Interaction of sea ice sediments and surface sea water in the Arctic Ocean: Evidence from excess 210Pb

[1] We measured the activities of 210 Pb, 226 Ra, 238 U and 137 Cs in a suite of ice-rafted sediments (IRS) from the Arctic Ocean in an attempt to assess the interaction of sea ice sediments and surface water. The concentrations of these nuclides were compared to those of the benthic sediments in the coastal and shelf regions of the Arctic Ocean, which are believed to be the major source region for the IRS. The concentration factors (CF = activity of a nuclide in IRS/ average activity in benthic sediments) are $1 and 4-92 for 137 Cs and 210 Pb, respectively. The CF values for 137 Cs are comparable to the values that can be obtained from the previously published data while we report the first set of high CF values of 210 Pb. A major portion of 210 Pb in some IRS samples is likely derived from surface waters and thus, the concentrations of 210 Pb combined with another particle-reactive radionuclide (such as 7 Be, 234 Th) in IRS might provide information on the residence time and transit time of sea ice-laden sediments.