Ice rafting is the dominant mechanism responsible for the transport of
fine-grained sediments from coastal zones to the deep Arctic Basin. T
herefore, the drift of ice-rafted debris (IRD) could be a significant
transport mechanism from the shelf to the deep basin for radionuclides
originating from nuclear fuel cycle activities and released to coasta
l Arctic regions of the former Soviet Union. In this study, 28 samples
of IRD collected from the Arctic ice pack during expeditions in 1989-
95 were analyzed for Cs-137 by gamma spectrometry and for Pu-239 and P
u-240 by thermal ionization mass spectrometry. Cs-137 concentrations i
n the IRD ranged from less than 0.2 to 78 Bq . kg(-1) (dry weight basi
s). The two samples with the highest Cs-137 concentrations were collec
ted in the vicinity of Franz Josef Land, and their backward trajectori
es suggest origins in the Kara Sea. Among the lowest Cs-137 values are
seven measured on sediments entrained on the North American shelf in
1989 and 1995, and sampled on the shelf less than six months later. Co
ncentrations of Pu-239 + Pu-240 ranged from about 0.02 to 1.8 Bq . kg(
-1). The two highest values came from samples collected in the central
Canada Basin and near Spitsbergen; calculated backward trajectories s
uggest at least 14 years of circulation in the Canada Basin in the for
mer case, and an origin near Severnaya Zemlya (at the Kara Sea/Laptev
Sea boundary) in the latter case. While most of the IRD samples showed
Pu-240/Pu-239 ratios near the mean global fallout value of 0.185, fiv
e of the samples had lower ratios, in the 0.119 to 0.166 range, indica
tive of mixtures of Pu from fallout and from the reprocessing of weapo
ns-grade Pu. The backward trajectories of these five samples suggest o
rigins in the Kara Sea or near Severnaya Zemlya.