nansen basin of the arctic ocean derived from a multitracer approach

Tritium/3He-, "C- and helium/neon data from a station located in the central Nansen Basin of the Arctic Ocean are reported and discussed. It is demonstrated that 3l-Ie is a valuable tracer for studies of the upper water column and, together with tritium, 5He provides a rough time scale of the ventilation of these waters. The apparent tritiurn/3He age is about 7 years in the surface water and about 14 years in the lower part of the halocine. Water of Atlantic origin defined by a temperature maximum shows tritiuxn/3He ages between 7 and 9 years. This variation of ages indicates that the circulation of the individual water layers of the upper water column is largely decoupled and occurs on different time scales. Tritium/3He ages observed in the Arctic Intermediate Water suggest a ventilation on a time scale of 15 to 20 years (depth <1000 in). The mean age of the Eurasian Basin Bottom Water is estimated on the basis of "C data to approximately 200 to 250 years. There is no indication of noble gas fractionation due to sea ice formation below the surface layer. From analysis of the 3He background it appears that there is a small primordial 3He component in Eurasian Basin Bottom Water.