We present 
14C and 39Ar data collected in the
Nansen, Amundsen and Makarov basins during two expeditions to the
central Arctic Ocean (RV Polarstern cruises ARK IV/3, 1987 and
ARK VIII/3, 1991). The data are used, together with published
14C values, to describe the distribution of
14C in all major basins of the Arctic Ocean (Nansen,
Amundsen, Makarov and Canada Basins), as well as the 39Ar distribution
in the the Nansen Basin and the deep waters of the Amundsen and Makarov
Basins. From the combined 14C and 39Ar
distributions, we derive information on the mean "isolation ages" of the
deep and bottom waters of the Arctic Ocean. The data point toward mean
ages of the bottom waters in the Eurasian Basin (Nansen and Amundsen
Basins) of ca. 250--300 yr. The deep waters of the Amundsen Basin
show slightly higher 3H concentrations than those in the Nansen Basin,
indicating the addition of a higher fraction of water that has been at
the sea surface during the past few decades. Correction for the bomb 14C
added to the deep waters along with bomb 3H yields isolation ages for
the bulk of the deep and bottom waters of the Amundsen Basin similar to
those estimated for the Nansen Basin. This finding agrees well with the
39Ar data. Deep and bottom waters in the Canadian Basin (Makarov and
Canada Basins) are very homogeneous, with an isolation age of ca. 450
yr. 14C and 39Ar data and a simple inverse model
treating the Canadian Basin Deep Water (CBDW) as one well-mixed
reservoir renewed by a mixture of Atlantic Water (29%), Eurasian Basin
Deep Water (69%) and brine-enriched shelf water (2%) yield a mean
residence time of CBDW of ca. 300 yr.
[Radiocarbon Volume 36, Number 3, 1994]